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Clean in Place – A Review of Current

Technology and its Use in the Food and

Beverage Industry

October 2005

Report for general circulation

Clean in Place – A Review of Current Technology and its Use in the Food and Beverage Industry

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Deakin Project Team Dr Laurence Palmowski A/Prof K. (Bas) Baskaran Dr Heidi Wilson Mr Brett Watson

October 2005 Project Contact Details Dr Laurence Palmowski School of Engineering and Technology Deakin University Geelong, VIC, 3217 Tel (03) 5227 2443 Fax (03) 5227 2167 Email: [email protected] Disclaimer This publication may be of assistance to you, but Deakin University and their employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes, and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.


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1 EXECUTIVE SUMMARY

The need to recycle water is becoming increasingly important. One of the main factors limiting the potential for water recycling is the high level of Total Dissolved Solids (TDS) found in treated water. Melbourne Water and City West Water, in their salinity reduction strategy for the Western Treatment Plant, have set a target of reducing TDS in treated water by 40% by 2009. Identified options to reduce TDS level in recycled water include end-of-pipe desalination technologies, segregation of salty streams at source, and TDS reduction and substitution at source. Following the waste hierarchy, TDS reduction and substitution at the source appear to be the best approaches as they avoid costly desalination technologies and the difficult handling of the segregated by-products.

The food and beverage industries are among the main contributors of TDS loads to the sewer. A large source of TDS, and particularly sodium, in these factories is the cleaning chemicals used to maintain high hygienic and quality levels in the factories. Conventional cleaning agents used in the food and beverage industry are usually based on sodium hydroxide, and/or require strong acids or bases for neutralization. This results in high dissolved solids levels, especially sodium levels, being discharged in effluent streams from factories. Therefore, to reduce TDS loads discharged to the sewer it is necessary to review current industrial cleaning practices.

The aim of this project was two-fold. The first aim was to identify cleaning chemicals that have the potential to replace traditional chemicals used in the food and beverage industry and that can reduce TDS in effluent discharged to the sewer. The second aim was to identify technologies that can be used to collect, treat and reuse cleaning solutions for subsequent cleaning cycles. This could lead to significant reduction in cleaning chemical usage.

The tasks of the project were as follows:

Conduct a critical desk-top review of CIP cleaning agents containing reduced levels of sodium or no sodium.

Undertake a desk-top review of CIP chemical recovery technologies via the trade and scientific literature.

There is a wide variety of cleaning agents currently available that could provide an alternative to sodium hydroxide. The alternative cleaning agents include built cleaning solutions (contain additives), low sodium alkaline cleaners, potassium hydroxide (KOH) based products, NaOH/KOH blends, biotechnology based

Intro-duction

Project aims

Alterna-tive cleaning chemicals


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cleaners and further alternatives including plant based products. Alternatives to conventional acid cleaners were also identified.

From this review, it was found that the use of built cleaning solutions can reduce cleaning times and/or cleaning chemical concentrations. The use of alkaline cleaners with medium and low sodium concentrations can lead to reductions in sodium discharge from CIP in the range of 78-99%. Even further reductions in sodium levels can be achieved by using KOH based products which do not contain sodium at all (almost 100% reduction in sodium discharge from CIP). However, the cost of KOH based cleaning agents is higher than that of NaOH, which is currently limiting its wide spread application in processing plants.

Enzyme based cleaners have been shown to be very effective for cleaning purposes in the food and beverage industries. However, the application of enzymes is mainly restricted to cleaning membranes due to their operating temperature. Further alternatives to alkaline cleaning agents, including plant-based products were found to be rarely used in large scale applications. In addition, there is little information available on these chemicals.

Alternative acid cleaners, which are mainly based on citric acid, have been shown to be effective for cleaning purposes but they have yet to become widely used in the food and beverage industries.

A number of different CIP systems are currently used in the food and beverage industries and can be categorised as follows: single use system, reuse system and multi-use system. A number of benefits and limitations are associated with each type of system. Reuse systems collect and reuse used CIP solutions for subsequent CIP cycles. As a result, reuse systems have lower running costs due to lower chemical requirements. However, they require trained operator and a centralised CIP infrastructure. Due to their simplicity, single use systems may be favoured over reuse and multi-use systems for certain applications. However, there will be situations where reuse and multi-use systems will be the better option. A table summarising the advantages and disadvantages of each system was produced to provide guidance for selecting the most appropriate technology for a specific application.

While reuse systems increase the life of CIP cleaning solutions, leading to cost and environmental benefits, the use of recovery technologies can further extend the life of CIP solutions. By removing organic and inorganic contaminants from cleaning solutions, recovery technologies such as centrifugation or membrane separation can reduce chemical usage by up to 97%.

Reuse and recovery of cleaning solutions


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Several optimisation methods can be implemented to help minimise the consumption of cleaning chemicals, thereby reducing the TDS load of the effluent. Some of these methods are the review of cleaning frequency, the use of mechanical action (pigging systems, high pressure sprayers and floor scrubbers) and CIP monitoring. Increased intervals between cleaning cycles have been found to have little or no negative impact on product quality and hygienic requirements in certain applications. Pigging systems are effective at removing product from pipes prior to chemical cleaning while high pressure spray and mechanical floor scrubbers can enhance the removal of biofilms from equipment. CIP monitoring systems can be used to fine-tune and optimise the cleaning operations of factories.

Further work is recommended including laboratory evaluation of alternative cleaning chemicals, followed by factory trials. Pilot-scale trials of reuse and recovery systems in factories are suggested. Of high priority is also the training on CIP practices and optimisation as well as the transfer of technology and knowledge to industry.

Re-commen-dations

CIP optimisation


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2 TABLE OF CONTENT

1 EXECUTIVE SUMMARY................................................................................ 2

2 TABLE OF CONTENT ................................................................................... 5

3 ACRONYMS ................................................................................................. 7

4 INTRODUCTION ........................................................................................ 10 4.1 CLEANING AND CIP......................................................................................... 10

4.1.1 Key factors for cleaning .....................................................................................................10 4.1.2 The benefits of CIP vs. manual cleaning ............................................................................12 4.1.3 Typical CIP cycle................................................................................................................13

4.2 AIM AND OBJECTIVES ..................................................................................... 13 4.2.1 Background.........................................................................................................................13 4.2.2 Aim and Objectives.............................................................................................................14 4.2.3 Scope of the project ............................................................................................................15

5 IDENTIFICATION OF REDUCED SODIUM AND NON-SODIUM CLEANERS..... 15 5.1 INTRODUCTION............................................................................................... 15 5.2 BUILT NAOH OR BUILT KOH............................................................................ 16 5.3 ALKALINE CLEANERS WITH MEDIUM OR LOW SODIUM CONCENTRATIONS ................... 16 5.4 POTASSIUM HYDROXIDE (KOH) BASED PRODUCTS................................................ 17 5.5 SODIUM AND POTASSIUM BLENDS ...................................................................... 18 5.6 ENHANCED CLEANING CHEMICALS ..................................................................... 19 5.7 BIOTECHNOLOGY CLEANING AGENTS .................................................................. 20

5.7.1 Enzyme-based cleaners.......................................................................................................20 5.7.2 Bacteria-based cleaners .....................................................................................................26

5.8 ALTERNATIVES TO ALKALINE CLEANING AGENTS INCLUDING PLANT-BASED CLEANERS.. 27 5.9 ALTERNATIVE ACID CLEANERS........................................................................... 29 5.10 ALTERNATIVE SANITISERS ............................................................................. 29

5.10.1 Alternative chemical sanitisers...........................................................................................30 5.10.2 Non-chemical sanitisers .....................................................................................................31 5.10.3 Combined acid detergent + sanitiser .................................................................................33

5.11 COMPARISON OF CLEANING CHEMICALS........................................................... 33 5.11.1 Comparison on cleaning performance ...............................................................................33 5.11.2 Comparison of cleaning efficiency for membrane cleaning ...............................................34 5.11.3 Comparison of cleaning efficiency for biofilm removal......................................................36 5.11.4 Comparison of cleaning chemicals through life cycle assessment .....................................36

5.12 DESK-TOP REVIEW OF THE IMPACT OF IMPLEMENTATION OF ALTERNATIVE CHEMICALS 37

5.12.1 Residue risk, OH&S and corrosion issues..........................................................................37 5.12.2 Sodium discharge reduction ...............................................................................................38

6 REVIEW OF CIP RECOVERY TECHNOLOGIES ............................................ 40 6.1 INTRODUCTION............................................................................................... 40 6.2 SINGLE USE SYSTEMS...................................................................................... 41 6.3 MULTI-USE SYSTEMS....................................................................................... 42

6.3.1 Benefits of multi-use systems ..............................................................................................42 6.3.2 Case studies ........................................................................................................................43

6.4 CIP REUSE SYSTEMS ...................................................................................... 44 6.4.1 General remarks .................................................................................................................44 6.4.2 Straight reuse vs. treatments...............................................................................................45 6.4.3 Reuse after gravity separation............................................................................................45 6.4.4 Reuse following physicochemical treatments .....................................................................48 6.4.5 Reuse following membrane separation...............................................................................49

6.5 REVIEW OF POSSIBLE IMPLEMENTATION OF CIP RECOVERY TECHNOLOGIES .............. 57


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6.5.1 Single use vs. reuse systems................................................................................................57 6.5.2 Selection summary of reuse treatment technologies ...........................................................58

7 OPTIMISATION OF CLEANING TOWARDS REDUCED CHEMICAL USAGE..... 60 7.1 FREQUENCY OF CLEANING................................................................................ 61 7.2 MECHANICAL ACTION TO SUPPORT CLEANING....................................................... 62

7.2.1 High pressure spray and mechanical scrubber ..................................................................62 7.2.2 Pigging systems ..................................................................................................................62

7.3 CIP MONITORING ........................................................................................... 63 7.4 CASE STUDIES ............................................................................................... 63

8 RECOMMENDATIONS FOR FUTURE WORK ................................................ 64

9 ACKNOWLEDGMENTS ............................................................................... 66

10 REFERENCES......................................................................................... 67

APPENDICES

Appendix A - Summary and classification of alternative chemicals


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3 ACRONYMS

BSA Bovine Serum Albumin

CAPEX Capital Expenditure

CIP Cleaning-In-Place

COD Chemical Oxygen Demand

CSCCO Combined Simultaneous Caustic Cleaning and Oxidation

CTAB Cetyle-Trimethyl-Ammonium Bromide

CWW City West Water

DEH Department of the Environment and Heritage

EDTA Ethylene Diamine Tetra Acetic Acid

EO Electrolysed Oxidizing

EPA Environment Protection Authority

ETBPP Environmental Technology Best Practice Program

H3PO4 Phosphoric acid

HCl Hydrochloric acid

HNO3 Nitric acid

KMS Koch Membrane Systems

LCA Life Cycle Assessment

LPS Lactoperoxidase System

MF Microfiltration

NaOH Sodium hydroxide

NF Nanofiltration

NFESC Naval Facilities Engineering Service Center

OH&S Occupational Health and Safety

PLC Programmable Logic Controller

PPM Parts Per Million

PVC Poly Vinyl chloride

RO Reverse Osmosis

RWPC Reconstituted Whey Protein Concentrate

SDS Sodium Dodecyl Sulphate

SME Small and Medium Enterprise

SPC Standard Plate Count

SS Suspended Solids


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TAZ Terg-A-Zyme

TOC Total Organic Carbon

TDS Total Dissolved Solids

TVC Total Viable Count

UF Ultrafiltration

UK United Kingdom

UNEP United Nations Environment Programme

UV Ultraviolet

Glossary

Caustic or caustic soda Other name for sodium hydroxide

Diafiltration Water is added during the filtration process to reduce the concentration of a component in the retentate or permeate (Wagner 2001)

Fouling Product residues, scale and other unwanted deposits. Word used inter-changeably with “Soil”

Flux Flow rate through a membrane divided by membrane surface area

Membrane recovery Defined as the volume of permeate obtained per total volume of stream processed

Permeate Stream passing through a membrane

Recirculation In most CIP cycles, there is a step where cleaning solutions are recirculated, i.e. pumped in closed loop through the equipment until an acceptable cleaning level is reached

Recovery Collection of cleaning solutions followed by treatment and subsequent use in following cleaning cycles

Recycling In this report, this term is limited to the recycling of water

Retentate Stream not passing through a membrane


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Reuse Collection of cleaning solutions and subsequent use in following cleaning cycles

Soil Product residues, scale and other unwanted deposits (Romney 1990a)

Specific energy Energy required in a membrane process per volume of permeate obtained

Volume retention ratio (VRR) Volume of retentate over volume of solution treated

Symbols

Symbol for a case study

Symbol for a scientific research outcome


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4 INTRODUCTION

4.1 Cleaning and CIP

Trägårdh (1989) defined cleaning as “a process where material is relieved of a substance which is not an integral part of the material.” In the food and beverage industry, cleaning is an essential procedure in the operation of a factory to achieve the following objectives (Garrick and Schiekowski 1980; Dresch et al. 2001):

Maintain the high hygienic levels required;

Remove soil (or fouling) to restore process performance (heat transfer, pressure drops). Soil is defined as product residues, scale and other unwanted deposits (Romney 1990a);

Maintain product quality.

4.1.1 Key factors for cleaning

Cleaning is a combination of physical and chemical action, in which the following aspects play an important role (Australian Standards 2001):

Contact time. The contact time between the chemical and the soil is important and needs to cover the following phases:

o Diffusion of the cleaning chemical into the soil layer o Swelling of the soil o Mass transfer phase from the soil layer into the liquid o Transport away from the surface, flush

Temperature o Cold: below 30ºC o Warm: 30 - 50ºC o Hot: 50 - 80ºC o Very hot: above 80ºC

Temperature influences diffusion, mass transfer and fluid characteristics, the various parameters are thus inter-linked.

Turbulence and resulting shear forces acting on deposits

Type of soil (Romney 1990a; Prasad 2004c)

o Organic soil: mainly of plant or animal origin, depending on the industry. Organic soil is usually cleaned by alkaline detergents, amongst which sodium and potassium hydroxide are the most common.

o Inorganic soil: mainly of mineral origin. It is mostly cleaned by acidic detergents, including inorganic acids (e.g.


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phosphoric, nitric and hydrochloric acids) and to a smaller extent organic acids (e.g. hydroxyacetic and citric acid)

o Combined organic/inorganic soil, which is the most common type

o Biofilms, which develop on equipment if soils are not removed frequently enough. Biofilms can lead to hygiene issues as well as adverse technological effects (Kumar and Anand 1998)

Concentration and type of cleaning chemical

A wide variety of detergents are used in the food and beverage industry. They can be classified according to their functions and applications (Australian Standards 2001). Brief descriptions of the different detergents commonly used in the food and beverage industry are given below. The following section has been taken directly from Australian Standards (2001).

Multi-purpose detergents – Multi-purpose detergents are intended primarily for use in manual, pressure or foam cleaning of all types of surfaces, in all areas.

Heavy-duty alkaline detergents – Heavy-duty alkaline detergents are intended for the removal of proteins, fats and other strongly adherent organic soils from surfaces.

Enzyme-assisted detergents – Enzyme-assisted detergents are detergent formulations which contain enzymes, which are intended to break down and solubilize otherwise difficult-to-remove food soils using relatively mild detergents and cleaning conditions.

Acidic detergents – Acidic detergents are used to remove mineral soils and other soils resistant to neutral or alkaline detergents.

Oil-lift detergents – Oil-lift detergents are detergents, typically containing water soluble solvents and surfactants, intended for the removal of accumulated grease and oil from walls and floors.

Smokehouse detergents – Smokehouse detergents are designed primarily for the removal of fats and tar from walls, floors and equipment in smokehouses.

It is common practice to add additives to pure cleaning chemicals such as NaOH to improve specific attributes of the chemicals. The attributes that a detergent should ideally have are described in the following section, which has been taken directly from Romney (1990a).

Dispersing and suspending power – to bring insoluble soils into suspension and prevent their redeposition on cleaned surfaces.


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Emulsifying power – to hold oils within the cleaning solution.

Sequestering power – the ability to combine with calcium and magnesium salts to form water-soluble compounds and to aid detergency.

Wetting power – to reduce surface tension and thus aid soil penetration.

Rinsing power – the ability to rinse away clearly and completely without leaving any trace of soil or the detergent chemical on the cleaned surface.

In membrane cleaning for example, surfactants perform a wide range of roles: they help to wet surfaces, facilitate soil removal, suspend materials, stabilize foam, adsorb on surfaces to amend properties of the surface and act as biocide (D'Souza and Mawson 2005).

4.1.2 The benefits of CIP vs. manual cleaning

Over the last few decades, the use of Cleaning-In-Place (CIP) systems has brought more reliability in equipment cleaning. CIP is defined as “the cleaning of complete items of plant or pipeline circuits without dismantling or opening of the equipment and with little or no manual involvement on the part of the operator. The process involves jetting or spraying of surfaces or circulation of cleaning solutions through the plant under conditions of increased turbulence and flow velocity” (NDA Chemical Safety Code, 1985).

The use of CIP shows numerous advantages compared to manual cleaning, including improved cleaning efficiency, shorter cleaning cycles, improved Occupational Health and Safety (OH&S) and reduced environmental impact (DEH 2003).

As an example, Cascade Brewery applied, extended and automated the reticulation of cleaning solution throughout their brewery and beverage plants. As a result, a 60% reduction in cleaning agents was achieved in the brewery, while the reduction reached up to 80% in the cider section of the beverage plant (DEH 2003).

The introduction of CIP systems in a Small and Medium Enterprise (SME) can also show economic and environmental benefits. At Food Spectrum, which produces ingredients for the food manufacturing industry, it is estimated that 20% of cleaning water can be reused by introducing a $50,000 CIP system, with a pay-back period of 3 years (Prasad et al. 2004). It was also reported that the CIP system has the potential to increase water reuse to 50%, leading to increased water savings and reduced payback period (EPA 2003).


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4.1.3 Typical CIP cycle

A typical CIP cycle is presented in the sequence below (Romney 1990a; Australian Standards 2001). It is important to note that this cycle will differ from one site to another and from one process to another at the same site.

1. Product flush to remove product residuals. This is often carried out using water but is not a necessity

2. Pre-rinse to remove any loosely-adherent residuals (and micro-organisms attached to these residuals). This is usually performed with water (or slightly alkaline solution) and reduces the amount of soil, which the main cleaning step has to remove.

