MEDRC

MEDRC Series of R&D Reports MEDRC Project: 97-BS-018

ZERO-WASTE DESIGN DEVELOPMENT AND PERFORMANCE EVALUATION FOR SMALL

HOME-USE RO UNITS

Principal Investigator Robert Lovo

Pacific Research Group USA

The Middle East Desalination Research Center Muscat, Sultanate of Oman

January 2005

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MEDRC Series of R&D Reports Project: 97-BS-018 This report was prepared as an account of work co-funded by the Middle East Desalination Research Center. Neither the Middle East Desalination Research Center, nor any of their employees, or funding contributors makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. References herein to any specific commercial product, process, or service trade name, trademark, manufacturer, or otherwise do not necessarily constitute or imply its endorsement, recommendation, or favouring by the Middle East Desalination Research Center. The views and opinions of authors expressed herein do not necessarily state or reflect those of the Middle East Desalination Research Center or third party funding contributors. Edited and typeset by Dr P M Williams, UK Email: p.m.williams@ntlworld.com Hard copies and CD of this report are available from:

Middle East Desalination Research Center P.O. Box 21, Al Khuwair / Muscat Postal Code 133 Sultanate of Oman Tel: (968) 695 351 Fax: (968) 697 107 E-mail: info@medrc.org.om Web site: www.medrc.org

© 2002 Middle East Desalination Research Center All rights reserved. No part of this report may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without prior written permission from the Middle East Desalination Research Center.

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Project participants Principal Investigator Robert Lovo Pacific Research Group 162 Fraser Lane Ventura, California, 93001 USA Tel: +1 805 643 1353 Fax: +1 805 643 9353 e-mail: rlovo@pacresgroup.com Partners Abulbasher M. Shahalam Ali Al-Harthy Alaa El-Zawahry Department of Civil engineering Sultan Qaboos University College of Engineering PO Box 33, Al-Khod, Muscat – 123 Sultanate of Oman

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MIDDLE EAST DESALINATION RESEARCH CENTER

An International Institution Established on December 22, 1996

Hosted by the Sultanate of Oman in Muscat

Mission Objectives of the Center:

1. to conduct, facilitate, promote, co-ordinate and support basic and applied research in the field of water desalination and related technical areas with the aim of discovering and developing methods of water desalination, which are financially and technically feasible

2. to conduct, facilitate, promote, co-ordinate and support training programs so

as to develop technical and scientific skills and expertise throughout the region and internationally in the field of water desalination and its applications and related technical areas

3. to conduct, facilitate, promote, co-ordinate and support information exchange,

including, but not limited to, electronic networking technology, so as to ensure the dissemination and sharing throughout the region and internationally of technical information concerning water desalination methods and research and related technical areas, and to establish with other states, domestic and other organizations such relations as will foster progress in the development, improvement and use of water desalination and related technical areas in the region and elsewhere

Further information about the Center activities is available on the web site (www.medrc.org). The following documents are available from the Center and can be sent on request in paper format or diskette. Alternatively they can be downloaded from the Center web site.

1. Guidelines for the Preparation of Research Proposals 2. Guidelines for the Preparation of Project Reports 3. Annual Requests for Proposals 4. Abstracts of On-going Projects and Summaries of Completed Projects 5. Research Reports 6. MEDRC Program Framework and Profile 7. MENA Universities and Research Institutes Directory 8. Partnership-in-Research Information for the Middle East 9. MEDRC Annual Reports

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TABLE OF CONTENTS

LIST OF TABLES………………………………………………………………. vi LIST OF FIGURES………………………………………………………........... vii EXECUTIVE SUMMARY……………………………………………………... viii ACKNOWLEDGEMENTS………………………………………………...….. ix 1. INTRODUCTION………………………………………………………….... 1 2. BACKGROUND………………………………………………………............ 2 3. SURVEY OF HOME-USE RO UNITS IN THE MENA REGION……..... 4

3.1. Home-use RO system suppliers……………………………………... 4 3.2. Application of home-use RO systems……………………………….. 5 3.3. Description of home-use RO systems………………………………... 7

3.3.1. Pre-treatment system……………………………………... 10 3.3.2. Reverse Osmosis module..……………………………….. 12 3.3.3. Post treatment system……………………………………. 13 3.3.4. Product water storage tank………………………………., 13 3.3.5. Ultraviolet disinfection…………………………………… 13 3.3.6. Recovery………………………………………………….. 14 3.3.7. Operation…………………………………………………. 14

4. MEMBRANE ELEMENT SURVEY………..............……………………… 17

4.1. Osmonics…………………………………………………………….. 17 4.2. Filmtec Membranes………………………………………………….. 19 4.3. Hydranautics…………………………………………………………. 19

5. EVALUATION OF CONVENTIONAL SYSTEMS……………………….. 21

5.1. System Description…………………………………………………… 21 5.2. Test Description………………………………………………………. 22 5.3. Instrumentation for data collection…………………………………… 23 5.4. PRG Test Results……………………………………………………... 23

5.4.1. Summary of test data…………………………………….... 23 5.4.2. Conventional system water wastage results………………. 25

5.5. SQU Test Results…………………………………………………….. 27 6. EVALUATION OF ZERO-WASTE SYSTEM…………………………….. 32

6.1. Description of Technology…………………………………………… 32 6.2. System Description…………………………………………………… 33 6.3. Test Description………………………………………………………. 37 6.4. Instrumentation for data collection…………………………………… 37 6.5. Zero-Waste System Test Results……………………………………... 38

6.5.1 Summary of test data……………………………………….….. 38

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7. DISCUSSION OF RESULTS……………………………………………….. 40 8. POTENTIAL APPLICATION AND ADVANTAGES…………………..... 41 9. CONCLUSIONS…………………………………………………………….. 42 REFERENCES.................................................................................................... 43 APPENDIX A: Membrane manufacturer’s technical data sheets………...... 44 APPENDIX B: Raw performance evaluation data…………………………... 58

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LIST OF TABLES Table 3.1: Home-use RO system suppliers………….………………………….. 5

Table 3.2: Sample ground water quality from Oman, UAE, Jordan and Egypt (Sinai)………………………………………………................. 6

Table 3.3: Sample ground water in Saudi Arabia……………………………….. 7

Table 3.4: Ground water quality profile with depth at Ma’abar depression, Oman............................................................... 7

Table 3.5: Price range of various small scale RO systems as of 1999…...……… 11

Table 3.6: Cost of home-use RO systems in Oman……….…………………....... 12

Table 4.1: Technical Data for Osmonics TFC Membranes…………………….... 18

Table 4.2: Technical Data for Osmonics CTA Membranes……………………... 18

Table 4.3: Technical Data for Filmtec’s TFC Membranes……………………..... 19

Table 4.4: Technical Data for Hydranautic’s TFC Membrane………………....... 20

Table 5.1: Performance Characteristics Summary……………………………..... 25

Table 5.2: Conventional home-use RO system water wastage results for CTA Membranes……………………………………………………………. 25

Table 5.3: Conventional home-use RO system water wastage results for TFC

Membranes………………………………………………………......... 26

Table 5.4: Quality of Tap water………………………..……………………........ 29

Table 5.5: Performance endurance test on continuous operation……………....... 30

Table 5.6: Flow and conductance of product and brine water………………....... 31

Table 6.1: Performance Characteristic Summary……………………………….. 39

Table 7.1: RO Systems Performance comparison………………………………. 40

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LIST OF FIGURES Figure 3.1: Typical different configurations of home-use RO systems………… 8

Figure 3.2: Typical four and five stage home-use RO systems………………… 9

Figure 3.3: Five stage home-use RO system configuration with booster pump... 10

Figure 3.4: Counter top home-use RO system………………………………….. 14

Figure 3.5: Under the sink home-use RO system………………………….....… 15

Figure 3.6: Continuous flow home-use RO system…………………………….. 15

Figure 3.7: Demand operation of home-use shutdown system…………………. 16

Figure 5.1: TGI-625UP home-use RO system tested………………………….... 22

Figure 5.2: Conventional RO Feed and Product Water Conductivity…………... 24

Figure 5.3: Conventional RO Turbidity and SDI………………………………... 24

Figure 5.4: Water Wastage and Recovery Rate Decline for conventional CTA Systems………......…………………………….... 26

Figure 5.5: Water Wastage and Recovery Rate Decline for conventional TFC Systems……………………………………………………….…....... 27

Figure 5.6: Portable House-Hold Reverse Osmosis System……………………. 28

Figure 5.7: Relationship between TDS and Electric Conductance……………... 29

Figure 6.1: Basic System Design……………………………………………….. 34

Figure 6.2: Zero-Waste Drinking Water System……………………………….. 34

Figure 6.3: Zero-Waste Softening & Drinking Water System………………….. 34

Figure 6.4: Zero-Waste Drinking Water System Installation Illustrated……….. 35

Figure 6.5: Zero-Waste Drinking Water System Installation Diagram…………. 36

Figure 6.6: Zero-Waste RO Feed & Product Water Conductivity……………… 38

Figure 6.7: Zero-Waste RO Turbidity & SDI…………………………………… 39

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EXECUTIVE SUMMARY

Small Home-use Reverse Osmosis systems are used worldwide. These systems have operational characteristics (low recovery) that have created significant concern in several regions of the world where they are installed. Water wastage by these membrane-based systems is high and limits residential applications. In arid regions, such as the MENA region, water supplies can fall critically short of population demands. The development of a home-use reverse osmosis system design that would significantly reduce or eliminate brine waste would have an important beneficial impact on desalination technology, as well as regional water supplies. It has therefore been the objective of this research effort to assess the current state-of-the-art and operational performance of conventional home-use RO systems currently available in the MENA region and to evaluate the performance of an innovative zero-waste system. Specifically, this effort included:

• Conducting a comprehensive survey and evaluation of all home-use RO units available in the MENA region

• Estimating the quantity and types of water currently treated by these units • Testing and evaluation of units shown to be most promising (with emphasis

given to highly efficient configurations) • Testing and evaluation of an efficient zero-waste design

Performance evaluation studies showed that conventional RO and Zero-Waste RO Systems performed equally as well at desalinating municipal water. However, results showed that conventional drinking water systems wasted a significant amount of water even when equipped with a water-saving device, such as an automatic shutoff valve. Recovery rates, as tested, for CTA and TFC membrane systems were shown to average 10% and 35% respectively. The Zero-Waste Water Treatment System; evaluated during this research effectively operated optimum recovery by eliminating the need to dump water to the drain. The Zero-Waste design corrects the two primary disadvantages present in current home-use RO units:

1. the discharge of water to the drain 2. an increase in the salinity of domestic waste-water

Because of this, a membrane-based water softener is now a realistic alternative for residential application. The Zero-Waste Water RO System design will result in the development of home-use design that utilizes an ‘open loop recirculation flow pattern’. As this project has shown, the result of this evolutionary flow pattern is the elimination of waste-water while demineralising municipal water with a membrane process for softening, drinking water, and other water treatment applications. This water-saving development will allow membrane-based treatment systems to operate more efficiently than conventional systems in residential systems. The use of a system that operates with zero-waste would have significant beneficial impact on desert/arid areas such as the MENA region.

