Product category:
Trade effluent monitoring + on-site treatment
News Release from: Zenon Environmental | Subject: ZeeWeed in Irish pharma plants
Edited by the Processingtalk Editorial
Team on 09 January 2007
Treatment of pharmaceutical wastewater
using MBR
Two pharmaceutical plants in Ireland used ZeeWeed membrane bioreactors for reliable and effective treatment of wastewater, avoiding some problems experienced with conventional settlement technology
Pharmaceutical plant wastewater (PWW) can be especially high in mixed liquor suspended solids (MLSS, 10000 - 20000 mg/l) and chemical oxygen demand (COD, 2000-4000 mg/l) It can also contain high ammoniacal nitrogen loads, with up to 1000 mg/l total Kjeldahl nitrogen (TKN)
This article was originally published on Processingtalk on 22 Nov 2004 at 8.00am (UK)
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Traditionally, conventional physical, biological and chemical treatment processes have been used to process this effluent prior to its discharge to sewer or directly to the environment.
Depending upon location-specific consent conditions, the treated effluent will normally be required to be reduced to a COD of 100-1000 mg/l and <10 mg/l ammonia.
Current implementation of IPPC legislation, which encompasses the pharmaceutical sector, may require improvements to be made to effluent treatment installations as environmental quality standards are reviewed by the regulators and best available technology (BAT) criteria applied.
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Conventional wastewater treatment approaches, for example on-site conventional activated sludge (CAS) treatment combined with liquor clarification, can successfully achieve the required contaminant reductions.
However, the reliability of successful treatment using conventional approaches can be problematic.
Industrial processes at pharmaceutical installations and the batch processing of wastewater give rise to specific challenges to wastewater treatment systems.
PWW can be variable in strength.
This can cause shock loading, adversely affecting treatment efficiency.
CAS treatment leads to high sludge production rates, resulting in difficulties with the final clarification stage and solids loading in the final effluent.
Variable dissolved solids loads in PWW, exacerbated by batch processing, can destabilise bacterial flocs.
This not only reduces COD treatment efficiency, but can "leak" biomass into the final effluent, compromising both COD and solids treatment.
Advanced wastewater treatment technologies such as ZeeWeed membrane bioreactor (MBR) systems offer a highly efficient, compact, and reliable alternative to CAS systems.
ZeeWeed MBR, manufactured by Zenon Membrane Solutions, a part of GE Water and Process Technologies, eliminates multiple process steps of CAS systems, combining clarification, aeration, and filtration into a single process step.
Durable reinforced hollow fibre membranes are specifically designed to operate in a high solids environment and produce near drinking-water quality effluent in a fraction of the space and time of CAS systems.
This highly automated and versatile technology can be retrofitted into existing plants to upgrade capacity and performance or completely replace a system in a new plant.
MBR technology is not compromised by variable influent quality or shock loads, and ensures absolute biomass retention.
ZeeWeed MBR technology offers a cost-effective wastewater treatment solution with proven effectiveness in the pharmaceutical sector, producing a consistently high quality effluent that can reliably achieve the demanding discharge consents in the current regulatory framework.
ULTRAFILTRATION USING HOLLOW FIBRES.
ZeeWeed hollow fibre membranes are manufactured from resilient PVDF.
Each fibre has billions of pores of 0.04 microns nominal size.
Groups of fibres are gathered together as Modules, which are combined into membrane cassettes.
These cassettes are directly immersed into the wastewater process tank.
Under slight suction at the head of the membrane cassettes, the wastewater is filtered through the membrane physical barrier from the outside of the fibre to the inside.
Fibre geometry provides a high UF surface area, and treated effluent is drawn from both ends of the cassette for enhanced permeability.
This system is physically robust.
The inside-out flow path ensures that the inside of the membrane comes into contact only with high quality permeate and is not subject to fouling.
Impurities and removed solids remain in the process tank.
Air diffusers located at the base of each membrane cassette generate an airflow that scours the external membrane surface with coarse bubbles, removing rejected solids.
The membrane cleaning process is completed by periodic automated back-pulsing of treated effluent.
ZeeWeed membranes are manufactured with reinforced (or supported) fibres for MBR applications, suited to high MLSS environments such as PWW treatment.
The membranes are mechanically strengthened by the infusion of the hollow fibres with a braid, dramatically improving ruggedness of the fibres and increasing membrane lifetime.
The reinforced membranes are tolerant to variable acidity, and can be safely used with common chemical treatment agents.
ZEEWEED MBR TREATMENT SYSTEMS.
ZeeWeed membranes are available in pre-packaged Z-Mod wastewater treatment plants.
Z-Mod units are complete UF systems, and are used in conjunction with a suitable aeration tank, permitting locally optimised design of hydraulic and biological treatment components, well suited to batch processing of variable strength effluent.
Z-Mod is produced as Modular "building-block" plant that can be linked together to facilitate site-specific upgrade or plant replacement, tailored to appropriate treatment capacity.
All pre-engineered units are factory-tested prior to despatch, and can be rapidly set-up in virtually any location either as independent treatment plant, or in-line with existing treatment facilities usually deployed in separate immersion tanks.
Simple construction requirements and small plant footprint facilitate retrofit requirements.