3. Main cleaning step to lift the soil from the equipment surface. The soiling compounds will be suspended or dissolved in the cleaning solution. This step, which is responsible for removing most of the soil and micro-organisms attached to surfaces, can be sub-divided into sub-steps to allow for various cleaning chemicals to be used. For example:

a. Caustic cleaning, followed by

b. Intermediate rinse, and

c. Acid cleaning step (when required)

4. Final rinse to remove residuals of cleaning solutions

5. Disinfection/sanitising step to reduce the number of micro-organisms from previously cleaned surfaces

6. Post-rinse might be necessary to remove residuals of sanitisers

Each food and beverage industry type has different CIP requirements. Furthermore, each area of a food and beverage factory can have different CIP requirements. For example, the CIP requirements differ in open systems (e.g. vessels) and in closed systems (e.g. pipes). The CIP performance in the former is easier to assess visually.

4.2 Aim and Objectives

4.2.1 Background

The need to recycle water in industry is becoming increasingly important. There is also a growing need to reduce sewer loadings to achieve a higher quality of trade waste discharges and of treated water. Total Dissolved Solids (TDS) levels in treated water have been identified as a key factor limiting water recycling due to their significant impact on soil productivity (DSE 2004). In the Western Melbourne metropolitan


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region, almost half of the TDS in treated water is produced by industry and commerce.

The government has shown its commitment to work with industry and water authorities to improve industrial water management. Urban water authorities are currently working with industrial and commercial customers and the Environment Protection Authority (EPA) to develop cleaner production programs and to reduce TDS discharges. In particular, Melbourne Water and City West Water in their salinity reduction strategy for the Western Treatment Plant have set a target of reducing the TDS content of recycled water by 40% by 2009 (DSE, 2004).

Identified options to reduce TDS content in recycled water include end-of-pipe desalination technologies, segregation of salty streams at source, and salt reduction and substitution at source. Following the waste hierarchy, salt reduction and substitution at the source appear to be the best approaches as they avoid costly desalination technologies and the difficult handling of the segregated by-products.

The food and beverage industry, which represents 22% of the total Victorian manufacturing turnover (ABS 2005), is a significant contributor to trade waste and TDS discharges. It is estimated that approximately 50% of the sodium found in trade waste from some of the food and beverage industries originates from CIP practices. The reason for this is that conventional cleaning agents used in CIP systems are usually based on sodium hydroxide, and/or require strong acids or bases for neutralization. This results in high dissolved solids levels, especially sodium levels, being discharged from factories in trade waste.

4.2.2 Aim and Objectives

The aim of this project was two-fold. The first objective was to identify CIP chemicals that have the potential to replace traditional CIP chemicals used in the food and beverage industry to reduce TDS in trade waste. The second aim is to identify the technologies that can be used to collect, treat and reuse cleaning chemicals for subsequent cleaning cycles.

The tasks of the project were as follows:

Conduct a critical desk-top review of CIP cleaning agents containing reduced levels of sodium or no sodium. To conduct this review, published literature, available case studies, and chemical suppliers have been consulted.

Undertake a desk-top review of CIP chemical recovery technologies via the trade and scientific literature. Technology suppliers have also been contacted for additional information.


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4.2.3 Scope of the project

The main focus of this report is on factories in the food and beverage sector, which are major contributors of TDS within the CWW boundary. Some information related to the utilisation of alternative chemicals and technologies has also been found from other industry sectors and has been included in the report.

All assessments have been made based on published literature, available case studies and information provided by suppliers of alternative chemicals and/or technologies. No experimental work was undertaken at this stage of the project.

5 IDENTIFICATION OF REDUCED SODIUM AND NON-SODIUM CLEANERS

5.1 Introduction

One of the main purposes of this project was to identify alternative CIP chemicals and processes to those currently used in the food and beverage industry with the intention of reducing TDS in effluent discharged to the sewer. Sodium hydroxide or caustic soda (NaOH) is the most widely used alkaline detergent in the food and beverage industry, due to its low price and high cleaning efficiency for fatty-type and protein soils. The most commonly used acidic detergents are nitric acid and phosphoric acid. These conventional cleaning chemicals contribute significantly to the TDS and sodium levels discharged by food and beverage industries. As a result of high TDS and sodium concentrations, the recycling of treated water is restricted to avoid any damage on soils and vegetation. Therefore, there is a clear need to identify alternative chemicals to reduce the use of traditional chemicals throughout the food and beverage industry.

The range of alternative cleaning chemicals can be classified as follows:

Built NaOH or built KOH. These chemicals contain additives which enhance the performance of the sodium and/or potassium hydroxide. As a result, lower salt/sodium concentrations can be used.

Low sodium alkaline cleaners

Potassium hydroxide (KOH) based products

NaOH/KOH blends

Biotechnology based cleaners, mainly consisting of enzyme-based cleaners

Alternatives to alkaline cleaning agents, including plant-based cleaners


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Alternative acid cleaners

Alternative sanitisers, including non-chemical based sanitisers

All these options, which offer a possible reduction in TDS and/or sodium in trade waste, are discussed in more detail below. Available case studies and literature references have been included. A complete list of all alternative chemicals can be found in Appendix A. It should be noted that some of the chemicals listed are currently not available in Australia and would need to be introduced if interest was shown.

Following this presentation of the alternative chemicals, a desk-top assessment of the possible reduction in sodium discharged to trade waste, as a result of the change over from traditional cleaning chemicals, is presented.

5.2 Built NaOH or built KOH

As discussed in the introduction to this report (section 4.1.1), additives (or builders) are often added to cleaning solutions to improve their properties and cleaning efficiency. Cleaning solutions containing additives are called “built” cleaning solutions. The use of built cleaning solutions can reduce cleaning times, rinse water consumption and/or cleaning chemical concentrations. This can therefore lead to improved trade waste discharges.

Typical additives include:

Dispersing and suspending agents

Emulsifiers and surfactants

Sequestrants

Wetting agents

Rinsing agents

As an example, sequestrants are widely used to remove hardness from water. Prasad (2004c) reported that “hard water can result in scale build-up, which affects the capacity of detergents and sanitisers to contact the surface and can lead to excessive scaling in boilers and cooling towers.” Therefore, hard water may need some treatment such as ion exchange or the use of detergents and sanitisers containing specially formulated additives (Prasad 2004c).

5.3 Alkaline cleaners with medium or low sodium concentrations

While the sodium concentration in chemical cleaners can reach 52% (pure or bulk caustic – see Appendix A for examples of these chemicals)), chemical manufacturers have developed products with lower sodium concentrations. Table 1 presents alkaline cleaners with medium sodium concentrations, while Table 2 shows alkaline cleaners


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with low sodium levels. The sodium concentration corresponds to the sodium concentration in the cleaning solution, after dilution. This has been calculated using the sodium content of the chemical and its range of recommended concentration. More details about these chemicals and their applications can be found in Appendix A.

Table 1: Alkaline cleaners with medium sodium concentration

Name Composition Na level in ready-to-use

cleaning solution [gNa/kg cleaning solution]

Chlorozolv

20% w/v as sodium hydroxide Active chlorine Stable chelating and dispersing agents Na content ≥ 11.5% 1.7 – 2.9

Suma Ilam L1.8

Sodium Hydroxide < 30% Sodium Hypochlorite < 4% available chlorine Na: 12.6% w/w Scale inhibitors 0.63 – 1.89

Table 2: Alkaline cleaners with low sodium concentration

Name Composition Na level in ready-to-use

cleaning solution [gNa/kg cleaning solution]

Diverwash VC24

Na: 1.8%w/w Wetting agents, buffering agents, sequestrants & dispersants 0.02 – 0.38

Flowsan

Sodium hydroxide 5-15% Sodium hypochlorite 5-15% Chlorine-based bleaching agents 5-15% Polycarboxylates <5% Na: 3.1% w/w 0.12 – 0.56

Glide

Alkaline Salts <20% Sodium Hypochlorite solution <3% Sodium Hydroxide <2% Na: 5%w/w 0.4 – 0.8

5.4 Potassium hydroxide (KOH) based products

The use of potassium hydroxide based cleaning agents is one of the approaches to reduce the sodium levels found in trade waste. However, the main limitation to use potassium hydroxide has been its price. Similarly to sodium hydroxide, potassium hydroxide is prepared by electrolysis of a brine solution. In the case of KOH, the brine solution consists of potassium chloride, which is not as ubiquitous as sodium chloride and needs to be extracted from mined resources. As a result, KOH is more expensive than NaOH. Additionally, different market drivers exist for sodium and potassium hydroxide, leading to different


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price fluctuations (Lech 2005). A list of potassium hydroxide based chemicals is presented in Table 3.

Table 3: Potassium based cleaning chemicals

Name Composition Industry sector

DairyChem (or Alka-San Potassium)

Potassium hydroxide >50% Surfactants <10% Chlorinated Agent <10% Sequestrant <20%

DairyChem HT 108 (or Dairy Alkali-Potassium Hydroxide Solution)

Potassium Hydroxide: 50% Sequestrants <5% Surfactants <5% Dairy industry

Divos 100

No sodium Caustic potash (Potassium hydroxide) Chelating agents & surfactants

Divos 110 No sodium Potassium Hydroxide <5%

Dairy industry Beverage applications Pharmaceutical applications

Solo

Potassium hydroxide 15-30% Tetrapotassium ethylenediaminetetraactetate 15-30% Diethylenetriaminepentaacetic acid (pentasodium salt) <5% EDTA 5-15% Anionic surfactants, phosphonates, non-ionic surfactants, phosphates <5%

Food industry Beverage industry Vegetable processing

Superquest

Potassium hydroxide ≥ 30% Tetrasodium ethylenediaminetetraacetate 5-15% EDTA 5-15% Phosphonates <5% Dairy industry

5.5 Sodium and potassium blends

To increase the price competitiveness of potassium hydroxide while partially maintaining his environmental benefits over pure sodium hydroxide, blends of potassium and sodium are available on the market from various suppliers. Table 4 presents some of these products, which are not a pure blend of NaOH and KOH but also incorporate some alternative products. As a result, their sodium content is relatively low.


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Table 4: Potassium and sodium blends


Detojet

Potassium hydroxide (7-13%) Sodium silicate (5-10%) Sodium hypochlorite (1.5%) Food industry

Profile

Potassium hydroxide <5% Sodium hypochlorite <5% Sodium hydroxide <5% Phosphates, chlorine-based bleaching agents <5% Na content: 5.2% w/w

Meat processing industry

Redes

Disodium/dipotassium metasilicate <5% Sodium hypochlorite <5% Phosphates 15-30% Chlorine-based bleaching agents <5% Na content: 4.4% w/w

Food and beverage industries

5.6 Enhanced cleaning chemicals

While additives can be added to cleaning solutions to improve their performance, the combined used of oxidation agents and cleaning chemicals has also been investigated.

The effectiveness of alkali cleaning combined with ozone pre-treatment was investigated for removing protein from equipment surfaces (Takehara et al. 2000). The authors used bovine serum albumin (BSA) as the model protein and particles of alumina (Al2O3), which is widely used as a ceramic membrane material. The Al2O3 particles were fouled with the BSA and then pre-treated using 0.3% (v/v) gaseous ozone. Takehara et al. (2000) found that the pre-treatment of the BSA-fouled Al2O3 particles markedly accelerated the removal of the BSA during alkali cleaning through partial decomposition of the BSA molecule. The authors concluded that ozone pre-treatment has the potential to reduce NaOH concentrations required for adequate alkali cleaning by at least one order of magnitude.

Gan et al. (1999) also developed and tested a combined simultaneous caustic cleaning and oxidation (CSCCO) process in a single stage cleaning operation. The cleaning solution used in the CSCCO process was comprised of NaOH and H2O2 at optimised levels of concentration. It was demonstrated that the CSCCO process had a greater cleaning power than the single-step caustic cleaning and the successive two-step process. In relation to this result, the authors stated that “the synergy achieved between caustic cleaning and oxidation has suggested that the combined chemicals provide a fast and effective cleaning process” (Gan et al. 1999).


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5.7 Biotechnology cleaning agents

Biotechnology based cleaning agents include bacteria-based agents and enzyme-based agents, the latter being far more widely used in industries. The main advantages and disadvantages of biotechnology based cleaning agents include (ETBPP 1998):

Advantages

Usually less harmful to the environment

Very specific cleaning action

Can be used at lower temperatures than conventional chemical

May be cheaper

Reduce effluent disposal costs as they produce an effluent with a lower COD

Non-corrosive

Disadvantages

May take longer to act than traditional chemical cleaners

ETBPP (1998) reported that a poultry processing company had extreme difficulty cleaning an area that was soiled with faeces, blood, urine, grease, fat and feathers, even with sodium hydroxide. They applied a biotechnology cleaning agent and found that all traces of organic mater were removed efficiently. There was a reduction in cleaning time as well as energy consumption because hot water was not required.

5.7.1 Enzyme-based cleaners

Enzyme-based cleaners in the food industry are becoming increasingly popular. There has been a resurgence of interest in enzymes because they offer a number of advantages over traditional caustic or acid cleaning regimes (D'Souza and Mawson 2005). One of the main factors responsible for the growing popularity of enzyme-based cleaners is new developments in enzymology (Kumar et al. 1998). Enzymes used for detergent production comprised 28% of the global market for industrial enzymes in 1994 (Kumar et al. 1998). A non-exhaustive list of enzyme based cleaning agents available on the market is presented in Table 5, while more details on these products can be found in Appendix A.


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Table 5: Enzyme based cleaning agents

Name Composition

Cipzyme P Contains proteolytic enzymes Divos 80-4 Enzyme cleaner

Paradigm

Protease cleaner 0.8% P2010 0.9% P2030

Properase 1600L Protease enzyme (liquid) Subtilisin (1-5%)

PURADAX EG 7000L Fungal cellulase enzyme (liquid) Cellulase (1-5%)

Purafect 4000E Protease enzyme (granulated) Subtilisin (1-5%)

Purastar ST 15000L Bacterial alpha-amylase enzyme (liquid) Amylase (1-5%)

Reflux E 2001

Enzyme cleaner NH compounds >60% Subtilsin (CAS 9014-01-1) <10%

Terg-a-zyme

Protease enzyme Sodium dodecylbenzenesulfonate (10-30%) Sodium carbonate (7-13%) Sodium phosphate (30-40%)

Zymex Enzymatic Cleaner

Enzymatic cleaning solution concentrate Aqueous mixture of enzymes and surfactants Isopropyl Alcohol (<10%) Triethanolamine (<10%)

A number of studies have been carried out in laboratories around the world comparing the cleaning abilities of enzyme-based cleaners against the cleaning abilities of conventional cleaning agents. However, most applications of enzyme-based cleaners in industry have mainly been reserved for the cleaning of membranes. This is due to the expense of purchasing large quantities of enzymes and formulating them into effective detergents (Trägårdh 1989). Therefore, a significant proportion of the following section is dedicated to the utilisation of enzyme-based cleaners for cleaning membranes.

5.7.1.1 Introduction to membrane cleaning

Trägårdh (1989) provided a comprehensive review of the state-of-the-art of membrane cleaning up till 1989. A number of important factors related to membrane fouling reduction and membrane cleaning were reviewed and discussed including flow conditions, pre-treatment, membrane properties, water quality, cleaning agents, and cleaning performance. D’Souza and Mawson (2005) presented a further comprehensive review of membrane cleaning in the dairy industry. They reviewed the key mechanisms governing cleaning performance.


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The characteristics of effective membrane cleaners can be summarised as follows (Trägårdh 1989; D'Souza and Mawson 2005):

ability to loosen and dissolve the fouling material, and keep the dislodged foulants in dispersion or solution to prevent the refouling of already cleaned surfaces

optimal active compound concentration, keeping the soil in dispersion and/or solution to avoid new fouling

good solubility and rinsing characteristics

low or moderate foam level

good compatibility with the membrane

good buffering capacity and stability with time

ability to promote disinfection of the wet surfaces

Trägårdh (1989) listed and briefly discussed the main cleaning agents and additives used to clean membrane plants. They are:

alkalis - hydroxides, carbonates and phosphates

acids - nitric and phosphoric

enzymes

surface-active agents - anionic, cationic and non-ionic

sequestering agents - ethylene diamine tetra acetic acid (EDTA)

formulated cleaning agents

combined cleaning and disinfecting agents

disinfectants - H2O2, metabisulphite, hypochlorite and heat treatment

Trägårdh (1989) also reported that “the choice of cleaning agents and cleaning conditions depends not only on the type of components deposited, but also on the chemical and thermal resistance of the membrane, the module and the rest of the equipment.”

Enzymatic cleaners are usually employed if the pH limitation of the membrane is at or below 10, or if a high level of soil is present. Enzymes offer a number of advantages over traditional caustic or acid cleaning regimes (D'Souza and Mawson 2005):

enzymes are biodegradable and cause fewer pollution problems

enzymes are less aggressive to the membranes and can therefore lengthen the lifespan of the membrane

rinsing volumes are reduced which in turn lower wastewater volumes

enzymatic agents can improve cleaning efficiency


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enzymes can reduce energy costs and the amount of chemical needed by working at a lower temperature

Leaver et al. (1995) conducted a study to test the effect that cleaning agents had on four coupling and four seal types. The cleaning solutions that the test pieces (coupling and seal) came into contact with were NaOH (1M) and Terg-A-Zyme (TAZ). Each test piece was filled with the cleaning agents and left for 24 hours at room temperature before being rinsed with tap water left to dry (Leaver et al. 1995). Pressure hold tests were then conducted to determine leak diameters. It was found that the couplings did not release liquid at the test conditions and that changes in leak diameters were relatively small. Leaver et al. (1995) reported that the largest increase in leak diameter was 9 µm when exposed to NaOH. It was acknowledged that the testing offered only a limited challenge to the seals and that further work was required to supplement these initial results (Leaver et al. 1995).

5.7.1.2 Case studies

Several milk processing plants have adopted alternative cleaning chemicals for CIP systems. Murray Goulburn used cold surface cleaners (enzymes in conjunction with mild detergents) to reduce caustic-based cleaners (Prasad, 2004c).

Dairy Farmers replaced phosphoric acid with nitric acid after it was found that equipment was not being cleaned properly. This initiative resulted in a superior clean and reduced phosphate load in the water used for irrigation.

