Embed Size (px)
Citation preview
Pall Aria™ Microfiltration System ConsistentlyClarifies River Water with High Turbidity Peaks
OverviewWith the increasing complexity of dairy equipmentand operations, there is a growing trend towardsmore reliable and higher quality water treatmentprocesses. In addition, as utilization of our waterresources becomes more intensive, meetingdemand may require using water from morechallenging sources. In many cases, the watersupply comes from a surface water source, often a river which may experience high turbidity peaksduring rainfall events.
In the past, conventional clarification and mediafiltration have been used in many of thesesituations. However as these systems age andregulations tighten, these plants can have difficultycoping with peak turbidity loads. In some casesadditional water treatment chemicals are requiredto maintain supply during a turbidity event; in other cases operation of the treatment plant issuspended until the event passes, an approachwhich can require considerable storage volumes of treated water.
The Challenge
A leading dairy producer operating one of theworld’s largest ingredient plants sourced processwater from two rivers nearby, which was thentreated with conventional clarification/filtration
systems. To support the production of more than60 tons of products per hour, including powders,dry salt cheese, cream and mozzarella, a consistentand regular supply of high quality water is critical.
On general day to day river water turbidity, theexisting water treatment plant meets the site waterquality and capacity requirements. However duringhigh turbidity events the site water treatment plantencountered problems in handling the higher solidsloading and the site’s water treatment capacity and quality decreases. Often the high turbidityevents experienced at the site last for a few days. However the treated water storage capacity at thesite is only a few hours. In extreme cases the highturbidity events can cause severe disruption anddowntime for the production site due to theshortage of treated water.
The producer needed to review filtrationrequirements in order to constantly produce highquality water, regardless of the turbidity variationsand spikes characterize their feed water.
App
licat
ion
Bul
letin
Pall Aria AP system
Tangahoe River at intake site – New Zealand
The Solution: Pall Aria MicrofiltrationSystem
Pall Aria membrane systems are designed to meetthe stringent requirements of dairy and otherindustries, producing high quality water irrespectivefrom raw feed water variance. The Pall Ariamodules use proprietary polyvinylidene fluoride(PVDF) hollow fiber membrane technology withadvanced bonding techniques for an exceptionallystrong module design.
The membranes have a nominal pore size of 0.1 μm and can remove suspended solids,bacteria, cysts and oocysts, organics and othercontaminants from surface and ground watersources.
The highly porous PVDF membrane is the heart ofthe system, which means a system can bedesigned at higher sustainable fluxes compared toother membranes, or it can be operated with lowerfouling resistance, lower pumping head pressure,or increased intervals between regenerationsequences — all of which have substantialoperational benefits including operational flexibilitywhen confronted with turbidity events.
To ensure maximum efficiency andlowest total cost of ownership, Pall hasdeveloped techniques to keep themembranes free of fouling materials.These are integrated as specificoperating modes within the automationsoftware.
• In normal conditions, water is filtered in direct mode outside-in through thehollow fiber. Depending on water quality,a small amount of the fluid may berecirculated, resulting in loweraccumulation of foulants and debris on the membrane surface.
• Backwash, or simultaneous airscrubbing and reverse flow (SASRF) atregular intervals (every 15-120 minutes),results in sustained flux over a longerfiltration time. Air is injected at lowpressure into the feed side of the
module as a mechanical process to remove debrisand decrease the rate of overall trans-membranepressure (TMP) increase. At the same time, filtratethat has been collected in the dedicated reverseflow tank is pumped in the reverse direction into themodule. After a 30 second SASRF cycle, most ifnot all of the accumulated debris has been sweptaway to drain. A forward flush circulating feedwater or filtrate at high velocity across the externalsurface of the membrane fibers completes theSASRF cycle.
• Enhanced flux maintenance (EFM) is anotherautomated cycle that uses warm water with mildchemical solutions tailored to specific foulants thatmay be present. The time interval between EFM isuser-defined and depends on the running conditionsof the membrane. EFM is used to reduce thefrequency at which a partially fouled membraneresults in the system operating at less than peakefficiency. By allowing the membranes to operateat high flux rates, EFM enables a smaller systemfootprint resulting in floor space and facility costsavings, as well as a lower average TMP,generating pumping energy savings. The durable,strong and chemically resistant PVDF hollow fibersmake this possible. They can be subjected tothousands of EFM cycles with no reduction inservice life.
• While SASRF and EFM are designed to removeparticulate matter and routine foulants, it may beoccasionally necessary to perform a complete CIPprocess (typically monthly). This 2-step protocolusing an acidic solution and a caustic solution with chlorine returns the modules to “nearly new”condition and can be performed hundreds of times over the life of the modules. Due to the lowfrequency of CIP operation, the process is semi-automated.
(left) Module cutaway showinghollow fibers. (above) Crosssection of a microfiltrationhollow fiber membrane.
