FEATURE

7Membrane Technology September 2006

A pharmaceutical wastewater stream (Figure 1)requires treatment to reduce its high chemical oxy-gen demand (COD), high mixed liquor suspendedsolids (MLSS) loads and its significant ammonicalnitrogen content prior to effluent discharge, eitherto sewer or directly to the environment.

Contaminant concentrationsContaminant concentrations in pharmaceuticalwastewater are typically in the range of2000–40 000 mg/l COD, 10 000–20 000 mg/l

MLSS and up to 1000 mg/l total Kjeldahl nitrogen(TKN). Treated effluent will normally be requiredto contain less than 100–1000 mg/l COD andbelow 10 mg/l ammonia, depending on the envi-ronmental sensitivity of the receiving water.

Although conventional physical and chemicaltreatment approaches are normally employed foron-site treatment of wastewater, such as conven-tional activated sludge (CAS) treatment with sub-sequent liquor clarification, pharmaceutical wastestreams pose specific problems for such traditionalapproaches.

Pharmaceutical wastewater can be variable instrength, and can potentially subject treatment

plants to shock loading causing areduction in plant treatment effi-ciency and a deterioration oftreated effluent quality.

ConventionaltreatmentWith conventional treatmentapproaches, the high rate ofsludge production can result inlimited success in final clarifica-tion stages and subsequent prob-lems with effluent solids loading.

In pharmaceutical wastewatertreatment systems, batch process-ing can lead to sludge bulking and

variations in dissolved solids content. This canresult in destabilization of bacterial flocs and thesubsequent loss of biomass into the final effluent,compromising the efficiency of COD treatment inthe process. Alternative treatment solutions forpharmaceutical wastewater clearly need to be con-sidered.

Membrane bioreactor systemsFor more than a decade Zenon MembraneSolutions, a part of GE Water & ProcessTechnologies, has developed ultrafiltration mem-brane bioreactor (MBR) systems.

These systems can replace or enhance conven-tional treatment systems and reduce overall plantsize by combining clarification, aeration and filtra-tion processes. The membrane technology ensuresabsolute biomass retention (thus more effectiveCOD removal), and a final effluent of consistentlyhigh quality because this technology is not com-promised by variable feed-water quality or shock-loads.

ZeeWeed MBR technology offers an approachto wastewater treatment with an effectiveness inthe pharmaceutical sector that has been provenover many years.

RegulationThe regulation of the pharmaceutical sectorwithin European Integrated Pollution Preventionand Control (IPPC) legislation will often requirea higher quality effluent to be produced, as envi-ronmental quality standards are reviewed by theregulators.

ZeeWeed MBR units can reliably treat pharma-ceutical wastewater to meet these demanding stan-dards in a cost-effective way.

Hollow-fiber technologyThe ZeeWeed MBR uses immersed hollow-fibermembranes to carry out ultrafiltration.

GE ZeeWeed MBR technology for pharmaceutical wastewater treatmentBy Jack Noble – Managing Director, Zenon Membrane Solutions Sheffield, UK

This feature describes how the ZeeWeed membrane bioreactor can provide supe-rior treatment of pharmaceutical wastewater. The article outlines some of thepotential problems that conventional activated sludge and settlement technolo-gy encounters in treating pharmaceutical wastewater, and the features and bene-fits of using an alternative technology based on membranes. Two case studies,covering GE ZeeWeed membrane bioreactor technology that has been success-fully installed at pharmaceutical installations in Ireland, are also presented toillustrate the consistent and high quality effluent treatment achievable.

Figure 1. Wastewater at a pharmaceutical site is high in chemicaloxygen demand (COD), mixed liquor suspended solids (MLSS) and total nitrogen.

FEATURE

8Membrane Technology September 2006

ZeeWeed fibers, manufactured from resilientpolyvinylidene fluoride (PVDF), each have bil-lions of pores of nominal 0.04 µm size. Fibersare gathered together as membrane cassettes(Figure 2). These membrane cassettes are usedby immersing them directly in the wastewaterprocess tank.

Through the application of a slight suctionto the head of the membrane cassettes, waste-water is filtered from the outside of the fiberto the inside. In this way, only the inside ofthe membrane comes into contact with the fil-tered wastewater. The removed solids andimpurities remain outside the membrane,without fouling the membrane surface, and apermeate of high-quality treated effluent isproduced.

Air diffusersCoarse bubble air diffusers, which are locatedat the base of each membrane cassette, gener-ate an airflow that scours the external mem-brane surface and removes rejected solids.

This airflow supplements the oxygenrequirements in the accompanying aeratedbiological treatment system. ZeeWeed mem-branes are periodically cleaned automaticallyby back-flushing with the permeate.

Pre-packagedZeeWeed cassettes, called Z-MOD, are madeavailable in pre-packaged plants for wastewatertreatment applications.