Kumar et al. (1998) reported that the use of alkaline proteases from Bacillus sp. strain MK5-6 have proved successful in laboratory scale tests. They also conducted a pilot scale evaluation of the same enzyme preparation for UF membrane cleaning. It was found that the enzyme preparation resulted in 100% of the flux being restored whereas TAZ only achieved an 80% restoration of the flux.

Allie et al (2003) used lipases and proteases to clean flat-sheet polysulphone membranes fouled in abattoir effluent. The motivation for this study was to demonstrate that enzymatic cleaning regimes are effective at removing foulants adsorbed onto these membranes and also increasing flux recovery. The lipases used were Candida cylindracea, Pseudomonas mendocina and Aspergillus oryzea. The proteases used were Bacillus licheniformis, Protease A (protein engineered protease) and Aspergillus oryzea. When the Candida, Aspergillus and Pseudomonas lipases were used alone in the cleaning mixtures, the lipid content on the membranes were reduced by 33, 46 and 55% respectively. The highest lipid removal was obtained with the Pseudomonas lipase, while the lowest percentage lipid removal was obtained with the Candida lipase. A significantly greater lipid removal was observed after the membranes were cleaned with the lipases in conjunction with the


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proteases than when the lipases were used alone. The Pseudomonas lipase was found to reduce lipids by 70% when used in conjunction with proteases. Allie et al. (2003) stated that these results indicate enzyme-based cleaning regimes are useful for membranes operating on abattoir effluents (Allie et al. 2003).

Maartens et al. (1996) tested the ability of a number of enzymes for cleaning polysulphone membranes fouled with abattoir effluent. The purpose of the study was to determine whether the different enzyme and enzyme/detergent mixtures could restore pure-water flux when used to treat the fouled membranes. The enzymes evaluated were protease A, lipase A, Alkazyme, Zymex, sodium dodecyl sulphate (SDS) and Triton X100. Maartens et al. (1996) compared the ability of each cleaning agent to remove adsorbed protein and lipid material from the membranes. Increasing the concentration of protease A, lipase A and a mixture of lipase A and Triton X100 beyond 3 mg/mL did not lead to further decreases in protein removal. In fact, no significant increase in protein removal was observed for concentrations beyond 1mg/mL. However, for the removal of lipid material, the optimal concentration was found to be 3 mg/mL for each enzyme.

In terms of incubation time, maximum protein removal was achieved after 60 min for lipase A while protease A and the lipase A:Triton X100 mixture required an incubation time of 90 min to achieve maximum protein removal. Lipase A required an incubation time of 90 min to effectively remove lipids, whereas protease A and the lipase A:Triton X100 mixture only required an incubation time of 60 min to achieve maximum lipid removal. Maartens et al. (1996) concluded that enzymes can be used effectively as cleaning agents in biological effluent streams. However, they stipulated that the effluent and fouling agents must be well characterised and identified to ensure that the correct enzymes or enzyme/detergent mixtures are selected.

In another study, the performance of two proteolytic enzymes was evaluated for cleaning inorganic membranes fouled by whey protein solutions (Argüello et al. 2003). The two cleaning agents, Maxatase® XL and P3-Ultrasil® 62, adopted for this study were enzymatic formulations. Tami® 150 + 4T membranes were employed. Argüello et al. (2003) reported that very high efficiencies (~100%) were achieved in short operating times (20 min). It was also found that higher amounts of enzyme resulted in a slight decrease in cleaning efficiency. The authors also stated “the optimum values of the operating conditions tested were related to the best conditions to hydrolyze whey proteins in a discontinuous reactor using the same enzyme preparations.”

Also investigated in the study was the potential to reuse the enzyme solutions for consecutive cleaning steps. It was shown that the enzymatic solutions could be reused used for consecutive steps. However, it was observed that there was a 30% loss in enzymatic


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activity during each cleaning cycle, regardless of the initial activity of the solution (Argüello et al., 2003).

In a later study, the ability of P3-Ultrasil® 62 was tested for cleaning a Carboseo® M1 membrane (Argüello et al. 2005). As with the earlier study (Argüello et al., 2003), very high cleaning efficiencies (~100%) were reached in short operating times (20 min). It was reported that the cleaning efficiency depended on the operating conditions. A decrease in the pH of the cleaning solution during the cleaning process was attributed to protein hydrolysis. However, Argüello et al. (2005) reported that chemical cleanliness was not achieved because residual matter was detected on the membrane surface after cleaning. This phenomenon was observed even when the hydraulic cleaning efficiency was 100%.

Muñoz-Aguado et al. (1996) investigated the effects of enzyme and surfactants on a totally retentive polysulfone membrane fouled with bovine serum albumin (BSA) and a reconstituted whey protein concentrate (RWPC). The cleaning agents employed were CTAB (cetyl-trimethyl-ammonium bromide), TAZ and α-CT (α-chymotryspin). It was found that the cationic surfactant, CTAB, was more effective when the pH of the fouled membranes was 7 than when the pH of the fouled membranes was only 5. The authors reported that the cleaning efficiency of CTAB increased with temperature and surfactant concentration. They also investigated the impact that the cleaning time had on cleaning efficiency. The optimum cleaning time for CTAB was found to be 1 hour. A concentration of approximately 0.01 wt% achieved the maximum flux recovery and resistance removal for α-CT. Increasing the concentration actually led to a decrease in cleaning efficiency. They also showed that cleaning the fouled membranes with α-CT before CTAB resulted in an improvement of the cleaning efficiency.

The use of a water rinse was shown to be an effective method of removing loose foulant pieces at little additional cost. However, this can only be carried out at the same temperature as the chemical cleaning, otherwise the fouling layer will be compacted. Muñoz-Aguado et al. (1996) conclude that the main disadvantage of the multi-step cleaning process is the time taken to carry out the cleaning, while a major advantage is that the milder cleaning conditions result in lower cleaning costs and a longer membrane lifespan (Muñoz-Aguado et al. 1996).

Sakiyama et al. (1998) compared the performance of various proteases for the removal of proteinaceous deposits from stainless steel surfaces. The protease solutions were fed into a packed column of stainless steel particles fouled with β-lactoglobulin and gelatin. The proteases used in the study were crystalline trypsin, crystalline thermolysin, several crude powder protease preparations (Protin AC10, Protin PC10, Thermoase PC10 and Tunicase FN), and several thermostable alkaline proteases (B21-2, B18’ and KuAP). Sakiyama et al. (1998) found that the cleaning kinetics depended greatly on the kind


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of protease used as well as on the type of protein to be removed. They also found that regardless of the protease used, the cleaning kinetics increased with protease concentration and became constant above a certain protease concentration. It was also shown that a small amount of β-lactoglobulin was left on the stainless steel surface after 120 minutes of enzymatic cleaning, irrespective of the protease used. The results of this study indicate that the choice of an enzyme to remove fouling deposits is critical for establishing an efficient enzymatic cleaning procedure (Sakiyama et al. 1998).

Flint et al. (1999) conducted a pilot-scale trial to evaluate the effectiveness of Paradigm in removing biofilms of thermo-resistant S. thermophilus from a pasteuriser. Following cleaning with acid and caustic cleaners the reduction in the total number of bacteria was less than 10-fold. However, when Paradigm was used the total number of cells was reduced by approximately 100-fold. Flint et al. (1999) concluded that the use of a proteolytic enzyme-based cleaning system may be more effective than acid or alkali cleaning in removing biofilms of thermo-resistant streptococci from the surface of commercial manufacturing plants.

An ice-cream manufacturing plant in Asia uses enzymes to remove milk protein from cold milk surfaces (UNEP, 2004). “A secondary component of the cleaning product removes fats and minerals, resulting in a single-phase clean and allowing the acid phase of the cleaning to be eliminated” (UNEP, 2004). An acid sanitiser is used after the enzymatic clean.

It is evident from the literature that a considerable amount of research has been carried out to evaluate the effectiveness of enzyme-based cleaners for cleaning membranes. However, little work has been done to date on determining the applicability of enzyme-based cleaners for cleaning larger pieces of equipment in factories, particularly pipes and tanks. This is primarily due to the expense of the enzymes. Therefore, most of the research has been confined to laboratory scale experiments which are of little value at the plant scale. In terms of being used for the cleaning of membranes, enzymes have been shown to perform as effectively as traditional cleaning agents. Given the results reported in the literature, it would be expected that the utilisation of enzyme-based cleaning agents for cleaning membranes will increase significantly in the future.

5.7.2 Bacteria-based cleaners

Several case studies of companies adopting biotechnology cleaning systems to replace more conventional cleaning methods have been reported in the literature. It is important to point out that the companies are not within the food industry.


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Wyko EMS, an electrical engineering company that specialise in refurbishing electrical motors and components, utilise a biological cleaning agent that contains bacteria that digest the oil and grease left on electrical components. The alternative product was found to be just as effective as the solvent-based cleaner that was previously used but has environmental and financial benefits as well (BIO-WISE 2002).

BIO-WISE (2002) also reported that a company specialising in heat treatment and electron beam welding has managed to save almost £3,000 per year since it began using a biological system to remove manufacturing oils from parts instead of an alkaline solution.

An electroplating company also installed a biological cleaning system to replace the utilisation of an alkaline solution needed to clean metal parts prior to electroplating (BIO-WISE 2001a). This measure helped the company reduce the cost of purchasing chemicals, saved time and labour and eliminated production downtime.

Glacier Vandervell, a company that manufactures bearings and bushes for the motor industry, used a biological cleaning system to clean and remove oils from bushes instead of a highly caustic detergent solution. It was reported that the biological cleaning system had considerably lower annual running costs than the original cleaning process (BIO-WISE 2001b). Two important aspects are also mentioned. Firstly, it was found that a sludge containing a mixture of particulates and dead bacterial cells settled to the bottom of the control unit. However, only a small volume (3 litres) needed to be removed from the system every three to four weeks. Secondly, the bacteria in the cleaning solution were found to attack natural rubber seals. This problem was solved simply by using PVC or silicone rubber seals instead (BIO-WISE 2001b).

5.8 Alternatives to alkaline cleaning agents including plant-based cleaners

Alternative cleaning agents, such as plant-based cleaners, are used in some circumstances as replacements for traditional alkaline cleaners. Although some information was obtained from suppliers or through a comprehensive internet search, it was often incomplete. In addition, there were very few references in the scientific literature on alternatives to alkaline cleaning agents and only a handful of cases studies could be found. Table 6 presents examples of these alternative cleaners, while further details about these products can be found in Appendix A. The categories of products include:

plant-based products, which can be of various origin:

o tall oil fatty acids, which are derived from pine pulp production


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o citrus based products, containing concentrated d-limonene

chemical origin, including ethylene and glycol derivatives

products of unknown composition or origin

Table 6: Examples of alternative cleaning chemicals as alkali replacement


Colloidal Concentrate

Non-ionic surfactant, as alcohols C12-16 ethoxylated 5% Tall oil fatty acids 0.5% Organic butter, as sodium iminodisuccinate 0-1%

Supersolve Tall oil fatty acids

Heavy Duty Surfactants < 5% Tall oil fatty acids <5% Succinimide <5%

Dairy farms Food preparation

Plant-based products

Citra-Solv

Concentrated d-limonen based product 80-95 wt% limonene fraction terpenes 1-10 wt% ethoxylated alcohols C9-C11 1-10 wt% coconut diethanolamide Manufacturing

Food Process Cleaner

Ethylene Glycol Monobutyl Ether (%wt) < 15%

Canneries Dairies Bakeries, Seafood processing Bottling plants Red meat processing Poultry processing Breweries

EASY-CLEAN Rig Wash

Alkyl aryl sulfonates & builders Nonhazardous blend (100% wt)

Meat and poultry

Chemical compounds

4171 TRITON X-100

Diethylene ether,1,4-dioxane Ethylene oxide Polyethylene glycol Triton X-100

Actisolve Not available Unknown origin Concept C20 Not available Dairy plants

The SGS U.S. Testing Company performed a 28-day biodegradability test on Citra-Solv® Cleaner and Degreaser to determine the biodegradability of this cleaning agent in a closed aqueous system. Citra-Solv® is a concentrated d-limonene based product derived from the extract of orange peels. The results of the study showed that Citra-Solv® degraded 75.6% as determined by Total Organic Carbon (TOC) reduction and 209% by CO2 evolution within 28 days (NFESC 1999).


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5.9 Alternative acid cleaners

Acids are used principally to dissolve precipitates of inorganic salts or oxide films. Conventional acid cleaners contain nitric and/or phosphoric acids, which can lead to nutrient problems in effluent discharges.

Alternative acid cleaners are mainly based on citric acid, as presented in Table 7. In membrane applications, citric acid is favoured over nitric acid because of its mildness. It also rinses easily and does not corrode surfaces (D'Souza and Mawson 2005).

In an interesting case study, Bonlac Foods replaced the nitric and phosphoric acid normally used in their CIP process with Stabilon® (DEH, 2005a,b). Prior to the changeover, 200 litres of nitric and phosphoric acid were used every day for CIP processes in the cheese manufacturing plant. DEH (2005b) reported that the use of Stabilon® decreased the CIP wash time by 1.5 hours per day. Consequently, this enabled the plant to increase production time by 9 hours per week. The net savings to the factory was $312 per day. Although phosphorus and nitric acid levels were reduced by using Stabilon®, the total wastewater volume actually increased. This was because more production took place each day. When the volume of wastewater was related to the amount of cheese produced, it was found that utilising Stabilon® resulted in the roughly the same volume of effluent discharged per tonne of cheese produced as from using nitric and phosphoric acid.

Table 7: Examples of alternative cleaning chemicals – acid replacement


Citrajet

Citric acid (10-30%) Phosphorus compounds < 1% Organic Carbon (%w/w) – 14% Blend of organic acids and surfactants Dairy industry

Citranox

Citric acid (10-30%) Blend of organic acids, anionic and non-ionic surfactants and alkanolamines. Organic Carbon (%w/w) – 17% Phosphate free. Food industry

Enviroscale

Citric acid, anhydrous <2% Lactic acid <2% Surfactant <1%

5.10 Alternative sanitisers

Many detergents have been found to have a disinfecting ability. However, the stand-alone application of a sanitizer (see sections 5.10.1 and 5.10.2) or the application of combined acid + sanitisers (see section


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5.10.3) is common practice to ensure adequate reduction in microbial numbers.

Typical sanitisers are based on chlorine, sodium hypochlorite, hydrogen peroxide and quaternary ammonium compounds. Details about several different alternative sanitisers are presented below.

5.10.1 Alternative chemical sanitisers

A wide range of chemical sanitisers are used within the food industry. (ADHS 2005) listed a number of criteria that the ideal chemical sanitiser should meet for application in the food industry. The criteria that the ideal chemical sanitiser should meet are as follows (taken directly from ADHS, 2005):

be approved for food contact surface application

have a wide range or scope of activity

destroy micro-organisms rapidly

be stable under all types of conditions

be tolerant of a broad range of environment conditions

be readily solubilised and possess some detergency

be low in toxicity and corrosivity

be inexpensive

It is impossible for any single sanitiser to meet all of these criteria. Therefore, it is important that the properties, advantages and disadvantages of a sanitiser are evaluated being used for a specific application (ADHS, 2005).

Dufour et al (2004) developed a laboratory scale system to quantify the effectiveness of chlorine and alternative sanitizers in reducing the number of viable bacteria attached to stainless steel surfaces. The experimental system, which consisted of a continuous flow reactor and recirculating test loop, was used to model the development of dairy biofilms on stainless steel surfaces under conditions of growth and cleaning regimes typically encountered in dairy processing plants. Stainless steel tubes were placed in the recirculating loop and exposed to a standard CIP regime. The tubes were then exposed to chlorine (200 ppm) and combinations of nisin (a natural antimicrobial agent, 500 ppm), lauricidin (a natural microbial product, 100 ppm), and the lactoperoxidase system (LPS) (enzyme-based, 200 ppm) for different lengths of time (10 min or 2, 4, 8, 18 or 24 h) (Dufour et al. 2004).

It was found that increasing the concentration of the chemicals did not always lead to a greater reduction in the number of attached cells. Log reductions varied between 0 and 2.1. Dufour et al. (2004) also investigated the effectiveness of chlorine, nisin + LPS, and lauricidin +


31

LPS against biofilms following the standard CIP regime. They reported that none of the sanitizers significantly reduced the number of attached cells after a 10-min treatment. However, after 2h of exposure, all three treatments significantly reduced bacterial counts on the stainless steel tubes. Exposure times greater than 2h did not achieve further significant microbial reductions.

Langsrud et al. (2000) carried out a study to determine the effects that peroxygen have on Bacillus cereus spores. They also investigated whether alkali treatment sensitised spores to the effect of peroxygen. The cleaning agents employed in this study were sodium hydroxide (NaOH), nitric acid (HNO3), Paradigm enzyme 10/30. The two peroxygen based sanitisers used were Parades and Oxonia aktiv (Langsrud et al. 2000).

The sporicidal effect of 1% Oxonia aktiv was generally poor at 20 and 30°C, even when exposed for 30 min. However, when the temperature was increased to 40°C the reduction in viable spores was significantly larger. Pre-treatment of spores with 1% NaOH at 60°C made the spores susceptible to even low concentrations of Oxonia aktiv. It was shown that pre-exposure of the spores to 0.25 and 0.5% NaOH was not as effective as 1% NaOH. Langsrud et al. (2000) investigated the influence of cleaning temperature on the potentiating effect of alkali. They found that alkali treatment alone only reduced spores significantly at 80°C, whereas alkali treatment followed by exposure to Oxonia resulted in significant spore reductions at 40°C. It was also shown that pre-exposure to Paradigm potentiated the effect of Parades. The results of the study indicated that peroxygen-based disinfectants have a good effect at lower concentrations and temperatures if the pores are exposed first to alkali or an enzyme based cleaner (Langsrud et al. 2000).

The use of ozone in CIP processes has been tested in the form of ozonated water. Lagrange et al. (2004) carried out a study to determine the antimicrobial efficiency of ozonated water applied in a CIP system on the surfaces of food processing plants. Under optimal conditions ozonated water showed excellent microbicidal and fungicidal characteristics within seconds. However, these characteristics were extinguished in the presence of protein soil. It was concluded that a suitable use of ozonated water for sanitation was only possible after efficient cleaning (Lagrange et al. 2004).