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ACKNOWLEDGEMENTS

The Pacific Research Group and Sultan Qaboos University would like to thank the Middle East Desalination Research Center for its financial support and their technical guidance which have contributed to the successful completion of this project.

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1. INTRODUCTION The Pacific Research Group and Sultan Qaboos University, Department of Civil Engineering, entered a Project Funding Agreement number 97-BS-018 in July of 1999. The objective of which, was to investigate the efficiency of home-use reverse osmosis units and propose potential improvements in product water recovery with particular emphasis on the needs of the Middle East/North Africa (MENA) region and included:

• Conducting a comprehensive survey and evaluation of all domestic RO units available in the MENA region

• Estimating the quantity and types of water currently treated by these units • Test and evaluation of units shown to be most promising (with emphasis given

to highly efficient configurations) • Testing and evaluation of an efficient zero-waste design

Small Home-use Reverse Osmosis systems are used worldwide. These systems have operational characteristics (low recovery) that have created significant concern in several regions of the world where they are installed. Water wastage by these membrane-based systems is high and limits residential applications. In arid regions, such as the MENA region, water supplies can fall critically short of population demands. The development of a home-use reverse osmosis system design that would significantly reduce or eliminate brine waste would have an important beneficial impact on desalination technology; as well as regional water supplies. It has therefore been the objective of this research to assess the current ‘state-of-the-art’ and operational performance of conventional home-use RO systems currently available in the MENA region and to evaluate the performance of an innovative zero-waste system.

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2. BACKGROUND All cross-flow membrane-based water treatment technologies; reverse osmosis, nanofiltration, ultrafiltration and microfiltration, create two streams of water as a result of their process. From a single source of water, these processes create a treated or product water stream and a concentrate or brine stream. The product water stream may have particulates and other solids removed by ultrafiltration and microfiltration and may also have salts, minerals and other dissolved solids removed by reverse osmosis and nanofiltration. However, in all cases, the product water has a reduced level of dissolved or undissolved substances while the concentrate or brine stream has an increased concentration of those substances rejected by the membrane. Using the reverse osmosis (RO) process as an example – the two streams exiting an RO element module is:

1. desalinated product water, which has passed through the membrane

2. concentrate or brine that has flowed across and rejected by the membrane surface

This waste brine stream is necessary to flush salts and minerals away from the membrane so they cannot accumulate and cause scaling of the membrane surface. A build up of salts and minerals in the feed water to an RO membrane must not be allowed to occur continuously or dissolved substances can precipitate and form a solid on the surface of the membrane. If this occurs, the membrane can become irreversibly scaled and may have to be replaced. This characteristic of the RO membrane process poses a significant challenge to reducing waste effluent and is the reason why RO membrane processes waste large quantities of water (relative to the quantity of water produced) and are considered inefficient. In an attempt to reduce the amount of water wasted using the RO process, several techniques have been created. One of these techniques is the ‘closed loop recirculation flow pattern’. This technique recycles a percentage of the waste brine into the feed water of an RO system. By doing this, the overall recovery of the system is increased and the percentage of water wasted decreases accordingly. In addition, the flow rate across the RO element remains above the manufacturer’s recommended minimum flow rate for concentrate removal from the RO element. The recovery of an RO system is defined as:

Recovery =RateWaterFeed

100%xRateWaterProduct

As concentrate/brine is recycled back to the feed water of the RO elements, less new feed water is required and consequently the recovery increases. As an example, with an original feed water flow rate of 100 GPM, and recovery of 25%, if 20% of the original 75 GPM brine-flow (or 15 GPM) is recycled back to the feed water; the flow of new water required in the feed water drops to 85 GPM (instead of 100 GPM) and the new recovery will be approximately 29% as shown in the following equations:

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Original Recovery = 25% = RateFlowWaterFeedGPM100

100%xRateFlowWaterProductGPM25

New Recovery = 29% = RateFlowWaterFeedGPM85

100%xRateFlowWaterProductGPM25

However, there is a practical limit to increasing the recovery of a conventional RO system because of the potential to precipitate the salts and minerals being concentrated at the membrane surface. For small home-use systems, precipitating salts and minerals inside an RO element results in replacing the element. Because of these concerns, most the small home-use RO systems use a conservative recovery of 15% to 30% (3 to 7 gallons of water wasted for every gallon of demineralised water produced). Another factor that greatly exacerbates water wastage in home-use RO systems is that these systems typically store product water in an air pre-charged, pressurized water tank. Product water delivered to the tank must overcome the pre-charge pressure (initially) and overcome an ever-increasing backpressure in the tank as water fills the storage tank. It has been estimated that this characteristic of non-pumped RO systems causes the actual amount of water wasted to be much more than the estimated 3 to 7 gallons for each gallon of demineralised water produced. Using an estimate of 5 gallons of water wasted for each gallon of product water, means that 50 million gallons of water are wasted daily for every 10 million residential RO drinking water systems if every location produces just 1 gallon of water per day. This level of water wastage is significant and could be a problem if there was a drought.

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3. SURVEY OF HOME-USE RO UNITS IN THE MENA REGION A survey has been conducted by contacting various home-use RO system suppliers in the Middle East and North Africa (MENA) region seeking the following information.

1. Number of units sold per year 2. Capacity of various residential units 3. Cost of the various residential units 4. Operating pressure 5. Desired feed water specifications 6. Type of feed pre-treatment, i.e. various filters used. Details about these filters

including the limitations and replacement requirements 7. Post treatment filters details 8. Recovery 9. RO Membrane details: type, size, salt rejection, percentage recovery (product

water produced per hour or day /feed water used), manufacturer, etc. 10. Pump details 11. Installation and operating manual 12. Names of other companies in their country or in the Gulf that manufacture

(not a selling agent) residential RO units Unfortunately, many have not responded to our e-mails. We have also personally interviewed the technical persons of the home-use RO supplier in Muscat. Based on the responses and interviews we have compiled the following details:

3.1. Home-use RO system suppliers

In the MENA region, home-use RO units are mostly imported. Few companies assemble the residential RO units by getting the various components of the system from different companies from various countries. Most of the suppliers of home-use RO systems are agents for some foreign companies and sell the systems by importing the complete unit from the parent company. For example, no company in Oman manufactures the complete home-use RO unit and only one company assembles it by importing the components. However, there are more than ten suppliers who sell these systems in Muscat. There are some manufacturers of home-use RO systems in Taiwan who supply the units in the name of selling agent company trade mark. This trend prevails in other countries in the MENA region. In Table 3.1, some of the residential RO system suppliers in the Gulf region are listed. There is only one company in Saudi Arabia, Saudi Industries for desalination membranes and systems (SIDMAS), in the MENA region that manufacture the membranes.

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Table 3.1: Home-use RO system suppliers

S. No. Name address Country 1 Ibn Hamed Trading & Contracting

P.O.Box 1013, Postal code 111, C.P.O. Seeb shawqee@hotmail.com

Oman

2 Oman National Electric Company b.ravi@onecprojects.com

Oman

3 Dan International LLC venu@danintl.com

Oman

4 Sharikat Famiya Omaniya kishorrp@omantel.net.om

Oman

5 Lufkin, Dubai Lufkin@emirates.net.ae

UAE

6 Bin Zayed group basyoty@emirates.net.ae

UAE

7 So Safe products LLC sales@sosafe.net

UAE

8 Corodex water treatment company corodex@emirates.net.ae

UAE

9 Salam enterprises Dubai mail@salamenterprisesllc.com

UAE

10 Crystal drops Bahrain 11 Water & environmental systems

younus@wese.com Saudi Arabia

12 Classic crystal Dubai ccdubai@emirates.net

UAE

13 M.A.H.Y. Khoory & Company sales@mahykhoory.com

UAE

14 Gulf water treatment company gwtcoltd@emirates.net.ae

UAE

15 Juma Al-Majid Est jumaprjs@emirates.net.com

UAE

3.2. Application of home-use RO system Home-use RO systems are used to treat the tap water in urban areas and brackish well water in rural villages in the MENA region. Generally, municipal tap water; mostly coming from large desalination plants in urban areas in the Gulf countries is soft with TDS, less than 100 ppm. In some locations, tap water has problems of bad taste, or is smelly or cloudy. This problem is usually the result of the distribution system effect on the water after it is treated. Contamination can come from old pipes that extend through a piece of ground that has been contaminated. The tap water is stored in the overhead tanks on the roof tops of the houses or in other storage tanks. Tap water can

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be contaminated if these tanks are not properly maintained. Therefore, in the Gulf countries, the affluent people use bottled mineral water or use residential RO systems to treat the tap water for potable purposes. Many countries in the MENA region are arid and renewable water resources are scare, but some countries have brackish water resources. The quality of ground water in some of the countries is given Table 3.2, 3.3 and 3.4. These brackish waters are desalinated by municipalities for water supplies to the cities and towns. Such supplies are lacking for some small settlements in remote locations, however, such locations usually have brackish water resources with less Total Dissolved Solids (TDS). Home-use RO systems are used in such villages to treat the water in the community wells or individual wells for potable use if the TDS is less than 2000 ppm. There are some municipalities in the North African region that supply brackish water of less than 1000 ppm to the residents and residential RO systems have an application there.