The ZeeWeed hollow-fiber membranes con-tained in Z-MOD units are specially supported(reinforced) membrane fibers. Each membrane isinfused with a braid to improve fiber robustnessand mechanical strength in a high MLSS waste-water environment.

Z-MOD units comprise a complete filtrationsystem and need to be used in conjunction witha suitable aeration tank. This allows the designof both the biological and hydraulic compo-nents to be optimized for site-specific require-ments and variable-strength waste streams.ZeeWeed membranes are not only mechanicallyrobust, but also chemically and oxidant resis-tant, and tolerant of variations in pH.

PerformanceZeeWeed MBR technology outperforms CAS-settlement treatment without the need forchemical dosing. If the pharmaceutical wastestream also requires phosphorus removal, chem-ical treatment will be required, as described laterin this article.

The volume of sludge produced by ZeeWeedMBR technology is lower than that generated byCAS treatment, offsetting costly sludge storage,treatment and disposal. The system offers a sim-ple and cost-effective process that reduces capitaland operating costs, compared with convention-al physical and chemical approaches (for exam-ple, CAS).

The high-quality effluent, consistently pro-duced by the robust ZeeWeed MBR process,typically achieves:

• COD and biological oxygen demand(BOD) > 90% (> 98% for BOD) removal,with permeate typically BOD5 < 5 mg/l.

• Total suspended solids (TSS) > 99%removal, permeate typically TSS < 5 mg/l.

• TKN > 90% removal, typically permeateammonia < 1 mg/l.

• Phosphorus > 90% removal, using appro-priate chemical dosing.

PhosphorusWhere it is necessary to reduce phosphorus lev-els from waste streams, coagulants can be addeddirectly to the aeration process.

ZeeWeed membranes are compatible with avariety of coagulants. The small membrane poresize virtually eliminates the discharge of particu-late phosphorus material allowing for consistentachievement of < 0.1 mg/l (and often better than0.05 mg/l) phosphorus.

Treatment capacityThe packaged plant Z-MOD system is pro-duced in three sizes, as modular ‘building-block’ packages to suit the required treatmentcapacity. Treatment capacity ranges fromapproximately 19 m3/day to over 3785 m3/day,and modules can be linked together to allowsite-specific scaling.

The pre-engineered modules are all factory-tested prior to dispatch, and can be rapidly set-up in virtually any location either as indepen-dent treatment plant, or easily fitted in-linewith existing treatment facilities to cope with

treatment capacity expansion or effluent qualityenhancement.

ZeeWeed membrane cassettes are usuallyimmersed in a separate tank. This is advanta-geous for a simplified construction when con-sidering retrofit applications. The ease andspeed of installation allows companies toadopt a cost-effective, flexibly scaled, just-in-time approach to effluent treatment.

The Z-MOD occupies a small plant foot-print – typically only 10% that of CAS. Sinceclarifiers are not necessary for ZeeWeed MBRsystems, capital costs are substantially lowerthan for CAS treatment systems.

AutomatedZ-MOD systems are automated and incorporate aprogrammable logic controller (PLC) to manageand control the process. The PLC will initiateautomated cleaning strategies as it detectsproblems such as fouling or accumulation onthe membranes.

The need for operator intervention is mini-mized by the high degree of automation and,since chemical dosing is not required for effec-tive treatment of most pharmaceutical waste-water by ZeeWeed technology, the ability tooperate the system remotely reduces laborcosts.

The intelligent system control and automatedself-cleaning allows for long-term system relia-bility in the production of optimum quality per-meate, and only minimal other system mainte-nance is necessary. ZeeWeed membrane cassetteshave sufficient spacing between the modules toallow solids to be easily removed from the fiberbundle to facilitate this occasional maintenance.

Running costsThe running costs for the Z-MOD systems arelow. The permeate pump exerts a small pressuredrop (7–55 kPa) across the membrane head andenergy requirements are small. As an alternative tosuction filtration, gravity withdrawal can be used,

Specializing in membrane systemsand productsZenon Membrane Solutions, a part of GEWater & Process Technologies, specializes inthe development and manufacturing of mem-brane systems and products for water treat-ment, wastewater treatment and water reuse.

With UK projects managed from its officebased in Sheffield, and hundreds of installa-tions worldwide, Zenon is providing cost-effective and reliable systems to meet thechallenges that municipalities, industry andgovernment agencies are facing.

Figure 2. ZeeWeed membrane cassettes areimmersed directly in the process tank.

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9Membrane Technology September 2006

providing site conditions allow sufficient differen-tial head across the membrane.

Overall, the capital and operating costs of theZeeWeed MBR technology are very favorablecompared with alternative technologies.

Pharmaceutical installationsThe ZeeWeed MBR technology outlined in thisarticle so far has been successfully used to pro-duce high-quality effluent from pharmaceuti-cal wastewater, meeting the specific require-ments at installations across Europe and the restof the world.