5.10.2 Non-chemical sanitisers

A number of non-chemical sanitisers have been reported in the literature including thermal sanitising, steam and hot water (ADHS 2005). UNEP (2004) report that two alternatives to using sanitation chemicals are ionisation and ultraviolet light. Ionisation involves the use of an electrode cell to release silver and copper ions into a stream of water. The positively charged silver and copper ions are attracted to the


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negatively charged surface of the micro-organisms, distorting the cell structure and preventing the absorption of nutrients (UNEP, 2004). Ultraviolet (UV) disinfection systems destroy micro-organisms through interaction with microbial DNA (UNEP, 2004).

A carrot processing plant in Australia is trialling a new ionisation system to sanitise 80 000 tonnes of fresh carrots using 200 000 L of sanitised water per day (UNEP, 2004). Although the trials are only in the preliminary stages, it is expected that ionisation will be just as effective as chlorination. This is based on overseas experience.

A cheese processing plant in South Africa required a non-chemical brine disinfection system that would not alter the quality of the cheese and would also be simple and easy to maintain (UNEP, 2004). The company installed an UV disinfection system. The operating costs for the UV system were reported to be far lower than the operating costs of pasteurisation.

A food processing plant in the UK has installed a medium-pressure UV disinfection system to treat water originating from a private borehole (UNEP, 2004). The water is treated using an iron and manganese filter before being passed through a membrane filter. The final stage of the treatment process is to pass the water through the UV system. Approximately 95% of the UV-treated water is used for washing and treating equipment while the remaining 5% is used in product make-up. The products from the plant are not affected in any way by using this source of water.

A number of physical methods have also been tested for the control of biofilms including (Kumar and Anand 1998):

super-high magnetic fields

ultrasound treatment

high pulsed electrical fields on their own and in combination with organic acids

low electrical fields both on their own and as enhancers of biocides

low electrical currents in combination with antibiotics

The utilisation of the last two methods for controlling biofilms appears to be very promising. Several studies reported in the literature have successfully employed low electrical currents to control biofilms (Davies et al. 1991; Costerton et al. 1994; Jass et al. 1995; Jass and Lappin-Scott 1996; Kumar and Anand 1998).1

Walker et al (2005) conducted a study to determine whether electrolysed oxidizing (EO) water could be used as an acceptable 1 Cited in Kumar and Anand (1998).


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cleaning and disinfecting agent for pipeline systems. EO water is produced by electrolysis of a weak salt solution into sodium and chlorine, with a membrane between the electrodes to separate the ions from each other, yielding alkaline and acidic EO water (Walker et al. 2005). Small pieces of materials commonly used in the milk processing industry, including stainless steel sanitary pipe, PVC milk hose, rubber liners, rubber gasket material and polysulfone plastic, were soiled using raw milk inoculated with a cocktail of four bacterial cultures similar to those commonly found in raw milk. The materials were then soaked in the alkaline EO water before being transferred to the acidic EO water. The materials were soaked for a series of time and temperature combinations.

It was found that most of the treatments at 60°C and several treatments at lower temperatures successfully removed all detectable bacteria. Based on these results, Walker et al. (2005) stated that EO water has the potential to be used as a cleaning and disinfecting agent for a range of materials commonly found in the milk processing industry.

5.10.3 Combined acid detergent + sanitiser

In many food processing plants it has become common practice to combine detergency and sanitisation to form one stage in the cleaning process instead of two separate stages. The main benefit of this approach is that it saves considerable time. However, it is important to realise that there can be a loss of disinfection action so it is important to consider the final effect of combing detergency and sanitising (Loghney and Brougham 2005).

Table 8: Examples of alternative combined acid cleaner + sanitisers


Envirowash No phosphates or nitrates Dairy plants

Iodosan (Triple 7) Iodine Iodophor

Abattoirs Dairies Livestock/Poultry Farms Wineries

5.11 Comparison of cleaning chemicals

5.11.1 Comparison on cleaning performance

Parkar et al. (2004) carried out a comprehensive study to determine the cleaning and sanitisation mechanisms that caused the removal (cleaning) and inactivation (sanitisation) of 18-h biofilms of a thermophilic Bacillus species growing on stainless steel. They tested a number of different cleaning strategies. The success of the cleaning regimes was determined by the removal of cells and organic debris and


34

the elimination of viable cells. A number of different cleaning agents were selected for the study including:

alkaline cleaners

enzyme based cleaners

oxidizing chemicals

a quaternary ammonium chloride

detergents

Parkar et al. (2004) found that caustic and acid cleaning with 2% NaOH at 75°C for 30 min was the most effective of all the caustic and acid treatments used to remove and kill biofilms. They also found that when the temperature of the full strength alkali and acid was reduced to 60 and 50°C the cleaning efficacy was reduced. A reduction in the temperature of the full strength caustic acid2 also led to a decrease in cleaning efficacy.

Parkar et al. (2004) reported that when Paradigm, an enzyme based cleaner, was used according to the manufacturers’ instructions at 60°C, no viable cells or cell debris were left behind on the stainless steel. The other enzyme preparations analysed in the study, namely Purafect®, Purastar™ and CellulaseL, were not as effective as Paradigm. Parkar et al. (2004) suggested that low wetability and the fact that the enzyme cleaners target only one part of the biofilm were possible causes for this.

The oxygen based agent Perform® was found to remove 100% of cells and attached polysaccharides. The other oxygen based agents, namely Oxine®, Halamid and sodium hypochlorite, did not perform as well as Perform® in terms of total cell reduction. However, in terms of loss of viability of the biofilms, Oxine® and Perform® were found to be the better performing agents (Parkar et al. 2004).

Parkar et al. (2004) stipulate that it is very important to use the right concentrations of agents and the recommended temperatures to achieve the best results. A decrease in the strength of the agents can kill the cells but can fail to remove all the cells from the surface. Parkar et al. (2004) concluded that several procedures, including caustic/acid and enzyme based cleaners, produce satisfactory results in terms of the removal and inactivation of biofilms from stainless steel, provided that the correct process parameters are observed.

5.11.2 Comparison of cleaning efficiency for membrane cleaning

Gan et al. (1999) carried out a series of experiments to formulate and optimise chemical cleaning methods for a chemical microfiltration 2 Parkar et al. (2004) consider caustic acid to be a combination of 2% NaOH and 1.8% HNO3.


35

membrane, which had been severely fouled by beer microfiltration. The cleaning agents considered in this study were NaOH, HNO3, H2O2 and Ultrasil 11 (consists of sodium hydroxide and unspecified anionic surfactants). The membranes used in the beer microfiltration rig were fouled during a typical 10h run. Sodium hydroxide was found to have the highest cleaning power, followed by Ultrasil 11 and last HNO3.

Gan et al. (1999) also investigated the effect of altering the concentration of the chemicals. Sodium hydroxide produced a similar result with a concentration of 0.3 wt% as it did for a concentration of 0.5 wt%. The optimal concentration for Ultrasil 11 was 0.3 wt%. Concentrations higher than 0.3 wt% were shown to have an adverse effect on cleaning. Chemical oxidation using hydrogen peroxide at ambient temperatures was found to be a very slow and ineffective cleaning process on its own. However, when oxidation was employed as a second cleaning step, it was found that the water flux recovery increased by between 8 and 18% for the three chemical agents (Gan et al. 1999).

A further study was carried out on the cleaning of reverse osmosis membranes fouled by whey (Madaeni and Mansourpanah 2004). A wide variety of agents were used to clean the fouled membranes, including acids, bases, enzymes and complexing agents. The authors employed two parameters, resistance removal and flux recovery, to evaluate cleaning efficiency. They found that hydrochloric acid (0.05 wt%, pH = 3) resulted in the maximum flux recovery and complete resistance removal. In contrast, the resistance removal for one of the other acids analysed, H2SO4, was considerably lower than that achieved by HCl, regardless of the concentration.

Furthermore, the study provided some interesting insights into how the concentration of different chemicals affected the cleaning effectiveness. Increasing the concentration of H2SO4 led to lower resistance removal and flux recovery. In the case of HCl, the cleaning efficiency increased with the cleaner concentration, reached an optimal value and then continually decreased. It was found that the cleaning efficiency of NaOH gradually increased up to a concentration of 0.1 wt%, but there was evidence to suggest that this cleaning agent caused damage to the membrane at high concentrations. Of the acids considered by Madaeni and Mansourpanah (2004), HNO3 was found to be the best for resistance removal, followed by H3PO4, NH4Cl, and oxalic acid. Of the surfactants, CTAB resulted in the greatest resistance removal followed closely by SDS. The other surfactant, Triton-x100, had a very poor resistance removal. NH3 exhibited a reasonably high resistance removal, whereas urea and EDTA had only moderate effects (Madaeni and Mansourpanah 2004).

A field study investigated the fouling of a reverse osmosis desalination system installed at a refinery thermo-power plant in China


36

(Luo and Wang 2001). Citric acid based cleaning solutions were used in the CIP process: Cleaner A (citric acid, special cleaner aids and buffer corrosives) and Cleaner B (citric acid and Na2EDTA). Cleaner A was found to restore 90.8% of the membrane performance. Although Cleaner A was originally designed for the cleaning of silica colloids only, it was shown that other foulants were removed simultaneously thus improving the overall cleaning performance.

5.11.3 Comparison of cleaning efficiency for biofilm removal

Bremer et al. (2005) used a laboratory scale bench top flow system to quantify the effectiveness of caustic and acid wash steps in reducing the number of viable bacteria attached to stainless steel surfaces. The system was designed to reproduce dairy plant conditions under which biofilms form. They found that a standard CIP regime (water rinse, 1% sodium hydroxide at 65°C for 10 min, water rinse, 1.0% nitric acid at 65°C for 10 min, water rinse) did not remove all the bacteria. The addition of a caustic additive (Eliminator) was found to enhance biofilm removal while the substitution of nitric acid with Nitroplus increased the cleaning efficiency. It was also reported that the incorporation of a sanitiser step into the CIP did not appear to enhance removal. The results of this study indicate that the effectiveness of a standard CIP can potentially be enhanced through the testing and use of caustic and acid blends (Bremer et al. 2005).

Kumar and Anand (1998) cover a number of studies reported in the literature detailing various chemical methods used to remove biofilm. It has been shown that enzymes can be effective in cleaning the extracellular polymers which form the biofilm, thereby helping in the removal of biofilms. The microflora making up the biofilm will largely determine the enzymes that should be used for cleaning (Kumar and Anand 1998).

5.11.4 Comparison of cleaning chemicals through life cycle assessment

A life cycle assessment (LCA) approach has been used to compare four scenarios of CIP methods for dairy plants (Eide et al. 2003). The CIP methods investigated were:

conventional alkaline/acidic cleaning by nitric acid and sodium hydroxide followed by hot-water disinfection

one-phase alkaline cleaning with acid chemical cleaning

enzyme-based cleaning with acid chemical disinfection

conventional alkaline/acidic cleaning with disinfection by cold nitric acid at pH 2

The main objective of the study was to compare the environmental impact of new and commonly used CIP methods, simulated in a model


37

dairy. The LCA covered the production of detergents, transport to the plant, the user phase and waste management of the packaging. Eide et al. (2003) found that the CIP methods with small volumes and low temperatures, such as enzyme-based cleaning and one-phase alkaline cleaning, were the best alternatives for the impact categories energy use, global warming, acidification, eutrophication and photo-oxidant formation.

However, Eide et al. (2003) also stated that the LCA did not give a clear-cut conclusion regarding the choice of CIP method because of the difficulty associated with assessing the toxicity impact of the cleaning agents. They reported that the one-phase alkaline method is likely to be the best alternative from an environmental point of view, but acknowledged that further research on the assessment of toxic substances is needed to reduce the uncertainty of this conclusion. Finally, Eide et al. (2003) pointed out that regardless of the choice of the CIP method, hygienic design and optimisation of the cleaning process are the most important effective steps to reduce the environmental impact (see section 7 for further information on CIP optimisation).

5.12 Desk-top review of the impact of implementation of alternative chemicals

The following section presents a desk-top assessment on the possible implementation of alternative chemicals. Where information was available from the chemical suppliers, literature references, internet sites or factories, this assessment has been done in terms of:

Sodium discharge reduction

residue risk (including product and environmental impacts)

OH&S of factory and sewer workers

Corrosion issues: in-factory, sewer infrastructure and treatment plants

No information could be obtained in relation to anticipated operational/capital cost-benefit to be gained from using alternative chemicals.

5.12.1 Residue risk, OH&S and corrosion issues

While some cleaning chemicals are food compatible, most of them will require a water rinse at the end of the CIP cycle before the food production can resume. Where information was provided by chemical suppliers on food compatibility or need for rinsing, this has been included in Appendix A.


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In relation to OH&S issues, the most relevant information has been extracted from chemical supplier information and Material Safety Data Sheets. The three major OH&S issues found with chemical cleaners are:

Corrosive substances due to alkaline or acid nature of the products (Class 8). This applies particularly to NaOH, KOH, NaOH/KOH blends, built NaOH and KOH

Toxicity of chlorinated alkali cleaners, which in contact with acid can produce toxic substances.

Oxidising substances (Class 5) such as hydrogen peroxide

Similarly, the corrosiveness of the cleaning agents is reported (where available) in the specification sheet for each product.

5.12.2 Sodium discharge reduction

To assess the potential reduction in sodium discharge that could be achieved through the change over to alternative cleaning chemicals, the sodium concentration in the cleaning solution itself (after dilution of the bulk chemicals) has been used. This was calculated using the sodium concentration of the bulk chemical as well as the chemical in-use concentration (as recommended by the chemical suppliers). The reference for comparison is pure sodium hydroxide, with a recommended in-use concentration of 0.5 – 4%, depending on the process and equipment to be cleaned. Sodium hydroxide was chosen as a reference because of its large use across many food and beverage industries.

The cleaning chemicals have been grouped according to their categories as identified in the sections above (where enough information about the product was available). The lower recommended concentration of each chemical was compared with the 0.5% NaOH solution, while the higher recommended concentration was compared with 4% NaOH solution. The results are presented in Table 9.


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Table 9: Sodium concentration in various cleaning solutions Sodium concentration in

cleaning solution

[gNa/kg cleaning solution]

Reduction

%

Pure NaOH (at 0.5 to 4% NaOH) 2.88 – 23 Referencea

Alkaline cleaners with medium sodium levels 0.63 – 2.9 78 – 87%

Alkaline cleaners with low sodium levels 0.02 – 0.8 99.3 – 96.5%

KOH based products 0 or negligible Almost 100%

NaOH/KOH blends 0.13 – 0.78 95.5 – 96.6%

Enzymes and other biotechnology based cleaners 0 or negligible Almost 100%

Alternatives to alkaline cleaning agents, including plant-based cleaners

0 or negligible Almost 100%

a Pure NaOH has been used as the reference for comparison with all other chemicals

Table 9 shows that the use of alkaline cleaners with medium and low sodium concentrations can lead to significant reductions in sodium discharge from the alkaline step of a CIP cycle. Large savings can also be obtained from NaOH/KOH blends, which can be attributed to the use of KOH instead of NaOH and also to the use of alternative chemicals in the blends. Furthermore, the use of potassium based cleaners, enzyme products or other alternative cleaning agents can reduce the sodium concentration to almost zero.

However, while these preliminary results are encouraging, it is necessary to test the efficiency of these alternative cleaning chemicals in factory environments and for specific processes and equipment. In some cases, the limitations of a cleaning agent are known, e.g. it is known that enzymes will not be able to operate at temperatures above 60ºC. In many cases however, the performance of a cleaning chemical for specific fouling and under various process conditions is unknown. Some information from case studies and literature references has been presented in this section. Further studies are required to measure cleaning performance of selected cleaning chemicals in factories.


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6 REVIEW OF CIP RECOVERY TECHNOLOGIES

6.1 Introduction

While following the same aim as the previous section to reduce the impact of cleaning chemicals on trade waste discharges, this section is taking a different approach. The approach in this section is to reuse the used cleaning solutions in subsequent cleaning cycles, extending its lifespan.

As a result of cleaning, the cleaning solution contains soil and an increased COD (mainly in soluble form), and has lost some active detergent compounds. This used cleaning solution can either be discharged (single-use CIP) or reused (multi-use or reuse systems). The different types of CIP systems are defined below (Davis 1980; Hamblin 1990):

Single use CIP system: The required amount of CIP solution is made up at the lowest possible concentration. The solution is used, recirculated during cleaning where appropriate, and then discharged to drain (see Figure 1).

Figure 1: Single-use CIP system (Hamblin 1990)

Reuse system: The same cleaning solution is used for a large number of cleaning operations. After use, the cleaning solution is returned to the multi-tank, where it can be treated to remove some


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contamination, before being reused for further cleaning applications (see Figure 2)

Multi-use system: After use, the cleaning solution is returned to a collection tank. It is subsequently reused for pre-wash and rinses before being discharged. This system presents the advantage of increasing the cleaning efficiency of the pre-rinses due to the presence of cleaning chemicals and also of reducing overall water consumption.

Note that all configurations can exist in one plant. Reuse and multi-use systems are often combined in one CIP system.

Figure 2: Reuse CIP system (Hamblin 1990)

6.2 Single use systems

In a single use system, the soiled cleaning solution is discharged to the drain after use. Historically, the first CIP systems installed were single use. Davis (1980) compared both single use and reuse systems and strongly recommended single use for almost all applications. The trend has now changed. However, some of the arguments in favour of single use system are:


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Reduced risk of cross-contamination

Lower initial capital costs

More applicable for decentralised CIP system, in which various CIP loops are specifically operated for one piece of equipment or process. In decentralised CIP systems, pipes are not connected centrally, making the use of reuse tanks and treatment technologies difficult to impossible. The costs associated with re-piping all CIP loops to transform a decentralised system into a centralised system are significant, leading to unattractive pay-back periods.

More appropriate for cleaning solutions with high contamination after the first use (e.g. evaporators)

More appropriate for applications requiring special cleaning regimes: different chemicals, concentrations, temperatures, etc. (e.g. membrane processes)

According to Davis (1980), single use systems are recommended for tank cleaning because lower chemical concentrations and lower temperatures are required for tanking than most other processes. The dilution effect in reuse system amounts to the quantity of fresh caustic for single use. There is therefore no incentive in reusing CIP solutions in the application (Davis 1980).