Table 3.2: Sample ground water Quality from Oman, UAE, Jordan and Egypt (Sinai)

OMAN UAE JORDAN EGYPT

Water Quality Parameter

Dofar area1 Batineh area2 Sharjah, 3, 4 Zarka area 5 Sinai area 6

Source of Water Groundwater Groundwater Groundwater Groundwater Groundwater EC, µs/cm 2700 2002 8200 490-1830 2000-5000 TDS, mg.l-1 1422 - 4695 307-1171 - Total Hardness, mg/l CaCO3

745 - - - -

Ca++, mg.l-1 132 63.9 310 1.17-35.2* 660 Mg++, mg.l-1 101 94.6 90 1.07-3.82* 1485 Na+, mg.l-1 213 198 1200 0.48-6.8* 12800 K+ , mg.l-1 4 - 52 0 - 0.2* 250 Fe++, mg.l-1 0 - 0 - - Mn++, mg.l-1 0 - - - - Total Alkalinity, mg.l-1 CaCO3

191 - - - -

Chloride, mg.l-1 442 322 2052 - 22970 Sulfate, mg.l-1 410 338 870 0-1.05* 3137 Nitrate, mg.l-1 2.6 3 - 0.6-99.7* - Fluoride, mg.l-1 3 0.1 2 - - Strontium, mg.l-1 - - 16 - - Bicarbonate, mg.l-1 267 - 54 4.1-5.8* 131 Br, mg.l-1 - 0.08 - - - Cu, mg.l-1 - - - - - Silica, mg.l-1 - - - - - PH - 7.96 7.42 6.8-7.9 - Temperature, oC - 26 28 - 30 * meq.l-1

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Table 3.3: Sample Groundwater in Saudi Arabia

SAUDI ARABIA

Water Quality Parameter Riyadh Area 7, 8

Deep-well Central area9

Shallow-well Central area9

EC, µs/cm 2000 - - TDS, mg.l-1 11350 1303 1265 Total Hardness, mg.l-1 CaCo3

670 645 623

Ca++, mg.l-1 470 183 161 Mg++, mg.l-1 200 46 53 Na+, mg.l-1 - 107 180 K+ , mg.l-1 - 23 18 Fe++, mg.l-1 0.4 0.65 0.16 Mn++, mg.l-1 - 0.06 0 Total Alkalinity, mg.l-1 CaCO3

160 162 214

Chloride, mg.l-1 265 268 217 Sulphate, mg.l-1 500 443 478 Nitrate, mg.l-1 10 7.7 15.8 PH 8 7.3 7.15 Temperature, oC 33 49 28.5

Table 3.4: Groundwater Quality Profile with depth at Ma'abar Depression, Oman [10]

Depth (m)

TDS (mg.l-1)

HCO3 (mg.l-1)

SO4 (mg.l-1)

Cl (mg.l-1)

Ca (mg.l-1)

Mg (mg.l-1)

Na (mg.l-1)

K (mg.l-1)

84 550 121 128 171 48 23 102 11 108 725 128 159 237 37 52 154 13 134 7773 174 875 3872 390 244 2210 53

TDS = Total Dissolved Solids, HCO3 = Bicarbonate, SO4 = Sulphate, Cl = Chloride, Ca = Calcium, Mg = Magnesium, Na = Sodium, and K = Potassium Numerous home-use RO systems sold by each company depend on the company marketing strategy and aggressiveness. One of the leading suppliers in Muscat sells on average approximately 20 home-use RO units every month. It is difficult to estimate how many home-use RO systems are in operation in the MENA region and how much water they treat. However, the contribution of the home-use RO system to the total supply of potable water in the region can be considered negligible, but it is certain that there is a demand for these units in the region and their use will increase in the future.

3.3. Description of home-use RO systems Home-use RO systems have a similar configuration as the big commercial units consisting of pre-treatment system, high pressure pump, RO module and post treatment system. They are available as three, four and five stage configurations

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depending on the type of water to be treated and the type of RO membrane used. Typical configurations of these three different systems are shown in Figure 3.1.

A: Three stage configuration

B: Four stage configuration

C: Five stage configuration

Figure 3.1: Typical different configurations of home-use RO systems

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In all three configurations, first feed water passes through a cartridge filter to remove the suspended solids. These particles, if not removed will deposit on the RO membrane surface and reduce the membrane life. The filtrate from the cartridge filter goes to two pre-carbon filters before entering the RO module in the five stage configuration, one pre-carbon filter in the four stage configuration and no pre-carbon filter in three stage configurations. The cartridge filter also helps in extending the replacement period of pre-carbon filter in the four and five stage configurations. The pre-carbon filters are generally used if a thin film composite (TFC) RO membrane is used in the system since TFC is sensitive to chlorine. These pre-carbon filters reduce the chlorine content and also remove colours, some heavy metals and other organic compounds. Pre-carbon filters are not used if Cellulose tri-acetate (CTA) RO membranes are used since CTA membranes needs chlorine in the feed water to protect it from bio fouling. In all three configurations; post treatment is done by a carbon filter to polish the filtrate by removing taste and odours. Booster pumps are provided in the home-use RO systems if high pressure is required to treat high saline water. Typical four and five stage configurations with a booster pump are shown in Figure 3.2.

A: Four stage configuration

B: Five stage configuration

Figure 3.2: Typical four and five stage home-use RO system configurations with

booster pump

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In home-use RO systems, ultraviolet light are also provided for disinfection of permeate. A typical five stage configuration with ultraviolet disinfection light is shown in Figure 3.3.

Figure 3.3: Five stage home-use RO system configuration with ultraviolet disinfection light

The cost of the home use RO systems vary depending on the features included in the system. Table 3.5, is prepared based on the information collected on the price in 1999 for small scale home-use RO systems supplied by various manufacturers and suppliers. The cost of various capacity systems sold in Oman are given in Table 3.6. 3.3.1. Pre-treatment system Pre-treatment of feed water is done by two or three stage treatment in home-use RO systems. The purpose of the feed pre-treatment is to reduce the Silt Density Index of the feed water and remove chlorine, colour, and odour and also to some extent; reduce the components responsible for scaling and fouling of the RO membrane. The feed water to be treated should be microbiologically safe and with a low TDS, less than 2000 ppm. In the three stage pre-treatment, which is generally used, feed water is first passed through the sediment cartridge filter consisting of a spun or wounded polypropylene yarn cartridge of 10” (0.254 m) to 40” (1.016 m) length and 28 mm inside diameter / 53 to 65 mm outside diameter with 1 to 100 μm pores. This filter removes dirt, sand clay, mud and other suspended solids particle size. The size of the cartridge depends on feed quality and system capacity. If a higher concentration of large size suspended particles is in the feed, then two cartridge filters will be employed with large pore size cartridge followed by a small pore size one. Generally, in residential RO systems 5 or 10 micron filter elements are used. Cartridge filter elements are replaced on regular basis, which depends on the amount of sediments in the feed water and the feed water

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rate. The pressure drop across the element is the right parameter to judge the element’s replacement. Normally, the sediment cartridge filter is replaced monthly for the municipal tap water feeds. The cost of the cartridge is approximately US $ 3 in Oman.

Table 3.5: Price Range of Various Small Scale RO Systems in 1999

Source: Manufacturer or Supplier

Products

Price in US dollar

ECO home products Hydroline-4000, 36 gpd, TFC membrane Filter Replacement (6-12 months)

190 28

Hydroline - base unit - <45 psi 200 Hydroline - with UV unit - <45 psi 300 Hydroline - with UV and booster or delivery pump -

<45psi 450

Hydroline - with booster or delivery pump 350 Hydroline - with Deionization 290 Hydroline RO + Deionization (2 faucets) 310 Parts:

Permeate pump Booster Pump Delivery Pump UV Light unit addition Bulb only Ceramic filter addition Deionization unit Storage Tanks:

10 Gallon 20 Gallon 44 Gallon 86 gallon

70 150 150 100 60 20 90

130 180 350 470

Tiger Systems Under-sink Unit - 15-100 gpd 4 gal tank for < 50 gpd 10 gal tank for > 50 gpd

Ranges 276 -882

Basic Unit with booster pump UV systems (1 gpm)

Ranges 452-1082 Ranges 272-286

Counter-top RO system - 15-25 gpd Ranges 326-673 Point-of-use RO/UV coolers - 25 gpd Ranges 768-1270 Crystal Pure Water Company

Under-sink RO Conquerer III-5 stage (Cartridge life 2 yrs) Cartridge replacement Conquerer II - 4 stage ( Cartridge life 1 yr) Cartridge replacement Gladiator II - 4 stage (LOW PRESSURE < 40 psi)

400 120 350 90 350

Counter-top RO system 300-400 Point-of-Entry Ro System 600-700

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Table 3.6: Cost in US $ of home-use RO systems in Oman

Capacity, gallons/day System configuration

50 100 150 200 Three stage 100 140 200 250 Four stage 120 160 225 300 Five stage 175 200 250 350 Three stage with booster pump 120 170 225 250 Four stage with booster pump 150 200 250 300 Five stage with booster pump 210 315 500 750 Additional cost for UV lamp 31 31 65 130

In the five and four stage configuration, feed water from the cartridge filter goes through a high pressure pump to a granular activated carbon filter or directly to granular activated carbon filter depending on the feed water pressure. Granular activated carbon filters will have different sizes, as sediment cartridge filters, to remove cloudiness, odour, colour, chlorine and organic impurities including some pesticides, trihalomethanes and many other solvents from the feed water and for improving its taste. In the five stage configuration, the feed water then passes through an activated carbon black filter to improve further the quality of the feed water. Carbon black filter is not included in the three and four stage systems. Activated carbon / carbon black filters do not remove nitrate, bacteria or metals. A study conducted by US Environmental Protection Agency of faucet mounted and under sink activated carbon filters concerning the growth of harmful bacteria in the filter bed indicated that the five types of bacteria found in the water quality samples are nonpathogenic, meaning they did not cause waterborne diseases. The study further indicated that while indigenous bacteria that exist in a water supply may multiply to relatively large numbers, the growth in an activated carbon filter bed created no significant health effects. The replacement schedules of the cartridges of granulated active carbon and carbon black of second and third stage of pre-treatment depends on the carbon contents of the filter and the amount of water filtered. They are generally replaced once in three months for residential RO units with tap water feed. If the filter is left in service too long the water quality may become worse than if the filter was removed from service entirely. The cost of each of these cartridges is about US $ 8 in Oman. 3.3.2. Reverse Osmosis module The Reverse Osmosis unit is the main component of the home-use RO system and it is primarily used to remove the dissolved solids from the feed water. Most RO systems remove 90% of TDS of feed; but efficiency will decline as the RO membrane ages. RO is probably the most common treatment technique used to reduce the dissolved solids from poor quality tap water or brackish well water. The feed water pressure to the RO unit can range from 40 to 200 psi depending on the quality of feed and required purity of the permeate. At an elevated pressure, water molecules pass through the membrane and the permeate flow to a storage tank and the reject brine