The treatment capacity at these installationsranges from modest (for example, approxi-mately 80 m3/day at Chemagis in Israel) toextensive (for instance, around 5500 m3/dayat Abbott Pharmaceuticals in Puerto Rico).

In the paragraphs that follow, two examplesare given of how ZeeWeed MBR technologyhas been successfully installed in Europe forinternational pharmaceutical organizations atsites in County Cork, Ireland – namely Pfizer(Ringaskiddy) and GlaxoSmithKline(Carrigaline). The systems consistently pro-duce the high quality effluent that is required.

Pfizer installationCommissioned during March 2001, Pfizerinstalled a containerized ZeeWeed MBR systemas part of its plant expansion and upgraderequirements (Figure 3), supplementing its exist-ing CAS plant.

The treatment capacity for the system isapproximately 1500 m3/day, for maximum flowrates of about 63 m3/hour and average rates of46 m3/hour.

The ZeeWeed MBR system that was installedconsists of two treatment trains, operating inparallel. Each train is a standard system, with awet section housing the membranes and aprocess section housing pumps, valves, instru-ments, and control and other ancillary equip-ment.

Pilot testingThe installation of this ZeeWeed MBR treat-ment system at Pfizer followed successful pilottesting at the plant over several months.

In the testing process, the effectiveness of sec-ond-stage treatment using Zenon membranetechnology was directly compared with tradi-tional clarifier treatment using the same first-stage feed-water effluent. The raw influent has aCOD of approximately 800 mg/l – reduced to400–600 mg/l by first-stage treatment.

The membrane technology consistently out-performed the conventional clarifier for second-stage treatment, producing a permeate withCOD in the range 150–250 mg/l – typically halfthe contaminant levels achieved by second-stageclarifier treatment (300–400 mg/l COD).

GlaxoSmithKline installationAlso commissioned during March 2001,GlaxoSmithKline (Cork) Ltd installed aZeeWeed MBR system as part of a plant expan-sion.

The plant is designed to treat sanitary wasteand utility blow-down streams, and has a treat-ment capacity of about 500 m3/day. This newplant has been integrated into the site’s overallwastewater treatment system.

It consists of an equalization tank, pretreat-ment screening, a combination bioreactor and

filtration tank that is equipped with a fine bubble, diffused aeration system for aerobic bio-logical treatment, and ZeeWeed ultrafiltrationmembranes.

The effluent feed-water has a contaminantloading (in kg/day) of 250 (COD), 160 (BOD)and 8.4 (total nitrogen, of which 4.9 is ammoni-cal). After treatment by the ZeeWeed MBR sys-tem, a guaranteed effluent quality (in mg/l) ofbetter than 50 (COD), 10 (BOD) and 5(ammonium) is achieved.

SummaryGE ZeeWeed MBR technology offers a provenalternative to conventional approaches to thetreatment of pharmaceutical wastewater.

This wastewater poses particular problems forconventional treatment plant because of variationsin feed-water strength, floc destabilization andCOD loss, and shock loading. ZeeWeed ultrafiltra-tion membrane technology, in combination withappropriate aeration treatment, is not compro-mised in this manner, and consistently generates aneffluent permeate of high quality that is suitable fordischarge into even sensitive environments.

ModularZeeWeed technology is incorporated into pre-engineered highly automated and self-cleaningZ-MOD treatment plant systems.

Modular Z-MOD packaged plant is easy toinstall, either as a stand-alone treatment system,or to increase the treatment capacity or upgradethe treatment quality of existing conventionalplant. The small footprint, flexible configurationand treatment capacity of ZeeWeed technologyhas proved valuable in achieving reliable andcost-effective treatment for the pharmaceuticalindustry across the world.

OutperformsIn Ireland, after initial pilot testing confirmedthat the membrane technology easily outperformsconventional clarification, ZeeWeed systems havebeen integrated into existing wastewater treatmentsystems to fulfill the requirements of plant expan-sion and to upgrade effluent quality.

This proven success demonstrates how ZeeWeedMBR technology can offer an effective and quicklyand easily installed treatment option to cope withexpansion at other pharmaceutical sites, or therequirements for improved effluent quality as dic-tated by regulators.

Contacts:Zenon Membrane Solutions, Bullhouse Mill, MillhouseGreen, Sheffield, South Yorkshire S36 9NN, UK. Tel: +44122 676 0600, Email: jpeace@zenonenv.co.uk,www.zenonenv.co.ukGE Water & Process Technologies, Zenon MembraneSolutions, 3239 Dundas Street West, Oakville, OntarioL6M 4B2, Canada. Tel: +1 905 465 3030,www.zenon.com

Figure 3. ZeeWeed membrane bioreactor (MBR) systems integrated into existing treatment facilitiesat Pfizer (County Cork, Ireland).