Single use systems are also recommended in the biotechnology area and for the cleaning of bioreactors (Chisti and Moo-Young 1994; Forday 2005). Single use systems avoid contamination with soil and microbial spores, which have long survival periods. Such systems also enable a higher quality control as the characteristics of the starting cleaning solution for each clean are well known. In contradiction to the previous authors, the company Koch Membrane Systems (KMS) suggests the use of a nanofiltration membrane (AlkaSave®) for the recovery of used cleaning solutions from fermentation equipment, which can enable reuse in subsequent cleaning cycles (KMS 2005). More details about the AlkaSave® process are provided in section 6.4.5.

6.3 Multi-use systems

6.3.1 Benefits of multi-use systems

In multi-use systems, used CIP solutions are collected in tanks and reused for pre-rinses in subsequent cleaning cycles. The introduction of multi-use systems leads primarily to savings in water consumption. Additionally, the presence of residual cleaning agents in the pre-rinse solution increases the efficiency of the pre-rinse, thus reducing the load on the main cleaning step.


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With the multi-use approach, where a used CIP solution is reused in the next cleaning cycle for pre-wash and rinses, the following achievements are reported (Davis 1980):

30% reduction in water consumption 15% reduction in energy consumption (due to heat recovery) 10-13% reduction in chemical usage

6.3.2 Case studies

For Pauls Limited, the disadvantages of single use CIP were summarised by (DEH 2001):

Cost inefficiency Excessive use of cleaning chemicals High time out of production schedule to clean on a continuous

basis

Pauls Limited conducted a major upgrade to install multi-use CIP to clean and sanitise all milk lines and pasteurised milk vats. All used cleaning chemicals (acid, sanitiser and sodium hydroxide) are returned to respective holding vats. In the holding vats, conductivity and temperature are measured and used to control the length of the following CIP cycles to ensure that specifications are met. After many cleaning cycles, when the organic build-up exceeds a set value, the spent CIP solution is discarded (DEH 2001). The new CIP system saves the dairy company $40,000 per year, with a payback period of 1 year (Prasad 2004b).

Golden Circle, QLD, installed a collection system to hold final rinses from CIP. The collected solutions are then used in pre-rinses for the next cleaning cycle. This has resulted in a saving of 4.35 ML of water per year, which is equivalent to $10,300 (UNEP 2004).

Schweppes Cottee’s, NSW, installed a tank, piping and a pump on a cordial line for the collection of final rinse water for the first wash in the next cleaning cycle. It has been estimated that this has halved the mains water consumption (UNEP 2004).

Taw Valley Creamery, UK, utilised two redundant tanks to collect used acid solutions and final rinse waters from evaporators and finishers. They installed a conductivity probe to detect interfaces between cleaning steps. The annual savings were reported to be:

56 m3 of 60% nitric acid

2.75 ML water

The payback was estimated to be just over 1 year. The overall benefits include cost savings, improved effluent quality, and a more reliable cleaning (ETBPP 1998). The only drawback reported is the need to control the tanks to avoid any deposits.


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Dairy Farmers have implemented two types of multi-use systems (Price 2004):

The reuse of rinse waters for less critical areas (outside CIP systems)

The reuse of cleaning solutions from pasteurisers to be used for pre-rinse on tanks. The pay-back period is only a few months.

6.4 CIP Reuse systems

6.4.1 General remarks

CIP reuse systems enable the collection of used cleaning solutions and their reuse in subsequent cleaning cycles. Prior to reuse, the cleaning solutions can be treated to remove parts of the soil, thus further extending the life of the cleaning chemicals. The types of treatments performed include:

Gravity separation (sedimentation and centrifugation)

Physicochemical methods (coagulation/precipitation)

Membrane separations

Before going into any more detail about these treatments, their benefits and related case studies in the following sections, a few common remarks on CIP reuse systems are described below.

1. In most CIP systems in the food and beverage industry, soil is mainly present in soluble form. Thus, it should not be expected to remove the majority of the soil using gravity or coagulation.

2. For any reuse system, whether straight reuse or following treatment, it is important to perform a good pre-rinse to extend the life of the cleaning solution. It has been shown that pre-rinsing can remove a large portion of the soil, while the main cleaning step will remove the more resistant soiling compounds.

3. It is also important is to prevent dilution of the cleaning solution with rinsing water. To isolate the different cleaning steps (see section 4.1.3 in relation to the cleaning steps), the use of air blows has been trialled but was proven to be very difficult to implement in factories (Davis 1980). Most systems are now defining interfaces between cleaning steps using electrical conductivity. This method, however, is not the best as the electrical conductivity does not vary linearly with the strength of the cleaning solution.

4. In many reuse applications, it will be necessary to re-dose cleaning chemicals to adjust their strength, and to add additives to compensate for those that have reacted in the previous cleaning cycle and/or have


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been removed by the treatment process (Trägårdh and Johansson 1998; Bhave et al. 2001; Bolch 2005).

5. While the reuse of CIP solutions is often reported as being operated within a production area of a factory, CIP solutions from one area can also be reused in another area of the factory. An example of this configuration is the use of dilute used caustic solutions for evaporators in the dairy industry (Bhave et al. 2001).

6. Alkaline and acid cleaning agents are the chemicals which are mostly reused. Disinfectants can also be collected and reused although the strength and contamination should be controlled (ETBPP 1998).

7. Recovery of cleaning solutions should be done on fresh streams to avoid chemical alteration of the contaminants. However, this leads to technical difficulties as the CIP flows are variable (Dresch et al. 1999). For membrane technologies, benefits of treating cleaning solutions without extended delays have also been reported by Henck (1995), as a cooling down of the solutions reduces membrane performances.

8. The maximum acceptable level of soil in a cleaning solution should be determined on a case by case basis. In study on evaporators in the dairy industry conducted by DPEC (2005), it was shown that a NaOH solution with 1% total alkalinity and a COP of up to 45,000mg/L could still satisfactorily clean. However, due to foaming problems, the authors recommended to keep the COD < 10,000mg/L for this application (DPEC 2005).

6.4.2 Straight reuse vs. treatments

Straight reuse consists in the direct reuse of used cleaning chemicals without any treatment. In bottle washing plants, it has been shown that there are better economic benefits for a straight reuse system compared to the inclusion of any treatment prior to reuse (Novalic et al. 1998).

However, in most cases, some form of soil removal will be applied, whether by gravity separation, chemical means or membrane separation. In these systems, the used cleaning solution is collected after the cleaning process and delivered to a storage tank. It is then treated in batches or in a continuous process. The aim of any of these treatments is to remove the soil from the used cleaning solutions to enable the reuse of the cleaning solution for subsequent cleaning applications before discharging it. This can result in energy, water and chemical savings, while maintaining cleaning efficiency (Trägårdh and Johansson 1998; Dresch et al. 1999).

6.4.3 Reuse after gravity separation 6.4.3.1 Reuse following sedimentation

In tanks where used CIP solutions are collected, sedimentation usually occurs and large suspended particles settle. This is beneficial because it


46

provides some treatment of the solution before reuse. However, the limitations of this technique are that (Bhave et al. 2001):

(1) the recovered caustic is not very clean, and

(2) large amounts of sludge can accumulate of at the bottom of the settling tank.

Decantation trials were conducted at room temperature for 3.5h with caustic soda from a dairy standardisation process (Dresch et al. 1999). A 22-35% reduction in total COD was measured, while soluble COD remained unchanged (Dresch et al. 1999). It should be noted that the effect of temperature on CIP solutions is important as gels form at lower temperatures, while nothing can be observed at process temperature of 50-60ºC. Therefore, these observations might not be replicable in industrial scale as used cleaning solutions would rarely have time to cool down.

6.4.3.2 Reuse following centrifugation

To improve the separation of suspended solids, the use of centrifugal forces can be used, either in hydrocyclones or in separators/clarifiers.

Hydrocyclones create centrifugal forces by moving the liquid. They can typically remove particles larger than 5µm if the density difference between the particles and the medium is more than 100 mg/kg (Prendergast 2005). Hydrocyclones operate better at higher temperature (due to reduced viscosity) and at higher flow rates (Prendergast 2005).

Advantages of hydrocyclones (Spinifex 2004; Bolch 2005; Prendergast 2005):

simple and reliable operation low maintenance no chemicals required no moving parts small footprint low capital costs slightly better recovery than sedimentation due to higher gravity

forces

Disadvantages of hydrocyclones (Spinifex 2004; Bolch 2005; Prendergast 2005):

removes suspended solids only does usually not perform as well as a centrifuge removes particles with density sufficiently different from that of

the medium

In addition to the previous successes detailed above, Pauls Limited is using a hydrocylone system (by Spinifex, $32,000), in which the CIP solution is pumped tangentially into the separator. Heavy suspended solids are accelerated against the outside of the hydrocyclone and


47

removed, while the cleaned solution can be reused. A removal efficiency of 80% for 10 micron particles is reported, increasing the lifespan of the cleaning fluid in the reuse system (DEH 2001; Spinifex 2004).

Ultraspin installed a hydrocyclone unit at a Nestlé dairy factory to clean their caustic solution. The unit was installed in an external loop off the already existing caustic recovery tank. This installation extended the life of the cleaning chemical from 10-14 days to beyond 40 days by removing suspended matter. The quality of the treated caustic solution was improved compared to solutions reused without treatment, leading to significant cost savings. It was found that an increasing amount of suspended matter in the solution increased the efficiency of the hydrocyclone (Prendergast 2005).

In a study conducted by DPEC (2005) on CIP solutions from evaporators in the dairy industry, the suspended solids were removed by up to 20% in a hydrocyclone, while total COD was reduced by up to 16%.

In centrifugal clarifier, the centrifugal force is created by rotation of the machine.

Advantages of centrifuges (Bhave et al. 2001; Bolch 2005):

no chemicals required slightly better recovery than hydrocyclones due to larger

centrifugal forces: removes suspended particles down to 5 µm

Disadvantages of centrifuges:

high capital cost high energy requirements removes suspended solids only removes particles with density sufficiently different from that of

the medium

Trials were conducted with caustic soda from a dairy standardisation process using a lab centrifuge at 3000g for 20min, at a temperature of 20ºC. The total COD reduction ranged between 26 and 36%. No soluble COD reduction was measured (Dresch et al. 1999).

An industrial centrifuge skimmer was also used for the same solution of caustic soda from a dairy standardisation process. The centrifuge was operated continuously, with 6000g at 80ºC. The results differed significantly from the lab centrifuge tests, as less than 4% of the total COD was removed (Dresch et al. 1999).

A Victorian dairy factory upgraded their evaporator CIP system by separating dirty and clean caustic solutions. The company also retro-fitted an old milk-separator to improve the quality of the recovered CIP


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solution. While suspended solids were removed by the centrifugal forces, no reduction in soluble COD was observed (DPEC 2005).

6.4.4 Reuse following physicochemical treatments

An alternative approach to remove soil from cleaning solution is to use a combination of chemical and physical processes, including:

Precipitation

Coagulation

Conventional filtration after chemical reaction

The Cedilar dairy factory in France has been using a physical-chemical process to clean their used CIP solutions. The process involves the addition of precipitation agent, coagulants, adsorbents and oxidants to the tank holding the used CIP solutions. As a result, dissolved impurities are precipitated, adsorbed or chemically transformed into compounds not affecting the cleaning process. The treated CIP solution is then passed through a belt-filter press and a fixed-bed reactor, before being reused in the factory (Jung and Niederhünigen 1996). According to the authors, the benefits of such process are:

Constant efficiency of cleaning solution due to COD and SS remaining constant

Reuse of solution for 10 weeks without discharging it. This results in:

o Reduced consumption in cleaning chemicals o Reduced environmental impact

According to the CEO of the company, the reuse could be extended for up to 24 weeks

Reduced water consumption Reduced energy consumption as warm cleaning solution is reused

Chemical processes are strongly affected by pH variations and temperature. Because of the nature of the cleaning solutions, extreme pH values and temperatures limit the use of some chemical processes: Flocculation processes suggested for CIP recovery typically operate below 30ºC (DPEC 2005). Furthermore, coagulation can only remove particles, not soluble compounds (Dresch et al. 1999). The neutral density of the flocs formed can also be a limitation as flocs do not settle easily (DPEC 2005).


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6.4.5 Reuse following membrane separation 6.4.5.1 Membrane selection

The pore size and physical characteristics of the various membranes define their ability to separate specific compounds from the cleaning solution (see Figure 3).

Figure 3: Membrane categories

It is important to select the membrane type and characteristics according to the CIP requirements, such as composition of the cleaning solution and type of soil present in the used cleaning solution. This would be different for a bottle washing plant, a cheese plant or a brewery (Jung and Niederhünigen 1996; Dresch et al. 1999). Extreme pH values of the cleaning solutions (highly acidic or highly basic), as well as elevated temperatures (50 - 80ºC) limit the choice of membranes (Bhave et al. 2001). For alkaline cleaning solutions, the available membrane types are summarises in Table 10.

MF enables recovery and reuse of cleaning solution for a number of cycles only, because soluble COD is not removed and builds up rapidly in a few CIP cycles. On the other hand, the flux through UF and NF membranes is smaller but this is outweighed by the longer life of the CIP solution and the lower cleaning requirements for the membrane themselves (Jung and Niederhünigen 1996). In terms of choosing between UF and NF, the decision depends on the compounds to be retained. UF retains all suspended solids, colloids and high molecular-weight compounds, and some bacteria but tensides and low molecular-weight compounds pass through: sugars, salts and colour-causing compounds. NF will additionally remove colour and almost all COD.

Microfiltration

Ultrafiltration

Nanofiltration

Reverse Osmosis

Suspended solids

Macromolecules, e.g. proteins

Sugars and colour

Salts

Water


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Table 10: Membranes available for used cleaning solutions (adapted from

Bolch (2005) and KMS (2005))

Membrane type

Material Characteristics Membrane life

Ceramic MF/UF

Inorganic membrane constructed of alumina

Robust Handles particles Provides coarse to medium filtration only

5+ years

Tubular NF Polymeric tubes Handles particles Provides finest filtration

2 years

Spiral NF Polymeric sheets Will not handle particles Provides finest filtration Example of application: Treatment of used acid solutions with low suspended solids

1 year

Performance versus cost of various types of membranes for sodium hydroxide recovery is summarised in Table 11.

Table 11: Performance and costs of various membranes for sodium hydroxide recovery (Bolch 2005)

Membrane type

Percentage of cleaning solution

recovered

Life of cleaning solution

Cost

Ceramic UF 60% 2 weeks High cost but longer life: $2100 per m2

Tubular NF 95% 2.5 – 4 months Medium cost: $600 per m2

Spiral NF 95% 2.5 – 4 months Low cost: $260 per m2

It was reported that 20 MF, 5UF and 8NF processes were used worldwide in 1997 to clean cleaning solution in the dairy industry alone (Horton 1997).


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6.4.5.2 Case studies

This section presents various industry case studies as well as scientific work published in the literature in relation to the use of membrane processes to remove soil from cleaning solutions.

The AlkaSave® process is based on a NF-membrane separation, which can operate at a pH range of 1-14 and at temperatures of up to 70ºC. The process is used in the dairy industry and enables a 95% recovery of the cleaning solution, leading to a 95% reduction in water consumption. AlkaSave® is reported to remove 95% of COD and colour, and 80-90% carbonate (Jung and Niederhünigen 1996; KMS 2005).

The AlkaSave® process is used in the brewing industry, where it can remove 90% of the total COD and 80% of the carbonates present in used caustic solutions. This leads to significant reductions in caustic usage, water consumption and effluent volumes. According to the membrane manufacturer, the use of additives, such as antifoaming agents, can also be reduced or eliminated in most cases (KMS 2005).

The AlkaSave® process can also be used for the recovery of acid solutions by removing 80-90% of the calcium (KMS 2005). The reject stream can be cleaned of the remaining salts by diafiltration and subsequently used in stockfeed. The return on investment is reported to be 2 years (Jung and Niederhünigen 1996).

Although not directly relevant to this project, it is worth noting that the AlkaSave® process is also successfully used to clean ion exchanger regeneration solutions from food and beverage processing as well as spent mineral acids in the metal processing and finishing industry (KMS 2005).

Sunkist Growers, a producer of juice in the US, has been using a ceramic Membralox® membrane, from GEA Filtration since 1994 for the treatment of used alkaline cleaning solutions. The daily caustic usage has dropped by more than 40% and “essentially eliminated spent caustic as a waste disposal issue”. The system has been operating reliably for seven years, with no membrane replacement (Bhave et al. 2001).

Another juice and juice by-products producer, Southern Gardens Citrus, USA, also installed a Membralox® membrane (Ultrafiltration). Recovered caustic solution was successfully reused in the plant, after its strength had been adjusted, leading to a 30% reduction in annual caustic consumption. Benefits are also reported in terms of reduced effluent treatment costs and energy consumption. In comparison with the centrifuge previously employed to recover used caustic solutions, the solution is much cleaner (Bhave et al. 2001).

The application of nanofiltration in the dairy and brewing industry has been reported by Bolch (2005). The rejection of active compounds


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(available NaOH) is very low as can be seen in Table 12. On the other hand the NaOH, which is bound to organic soil and thus not longer active, is significantly removed (>85%). Similar trends are seen for the total COD. Additives such as sequestrants are large molecules and are fully removed by nanofiltration, thus the need to re-dose them prior to subsequent cleaning cycles. Nitrogen and calcium, are usually well removed, which is critical to prevent foaming and fouling in subsequent cleaning cycles (Bolch 2005).

Table 12: Rejection of various compounds from sodium hydroxide cleaning solution using an NF plant (Bolch 2005)

CIP system in following applications

Rejection of following compounds

Dairy powder Dairy fat Brewery

Available NaOH <5% <5% <5%

Bound NaOH >85% >85% >85%

Sequestrant 100% 100% 100%

COD >70% >75% >90%

Nitrogen >60% >35% >75%

Calcium >85% >95% >95%

A comparison of MF and UF ceramic membranes for the treatment of cleaning solutions from the dairy industry was preformed using a pilot-plant (Henck 1995). All results showed better organic matter retention with UF than with MF. For protein contaminated cleaning solutions, no decline in flux was observed when using UF as compared to MF. On the other hand, fat contaminated cleaning solutions showed a strong decline in flux when using tighter membranes. An increase in trans-membrane pressure above 2bar or an increase in flow velocity only increased membrane performance for fat containing solutions or when strongly hydrolysed proteins were present in solution (stored or highly heated cleaning solutions). From these results, a 70% reduction in cleaning chemicals was estimated for factories.