13

goes to the drain. The efficiency of the RO membranes depends on the type of membrane and operating pressure. Normally, rejection of inorganic ions generally present in tap or brackish water by RO membranes is above 90% except for nitrates. Most of the RO membranes remove bacteria, Giardia and amoebic cysts. However, the RO membranes should not be relied on for primary removal of these organisms. Any deficiency in the RO membrane will immediately allow disease producing micro organisms into the drinking water and this may occur without warning. Home RO systems do not remove 100% of most chemicals, although RO membranes remove many organic chemicals, it does not remove all. For instance, it will not remove chloroform. If nitrates or nitrites are present i.e. greater than 10 mg per litre, removal is achieved better at a higher feed pressure (100 psi). There are special RO membranes designed specifically to remove these contaminants. The life of RO membrane in home-use RO systems can be from 1 to 3 years depending on the quality of water. RO membranes are not cleaned to the same extent as in large scale commercial membranes. If TDS of the feed exceeds more than 2000 ppm, the life of the RO membrane decreases drastically; some times less than 3 months. The cost of the RO membrane may vary significantly from different suppliers; depending on the type and size. The typical cost of a membrane in Oman is US$ 31. 3.3.3. Post treatment system The RO permeate in all three configurations is passed through a fine carbon filter for polishing the filtrate by removing taste and odours. The particle size of the carbon is small compared to that in the pre-carbon filters. The post treatment gives a pleasant taste to the water and the post treatment filter may be replaced every six months and its cost is approximately US$ 8 in Oman. 3.3.4. Product water storage tank The water from the RO system is stored in a storage tank before it is used and it is required for continuous operation of the RO system. One drawback of the use of storage tank, is that once the water passes through RO module with TFC membranes which are not chlorinated, it allows bacteria colonising in the storage tank. Therefore, it is recommended to disinfect the storage tank with bleach and to rinse it to drain on a regular basis. 3.3.5. Ultraviolet disinfection The use of ultraviolet light is the best way to ensure the quality of product water. The water from the storage tank passes through the high intensity ultraviolet light before it goes to the faucet. This kills all forms of bacteria that may exist in the water from the storage tank. The ultraviolet light is replaced once a year and its costs US$ 20.

14

3.3.6. Recovery Recovery rates in home-use RO system is about 15 to 20 %. If a higher recovery is used, the RO module’s life is reduced due to concentration polarization. 3.3.7. Operation The general operation of all home-use RO systems is the same i.e. by splitting the feed stream into permeate which has diffused through the membrane, and the concentrate brine which passes over the membrane; carrying away the minerals to waste. This waste flow should pass to drain via a proper air gap so that contamination of the RO system does not occur if drain water backs up in the drainpipe. Home-use RO systems are operated at low pressure with a feed pressure of less than 100 psi (6.8 bar). There are two types of home-use RO systems:

1. under the kitchen sink 2. counter top

The common counter top and under sink RO system configurations are shown in Figure 3.4 and 3.5, respectively.

Figure 3.4: Counter top home-use RO system

For the counter top RO system, the storage tank is maintained at atmospheric pressure. Whereas, the under sink RO system utilize accumulator storage vessels with initial air charge. When the water is added to the air charged tank in the under sink system, air is compressed and thus the pressure in the tank rises. This elevated pressure is used to displace the drinking water from the storage tank to the faucet. The accumulated pressure in the storage tank, however, acts as backpressure on the membrane. Therefore, as tank pressure increases, the differential pressure across the membrane decreases and hence the water production rate drops. However, the salt passage is unaffected with the decrease in differential pressure across the membrane, so the quality of the permeate drops significantly if the differential pressure is allowed to become too low. Therefore, most systems include some provision for limiting the storage tank pressure to some value less than the line pressure. A ratio of two thirds is a commonly chosen limit as shown in the configuration of Figure 3.6.

15

Figure 3.5: Under the sink home-use RO system

The flow control in Figure 3.6 is a split capillary system, which is a very inefficient design. In this system, when the storage tank is filled to the point at which its pressure equals two thirds of line pressure, permeate is diverted to the drain; resulting in wastage of feed water and feed pumping energy. In order to overcome this problem, a control called ‘shutdown’ is employed that use shutoff valves and is illustrated in Figure 3.7. In this design the feed to the system is shut off when the ratio of storage tank to line pressure reach a preset value. The valve will open again when sufficient pressure reduction is sensed at the storage tank.

Figure 3.6: Continuous flow home-use RO system

16

In order to overcome the backpressure problem in the under sink RO systems, a permeate pump is used which utilizes the energy of the discharge brine from the system for pumping permeate to the pressurized storage tank. Permeate is propelled by using hydraulic energy of the discharge brine that normally goes to the drain; unused. This configuration isolates the storage tank from the membrane and lets the membrane perform similar to an atmospheric tank system without the backpressure problem.

Figure 3.7: Demand operation of home-use shutdown system

17

4. MEMBRANE ELEMENT SURVEY A survey was conducted to identify a cross-section of membrane element types from manufacturers considered to represent the current ‘state-of-the-art'. The survey focused on: (1) thin film composite (TFC) non-chlorine tolerant, and (2) cellulose tri-acetate (CTA) chlorine tolerant technologies produced by the top three manufacturers of home drinking water RO elements. These manufacturers included: Filmtec Membranes of the Dow Chemical Company, Osmonics – Household Water Group, and Hydranautics a Nitto Denko Corporation. Although there are a number of other manufacturers around the world, the companies surveyed are considered to represent the current ‘state-of-the-art’.

4.1. Osmonics Osmonics manufactures the Autotrol® brand of reverse osmosis elements. These elements are used primarily in tap water home-use reverse osmosis systems. Osmonics, supplies many of the top systems’ manufacturers with membrane elements and their spiral-wound modules can also be used as replacements for the most popular configurations. Standard features include:

• Polyethylene brine seal: which provides feed-to-brine sealing and prohibits seal from flipping inside the housing

• Anti-telescoping device (ATD): prevents the natural tendency of spiral-wound elements to telescope

• Self-centring ATD: acts as a centring device to assist in positive engagement of product adapter in housing, eliminating hunting

• Pull ring: makes the element’s removal easy and eliminates the need for special tools

Osmonics manufactures both TFC non-chlorine tolerant and CTA chlorine tolerant elements. Manufacturer’s technical data sheet is included in Appendix A. The Autotrol® TFC non-chlorine tolerant membrane offers a good combination of flow and rejection where high rejections (98-99%) are demanded. A single element can supply up to 100 gallons per day of product water from a standard home water supply. Table 4.1, provides technical data for the configurations available in the TFC element. NB. This membrane must not be used on a chlorinated water supply without adequate de-chlorination, such as carbon filtration. However, the membrane does possess limited chlorine tolerance which will allow it to withstand minor excursions due to the failure of the carbon pre-filter.

The Autotrol® CTA membrane is a proprietary formulation that reportedly combines the high flow and high rejection properties of the TFC membranes while providing chlorine tolerance and the price advantage of cellulosic elements. Table 4.2, provides technical data for the configurations available with the CTA element.

18

Table 4.1: Technical Data for Osmonics Thin Film Composite Membrane

Part

Number

Model

Number

Avg NaCl

Rejection (%) 1220188 TFM-18 98.0 1220189 TFM-24 98.0 1220190 TFM-36 98.0 1204694 TFM-50 98.0 1204487 TFM-75 96.0 1221122 TFM-100 96.0

Operating Parameters Maximum Operating Pressure = 120 psig pH Range = 4-11 Maximum Feed Chlorine = less than 0.1 ppm Minimum Concentrate (Brine) Flow Rate = 5-9 times permeate Maximum Silt Density Index = 5.0 (15 min) Maximum Temperature = 100 degrees F Maximum Feed Turbidity = 1.0 NTU Table 4.2: Technical Data for Osmonics Cellulose Triacetate Membrane

Part Number

Model

Number 1201330 CTA-10 1201332 CTA-16 1201336 HFCTA-22

Operating Parameters Maximum Operating Pressure = 250 psig pH Range = 3-9 Maximum Feed Flow Rate = 2 gpm Maximum Feed Chlorine = No maximum, typically requires residual chlorine Minimum Concentrate (Brine) Flow Rate = 5-9 times permeate Maximum Silt Density Index = 5.0 (15 min) Maximum Temperature = 100 degrees F Maximum Feed Turbidity = 1.0 NTU

NB. It is recommended that these membrane elements be used on a chlorinated water supply with a minimum chlorine concentration of 0.2 ppm.

19

4.2. Filmtec membranes Filmtec manufactures a line of non-chlorine tolerant Home-use RO membrane elements. These elements are NSF/ANSI Standard 58 listed. Designed to operate at an applied pressure of 50 psig, permeate flow rates range from 24 to 75 GPD (3.8 to 12 l/h). Table 4.3, provides technical data for the available elements.

Table 4.3: Technical Data for Filmtec’s Polyamide Thin Film Composite

Membrane

Product Number

Applied Pressure

(psig)

Permeate Flow GPD (l/h)

Stabilized Salt

Rejection (%)

Overall Length (inches)

Scroll Length (inches)

Maximum Diameter (inches)

TW30-1812-24

50 24 (3.8) 98 11.74 10.0 1.75

TW30-1812-36

50 36 (5.7) 98 11.74 10.0 1.75

TW30-1812-50

50 50 (7.9) 98 11.74 10.0 1.75

TW30-1812-75

50 75 (12) 98 11.74 10.0 1.75

Operating Limits Membrane Type = polyamide thin-film composite Maximum Operating Pressure = 300 psig Maximum Operating Temperature = 113 degrees F Maximum Feed Flow Rate = 2.0 gpm (7.6 lpm) pH Range, Continuous Operation = 2-11 Maximum Feed Silt Density Index (SDI) = 5 Free Chlorine Tolerance = Less than 0.1 ppm

Manufacturer’s technical data sheet is included in Appendix A.