Running costs for Z-Mod systems are low; energy requirements are small, as the required pressure drop applied across the membrane cassettes is only 7-55 kPa (and can be achieved by gravity withdrawal at some locations).
Z-Mod systems are highly automated.
Each unit incorporates advanced programmable logic controller (PLC) based process management and control.
The PLC detects problems such as deterioration in treatment efficiency due to membrane fouling, and initiates automated cleaning systems.
Automation minimises the requirement for operator intervention, and, since the ZeeWeed MBR system does not require chemical dosing in most PWW treatment applications, labour costs are minimised.
Intelligent system control and membrane robustness ensure long-term reliability.
ZeeWeed membranes have sufficient spacing between the Modules to facilitate occasional maintenance.
ZeeWeed capital and operating costs are favourable compared to alternative technologies, and the flexible Modular Z-Mod offers an option for rapid improvement of effluent quality or increased capacity requirements.
ZEEWEED MBR PERFORMANCE.
ZeeWeed MBR outperforms CAS treatment, usually without the need for chemical dosing.
High quality permeate is consistently produced even under the challenging conditions posed by PWW.
Conventional aerobic COD treatment can be compromised by problems with clarification stages and by biomass leakage into the final effluent.
ZeeWeed MBR technology reliably achieves a final treated effluent quality of < 5mg/l BOD (i.e >90% COD removal and >98% BOD removal), total suspended solids < 5 mg/l (>99% removal) and ammonia < 1 mg/l (TKN removal > 90%).
Treatment easily meets most discharge requirements, even those directly to sensitive locations.
High permeate quality also enables savings in water use (another aspect of IPPC BAT), allowing recycling of used water back to production systems.
Sludge production rates are lower than for CAS, reducing expensive sludge storage, treatment and disposal costs.
At installations where treatment of phosphorus is required, notably in eutrophic catchment areas or where the use of phosphorus compounds in the production process is high, suitable coagulants can be added directly at the aeration stage.
The excellent chemical resistance of ZeeWeed membranes means they are compatible with a variety of coagulants.
The small membrane pore size virtually eliminates particulate phosphorus discharge resulting in a permeate quality of <0.1 mg/l phosphorus (>90% removal efficiency).
The GE ZeeWeed MBR technology has been successfully deployed at pharmaceutical installations around the world.
Wastewater treatment capacity ranges from small (80 m3/day at Chemagis in Israel) to large (5500 m3/day at Abbott Pharmaceuticals in Puerto Rico).
In Europe, four PWW projects have been completed by GE to date.
Two of these sites are situated in County Cork, Ireland, one at Pfizer (Ringaskiddy) and the second at GlaxoSmithKline (Carrigaline).
These were commissioned in March 2001.
PFIZER RINGASKIDDY.
Pfizer commissioned its complete ZeeWeed MBR treatment system after extensive pilot testing lasting several months.
Pilot work directly compared ZeeWeed MBR treatment against CAS technology.
First stage treated wastewater (COD 400-600 mg/l) was used as feed-water for the two alternative treatment systems.
ZeeWeed technology outperformed the conventional clarifier for second-stage treatment, with resultant second stage treatment effluent COD loadings of 150-250 mg/l (membrane technology) approximately half that of the conventional alternative (300-400 mg/l).
Pfizer installed a containerised ZeeWeed MBR system as part of its plant expansion and upgrade requirements, supplementing their existing CAS plant.
It consists of two parallel treatment trains, each with a standard Z-Mod system.
A wet section houses the membranes and a process section houses process pumps, valves, instruments, control and ancillary equipment.
The treatment capacity for this system is approximately 1500 m3/day.
GLAXOSMITHKLINE AT CARRIGALINE.
GlaxoSmithKline installed a ZeeWeed MBR system as part of its plant expansion.
Here, the plant treats approximately 500 m3/day of sanitary waste and utility blow-down streams.
The ZeeWeed MBR has successfully been integrated into the existing site wastewater treatment system.
It consists of an equalisation tank, pretreatment screening, a combination bioreactor and filtration tank equipped with fine bubble diffused aeration for aerobic biological treatment and ZeeWeed UF membranes.
After treatment by the GE MBR system, effluent quality better than 50 mg/l COD (10 mg/l BOD) and 5 mg/l ammonia is reliably achieved from feed-water loadings of 250 kg/day COD and 8.4 kg/day TKN.
RESULTS WITH ZEEWEED MBR.
ZeeWeed MBR technology offers a proven alternative to conventional approaches to the treatment of PWW, which poses particular problems for conventional treatment technology due to variations in feed-water strength and potential shock loading, and high dissolved solids content leading to floc destabilisation and subsequent biomass leakage, resulting in a deterioration in treated effluent quality.
ZeeWeed membrane technology is not compromised in this application as UF provides a physical barrier against solids and biomass.
This generates an effluent permeate of consistently high quality, superior in performance to CAS alternatives.
GE ZeeWeed MBR technology has proved valuable in achieving reliable and cost-effective treatment for the global pharmaceutical industry.
This article has described how these systems have been successfully integrated into existing wastewater treatment systems at two pharmaceutical installations in Ireland.
This demonstrates how the technology offers an effective treatment option, capable of being rapidly and easily installed, to cope with expansion at other pharmaceutical sites, or to achieve requirements for improved effluent quality.
[This article was provided by Jack Noble from the Zenon Environmental UK office].
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