Trägårdh and Johansson (1998) used various types of ceramic membranes to investigate the soil removal from used cleaning solutions from the dairy industry. The ceramic membranes used were:

UF membranes with nominal pore size of 20 nm, operated at a pressure of 0.15-0.2MPa


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for dairy evaporators, new nanofiltration membranes with molecular cut-off of 5000 and 1000 Dalton, operated at pressures 0.5-0.7MPa, were also tested

The results obtained using caustic detergents from various sources showed that all sodium hydroxide passed through, while 20% of the complexing agents were retained. High and stable fluxes were observed through the membranes although some scaling issues occurred with high hardness waters and low levels of complexing agents. Some cationic surfactants are problematic for membranes and these solutions could not be filtered.

Overall, the COD retention was between 30-70%, depending on the origin of the cleaning solution and the cleaning agents used. No advantage was found in using smaller pore size membrane as compared to UF. It should be noted that the cleaning efficiency of recovered solution was not tested in this study.

A further comparison of membrane technologies in the dairy industry investigated 0.1µm MF, 300 and 15kDalton UF, Sol-gel and organic NF (Dresch et al. 1999). Both caustic and nitric acid solutions of various strengths (SS between 5 and 1000 mg/L, COD from 100 to 18,600 mg/L, of which 60-83% was soluble COD) from different parts of the plant were tested.

The results show that UF removed 9 to 50% of total COD and more than 99% of SS leaving a clear but coloured cleaning solution after treatment. However, it was found that only a small amount of soluble COD was removed. Short-chained proteins, amino-acids, soaps and lactose by-products were not retained by UF. Some irreversible fouling was observed (Dresch et al. 1999).

Nanofiltration removed more soluble COD than ultrafiltration. It was also found that more than 99% of SS was removed at satisfactory and stable fluxes. Only slight irreversible fouling was observed. The NF permeate was clear and uncoloured. Calcium and phosphorous were efficiently removed (Dresch et al. 1999). The hardness removal is an additional benefit of NF versus MF or UF as it reduces subsequent mineral fouling on equipment (Novalic et al. 1998). A MF-pre-treatment prior to NF was not recommended (Dresch et al. 1999).

With the aim of recovering as much cleaning solution (permeate) as possible and of producing the lowest amount of by-product (retentate), it is recommended to operate the membrane system at high volume retention ratio. The volume retention ratio (VRR) is defined as volume of retentate over volume of solution treated. In the study by Dresch et al. (1999), the VRR could be increased up to 50, leaving 2% of sludge on the retentate side. The downsides of operating high VRR are the increased fouling (still moderate) and increased COD in permeate. According to the authors, a volume retention ratio of 100 should give


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the best outcomes to industries (1% sludge). However, the cleaning efficiency of the recovered cleaning solution would need to be proven (Dresch et al. 1999).

Further work was conducted in the dairy industry on the comparison between a straight reuse system and various configurations of nanofiltration (Dresch et al. 2001). The use of nanofiltration maintained much lower COD levels in the cleaning solution than straight reuse systems. Furthermore, the process configuration where cleaning solution is treated continuously in an external loop attached to the CIP reuse tank was found to be easier to set-up and less expensive than batch systems. This configuration gave good COD removal and slow fouling.

Merin et al. (2002) studied the cleaning performance of reused NaOH solutions after they had been reused a number of times, in some cases up to 400 times. The authors compared:

newly prepared NaOH solutions

untreated used NaOH solutions

used NaOH solutions after MF + NF treatment

The used cleaning solutions had been reused for one week at a dairy plant at 70-80°C. An ultrafiltration membrane fouled with reconstituted whey proteins was used to test the cleaning efficiency of the various solutions.

Merin et al. (2002) found that the cleaning efficiencies of the NaOH solutions that had been reused in the CIP processes were higher than the newly prepared NaOH solutions. In addition the cleanliness of the UF membrane after the cleaning tests had been performed was better for the reused NaOH solutions than the clean NaOH solution. Despite these promising results, the authors recommend further testing to gain further understanding of the physical and chemical phenomena (Merin et al. 2002).

6.4.5.3 Costs of membrane technologies and pay-back periods

Payback periods have been reported by various authors and the results show large fluctuations. Indications of the range are given below but return on investment must be calculated case by case (Novalic et al. 1998). The major influencing parameters are:

Price of caustic, which fluctuates strongly depending on world market demand

Size of the plant

Industry and process type in which the membrane system is installed (including the concentration of the cleaning chemicals in solution)


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A cost calculation has been performed by Bolch (2005) for a plant with a CIP capacity of 50m3/d. The single use system (Table 13) is compared with a recovery system using a nanofiltration, which enables a reuse of the cleaning solution for 3 months (Table 14). The payback period is reported with 3.1 years.

Table 13: Operating costs for a 50m3/d caustic CIP plant – Single use (Bolch 2005)

Item A$ p.a.

Caustic cost (@ $0.40/L) 150,000

Caustic make-up water (@ $0.50/m3) 6,000

Heating cost (@ $2.39/m3) 32,000

Trade waste disposal costs (@ $1.00/m3) 13,000

Total annual costs for single use system 201,000

Table 14: Operating costs for a 50m3/d caustic CIP plant – with NF membrane recovery of used caustic solution (Bolch 2005)

Item A$ p.a.

Caustic cost (@ $0.40/L and with 90 days reuse) 10,000

Caustic make-up water (@ $0.50/m3) 400

Make-up heating cost (@ $2.39/m3) 2,000

Power cost (@ $0.065/kWh) 8,000

Membrane replacement cost 9,600

Additive re-dosing cost 25,000

Total annual costs for NF reuse system 55,000

Total Plant capital cost 410,000

Typical pay-back time 3.1 years


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Due to the economy of scale, the return on investment becomes more favourable for larger CIP systems, as shown in Table 15.

Table 15: Cost analysis summary for various size CIP systems (Bolch 2005)

30m3/d 50m3/d 100m3/d 150m3/d

Total annual costs for single CIP ($)

121,000 201,000 403,000 604,000

Total annual costs for NF reuse system ($)

34,000 55,000 102,000 152,000

Savings ($) 87,000 146,000 301,000 452,000

Total Plant capital cost ($) 260,000 410,000 690,000 880,000

Typical pay-back time (years) 3.3 3.1 2.5 2.2

A wide range of payback periods have been reported in the literature and have been listed below:

In the study conducted by Dresch et al. (2001), which was mentioned above, a 14-year pay-back period was estimated for an NF plant.

Henck (1995) estimated payback periods for an 8m3/d plant using ceramic MF or UF. For 1.5% NaOH solutions, the payback period was 8 years, while for more concentrated solutions (such as from dairy evaporators, 5% NaOH), the payback was reduced to 1.5 year. As discussed above, the authors also expected shorter payback periods for larger plants.

In the case study presented earlier with Sunkist, the annual savings have been estimated at US$135,000, and the payback period was 2 years. For Southern Gardens Citrus, the savings were approximately US$90,000, leading to a payback period of 1.5 year (Bhave et al. 2001)

Bonlac Foods in Cobden, Victoria, upgraded the cleaning solution regeneration plant, leading to $83,000 savings p.a., with a payback period of 2.3 years (Prasad 2004a).


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6.5 Review of possible implementation of CIP recovery technologies

6.5.1 Single use vs. reuse systems

To facilitate the selection of processes that could be implemented in factories, the following section presents a comparison of single use versus reuse systems. While reuse systems require additional pipes and tanks, the benefits of reuse systems are numerous.

Table 16: Comparison between single and reuse systems (Adapted from (Davis 1980; Hamblin 1990; Romney 1990b))

Criteria Single use Reuse

Space Less required Large floor and plant areas required. Long supply and return headers

Simplicity Equipment and control are simpler Equipment and control are complex

Running costs

Water: higher costs

Trade waste: higher costs

Heating: higher

Chemicals: higher

Water: lower, especially if both the main CIP solutions and the post-rinses are reused

Trade waste: lower costs

Heating: lower costs as heat recovery from warm used CIP solution (particularly beneficial for hot CIP)

Chemicals: lower costs. NB: If a reuse system is installed and centralised across an entire plant, the chemical concentration needs to meet the requirements of the most stringent applications and will therefore exceed the minimum requirements in some parts of the plants. Overall however, the chemical needs will be lower than in a single-use system.

Capital costs

Lower Higher


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Table 17 continued

Criteria Single use Reuse

Type of applications

Heavy soil loads (e.g. butter or first few minutes of main cleaning step)

Areas where cross-contamination is a high risk

Plants with large variety of processes and CIP requirements, unless various tanks are used to collect solutions of various strengths and temperatures

Plants with decentralised CIP systems

Applications where blends of chemicals are used with large amounts of additives, which get use in the first cleaning cycle (NB: chemicals can be re-dosed in a reuse system)

Recommended for most applications where

chemical balance of compounds in cleaning solution can be maintained

soil removed during each cycle is reasonably low

6.5.2 Selection summary of reuse treatment technologies

Table 18 summarises the advantages and disadvantages of the various technologies described in the previous sections, as a tool for selection for specific applications. Not mentioned in the table is the fact that for all of these technologies successful applications in large scale systems have been reported.

Table 18: Selection of treatment technology for CIP recovery and reuse

Technology Advantages Disadvantages

No technology: straight reuse

Simple

Cost-effective

Number of CIP cycles before full discharge to sewer: 7 (DPEC 2005)a

Life of NaOH: 3.7 cycles (DPEC 2005) a

Reduction in sodium discharges from CIP: 73% (DPEC 2005) a

No removal of soil from the cleaning solution

Sedimentation Increased cleaning solution quality

Reduced plant downtime

Short payback period

Does not remove soluble COD

Low quality of recovered cleaning solution

Removes only particles with density sufficiently different from that of the medium


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Table 19 continued


Hydrocyclone Simple and reliable operation, low maintenance

No chemicals required

Small footprint

Low capital costs

Very good removal of heavy suspended solids

Slightly better recovery than sedimentation


Removes only particles with density sufficiently different from that of the medium

Centrifuge No chemicals required

Slightly better recovery than hydrocyclones: removes suspended particles down to 5 µm

Number of CIP cycles before full discharge to sewer: 7 (DPEC 2005)a

Life of NaOH: 3.5 cycles (DPEC 2005) a

Reduction in sodium discharges from CIP: 71% (DPEC 2005) a


High capital cost

High energy requirements

Removes particles with density sufficiently different from that of the medium.

Chemical separation

Better recovery than with sedimentation

Lower capital costs than centrifuge

Coagulation does not remove soluble COD

Extreme pH values and temperatures limit the use of some chemical processes

Microfiltration Better soil removal than any of the above systems: removes all suspended solids thus longer life of CIP solution

Usually higher flux than UF and NF

Lower pressure required than for NF

Less loss of cleaning chemical compounds than NF

Ceramic MF are robust, with life spans of 5y+ and can handle particles

Number of CIP cycles before full discharge to sewer: ∞ (DPEC 2005)a

Life of NaOH: approx. 4 cycles (DPEC 2005) a

Reduction in sodium discharges from CIP: ~75% (DPEC 2005) a


Extreme pH values and temperatures limit the use of some membrane materials

High costs of ceramic MF

Higher membrane cleaning requirements than UF or NF


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Table 20 continued


Ultrafiltration Better soil removal than MF as some soluble compounds are removed, thus longer life of CIP solution

Higher flux than NF

Lower pressure requirements than NF

Less loss of cleaning chemical compounds than NF

Ceramic UF are robust, with life spans of 5y+ and can handle particles

Removes only part of soluble COD


High costs of ceramic UF

Smaller flux than MF

Nanofiltration Usually much better retention of low molecular organic compounds present in used cleaning solution as compared to UF. No colour remaining in the treated solution.

NF removes most of nitrogen, phosphorous and calcium, which reduces foaming and mineral fouling during subsequent cleaning

Higher percentage of cleaning than with MF or UF = lower volume of waste (retentate)

Lower initial capital costs than ceramic MF/UF

Number of CIP cycles before full discharge to sewer: ∞ (DPEC 2005)a

Life of NaOH: between 10 and 30 cycles (DPEC 2005) a

Reduction in sodium discharges from CIP: 89-96.6% (DPEC 2005) a


Loss of all additives present in cleaning solution: need to re-dose them prior to reuse of the cleaning solution

Smaller flux than MF and UF

Shorter lifetime of NF membranes compared to ceramic MF or UF membranes

a: Figures from DPEC (2005) are related to CIP solutions from evaporators used in the dairy industry

7 OPTIMISATION OF CLEANING TOWARDS REDUCED CHEMICAL USAGE

Although this was not directly part of the project brief, a third approach to reduce the impact of cleaning chemicals on trade waste discharges is to optimise CIP cycles. Information found during the literature review that was considered to be relevant to trade waste customers is


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presented below. This is not a comprehensive review as it was not the main focus of the work.

There may be opportunities to improve the efficiency of CIP systems by reviewing (Prasad 2004b):

chemicals and blends (refer to section 5)

chemical concentrations

cleaning cycle length

in-line monitoring instrumentation

temperatures

opportunities to recover more rinse water and spent solution

water treatment effectiveness

operator training and supervision

equipment operation and maintenance

7.1 Frequency of cleaning

While many food and beverage plants clean on a daily basis, investigations and site trials have shown the benefits of increased intervals between cleans, without negative impact on product quality and hygienic requirements.

Holm et al. (2002) investigated the efficacy of a 62h cleaning frequency in the manufacturing of ice-cream. Samples were taken from various products and product contact surfaces progressively throughout the time period between cleaning cycles and analysed for microbial growth (Holm et al. 2002). Samples were collected from a silo, fillerhead, flavour vat and liquifier.

Coliform loads in product samples were found to be consistently low over the entire time period. However, standard plate count (SPC) levels increased slightly over time after CIP. There were no significant differences in microbial counts (coliform and SPC) of the product contact surfaces at the various times that the samples were collected (0, 24, 48 and 62h). However, there were significant differences in the SPC microbial counts at the different locations the samples were collected from. They also found that production variables influenced microbial growth during the manufacturing process. A greater number of flavours manufactured in the 24h time interval were beneficial at decreasing SPC microbial counts. However, by the 48h time interval, the number of flavours was at a threshold, and more flavours manufactured increased SPC microbial counts. Holm et al. (2002) concluded that there were no differences in the microbial growth over time at 0, 24, 48, or 62h from


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CIP. Therefore, food safety was not compromised by the utilisation of a 62h CIP cycle (Holm et al. 2002).

7.2 Mechanical action to support cleaning

7.2.1 High pressure spray and mechanical scrubber

Gibson et al. (1999) evaluated other cleaning methods, including a high pressure spray and mechanical floor scrubber. The efficacy of factory cleaning and disinfection programmes were assessed by swabbing and total viable count (TVC) analysis of surfaces before cleaning, after cleaning and after disinfection. Biofilms of Pseudomonas aeruginosa and Staphylococcus aureus were used in the cleaning trials.

The authors found that the high pressure spray and mechanical floor scrubber were more effective cleaning methods, but warned that both methods can be responsible for the spread of contaminants by aerosols (Gibson et al. 1999).

7.2.2 Pigging systems

It is important to remove as much product as possible from pipes before wet cleaning commences to avoid increasing wastewater loads and wasting product (UNEP 2004). ‘Pigging systems’ or low-pressure blowers have shown to be effective at cleaning pipes. A ‘pig’ (solid material plug) is propelled along the pipe to push out the product. Pigs are very useful for the removal of viscous liquids, but usually require specially designed or modified pipe work because the pig cannot get trough pumps or values (UNEP, 2004). Several companies have used pigging systems to great effective.

A jam processing plant in the United Kingdom installed a pigging system to clean its sumps, gulleys and food traps (UNEP, 2004). The amount of water used to flush the pipeline fell from 2020 kL/year to only 310 kL/year, while 173 tonnes of saleable product is recovered annually. It was also found that the COD of the plant’s effluent was reduced by 76%.

Food Spectrum in Queensland, which produces stabilised fruit product, modified their pasteuriser to introduce a new silicon rubber pig that better adhered to the pipe work than the starch pig that was previously used (UNEP, 2004). The company saved approximately 10 minutes of water rinsing per product batch. This amounted to a saving of about $700 per year in water supply and discharge costs. The new system was also responsible for the recovery of $14,600 of product every year.


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7.3 CIP Monitoring

Dodd (2003) described the CIP monitoring system ShurLogger which was developed by JohnsonDiversey. ShurLogger has up to 16 analogue inputs which enables the flow, temperature and conductance to be recorded and displayed. These three variables are considered to be the main variables that show a clean process is operating. The 16 available analogues enable 4 CIP channels to be monitored simultaneously. ShurLogger is very flexible in its set-up, enabling JohnsonDiversey’s technical specialists to configure the device to monitor exactly the operation of vales and pumps on a CIP unit (Dodd 2003). Dodd (2003) reported that several customers in a range of food sectors, including dairy factories, have benefited from using this technology.

7.4 Case studies

Optimisation of CIP systems can lead to significant reductions in chemical usage. Prasad (2004b) briefly presented several case studies about the optimisation of CIP systems at different dairy plants. The case studies include the reuse of water by a CIP system, validation and fine-tuning of a CIP system, and burst rinsing.

For example, a Victorian milk processing plant assessed 15 separate CIP wash cycles (UNEP, 2004). Modifications were made to the Programmable Logic Controller (PLC) programs, pipework/valving and return pumps for each cycle to maximise recovery and reuse of caustic soda. It was reported that caustic usage was reduced by 50%.

In another example, the Taw Valley Creamery reduced cleaning times and detergent consumption by 15% after installing conductivity sensors on all its CIP systems (UNEP, 2004).

The dairy manufacturer Pauls Limited incorporated a central computerised system to manage the CIP systems. The new system enables sensitive measuring and control of CIP and through automation, led to optimisation of CIP cycles (DEH 2001).

Prasad (2004c) reported that National Foods in Morwell, Victoria, identified that cleaning times were above recommended levels after conducting an audit of dosing equipment. Reduction of caustic and acid timer settings did not compromise product quality. The plant also managed to reduce caustic and acid usage by utilising automatic dosing systems and optimising the concentration of chemicals for each different task. This resulted in a saving of $100,000 per year.

Dairy Farmers also conducted an audit of all its CIP processes (Prasad, 2004c). They installed optical sensors to fine-tune water and milk interfaces as well as conductivity and turbidity meters to improve


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cleaning operations. The savings for the plant was estimated to be $211,500 per year.