4.3. Hydranautics Hydranautics in Oceanside, California, produces non-chlorine tolerant TFC membrane modules for home-use RO systems. These elements are designed to operate with a line pressure of 65 psig with permeate flow rates ranging from 24 to 300 GPD. Table 4.4, provides technical data for the elements available.

20

Table 4.4: Technical Data for Hydranautics Thin Film Composite Membrane

Model Number

Nominal Membrane Area (sq ft)

Avg NaCl Rejection (%)

Permeate Flow Rate

GPD @65 psi

1812-24 3.3 96.0 24 2012-70 4.8 96.0 70 2026-300 12.0 98.0 300

Application Data Membrane Type = composite polyamide Maximum Operating Pressure = 300 psig Maximum Operating Temperature = 113 degrees F pH Range, Continuous Operation = 3-10 Maximum Feed Silt Density Index (SDI) = 5 Free Chlorine Tolerance = Less than 0.1 ppm Maximum Feed water Turbidity = 1.0 NTU Maximum Ratio of Concentrate to Permeate Flow = 5:1 Maximum Pressure Drop for Each Element = 10 psi

Manufacturer’s technical data sheet is included in Appendix A.

21

5. EVALUATION OF CONVENTIONAL SYSTEMS The ultimate objective of this project is to investigate the efficiency of current ‘state-of-the-art’ of home-use reverse osmosis systems and propose potential improvements on recovery with particular emphasis on the needs of MENA region users. This system evaluation involves the testing of units shown to be the most promising (with emphasis given to highly efficient configurations) found in the survey. Successful completion of this objective would result in significant improvements in the efficiency and recovery rates over present day conventional systems.

5.1. System description Based on the survey and evaluation conducted in Section 3, components for two home-use RO systems were selected and procured for test and evaluation by SQU and Pacific Research Group. These systems consisted of the following components:

• Two stages of prefiltration – 20 micron and 1 micron cartridge filters • Pressure pump • RO element – Cellulose Tri-Acetate (CTA) 15 GPD • Ultraviolet light disinfection unit • 10 gallon product water storage tank • Carbon block cartridge filter as post treatment • Shut off valve • Frame and associated tubing and transformers for electrical devices

The conventional home-use RO system selected and procured for baseline testing in the US by Pacific Research Group (PRG) and by SQU is shown in Figure 5.1. These systems were manufactured by Topway Global Inc. (www.tgipure.com). The system selected was the TGI-625UP, which was designed for applications where feed water has a very low pressure or where the source water contains slightly higher than normal amounts of dissolved solids. This design allows the feed water to pass through a sediment filter before the booster pump avoiding pump valve clogging caused by sediment particles. Operating parameters for this system include:

• Inlet pressure = 10 – 120 psig • pH = 3-11 • Temperature range = 5-38 C • Product Water (24 hr) = 25 GPD • TDS (ppm) = 0 – 2000 • Recovery (%) = 20 – 25 • Rejection (%) = 96

22

Figure 5.1: TGI-625UP Home-use RO system tested 5.2. Test description A conventional home-use RO system (TGI-625UP) installed in a residential location in California was tested to document its performance characteristics. The unit was a typical ‘under-a-sink’ type of installation where the feed of the RO element was connected to the cold water supply line of a municipal water source and the RO element concentrate line was connected to drain. The RO membrane used in this system was a conventional cellulose tri-acetate or CTA type of RO membrane that was chlorine-resistant. The system uses a nominal 20-micron and a 1-micron particulate filters; for pre-treatment. Since this RO system was purchased and installed in California, it included an automatic shutoff valve designed to stop water flow to the RO element when the pressure inside the product tank is at 2/3’s of the municipal line pressure. The purpose of the valve is to save water by stopping the flow of waste to drain when the product water tank is full. During operational evaluation of this system, data on all operation and maintenance parameters were collected. Operational data collected included:

Sample / Parameter TDS Turbidity SDI Feed water X X X Product water X

Maintenance data collected included any and all maintenance performed on the system during the operational period.

23

5.3. Instrumentation for data collection The following paragraphs describe the instruments and associated specifications used to measure and collect operational data. Flow Measurement All flow measurements were performed using in-line, direct reading rotameters with an accuracy of 3% of full scale. Calibration was performed using a timed volume technique. Turbidity Turbidity measurements were performed using a 'Hach 1720D Low Range Turbidimeter' and 'AquaTrend Interface' system. This unit is an in-line system that provides the sensitivity to accurately track turbidity levels down to 0.001 NTU. It is capable of measuring turbidity from 0.001 to 100.0 NTU with accuracy at 2% of full scale. Silt Density Index The SDI apparatus utilized the 0.45 µm, 47 mm diameter MF-Millipore membrane filters. This system was designed to accurately maintain filter pressure at 30 psi (2 bar), during the test run. Conductivity Conductivity measurements were achieved using a YSI conductivity/salinity meter, Model 34, having an accuracy of 0.5% full scale.

5.4. PRG test results Performance data achieved during the test and evaluation period was reduced and is presented in Figures 5.2 and 5.3. The raw data collected during this test period is presented in Appendix B. 5.4.1. Summary of test data The conventional RO test system was operated for 1335 hours using a municipal water source as feed water. The performance characteristics measured for this system during the operational test period are summarised in Table 5.1.

24

Conventional RO Feed & Product Water Conductivity

0

100

200

300

400

500

600

700

800

900

0 200 400 600 800 1000 1200 1400

Operating Hours

Con

duct

ivity

( μm

hos)

Feed Water Cond Product Water Cond

Figure 5.2: Conventional RO Feed and Product Water Conductivity

Conventional RO Turbidity & SDI

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

0 200 400 600 800 1000 1200 1400

Operatng Hours

Silt

Den

sity

Inde

x

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

Turb

idity

(NTU

)

Feed SDI Feed Turb

Figure 5.3: Conventional RO Turbidity and SDI

25

Table 5.1: Performance Characteristics Summary

Parameter Feed water Data Range Product water Data Range

TDS 730 - 782 μmhos 52 – 72 µmhos Turbidity 0.042 – 0.091 NTU - SDI 3.76 – 4.9 -

5.4.2. Conventional system water wastage results Quantities of permeate produced by the conventional RO drinking water system and delivered to a conventional air-charged product water storage tank, as well as brine produced during the same period of time, were measured to determine the system’s recovery. This test was conducted for both CTA and TFC membrane modules. As noted earlier, in a conventional RO system, demineralised product water must overcome the pre-charge air pressure in the tank (initially) and overcome an ever-increasing back-pressure as water fills the storage tank. Consequently, there is an ever-decreasing driving force across a membrane in a conventional RO system as the storage tank fills. At the beginning of each test, the air pre-charge of the empty water storage tank was measured to be 5 psi (0.34 bar). Test results for the CTA membrane module are presented in Table 5.2 and Figure 5.4. As can be seen from the Table 5.2, 135.01 litres (35.7 gallons) of water were sent to drain during the production of 12.66 litres (3.34 gallons) of demineralised water. Therefore, during this test, 10.66 litres of water were wasted for each litre of RO demineralised water produced. Also, as can be seen in Table 5.2, although the recovery of the RO system started at 16%, each hour of operation reduced the recovery and by the time the automatic shut-off valve stopped the system’s operation; the recovery had been reduced to only 2.5%. This illustrates the effect that an air pre-charged product water storage tank has on the recovery of a conventional RO drinking water system.

Table 5.2: Conventional home-use RO System Water Waste Test Results

for CTA Membrane Module

Hours Product Water (litres) Brine Water (litres) % Recovery 1 2.45 13.01 16 2 2.24 13.64 14 3 1.83 13.62 12 4 1.55 13.32 11 5 1.13 13.40 8 6 0.93 13.55 6 7 0.97 13.32 7 8 0.71 13.70 5 9 0.50 13.75 3.5

10 0.35 13.70 2.5 Total 12.66 135.01

26

Figure 5.4: Water Wastage and Recovery Rate Decline for Conventional CTA Systems

Test results for the TFC membrane module are presented in Table 5.3 and Figure 5.5. A total of 20.99 litres of brine water was disposed to drain during the production of 11.3 litres of demineralised water. During this test, 1.86 litres of water was wasted for each litre of RO demineralised water produced. The TFC system proved to be more efficient than the CTA module; however, approximately 65% of the total water entering the TFC RO system was still dumped to drain.

Table 5.3: Conventional home-use RO System Water Waste Test Results for TFC Membrane Module

Hours Product Water (litres) Brine Water (litres) % Recovery 0.25 1.82 2.62 41 0.50 1.75 2.62 40 0.75 1.66 2.58 39 1.00 1.45 2.50 37 1.25 1.29 2.43 35 1.50 1.18 2.44 33 1.75 1.04 2.45 30 2.00 0.86 2.47 26 2.06 0.25 0.88 22

Total 11.3 20.88 35 (average)

0

2

4

6

8

10

12

14

16

18

1 2 3 4 5 6 7 8 9 10

Time (hrs)

Brin

e Fl

ow (l

itres

) - R

ecov

ery

(%)

0

0.5

1

1.5

2

2.5

3

Prod

uct F

low

(litr

es)

Brine Water (liters) % Recovery Product Water (liters)

27

Figure 5.5: Water Wastage and Recovery Rate Decline for Conventional TFC Systems

5.5. SQU test results This section presents the operating data collected from a home-use Reverse Osmosis system, ‘TGI-625UP/DX’, of TOPWAY GLOBAL, INC., Brea, Calif. 92821, U.S.A. The system was tested and certified to ANSI/NSF Standard 58.