Concentration of feed water particulate in Pall Aria System reject streams relative toturbidity (NTU) and TSS (ppm).
Pilot testing was performed at the dairy site over a period of 8 months to confirm the preliminarydesign parameters of the microfiltration (MF)system, including operating flux and fluxmaintenance processes. Pre-treatment with 2.5-5ppm of polyaluminium chloride, selected fromamong flocculation chemicals used in the existingwater treatment plant, directly injected into the pilotMF feed tank, was shown to be beneficial bothduring normal water conditions and high turbidityevents.
SASRF cycles, every 15 to 20 minutes, and a daily EFM with 500 ppm of sodium hypochlorite
proved to be highly efficient in maintaining the TMPbelow 1.5 bar during the turbidity events, with aflux of 65 lmh. The Pall MF pilot system was ableto continue operating with feed water turbidity ashigh as 450 NTU. There was no need to shutdown the MF system due to any high feed waterturbidity events that were experienced during thetrial period. At all times during the trial the MFfiltrate turbidity remained below 0.1 NTU.
The Pall Aria microfiltration system demonstrated it could provide an uninterrupted supply of highquality water to the dairy site, from both riversources, during normal and high-turbidity events.
1 2 3 4 5 6
TP
M(b
ar)
NT
U
100
90
80
70
60
50
40
30
20
10
0
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
0.5
0.4
0.3
0.2
0.1
0
Flu
x(L
MH
), Tem
pera
ture
(°C
), F
eed
tu
rbid
ity
(NTU
)
Pall Aria Microfiltration System Performance
Filtrate turbidity from Pall Aria microfiltration system and from filtration plant in place
20-Feb-10 22-Feb-10 24-Feb-10 26-Feb-10 28-Feb-10 2-Mar-10 4-Mar-10 6-Mar-10
▼ ▼
TMP ◆ Flux x Temperature Feed Turbidity
Date
Date
– Flux MF Filtrate
▼
20-Feb-10 22-Feb-10 24-Feb-10 26-Feb-10 28-Feb-10 2-Mar-10 4-Mar-10 6-Mar-10
The Benefits
The Pall Aria water treatment system demonstratedits ability to produce the required volumes of highquality water even during high turbidity events,replacing traditional clarification techniques cost-effectively.
• 80% operating cost savings, based on chemicaland electrical use, was provided by the Pall Ariasystem. Consistent high filtrate quality regardlessof raw water quality and turbidity spikes cangenerate further savings in downstream waterprocessing, with reduced hypochlorite consumptionfor pipeline disinfection and reduced fouling ofmembrane filters at point of use.
• Consistent >95% recovery rate was demonstratedon all types of feed water quality, compared to<90% on low turbidity water and down to 20%on higher turbidity water with the conventionalsystem.
• Sustained productivity during high turbidityevents significantly reduces the need forincreased water storage and can preventshortage of high quality water.
• High degree of microbial control, typically 6 logremoval for Cryptosporidium and Giardia cysts,provides process security.
• Automation, operational simplicity, compactfootprint and modular design ease systemintegration into existing installations. Significantlyless operator inputs were required to operate the Pall Aria system.
• Long module life, low energy consumption(typically 0.09 kWh per m3 filtered water), lowchemical consumption, minimal water losses (up to 98% water recovery) and overall costimprovement ensures a low cost of ownership.
Reference:
Peter Stark, Tony Foskett, Mike Thompson and Ben McSweeney – Pall Corporation, Membranetreatment of high turbidity water – Pilot studies onNew Zealand river water
About Pall Corporation
Pall Corporation is a global filtration, separationand purification leader providing solutions to meetthe critical fluid management needs of customersacross the broad spectrum of life sciences andindustry. We work with our customers to advancehealth, safety and environmentally responsibletechnologies.
Pall Food and Beverage provides products andservices to ensure product quality and maintainprocess reliability in beverage and food production.Our solutions also assist in consumer protection,the reduction of operating costs and wasteminimization.
Pall Food and Beverage
25 Harbor Park DrivePort Washington, NY 11050 +1 516 484 3600 telephone+1 866 905 7255 toll free US
© Copyright 2012, Pall Corporation. Pall, and Aria are trademarks of Pall Corporation. ® Indicates a trademark registered in the USA. Filtration. Separation. Solution.SM and Total Fluid ManagementSM are service marks of Pall Corporation.
FBABARIARWEN October 2012
Visit us on the Web at www.pall.com/foodandbev
Pall Corporation has offices and plants throughout the world. For Pall representativesin your area, please go to www.pall.com/contact
Please contact Pall Corporation to verify that the product conforms to your nationallegislation and/or regional regulatory requirements for water and food contact use.
Because of technological developments related to the products, systems, and/orservices described herein, the data and procedures are subject to change without notice.Please consult your Pall representative or visit www.pall.com to verify that thisinformation remains valid.