8 RECOMMENDATIONS FOR FUTURE WORK

Further recommendations for future work are discussed below. These are mainly focusing on the following aspects:

testing identified and promising alternative chemicals,

testing of reuse and recovery systems

optimisation of existing CIP systems to reduce chemical usage

technology transfer to factory representatives

cost-evaluation of the various options

Collection of further information and selection of sites for factory trials

Using information made available from this project and from further data collection, it is recommended to select some food and beverage industrial sites, discharging high salt loads to sewer as a result of their CIP systems and presenting high potential for TDS reduction through identified approaches.

Testing the efficiency of alternative cleaning chemicals

This project has identified a range of alternative chemicals, from low sodium chemicals to enzymes or plant-based products. The use of any of these chemicals by factories is highly improbable unless trials have shown their efficiency on the specific equipment and products used in factories. It is therefore recommended to evaluate the efficiency of alternative cleaning chemicals. This should be carried out in several phases: lab trials followed by pilot-scale trials and large scale trials in factories.

The first task would be to short-list some chemicals that appear to be the most promising for a selected factory. The selection should be based on data collected as part of this report but also on the type of product manufactured and processing equipment used. Consultation with chemical suppliers and factory sites is strongly recommended.

To evaluate the cleaning performance in the laboratory, a piece of equipment representative of factory processes should be used. It should then be fouled with product originating from the factory or with a model product. The efficiency of selected alternative cleaning chemicals should then be tested. A preliminary evaluation of costs and environmental


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benefits could then be performed in terms of reduced TDS and sodium loads. The results should be made available to the industry.

Based on the results of these laboratory experiments, a restricted number of chemicals should be selected for factory trials. An experimental protocol should be developed in collaboration with operational staff from the selected factory site, while the factory area should be prepared for the investigations (addition of valves, sampling points, flow meters etc.).

The cleaning efficiency of alternative cleaning chemicals would have to be tested in comparison with conventional products used on site. The parameters to consider in the performance evaluation are:

anticipated operational/capital cost-benefit

reduction of trade waste TDS (and sodium) load

reduction of water consumption (compared with existing on-site practices)

reuse potential of treated effluent

residue risk (including product and environmental impacts)

regulatory risk


Corrosion issues: in-factory, sewer infrastructure and treatment processes

Once the trials are completed and the performance evaluated, the results should be communicated to industry operational staff and other factories that could benefit from the outcomes of these investigations.

Reuse of cleaning chemicals (with or without recovery technologies)

According to the case studies presented in this report, the reuse of used cleaning solutions (with or without recovery technologies) can lead to significant reduction in chemical usage. The possibilities for straight reuse of used cleaning solutions should be explored first.

The possibility to collect used cleaning solutions for reuse in other “less demanding” process sections with lower hygienic requirements should be considered too. The notion of “fit-for-purpose” can lead to chemical savings too. Furthermore, the use of recovery technologies presented in this report should be considered for some sites.

Following these considerations, an experimental protocol for testing of these technologies in selected factory sites should be developed in collaboration with operational staff. After preparation of the site, experimental trials should be conducted. The performance evaluation of the trials should be based on the following criteria:


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anticipated operational/capital cost-benefit

reduction of trade waste TDS load

reduction of water consumption


Corrosion issues: in-factory, sewer infrastructure and treatment processes

Once the trials are completed and the performance evaluated, the results should be communicated to industry operational staff and other factories that could benefit from the outcomes of these investigations.

Optimisation of CIP cycles through engagement and training of industry operational staff

Engaging factory staff has proven to be a key element to improve CIP operation. It is recommended to conduct a training program for interested industry operational staff, focusing on techniques to optimise CIP cycles. The factory staff should be encouraged to identify and conduct small trials relevant to their site between the training sessions. Site visits or demonstrations could also be a useful tool to promote best practice in CIP management.

Outcomes and findings from this report should be disseminated to the wider industry. For this reason, a cut-down version of this report has been prepared focusing on case studies from industry. It is recommended to circulate this document widely.

9 ACKNOWLEDGMENTS

The project team would like to thank

City West Water, and in particular Mr Nigel Corby, for initiating and supporting this project

The companies that provided input into the project

The chemical suppliers for supplying information on chemicals, including low sodium chemicals, and

Mr Craig Bolch and Mr George Lech for making information available for this project


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APPENDIX C.1 ACIDS AND SANITISERS

ACID DETERGENTS

Name Composition Recommended ConcentrationCase Studies Industry sector Applications Comments

DairyChem RS-105 (or Steel Bright)

Phosphoric acid: 10-30%Nitric Acid: 20-70%Surfactant: <10% Dairy plants

Divos 2Nitric acid < 35%Phosphoric Acid < 15%

0.5-1.0% w/wTemperature: 50-60ºC (65ºC max.)Contact time:30-90 mins with recirculation Dairy Acid cleaning for MF, UF & RO membranes

ReclaimableRemoves calcium based scales, including milkstone & beerstonePenetrates soil matrices & dissolves inorganic scale components and acid soluble proteins

Divosheen 209Nitric acid: 30-60%Phosphoric acid: 0-10% 0.5-2.5% w/w

Food industryBeverage industryDairy plantsBrewery industry

Used prior to or after a caustic wash to remove difficult inorganic or organic soil deposits

Reclaimable (specially designed for reclamation)Can be used as a detergent in its’ own right on some soilsLow foaming product

Divosheen Dilac Phosphoric acid < 35%

0.6-2.4% w/wManual Milkstone removal: brush method – diluted 3-4 parts water soak treatment – use 1% v/v at 60ºC circulation cleaning – use 0.5-2.0%v/v for 20-30min

Food, beverage, meat and dairy industry Cleaning, de-scaling & de-rusting processing equipment

Easy removal of heat modified soil & scale controlLow foamingNot reclaimable

Divosheen shiftSodium Bisulphate 15-30%Sulphamic acid 60-100%

0.5-1.0% w/w for 25-30 mins at 75-90ºC0.5% w/w normally sufficientMay be preceded by an alkali wash Dairy plants

Specifically used for circulation cleaning on milk processing equipment in dairy factories

ALTERNATIVE ACID DETERGENTS


Citrajet

Citric acid (10-30%)Phosphorus compounds < 1%Organic Carbon (%w/w) – 14%Blend of organic acids and surfactants 1-2 % solution (10-20 mL/L) Dairy industry Used to clean dairy equipment, pipes, tanks, boilers, reactors

Concentrated – saves moneyPhosphate free, biodegradable, readily disposableRemoves metal oxides, salts, inorganic residues

Citranox

Citric acid (10-30%)Blend of organic acids, anionic and non-ionic surfactants and alkanolamines. Organic Carbon (%w/w) – 17% Phosphate free. 1-2 % solution (10-20 mL/L) Food industry Used to clean dairy equipment, pipes, tanks, boilers, reactors

Concentrated – saves moneyPhosphate free, biodegradable, readily disposableLow foamingRemoves metal oxides, salts, inorganic residues

Enviroscale

Citric acid, anhydrous <2%Lactic acid <2%Surfactant <1% For typical applications dilute 1:10 1 boilers, pipework, heat exchangers and wet scrubbers

No caustics, phosphates, strong acids, ammonium compoundsHigh performance, non-toxic, non-hazardous, biodegradable productClean equipment while in operation – saves shutdown time, loss of production, labour costs

COMBINED ACID DETERGENTS and SANITISERS


DairyChem CS-111 (or Iodosan)

phosphoric acid <10%Non-ionic surfactants 10-30%Available Iodine <10% Acid detergent + sanitiser

ReclaimableNon-foaming: allows free rinsing & better solution controlVersatile: used hot as a cleaner/sanitiser, or cold as a sanitiser after alkali clean

DairyChem RS-108 (or Acid-Quat)

Phosphoric acid >10%Quat ammonium compounds >10%Organic acid >5% Dairy plants Milkstone remover and sanitiser

ReclaimableWater & time saving – no need for potable water rinseStone remover / sanitiser saving a further 2 steps in cleaning cycle

Divosan DividendPhosphoric acid 30-60%Anionic surfactant 5-10%

0.35-0.6% w/wUsed as a final rinse for CIP applications at 0.3% v/v after alkali clean

Food processing operationsDairy operationsBrewery operationsBeverage operations

Acid detergent + sanitiserStable in cold or hot water

Divosheen No. 5Phosphoric acid < 25%Surfactants < 10%

0.35-1.2 w/wSanitiser only: - use 0.3-0.5% v/v from ambient to 70ºC, recirculate for 5mins & reclaimCleaner/sanitiser – use 0.5-1.0% at 60-70ºC on white milk areas, circulate for 10-15mins & reclaim 1 Dairy plants

Acid cleaner and sanitierUsed hot as a cleaner/sanitiser, or cold as a sanitiser after alkali cleanRemoval of dairy soils, milkstone & hard water scale

ALTERNATIVE COMBINED ACID DETERGENTS and SANITISERS


Envirowash No phosphates or nitrates

0.25% v/v with hot water and circulate at 60-70ºC for 5-10 minutesA periodic wash Chlorozolv is recommended as an alternative cleaning regime Dairy plants

Acid detergent + sanitiserStainless steel & rubber surfaces exposed to cold milk Increased wetting and wide spectrum germicide for sanitising

Iodosan (Triple 7)IodineIodophor

Iodine concentrations with 25-75 ppm available iodineFor sanitizing dilute Iodosan 1:500

Abattoirs Dairies Livestock/Poultry FarmsWineries Acid detergent + sanitiser

Excellent cleaning abilityVery safe, user friendlyFood compatible and leaves no residual taste

APPENDIX C.1 …/continued

SANITISERS ONLY

Name Composition Recommended Concentration Case Studies Industry sector Applications Comments

Dairy Cleaner & Sanitizer

n-Alkyl dimethyl benzyl ammonium chlorides = 5%n-Alkyl dimethyl ethylbenzyl ammonium chlorides = 5%ammonium chlorides = 90%

For sanitizing clean surfaces and equipment add 1 ounce to 4 gallons of water

food, dairy, beverage, meat, poultry, egg and seafood processing plants

safe to use kills bacteria, yeasts & mouldseffective in hard or soft waterNot reclaimableNot recommended for use on aluminium

Disinfectant/Sanitizer

n-Alkyl dimethyl benzyl ammonium chlorides = 5%n-Alkyl dimethyl ethylbenzyl ammonium chlorides = 5%inert compounds = 90%

To sanitize pre-cleaned and potable water-rinsed surfaces prepare200 ppm active solution by adding ounce to 4 gallons of water

bakeriesfood processing plantsdairiesegg and egg product processing plants

Wide antibacterial and anti-microbial spectrumNot reclaimableAvoid prolonged contact with aluminium & galvanised surfaces

Divosan HypochloriteSodium Hypochorite < 15% Cl activeNa: 3.9% w/w

0.15-3.5 w/wCirculation cleaning of equipment: 3mL/L.Final rinse sanitising: 12mL/LProtein removal in acidified boiling water plants: 30mL/L

Most powerful biocides – affective against yeasts, moulds, fungi, bacteria & spores also virusesNo foam therefore ideal for CIP situationLower BOD/COD in trade waste outlets

Divosan Safsol

Inorganic sodium hypochlorite & bromide saltsChlorinated Phosphate Salt 60-100%Na: 41% w/w 0.3-0.5% w/w 2

Bakeries, BreweriesBeverage plantsCanneries, DairiesEgg breaking, PoultryConfectionary plantsMeat packers, Fish packersWineriesOther food processing plants

proven antimicrobial & biofilm propertieseffective over a large pH range & in the presence of organic load.Not reclaimable

Jonclean 210 Phosphoric acid <60% 2-4ppm Used to activate Jonclean 410

ultra high antimicrobial activity, incl biofilmeffective over a broad pH range (1-10)resists neutralisation due to organic loadNot reclaimable

Jonclean 410Available chlorine dioxide – 2.0-2.2%Na <1.3% w/w 2-4ppm

PerformPeracetic acidHydrogen peroxide 1 Oxidative sanitiser

Proxitane

Peracetic acid <10%Hydrogen peroxide <30%Acetic acid <10% 0.25-1.25% w/w

Brewery plantsBeverage plantsDairy plants

Single use applications – ambient temperatures to 70ºCFinal sanitising in the brewery, beverage & dairy plantsIdeal for breweries using cleaning under CO2 top pressure Can be environmentally hazardous to lakes, rivers, ponds, etc.

APPENDIX C.2 ALKALI AND REPLACEMENTS

ALKALI DETERGENTS with HIGH SODIUM CONTENT

Name Composition Recommended ConcentrationNa level in ready-to-use cleaning solution

[gNa/kg cleaning solution] Case Studies Industry sector Applications Comments

Divoflow GlotakSodium Hydroxide <85%Na content: 24.8% w/w

1.0-3.0%w/wCold milk – use at 0.5% NaOH at 60-70ºC for 10-15 minHeat exchangers – use at 0.5-1.0% NaOH for 20-30 minEvaporators – use at 1-1.5% NaOH for 1h at reduced vacuum 2.48 - 7.44

Dairy plantsBreweriesBeverage industryProcessed food industry

ReclaimableLow foaming – excellent for CIP & spray washing applications

Divoflow GTP

Sodium Hydroxide 60-100% (Na: 52% w/w)Alkaline Salts 1-10%Phosphates – 0.76% as P 0.7-1.2% w/w 3.64 - 6.24

Dairy plantsBeverage industryFood processing industry

Formulated for circulation cleaning of dairy, beverage & food processing equipment, with medium to heavy soilsHeat exchangers & food equipment

ReclaimableExcellent rinsability, low foam generationFormulated to prevent scale build-up, resulting in less motor drag & more efficient heatingRequires no additives as it is a full formulated caustic detergent

Divoflow HE

Sodium Hydroxide 30%Na content: 17.25% w/wHighly wetted and sequestered

Wort complexing vessels & lines: 2-5% v/v & circulate @ 60-80ºC for 20-30minEvaporators: 3% v/v & circulate at norm. cleaning temps for 30-60minPasteurisers: 2% v/v & circulate at 60-80ºC for 15-20minCold milk: 0.4-0.6% v/v & circulate at 60-80ºC for 15-20min 0.86 - 6.9

Dairy plantsBreweriesBeverage industryProcessed food industry Stable in hot or cold conditions

ReclaimableHighly sequestered – to remove inorganic soil, protein and other organic soilsHighly wetted – surfactants provide better penetration and easier rinsing, saving time and waterLow foaming

Divoflow Whirl

Sodium Hydroxide 30-60%Na: 45.5% w/wAlkaline Salts 30-60%Sodium Dichloroisocyanurate 0-10% 0.3-1.2% w/w 1.37 - 5.46 Dairy farm and dairy processing

CIP on dairy farms & dairy processing equipmentCirculation cleaning of dairy farm, milking shed equipment with medium to heavy soil loads

ReclaimableContains sequestering agent to effectively prevent scale formation.Should not be use on aluminium or soft metals

Food Plant Degreaser

Sodium hydroxide (%wt) = 5%Sodium metasilicate anhydrous (%wt) = 5%Na >=4.8%

Light soil conditions – 10:1 with waterMedium soil conditions – 5:1 with waterHeavy soil conditions – straight 4.8 - 48 ?

meat processingpoultry processing

For use in soak, spray on, steam and mechanical devises in meat, poultry and processing establishments

100% biodegradableWater solubleContains no hazardous ingredientsContains enzymes

Food Plant Degreaser "concentrate"

Sodium hydroxide (%wt) < 20%Sodium metasilicate anhydrous (%wt) < 20%Na < 19.2%

Light soil conditions – dilute 1 part cleaner to 10 parts waterMedium soil conditions – dilute 1 part digester to 5 parts waterHeavy soil conditions – use straight 19.2 - 192 ?

bakeriesmeat packerspoultry processesbottling plants

For use in bakeries, meat packers, poultry processes, bottling plantsCan be used for food processing and wrapping machines

Saves money and shipping costsConcentrated form of the regular Food Plant DegreaserContains enzymes

Galaxy HE

Sodium Hydroxide 30-60%Na: 17.25% w/wHighly wetted and sequestered

0.5-4.0% w/wEvaporators: 3% v/v & circulate at normal cleaning temperture for 30-60minPasteurisers: 2% v/v & circulate at 70-80ºC for 30minCold milk: 0.4-0.6% v/v & circulate at 60-80ºC for 15-20min 0.86 - 6.9 Dairy plants

Stable in hot or cold conditionsEvaporators, pasteurisers & other heat exchange surfaces

ReclaimableHighly sequestered – to remove inorganic soil, protein and other organic soilsHighly wetted – surfactants provide better penetration and easier rinsing, saving time and waterLow foaming

Spectak PSodium Hydroxide 60-90% (Na: 52% w/w)

0.3-1.2% w/wBottle washing – remove any scale, use 3% in the main soak tank of multi-tank machine & in the soak tank of Soaker-hydro machines 1.56 - 6.24 Food processing industry Heavy duty detergent for food processing industry

ReclaimableShould not be used on aluminium or other soft metals

SU193 Cipmax

Sodium Hydroxide 30-60%Disodium Metasilicate 0-10%Na: 40% w/w 1.0-2.0%w/w 4 - 8

ReclaimableHighly efficient Low foaming & can be used in all CIP systems

ALKALINE CLEANERS with MEDIUM SODIUM CONCENTRATION



Chlorozolv

20% w/v as sodium hydroxideActive chlorineStable chelating and dispersing agentsNa content >= 11.5%

0.3-0.5% w/v NaOH (1:66-1:40 v/v) & circulate at 50-60ºC (not above 70ºC) 1.7 - 2.9

Dairy farms & factories Meat industryFood industries

Use for cleaning stainless steel plants in dairy & food industriesFood processing equipment, silos, pipelines & heat exchangersPeriodic cleaning of long-term protein fouling on stainless steel plant

Low foamExcellent protein dissolving power Bactericidal propertiesEffective milkstone removal

Suma Ilam L1.8

Sodium Hydroxide < 30%Sodium Hypochlorite < 4% available chlorineNa: 12.6% w/wScale inhibitors, caustic alkali & chlorine bleach 0.5-1.5% w/w 0.63 - 1.89 Dishwashing

ReclaimableIntensive cleaning action to rapidly remove fats, starch & proteins and tannins

LOW SODIUM ALKALINE CLEANERS



Diverwash VC24

Na: 1.8%w/wWetting agents, buffering agents, sequestrants & dispersants 0.12-2.1% w/w 0.02 - 0.38