0

5

10

15

20

25

30

35

40

45

0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.06

Time (hrs)

Brin

e Fl

ow (l

itres

)

0

0.5

1

1.5

2

2.5

3

Prod

uct F

low

(litr

es) -

Rec

over

y (%

)

% Recovery Product Water (liters) Brine Water (liters)

28

6th stage 5th stage Tank switch UV transformer Check Valve To drain 4th stage Electric Pump Shut-off valve Product water tank

3rd stage 2nd stage 1st stage Pump transformer SPECIFICATIONS: Ist stage: Sediment filter, 5 micron, 25 cm 2nd stage: GAC carbon filter, 20 micron, 25 cm 3rd stage: Carbon block filter, 10 micron, 25 cm 4th stage: TFC membrane, 30 GPD@60 PSI/45 GPD@100 PSI 5th stage: UV filter 6th stage: Inline carbon filter Auto shutoff valve, Operating pressure: 10-120 psi Operating temperature: 40-100 F Recovery rate: 16%

Figure 5.6: Portable house-hold Reverse Osmosis System

29

EXPERIMENT 1: House hold tap water is the input

Table 5.4: Quality of tap water

Quality Parameter Tap water

pH 8.1

Total dissolved solids, mg.l-1 1.16

Calcium, mg.l-1 18.03

Magnesium, mg.l-1 1.5

Chloride, mg.l-1 2.2

Dissolved Solids, mg/l

0200400600800

10001200

382 932 1412

Conductance, μmhos/cm

Con

cent

ratio

n of

di

ssol

ved

solid

s,

mg/

l

Dissolved

Figure 5.7: Relationship between dissolved solids vs. Electric conductance

30

Table 5.5: Performance Endurance test on continuous operation for 744 hours

Product Brine

Remark Date

Flow, ml/min

Conductance μmhos/cm

Flow, ml/min

Conductance μmhos/cm

10.12.01 32 37 295 255 11 32 37 290 254 12 31 35 291 255 13 30 32 285 257 14 34 38 287 250 15 35 38 287 252 16 38 35 284 252 17 36 38 284 253 18 37 39 283 252 19 38 40 289 250

Raw water Conductance = 234 μmhos/cm

20 38 10 354 165 21 38 8 348 165 22 36 10 357 170 23 36 5 354 165 24 35.7 7 357 165 25 37.2 7 348 165 26 36.4 5 345 174 27 37 9 345 160 28 36 3 345 160 29 36.8 3 345 158 30 36 2 345 160 31 36 5.2 345 168 1.1.02 34.9 7.1 348 181 2 36.4 7 348 195 3 35 7 346 195 4 36.6 10 345 180 5 36 8 351 180 6 36.5 8 353 180 7 36 7 352 183 8 36.5 8 353 181 9 36 8.5 352 180 10 37 8 352 180

Raw water Conductance = 135 μmhos/cm

31

EXPERIMENT 2: INPUT WATER IS FROM A LOCAL WELL IN AL-SEEB AREA Table 5.6: Flow and Conductance of Product and Brine water at pressure 25 psi

when input source is groundwater

Product Brine

Remark Date

Flow, ml/min

Conductance μmhos/cm

Flow, ml/min

Conductance μmhos/cm

16.1.02 32.8 75 345 1200

32

6. EVALUATION OF ZERO WASTE SYSTEM The overall objective of this research is to assess the current ‘state-of-the-art’ and operational performance of conventional home-use RO systems currently available in the MENA region and to evaluate the performance of an innovative zero-waste system soon to be commercially available. If the results of this work are successful, significant improvements in the efficiency and recovery rates over present day conventional systems can be achieved. The use of a system that utilises a zero-waste design with a recovery rate of 100% would have a significant beneficial impact on desert/arid areas such as the MENA region, when compared to a 20-30% recovery rate for conventional systems.

6.1. Description of technology The Zero-Waste RO System design describes a home-use RO (POU and POE) water treatment system that can be used to purify a municipal water source. Although the system uses a membrane water treatment process, the zero-waste design does not create a waste effluent that must be disposed to drain. The zero-waste design is an evolution of the conventional closed loop recirculation flow pattern. This development is called an ‘open loop recirculation flow pattern’. The ‘open loop recirculation flow pattern’, allows an RO system’s concentrated salts and minerals to accumulate inside a recirculation tank, which is also connected to piping that feeds other water-use fixtures in a building. The recirculation tank provides a buffer volume to permit continuous production of desalinated water even when no water is being used by water fixtures at a location. As shown in Figure 6.1, product water is delivered into a flexible bladder that occupies the top of the recirculation tank. Since the bladder is sitting in a tank pressurised by the municipal line pressure, product water in the bladder is also pressurised by municipal line pressure and is therefore delivered at municipal line pressure without the need for an additional depressurisation pump. This feature allows the delivery of membrane-produced desalinated water to be consistent and appear ordinary without the pressure fluctuations common with re-pressurisation systems. Another characteristic of the zero waste design is that the percentage of volume that a full product water bladder occupies in the recirculation tank effectively sets the recovery of the RO system even when a location’s water fixtures are not using water. Therefore, if a full product water bladder occupies 50% of the recirculation tank volume, then the recovery for the system is limited to 50% even if no water is being used by water fixtures at a location (and as long as additional purified water is not being used). This ability to determine and set the recovery of a zero-waste membrane system greatly reduces the likelihood of membrane scaling. This feature of the design is an important advantage over other attempts to re-use water with a membrane process at the point of use. In the zero waste design, the use of water fixtures at a location permits periodic dilution of concentrated salts and minerals that build up during an RO membrane process. In this way, effluent from a membrane system does not go directly to drain but instead is diluted and used throughout a building’s plumbing system for other than purified water applications. This usually means

33

purified water is used for drinking, cooking, ice making, and dishwashing, while diluted concentrate is used for showers, toilets, faucets, equipment cooling and landscape irrigation. Figure 6.2, shows the design of a Zero-Waste Drinking Water System. Because product water is delivered at municipal line pressure, this equipment can be placed where municipal water enters a building and small diameter tubing can be routed to water fixtures wherever high quality water is desired. That is, the consistent and relatively high pressure of the design’s product water flow eliminates the need to place equipment under each sink at locations where product water is needed. Consequently, this feature allows a single water treatment system to be placed in one location to produce drinking water for distribution throughout a building. In addition, the zero-waste design is flexible enough to accommodate a conventional ‘under a sink’ configuration. Figure 6.3, shows the design of a combination Zero-Waste Water Softening and Drinking Water System. This configuration would be especially useful for commercial locations, such as restaurants, since it produces softened hot water necessary for dishwashing, as well as demineralised water suitable for drinking, cooking and ice making.

6.2. System description Pacific Research Group selected and procured components for a Zero-Waste home-use RO system for test and evaluation. These components are:

• Two stages of pre-filtration – 20 micron and 1 micron cartridge filters • Pressure pump • RO element – Cellulose Tri-Acetate (CTA) 15 GPD • 4 gallon product water storage tank with bladder • 6 watt ultraviolet light disinfection unit • Carbon block cartridge filter as post treatment • Frame and associated tubing and pump transformer

Figure 6.4, shows the Zero-Waste Drinking Water system as installed in a residence in Southern California, USA. A diagram indicating where the system was installed relative to other water fixtures in the residential piping layout is provided in Figure 6.5.

34

Figure 6.1: Basic System Design

Figure 6.2: Zero-Waste Drinking Water System

Figure 6.3: Zero-Waste Softening & Drinking Water System

WaterSupply

IntoHome /

Building

Kitchen Sink

Ice Maker

Wet Bar

Bathroom Sink

Water Supply

Under Sink Unit

MultipleLocation

Unit

DemineralizedDrinking Water

Zero Waste Membrane Demineralization DrinkingWater System

WaterSupply

IntoHome /

Building

Kitchen Sink

Ice Maker

Wet Bar

Bathroom Sink

Water Supply

Under Sink Unit

Under Sink Unit

MultipleLocation

Unit

DemineralizedDrinking Water

Zero Waste Membrane Demineralization DrinkingWater System

HotWaterTank

HotHotWaterWaterTankTank

SoftenedHot

Water

DemineralizedDrinking

Water

ColdWater

WaterSupply

IntoHome /

Building

Zero Waste Membrane DemineralizationWater Softening - Drinking Water System

HotWaterTank

HotHotWaterWaterTankTank

HotWaterTank

HotHotWaterWaterTankTank

SoftenedHot

Water

DemineralizedDrinking

Water

ColdWater

WaterSupply

IntoHome /

Building

Zero Waste Membrane DemineralizationWater Softening - Drinking Water System

W aterSupply

W aterSupply

Dem ineralizedDrinking

W ater

Com binationRecirculation /Product W aterStorage Tank

RO M em brane

Booster /Recirculation

Pum p

ProductProductW aterW ater

StorageStorageBladderBladder

O pen Loop RecirculationFlow Pattern

Zero W aste M em brane Dem ineralization Basic Design

Concentrate

Flow

Recirculation

Flow

W aterSupply

W aterSupply

Dem ineralizedDrinking

W ater

Com binationRecirculation /Product W aterStorage Tank

RO M em brane

Booster /Recirculation

Pum p

ProductProductW aterW ater

StorageStorageBladderBladder

O pen Loop RecirculationFlow Pattern

Zero W aste M em brane Dem ineralization Basic Design

Concentrate

Flow

Recirculation

Flow

35

Figure 6.4: Zero-Waste Drinking Water System Installation Illustrated

Figure 6.5: Zero-Waste Drinking Water System Installation Diagram

Water Supply

Kitchen Faucet

Bathroom 1

Faucet Shower

Bathroom 2

Faucet Shower

Bathroom 3

Faucet Shower

Outside Water

Dishwasher

Refrigerator Icemaker

Drinking Water Faucet

Cold Water Supply

Hot Water Tank

Zero-Waste RO System

Toilet Toilet Toilet Toilet

36

37

6.3. Test description A Zero-Waste RO Drinking Water System, see section 6.2, installed at a residence in California, USA was tested to document performance characteristics. During the test, the Zero-Waste System used a conventional cellulose tri-acetate or CTA type of RO membrane that was chlorine-resistant. Pre-treatment of the municipal water in front of the RO membrane consisted of two conventional wound-style particulate filters in series, one with a 20-micron nominal retention and the other with a 1-micron nominal retention. A 6-watt ultraviolet (UV) light was installed in the lines going to and from the product water storage bladder to help keep the product water disinfected during storage. Carbon filters were used at each of the two RO product water fixtures – the refrigerator icemaker and the drinking water faucet were located in the kitchen. During the test, the residence had four people living there full-time, comprising a father, mother, teenage son and a teenage daughter. The quantity of water used in the residence was not measured but is anticipated to be similar to the quantities documented in a study of indoor water use patterns of 16 homes in Boulder, Colorado during the months of June to September 1994 [11]. During the study, water use results averaged 58.8 gallons of indoor water used per capita. Extrapolating from this per capita average, the quantity of indoor water assumed to be used in the residence where the Zero-Waste RO System was installed is about 235 gallons per day. As one might expect, the amount of water used indoors is only a small percentage of the total residential water consumed when an irrigation system is used to water vegetation around a home. The amount of water used inside the homes in Boulder, Colorado during the test period was about 46% of the total water consumed by the households (on an annual average basis). Therefore, the annual average amount of water used outside the homes was about 511 gallons per day for a total of 746 gallons used on-average inside and outside the test homes per day. This amount of water usage readily accommodates the dilution required to allow Zero-Waste RO Systems to operate very efficiently in all residential locations.

During the operational evaluation of this system, data on all operational and maintenance parameters were collected. Operational data collected included:

Sample / Parameter TDS Turbidity SDI

Feed water X X X Product water X

Maintenance data collected included any and all maintenance performed on the system during the operational evaluation period.

6.4. Instrumentation for data collection The same instruments and associated specifications described in section 5.3, are used to measure and collect operational data.

38

6.5. Zero-waste system test results Performance data achieved during the test and evaluation period for the Zero-Waste System was reduced and is presented in chart form in Figures 6.6 and 6.7. The raw data collected during this test period is presented in Appendix B. 6.5.1. Summary of test data The Zero-Waste RO test system was operated for 1470 hours using a municipal water source as feed water. The performance characteristics measured for this system during the operational test period are summarized in Table 6.1.

Zero-Waste RO Feed & Product Water Conductivity

0

100

200

300

400

500

600

700

0 200 400 600 800 1000 1200 1400 1600

Operating Hours

Con

duct

ivity

( μm

hos)

Feed Water Cond Product Water Cond

Figure 6.6: Zero-Waste RO Feed & Product Water Conductivity

39

Zero-Waste RO Turbidity & SDI

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

5.50

6.00

0 200 400 600 800 1000 1200 1400 1600

Operating Hours

Silt

Den

sity

Inde

x

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

Feed SDI Feed Turb

Figure 6.7: Zero-Waste RO Turbidity and SDI

Table 6.1: Performance Characteristics Summary

Parameter Feed Water Data Range Product Water Data Range

TDS 567 – 638 μmhos 90 – 99 μmhos Turbidity 0.048 – 0.087 NTU - SDI 4.48 – 5.46 -

40

7. DISCUSSION OF RESULTS Previous discussions in Sections 5. and 6., presented performance and evaluation data achieved for both the conventional and zero-waste RO systems. Each system was operated using a municipal water supply as a feed water source. Both systems performed in a very similar manner with no apparent fouling or decrease in membrane performance. Cleaning or maintenance was not required for either system during the operational periods, which exceeded 1200 hours each. Table 7.1, summarizes the water quality and performance differences between the two systems.

Table 7.1: RO System Performance Comparison

Average Range Parameter Conventional

RO Zero-Waste

RO Conventional

RO Zero-

Waste RO Feed conductivity (µmhos)

753 599 730 - 782 567 – 638

Feed Turbidity (NTU) 0.049 0.060 0.042 – 0.091 0.048 – 0.087

Feed SDI 4.42 5.07 3.76 – 4.90 4.48 – 5.46Productivity Conductivity (µmhos)

60 93 52 - 72 90 – 99

% Recovery/feed utility 10% (CTA) 35% (TFC)

100% 3.5 – 16% 22 – 41%

100%

From Table 7.1, it can be seen that except for the % recovery of the two systems, the water quality and performance characteristics are about the same. While the zero-waste system exhibited 100% utility by not discharging any water to the drain, the conventional systems achieved an average of 10% and 35% respectively for the CTA and TFC membranes.

41

8. POTENTIAL APPLICATIONS AND ADVANTAGES An important characteristic of the zero-waste membrane systems is that the design features are extremely flexible and can accommodate a wide variety of applications and product water flow requirements. This is demonstrated by the fact that the design can create small capacity ‘under a sink’ drinking water systems for residential use; as well as large capacity water softeners and purified water systems suitable for large commercial businesses. In summary, the applications for the design include the following: 1. A zero-waste Drinking Water System suitable for residential and commercial

applications (see Figure 6.2). 2. A zero-waste Water Softening and Drinking Water System suitable for residential

and commercial applications, especially restaurants, hotels and office buildings, etc. (see Figure 6.3).

In addition to eliminating water wastage from conventional membrane-based water treatment systems, there are other advantages of the zero-waste design (as compared to conventional POU equipment). These include: • Eliminates waste water

The open-loop recirculation flow pattern allows salts and minerals to be dissipated without requiring drain disposal of concentrate

• Discharges RO product water at municipal line pressure The unique bladder design provides product water at the exact municipal line pressure; this produces a consistent flow rate of RO product water without the need for an additional pump

• Allows multiple product water locations in a building with one treatment unit Treatment unit can be located near water pipe entrance into user location (residence, building or office suite) while small diameter 1/4 inch (0.00635 m) tubing distributes purified water anywhere in the location

• Eliminates the need for bulky water treatment equipment under every sink

The ‘open loop recirculation flow pattern’ design was created to produce a membrane-based system that has, in effect, a 100% utility capability. It has the potential to operate most efficiently in residential, commercial, and industrial locations where today’s system efficiencies are low and water wastage is very high.

42

9. CONCLUSIONS Conventional RO drinking water systems waste a significant amount of water even when equipped with a water-saving device, such as an automatic shut-off valve. The Zero-Waste Water Treatment System evaluated during this test program eliminated all waste-water and therefore operated, in effect, at 100% water utility. The Zero-Waste design corrects the two primary disadvantages present with current home-use/POU systems:

1. the discharge of water to the drain 2. an increase in the salinity of domestic waste-water

Because of this, a membrane-based water softener is now a realistic alternative for the home-use/POU water treatment industry. The inherent characteristics of the Zero-Waste Drinking Water Systems will accommodate municipal water re-use efforts in the future since these systems will reduce the need for salt-regenerated softeners, thus reducing salinity in domestic waste-water while conserving water. The Zero-Waste Water RO System design will result in the development of POU and POE equipment that utilizes an ‘open loop recirculation flow pattern’. As this project has shown, the result of this evolutionary flow pattern is the elimination of waste-water while demineralising municipal water with a membrane process for softening, drinking water, and other water treatment applications. This water-saving development will allow membrane-based treatment systems to operate more efficiently than conventional systems in residential, commercial and industrial locations. This, in turn, should encourage an expanded use of membranes in the POU industry.

43

References

[1] Personal Communication, Ministry of Water Resources, Sultanate of Oman, (May, 2000)

[2] King Lee Technologies, Fouling Prevention Information. Fax: 01-619-693-

4917. Email: klt@kingleetec.com. ProTec RO, ProTec RO-B and ProTec RO-C

[3] Al-Mutaz, I.S., B.A. Al-Sultan, (1995), Prediction of Performance of RO

Desalination Plants, IDA World Congress, Vol. II [4] Isnasious, Z., and Ayoub, M. A., (1995), Performance of Polymer in Brackish

Water R.O. Systems, IDA World Congress, Vol. IV [5] Al Alawi, J. et al, (1993), “ Water in the Arabian Peninsula: Problems and

Perspectives”.,- Water in the Arab World, Harvard University [6] Eissa, S.H., Khedr, M.A. and Refai, A., (Nov. 18-24. 1995),

Evaluation of Desalination Stations in Sinai (South and North), Egypt, IDA World Congress., Vol. V. Abu Dhabi.

[7] Alabdula’aly, A.I., (1995), Experimental Evaluation of Hardness Removal from Buraydah Groundwater Supplies, IDA World Congress, Vol. II

[8] Al-Mudaiheem, R.I.S., et al, (1995), Performance Evaluation of Ten Years

Operation Experience of Brackish Water R.O. Desalination in Man Foulta Plants, Riyadh, IDA World Congress, Vol. II

[9] Alabdula’aly, A. I., (Nov. 18 – 24, 1995), Groundwater Quality and Treatment

in Riyadh, Saudi Arabia. IDA World Concress on “Desalination and Water Sciences”., Vol.VI. Abu Dhabi

[10] Mecumber,P.G., (1995), Freshwater Lenses in the Hyper – Arid Region of

Central Oman. IDA World Congress, Vol. II

[11] William Butler DeOreo, James Patrick Heaney and Peter W. Mayer, (January 1996) “Flow Trace Analysis to Assess Water Use”, Table 2, AWWA Journal

44

APPENDIX A

Membrane Manufacturer’s Technical Data Sheets

45

46

47

48

49

50

51

52

53

54

55

Membrane Element 1812-24

Performance: Permeate Flow: 24 gpd (0.09 m3/d) Salt Rejection: Minimum 96.0 %

Type Configuration: Spiral Wound Membrane Polymer: Composite Polyamide Nominal Membrane Area: 3.3 ft2

Application Data Maximum Applied Pressure: 300 psig (2.1 MPa) Maximum Chlorine Concentration: < 0.1 PPM Maximum Operating Temperature: 113 °F (45 °C) FEED WATER pH Range: 3.0 - 10.0 Maximum FEED WATER Turbidity: 1.0 NTU Maximum FEED WATER SDI (15 mins): 5.0 Maximum Feed Flow: 2 GPM (7.5 l/m) Minimum Ratio of Concentrate to Permeate Flow for any Element: 5:1 Maximum Pressure Drop for Each Element: 10 psi

Test Conditions The stated performance is initial (data taken after 30 minutes of operation), based on the following conditions: 500 PPM NaCl solution 65 psi (0.45 MPa) Applied Pressure 77 °F (25 °C) Operating Temperature 10% Permeate Recovery

6.5 - 7.0 pH Range

A, inches (mm)

B, inches (mm) C, inches (mm) F, inches (mm) Dry Weight, lbs. (kg)

11.8 (299) Fits 2”sch 40 PVC pipe

10.25 (260) 0.68 (17) 0.5 (0.25)

Core tube extensions: D = 0.75” (19 mm) E = 0.94” (24 mm) Note: Core tube on brine seal side (dimension “D”) is plugged. Permeate flow is through o-ring side of tube only.