Food industryBeverage industryMeat industryDairy industryConfectionary industryAirline service industry CIP and spray washing applications

ReclaimableSafe for use on soft metals, eg aluminium & galvanised mild steelLow foaming & therefore suitable for use under conditions of high turbulence & high pressure

Flowsan

Sodium hydroxide 5-15%Sodium hypochlorite 5-15%Chlorine-based bleaching agents 5-15%Polycarboxylates <5%Na: 3.1% w/w 0.4-1.8% w/w 0.12 - 0.56

Beer & other beverage industry Dairy industry Processed food

Used at temperatures ranging from ambient to 50ºCBrewing & beverage applications in fillers, sugar/syrup tanks, open vessels, yeast handling & filtration equipmentSingle stage cleaning in milk reception for dairiesCIP of freezersDrain cleaning in processed food

ReclaimableLow foaming under high turbulence excellent detergency, soil suspension & disinfection properties for spray washing & CIP

Glide

Alkaline Salts <20%Sodium Hypochlorite solution <3%Sodium Hydroxide <2%Na: 5%w/w

0.8-1.6%v/v @ 50ºC for 30-45minsRemoval of heavy soils: use 1.6%v/vRemoval of light soils: use 0.8% 0.4 - 0.8 Butter plants

Automatic butter makers, butter churns, trolleys & associated equipment & pipe work

excellent protein, fat & grease removal propertiescontains silicate to give after cleaning ‘slip’ on butter making surfaces; increases production hard water tolerant thus ensuring scale free equipment & improved operational efficiencyfoaming properties ensure that all surfaces including internal, of the butter maker are thoroughly cleaned


ALKALI DETERGENTS with UNKNOWN SODIUM CONTENT



Avoid Caustic alkaline cleaner 10 to 50 mL/L (at 60ºC-65ºC) unknown

DairyBeverageBrewery Food industry

Fully formulated alkaline detergent which minimises or eliminates acid cleaningContains sequestrants to disperse and prevent scalingContains surfactants to assist in wettingLow foaming

CIP-Safe Alkaline salt detergent 0.5 – 3.0% v/v unknown Food industryDeveloped to clean all types of food and beverage soils and scale including tannin stains, fats, oils, milk, brewery soils and scale

EconomicalRemoves fats and proteins effectivelyContains chelating and anti-deposition agents to maximise efficacyCan be used in soft to very hard watersLow foamingChlorine, caustic and phosphate freeEffluent does not require neutralization

Glissen Heavy duty liquid alkaline detergent

Heat treatment units – 10-40 mL/L of water at 75ºC for 10-40 minutesCold milk vessels, tankers, etc. – 10-20 mL/L of water at 65ºC for 10-12 minutesBottle washing - refer to Technical appraisal supplied by Ecolab unknown

Used to clean equipment such as pasteurisers, cream treatment units, vacuum pans, concentrators, milk and beverage holding tanks cheese making machines and other equipment cleaned by automatic CIP cleaning systems

Rapid soil penetrationPrevents mineral scale formationLow foaming

POTASSIUM / SODIUM BLENDS


Detojet

Potassium hydroxide (7-13%)Sodium silicate (5-10%)Sodium hypochlorite (1.5%) 0.5-1% solution (5-10 mL/L) Food industry Used to clean industrial parts, tanks, reactors

Concentrated – saves moneyBiodegradable and disposableLow foaming heavy duty detergentFree rinsing

Profile

Potassium hydroxide <5%Sodium hypochlorite <5%Sodium hydroxide <5%Phosphates, chlorine-based bleaching agents <5%Na: 5.2% w/w

0.5-1.5% w/w (0.4-1.3% v/v) at ambient to 50ºC for soak applications & at 50ºC for 10-20mins for CIP milk tanks, tray washing and packing machines Meat processing industry

Used at ambient to 50ºC for soak applicationsUsed at 50ºC for CIP and spray washing applicationsUsed at 40-50ºC for CIP of milk tanks and packing machinesUsed in meat processing industry for mechanical soak cleaning & tray washingHeavy duty applications

ReclaimableExcellent protein removal properties Low foaming under high turbulence

Redes

Disodium/dipotassium metasilicate <5%Sodium hypochlorite <5%Phosphates 15-30%Chlorine-based bleaching agents <5%Na: 4.4% w/w

0.3-1.2% w/w (0.5-1%v/v) at ambient to 50ºC for soak applications and at 50ºC for CIP and spray washing applications Food and beverage industries

Used at ambient to 50ºC for soak applicationsUsed at 50ºC for CIP and spray washing applicationsUsed at 40-50ºC for CIP of milk tanks and packing machinesCIP and spray washing applications across the food & beverage industriesUsed in meat processing industry for mechanical soak cleaning, soft metal safe spray washing & CIP of freezersPacking machinesMilk tanks

ReclaimableLow foaming under high turbulenceExcellent protein removal propertiesUse on polycarbonate & PET bottles, containers & mould cleaning

POTASSIUM BASED CLEANERS


DairyChem (or Alka-San Potassium)

Potassium hydroxide >50%Surfactants <10%Chlorinated Agent <10%Sequestrant <20% 0.2-0.6 % w/v Soft metal safe

DairyChem HT 108 (or Dairy Alkali-Potassium Hydroxide Solution)

Potassium Hydroxide: 50%Sequestrants <5%Surfactants <5% 0.5-3% in water at an elevated temperature Dairy Soft metal safe

Divos 100

No sodiumCaustic potashChelating agents & surfactants 1.0-2.5% w/w UF & RO membranes (depending in type)

No sodiumNot compatible with soft metals such as aluminium or zinc

Divos 110No sodiumPotassium Hydroxide <5%

1.2-2.4% w/wFor 11-11.5 pH tolerant membranes – use at 1-2% v/v at 55-75ºC circulated for 20-40mins, with 120ppm chlorine

Dairy applicationsBeverage applicationsPharmaceutical applications Cleaning chlorine stable UF & MF membranes

No Sodium (potassium based)Highly effective removal of protein & fat build-up, & prevents scale build-upTested to be safe to use on all chlorine stable UF & MF membrane types

Solo

Potassium hydroxide 15-30%Tetrapotassium ethylenediaminetetraactetate 15-30%Diethylenetriaminepentaacetic acid (pentasodium salt) <5%EDTA 5-15%Anionic surfactants, phosphonates, non-ionic surfactants, phosphates <5% 0.5-2.5% w/w (0.4-1.8%v/v) at temperatures ranging from 60-90ºC

Food industryBeverage industryVegetable processing

Used at temperatures ranging from 60-90ºC depending on the applicationCold surfacesDairy: HTST, heat treated surface, homogenisers, storage, mixing & ageing tanks used in ice cream manufactureWide range of applications across food & beverage industries, e.g. vegetable evaporators in processed food plants

ReclaimableHighly effective if very high levels of protein & calcium soilingLow foaming, Suitable for use in CIP systems under condtions of high turbulence

Superquest

Potassium hydroxide >=30%Tetrasodium ethylenediaminetetraacetate 5-15%EDTA 5-15%Phosphonates <5% 0.5-3.0% w/w (0.4-2.1% v/v) at temperatures ranging from 55-80ºC Dairy industry

Used at temperatures ranging from 55-80ºC depending on the applicationHighly effective at removing heat-treated organic & inorganic soils in single stage CIP

ReclaimableLow foaming & suitable for use in CIP systems under conditions of high turbulenceCan be used for crate washing in soft water areas, where high causticity is required


ENZYME-BASED CLEANERS


Cipzyme P Contains proteolytic enzymes 0.5 – 1.5% v/v in water at temperatures up to 60ºC

Dairy industryAbattoirsPoultry industryFood processing industries All situations where proteinaceous food soils need to be cleaned from equipment

Does not contain caustic or sodium hypochloriteSafe to use on all surfacesContains buffering agents to maintain cleaning solution at pH optimum enzyme activity

Divos 80-4 Enzyme cleaner0.5-1.0% w/wUse maximum of 1% v/v in conjunction with Divos 100 or 110

UF & RO Membranes in conjunction with Divos 100 or 110, alkaline membrane cleaners Not reclaimable

Paradigm

Protease cleaner0.8% P20100.9% P2030 3

Properase 1600LProtease enzyme (liquid)Subtilisin (1-5%) Used in the cleaning industry

PURADAX EG 7000LFungal cellulase enzyme (liquid)Cellulase (1-5%) Used in the cleaning industry

Purafect 4000EProtease enzyme (granulated)Subtilisin (1-5%) Used in the cleaning industry

Purastar ST 15000LBacterial alpha-amylase enzyme (liquid)?-amylase (1-5%) Used in the textile industry

Reflux E 2001

Enzyme cleanerNH compounds >60%Subtilsin (CAS 9014-01-1) <10% Incompatible with oxidising agents

Tergazyme

Protease enzymeSodium dodecylbenzenesulfonate (10-30%)Sodium carbonate (7-13%)Sodium phosphate (30-40%) 1% solution (10 g/L) Food industry

Used to clean dairy equipment, reverse osmosis and ultrafiltration membranes, manufacturing equipment, tubing, pipes, process equipment, tanks, reactors

Concentrated – saves moneyBiodegradable and readily disposableReplaces corrosive acids and hazardous solventsFree rinsing

Zymex Enzymatic Cleaner

Enzymatic cleaning solution concentrateAqueous mixture of enzymes and surfactantsIsopropyl Alcohol (<10%)Triethanolamine (<10%)

ALTERNATIVE CLEANERS


4171 TRITON X-100

Diethylene ether,1,4-dioxane (?)Ethylene oxidePolyethylene glycolTriton X-100 General purpose detergent

ActisolveIdeal solvent for removing gum, adhesives, silicone, dried lubricants, fuel, urethane sealants.

Citra-Solv

Concentrated d-limonene based product 80-95 wt% limonene fraction terpenes1-10 wt% ethoxylated alcohols C9-C111-10 wt% coconut diethanolamide 9 Manufacturing Degreaser

BiodegradableConcentratedDerived from renewable sourceNon-carcinogenic

Colloidal Concentrate

Non-ionic surfactant, as alcohols C12-16 ethoxylated 5%Tall oil fatty acids 0.5%Organic butter, as sodium iminodisuccinate 0-1% 5

Used in all types of machine applications such as soak tanks, manufacturing, process cleaning, pressure washers, steam cleaners, closed cabinets, ultrasonics and centrifugal machines.

Free of caustic, solvents and hazardous materialsNon-aromatic, no VOCsReadily Biodegradable

Concept C20

Evaporator & UHT Cleaning: 1.0 - 3% w/v Separators & Pasteurizer: 1.0 - 2% w/v Silos, Lines & Tanks: 0.5 - 0.8% w/v Concept C20 can be used at approximately 30% lower strength than a solution of Sodium Hydroxide 1 Dairy plants

milk evaporator; underneath disperser plates, the internal walls of separator bodies and inside vapour ducts

Ability to clean in the vapour phaseSuperior environmental performance & superior CIP effectiveness and performance comparatively to NaOH

EASY-CLEAN Rig WashAlkyl aryl sulfonates & buildersNonhazardous blend (100% wt) Meat and poultry Detergent concentrate for cleaning oilfield & industrial equipment

Food Process Cleaner Ethylene Glycol Monobutyl Ether (%wt) < 15%

General cleaning – dilute 1 part in 20 parts waterHeavy-duty cleaning – dilute 1 part in 4 to 10 parts waterSoak tanks and mechanical cleaning – dilute 1 part with 20-50 parts water

canneriesdairiesbakeries,seafood processing plantsbottling plantsred meat processing plantspoultry processing plantsbreweries General surface cleaner

BiodegradableDissolves greasy grimeKeeps food preparation areas free from grease build up

Heavy Duty

Surfactants < 5%Tall oil fatty acids <5%Succinimide <5% 1

Dairy farmsFood preparation

Degreasing agent, surfactant, cleanerMilk stone from vat and pipework

Readily biodegradable Reduction in use of sanitizersCleaning can run at lower temperatures

Supersolve Tall oil fatty acids Removes stains and vegetable fats from equipmentReusable and filterable to 0.01 micronsNon-hazardous

APPENDIX C.3 ADDITIVES TO CAUSTIC

CAUSTIC ADDITIVES


Booster

hydrogen peroxide >=30% oxygen based bleaching agents >=30% phosphonates <5%

0.1% w/w (0.9%v/v) dosed into the dilute caustic solution Ambient to 70ºC Used at ambient temperatures to 70ºC

ReclaimableWhen added to blended caustic detergents, improved detergency therefore shorter cleaning times

Complex

Tetrasodium ethylenediaminetetraacetate 15-30%Tetrapotassium etylenediaminetetraacetate 5-15%Dipotassium metasilicate <5%Trisodium nitrilotriacetate <5%

0.3-2.0% w/w (0.2-1.5% v/v) depending on application, soiling and water hardnessTo be added to dilute caustic (0.3-2%w/w) solutions in CIP recovery tankHTST: 0.3-1%w/wFor evaporators: 1-2%w/w

Food industryBeverage industryDairy plants

Single stage CIP recovery systems, eg for evaporator & HTST installationsBrewhouse CIP, beerstone removal and mould removalUsed with caustic for single stage cold surface cleaning of bioenzymatic applications

ReclaimableLow foaming in use, hard water tolerant & highly effective in the removal of milk soils

Defoamer

Alkoxylate surfactantEthanol 30-60%Ethyl alcohol

No recommended concentration, starting point of 20ppm suggestedDosing every 2-4h is typical

Food industryBeverage industry

Useful in aqueous solutions above 34ºCFor use in caustic bottle washing & CIP solutions in food & beverage industries Reclaimable

Divo 1040Sodium hydroxide <10%Na: 5.3% w/w

16-32% w/w<150ppm hardness – use 11L to 100L caustic(50%) = 1part of Divo 1040 to 6 parts caustic (solid) w/w >150ppm hardness – use 22L to 100L caustic(50%) = 1part of Divo 1040 to 3 parts caustic (solid) w/w

Bottle washing CIP and spray cleaning Reclaimable

Divo 400 Na content - 8% w/w 0.65-1.35% w/wPre-clean fryer tank: 0.5-1.0% v/v at 90ºC

Can be used up to 90ºC (rolling boil)Fryer belts Reclaimable

Divo HE

Blend of sequestrants, low foam surfactants & soil suspending agentsAliphatic amines & derivatives < 30%Na: 8.8% w/w 1.0-2.5% v/v

ReclaimableSequestered & wetted – enables organic & inorganic soils to be removed simultaneouslyImproved cleaning – provides superior results at reduced caustic concentrationsImproved rinsing – highly effective low foam surfactant system reduced rinse time, saving on water & effluent costs

Divo MR

Tetrasodium ethylenediaminetetraacetate >= 30%Trisodium nitrilotriacetate < 5%Sodium hydroxide < 5%EDTA 15-30%Nitrilotriacetic acid < 5%

0.1-1.0% w/w (0.08-0.8%v/v) depending on soiling, scale and water hardness

Food industryBeverage industryDairy plantsBrewery industry

Used across food & beverage industries as a secondary additive for bottle washing & CIP

ReclaimableSuitable for the removal of calcium oxalate (beer stone) & calcium phosphate (milk stone)Highly effective in removing mould, fungi & larvae in bottle washing applicationsSignificantly enhances detergency, improving cleaning performance

Divo Peroxy

hydrogen peroxide >=30%alkyl alcohol ethoxylate, modified <5%oxygen-based bleaching agents >=30%non-ionic surfactantsphosphonates <5%

0.3-0.5% w/w (0.3-0.4%v/v) dosed into dilute caustic detergent solution at 70-80ºC

Brewing kettles Brewhouse equipmentDairy Processed food Used at temperatures between 70-80ºC

ReclaimableWhen added to blended caustic detergents, improved detergency therefore shorter cleaning times

Divos ADD 3

Alkylbenzene Sulfonic Acid >95%Sulfuric Acid <5%Sulfur Dioxide <1%

0.03-0.1% w/wUse 0.03-0.05%w/w in combination with Divos 108 on NF & RO membranesUse 0.03-0.1% w/w in combination with Divos 110 on UF & MF membranes

Dairy plantsFood industryBeverage industry

MF, UF, NF and RO membranesDairy applications where fat and proteins are a problem

Highly effective with Divos 110 for MF membranes, chlorine stable UF membranes & high temperature tolerant UF membranesChlorine stable:ability to be used with other Divos products to improve protein removal & other organic soiling from membranes, reducing the number of steps & saving timeNot reclaimable

Eliminator Blend of chelating & sequestering agents

1) dosage to dilute caustic solution (0.5-2.0% v/v): 0.25-0.4%v/v2) dosage to concentrate alkali chemicals: add 1.5L of Eliminator to every 2L of concentrate caustic/caustic blend dosed

Dairy plantsFood processing industryMeat industry

Light to medium soil areas in dairy & food processing plants, e.g. cold milk handling area, silos & general line CIP duties, separators, pasteurisers, cream chillers & cheese make tanks.Single stage cleaning of milk powder drier concentrate feed lines

One step CIP additiveEnhances soil removal from hard surfacesReduces water consumption, acid usage, cleaning time & effluent volumes

Enhance0.1-0.5% v/v into dilute caustic soda CIP solution at 50-80ºC 1 Dairy plants

milk protein removalRemoval of calcium scale

Low foam, Active defoamerOne step additiveIncreased CIP performanceSafer handling: Not classified as a dangerous good

Fomex Delta Can be used at temperatures ranging from 14-80ºCReclaimableConcentrated product that prevents foam

Stabilon CIP

Combination of complexing agents, wetting agents, anti-foaming agents, cleaning activators and emulsifiers

General purpose/cold milk area – 0.1-0.5% at 65ºC-85ºCHeavily polluted/pasteurisers – 0.3-1.0% at 75ºC-85ºC 1

Dairy, brewing, beverage, fruit and potato processing industries

Used to clean tankers, filling machines, cheese production equipment, pasteurisers

Excellent stone removing propertiesVery good cleaning results with fatty production residues Re-using the cleaning solution is possibleNo necessity for acid cleaning to follow the alkali

Stabilon HAContains a blend of surfactants, builders and water conditioners Add 1kg Stabilon HA to 20 kg of 50% caustic soda Cooling equipment, filtration tanks, CIP circuits

Removes complex beer kettle soilsEmulsifies fatty resins and oilsEnhances biocidal properties of caustic cleaning solutionDoes not corrode stainless steelLow foamingLow use rateReduces cleaning time at a lower temperature

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