Notice: Minimum permeate flow for individual elements 15 percent below listed flow. All membrane elements are supplied with a brine seal and o-rings. Elements are vacuum sealed in a polyethylene bag containing less than 1.0% sodium meta-bisulfite and 10 % propylene glycol solution, and then packaged in a cardboard box. Hydranautics believes the information and data contained herein to be accurate and useful. The information and data are offered in good faith, but without guarantee, as conditions and methods of use of our products are beyond our control. Hydranautics assumes no liability for results obtained or damages incurred through the application of the presented information and data. It is the user’s responsibility to determine the appropriateness of Hydranautics’ products for the user’s specific end uses. 7/11/02

D E

56

Membrane Element 2012-70

Performance: Permeate Flow: 70 gpd (0.27 m3/d) Salt Rejection: Minimum 96.0 %

Type Configuration: Spiral Wound Membrane Polymer: Composite Polyamide Nominal Membrane Area: 4.8 ft2

Application Data Maximum Applied Pressure: 300 psig (2.1 MPa) Maximum Chlorine Concentration: < 0.1 PPM Maximum Operating Temperature: 113 °F (45 °C) FEED WATER pH Range: 3.0 - 10.0 Maximum FEED WATER Turbidity: 1.0 NTU Maximum FEED WATER SDI (15 mins): 5.0 Maximum Feed Flow: 3 GPM (7.5 l/m) Minimum Ratio of Concentrate to Permeate Flow for any Element: 5:1 Maximum Pressure Drop for Each Element: 10 psi

Test Conditions The stated performance is initial (data taken after 30 minutes of operation), based on the following conditions: 500 PPM NaCl solution 65 psi (0.45 MPa) Applied Pressure 77 °F (25 °C) Operating Temperature 10% Permeate Recovery 6.5 - 7.0 pH Range

A, inches (mm)

B, inches (mm) C, inches (mm) F, inches (mm) Dry Weight, lbs. (kg)

11.8 (299) Fits 2”sch 40 PVC pipe

10.25 (260) 0.68 (17) 0.5 (0.25)

Core tube extensions: D = 0.75” (19 mm) E = 0.94” (24 mm) Note: Core tube on brine seal side (dimension “D”) is plugged. Permeate flow is through o-ring side of tube only.

Notice: Minimum permeate flow for individual elements 15 percent below listed flow. All membrane elements are supplied with a brine seal and o-rings. Elements are vacuum sealed in a polyethylene bag containing less than 1.0% sodium meta-bisulfite and 10 % propylene glycol solution, and then packaged in a cardboard box. Hydranautics believes the information and data contained herein to be accurate and useful. The information and data are offered in good faith, but without guarantee, as conditions and methods of use of our products are beyond our control. Hydranautics assumes no liability for results obtained or damages incurred through the application of the presented information and data. It is the user’s responsibility to determine the appropriateness of Hydranautics’ products for the user’s specific end uses. 7/11/02

D E

57

Membrane Element 2026-300

Performance: Permeate Flow: 300 gpd (1.14 m3/d) Salt Rejection: Minimum 98.0 %

Type Configuration: Spiral Wound Membrane Polymer: Composite Polyamide Nominal Membrane Area: 12.0 ft2

Application Data Maximum Applied Pressure: 300 psig (2.1 MPa) Maximum Chlorine Concentration: < 0.1 PPM Maximum Operating Temperature: 113 °F (45 °C) FEED WATER pH Range: 3.0 - 10.0 Maximum FEED WATER Turbidity: 1.0 NTU Maximum FEED WATER SDI (15 mins): 5.0 Maximum Feed Flow: 3 GPM (11 l/m) Minimum Ratio of Concentrate to Permeate Flow for any Element: 5:1 Maximum Pressure Drop for Each Element: 10 psi

Test Conditions The stated performance is initial (data taken after 30 minutes of operation), based on the following conditions: 1500 PPM NaCl solution 225 psi (1.55 MPa) Applied Pressure 77 °F (25 °C) Operating Temperature 10% Permeate Recovery 6.5 - 7.0 pH Range

A, inches

(mm) B, inches (mm) C, inches (mm) F, inches (mm) Weight, lbs. (kg)

26.0 (660) Fits 2”sch 40 PVC pipe

23.8 (600) 0.68 (17) 1.5 (0.75)

Core tube extensions: D = 1.0” (25 mm) E = 1.2” (30.5 mm) Notice: Minimum permeate flow for individual elements 15 percent below listed flow. All membrane elements are supplied with a brine seal and o-rings. Elements are vacuum sealed in a polyethylene bag containing less than 1.0% sodium meta-bisulfite and 10 % propylene glycol solution, and then packaged in a cardboard box. Hydranautics believes the information and data contained herein to be accurate and useful. The information and data are offered in good faith, but without guarantee, as conditions and methods of use of our products are beyond our control. Hydranautics assumes no liability for results obtained or damages incurred through the application of the presented information and data. It is the user’s responsibility to determine the appropriateness of Hydranautics’ products for the user’s specific end uses. 7/11/02

58

APPENDIX B

Raw Performance Evaluation Data

59

Conventional RO Performance Evaluation Data

Day

Op: Hours

Feed Cond: (μmhos)

Feed Turb: (NTU)

Feed SDI

Prod: Cond: (μmhos)

1 10.2 752 0.055 4.65 53 2 35.6 755 0.052 64 3 59.4 768 0.055 70 4 84.8 745 0.056 4.59 72 5 106.5 738 0.05 58 6 133.6 745 0.048 55 7 156.7 760 0.051 4.03 63 8 178.3 750 0.045 70 9 205.4 765 0.048 4.09 64

10 227.2 780 0.045 60 11 251.7 753 0.053 60 12 276.3 745 0.049 3.85 63 13 298.1 740 0.048 58 14 323.8 738 0.053 55 15 349.5 730 0.055 3.76 61 16 371 740 0.052 66 17 395.4 765 0.049 59 18 421.6 755 0.052 4.6 70 19 444.5 743 0.045 58 20 466.4 754 0.051 64 21 493.7 765 0.048 4.02 66 22 515.3 744 0.047 65 23 540.9 730 0.045 69 24 563.8 760 0.043 4.32 65 25 588.3 773 0.091 62 26 611.4 781 0.047 66 27 638.7 762 0.049 4.67 62 28 659 772 0.047 56 29 684.3 746 0.043 60 30 710.6 730 0.048 4.35 62 31 732.4 756 0.053 58 32 755.8 743 0.047 4.7 63 33 778.9 773 0.051 65 34 803.1 754 0.055 60 35 829.4 750 0.053 4.7 54 36 852.8 752 0.053 57 37 875 764 0.049 53 38 899.4 782 0.053 4.77 55 39 926.8 749 0.045 57 40 947.4 740 0.043 53 41 972.3 737 0.047 4.85 60 42 996.6 730 0.043 61 43 1018.2 733 0.045 54 44 1043.3 756 0.048 4.9 63 45 1069.9 755 0.043 57 46 1092.5 740 0.042 60 47 1115.4 735 0.049 4.39 54 48 1139.8 750 0.055 54 49 1165.2 765 0.054 59 50 1188.9 780 0.051 4.39 56 51 1213.7 775 0.052 61 52 1235.5 740 0.047 62 53 1259.7 745 0.043 4.43 57 54 1285.3 750 0.05 55 55 1307.6 760 0.053 58 56 1334.9 772 0.05 52

60

Zero-Waste RO Performance Evaluation Data

Day

Op: Hours

Feed Cond: (μmhos)

Feed Turb: (NTU)

Feed SDI

Prod: Cond: (μmhos)

1 5.5 578 0.055 90 2 31.7 582 0.048 5.37 91 3 52.1 572 0.052 95 4 76.5 598 0.05 92 5 100.3 582 0.049 5.35 94 6 126.3 607 0.059 93 7 147.6 610 0.063 90 8 171.6 591 0.057 5.15 96 9 195 568 0.072 90

10 220.4 599 0.077 90 11 242.4 612 0.064 5.13 94 12 267.1 623 0.062 92 13 292.7 625 0.062 90 14 318.8 605 0.059 5.12 94 15 339.2 594 0.064 90 16 361.4 638 0.068 92 17 387.6 578 0.06 5.46 96 18 411.8 625 0.054 90 19 438.4 597 0.059 97 20 461.8 615 0.055 4.91 94 21 484.7 610 0.052 92 22 511.3 606 0.05 96 23 533.3 591 0.05 5.00 90 24 560.7 605 0.058 92 25 582.8 602 0.052 90 26 609.1 598 0.062 92 27 628.5 607 0.066 4.99 90 28 654.6 587 0.074 95 29 677.9 582 0.054 94 30 701.5 568 0.059 90 31 725.6 578 0.057 5.03 96 32 751.3 571 0.071 90 33 772.8 603 0.064 94 34 798.2 588 0.073 5.34 90 35 822.7 610 0.058 96 36 849.8 631 0.054 90 37 869 627 0.062 5.27 94 38 893.5 601 0.087 90 39 916.4 607 0.073 92 40 943.6 585 0.062 4.95 96 41 965.7 567 0.055 94 42 989.3 587 0.066 92 43 1013.6 594 0.052 5.18 90 44 1037.2 598 0.059 94 45 1060.8 607 0.061 94 46 1086.1 603 0.056 4.79 92 47 1109.2 612 0.062 90 48 1135.8 610 0.058 96 49 1159.9 591 0.064 4.85 94 50 1181.4 594 0.066 90 51 1205.6 600 0.062 90 52 1230.4 584 0.06 5.09 92 53 1253.4 604 0.058 96 54 1276.9 607 0.057 90 55 1302.4 623 0.055 4.82 96 56 1327.1 631 0.057 90 57 1349.6 617 0.056 93 58 1373.2 600 0.059 90 59 1398.1 587 0.056 4.48 99 60 1423.7 606 0.057 90 61 1445.6 570 0.054 96 62 1470.3 584 0.058 93