MEMBRANE BIOREACTORS

Membrane Bioreactors (MBR) for Wastewater Treatment

1. INTRODUCTION

The technologies most commonly used for performing secondary treatment of

municipal wastewater rely on microorganisms suspended in the wastewater to treat it. Although

these technologies work well in many situations, they have several drawbacks, including the

difficulty of growing the right types of microorganisms and the physical requirement of a large

site. The use of microfiltration membrane bioreactors (MBRs), a technology that has become

increasingly used in the past 10 years, overcomes many of the limitations of conventional

systems. These systems have the advantage of combining a sus-pended growth biological

reactor with solids removal via filtration. The membranes can be designed for and operated in

small spaces and with high removal efficiency of contaminants such as nitrogen, phosphorus,

bacteria, bio-chemical oxygen demand, and total suspended solids. The membrane filtration

system in effect can replace the secondary clarifier and sand filters in a typical activated sludge

treatment system. Membrane filtration allows a higher biomass concentration to be maintained,

thereby allowing smaller bioreactors to be used.

Membrane bioreactors are able to provide the benefits of biological treatment with a

physical barrier separation. Compared to conventional treatment processes, membranes are

able to provide better quality effluent with a smaller, automated treatment process.

DEPT. OF CIVIL ENGG., GMIT Page 1


2. APPLICABILITY

For new installations, the use of MBR systems allows for higher wastewater flow or

improved treatment performance in a smaller space than a conventional design, i.e., a facility

using secondary clarifiers and sand filters. Historically, membranes have been used for smaller-

flow systems due to the high capital cost of the equipment and high operation and maintenance

(O&M) costs. Today however, they are receiving increased use in larger systems. MBR

systems are also well suited for some industrial and commercial applications. The high-quality

effluent produced by MBRs makes them particularly applicable to reuse applications and for

surface water discharge applications requiring extensive nutrient (nitrogen and phosphorus)

removal.

3. ADVANTAGES

The retention of all suspended matter and most soluble compounds within the

bioreactor leads to excellent effluent quality capable of meeting stringent discharge

requirements and opening the door to direct water reuse.

The possibility of retaining all bacteria and viruses results in a sterile effluent,

eliminating extensive disinfection that would be required otherwise and eliminate the

corresponding hazards related to disinfection by products.

It results in more compact systems than conventional processes significantly reducing

plant footprint making it desirable for water recycling applications.

The process is more compact than a Conventional Activated Sludge process (CAS),

skipping three (3) individual processes of the conventional scheme. The feed

wastewater only needs to be screened (1-3 mm) just prior to removal of larger solids

that could damage the membranes.

In addition it is easier to operate and maintain.

It has a higher Nitrogen Removal rate than any other treatment process.

Finally, it has a comparatively low sludge yield; thereby reducing the IOM cost of

sludge handling.



4. MEMBRANEDuring MBR wastewater treatment, solid-liquid separation is achieved by

Microfiltration (MF) or Ultrafiltration (UF) membranes. A membrane is simply a two-

dimensional material used to separate components of fluids usually on the basis of their relative

size or electrical charge. The capability of a membrane to allow transport of only specific

compounds is called semi-permeability (sometimes also permselective). This is a physical

process, where separated components remain chemically unchanged. Components that pass

through membrane pores are called permeate, while rejected ones form concentrate or

retentate.

Fig 1:Structure of membrane unit

4.1 MEMBRANE TYPES

4.1.1 Plate and Frame – The plate and frame membranes consist of two flat sheets of

membrane material, usually an organic polymer, stretched across a thin frame. The space

between the membrane sheets is placed under vacuum in order to provide the driving force for

filtration. Several plates are arranged in a cassette to allow for increased surface area and

convenient modular design. The membrane cassette is immersed in the mixed liquor and the

separation flow is from outside-in. For example, Kubota membranes have air induced liquid

cross-flow along the plates. This creates turbulence and hinders cake formation and subsequent

fouling. The organic polymer, polyethylene for example, has the required flexibility to move

slightly in the cross-flow to allow three-dimensional dynamic forces to reduce cake formation.

The cross-flow of air also acts to dissolve oxygen to and mix the contents of the reactor.



4.1.2 Hollow fibre – Hollow fibre membranes consist of long strands, or fibres, of hollow

extruded membrane. They are most often of organic polymer construction and are applied

much the same as plate and frame membranes. The fibres are mounted to a supporting structure

that serves as a manifold for permeate transport as well as an air delivery system. Similar to the

plate and frame modules, air induced liquid cross flow prevents excessive cake formation and

increases the lifespan of the membrane.

Fig 2:Hallow fiber membrane Fig 3:Flat Plate membrane

4.1.3 Tubular – As the name implies, tubular membranes are hollow tubes with the membrane

placed on the surface of the tube. Below the membrane surface is a supporting structure with

high porosity. In most cases, tubular membranes are made of inorganic material such as

ceramic and have a metal oxide membrane surface to provide a small nominal pore size.

Tubular membranes have a different separation driving force than the previous two. Rather

than vacuum pressure, the material to be separated flows along the membrane at high velocity

under pressure. The velocity provides a transverse force to drive the water through the

membrane while leaving the larger diameter particles behind. A tubular membrane could be

used in the outside-in arrangement with the feed water flowing along the centre of the tube and

the permeate passing to the outside walls, or the inside-out arrangement where the influent

travels along the centre of the tube and travels axially outward.



Fig 4: Tubular membrane

5. MEMBRANE CHARACTERISTICSMembrane treatment is an advanced treatment process that has become increasing

popular over the past ten years. Membrane processes have been understood but underutilized

since the 1960’s due to high capital costs. Recent developments in membrane manufacturing

have enabled the production of better quality membranes at a reduced price. Compared with

increasing conventional water treatment costs, membrane treatment is now considered

economically feasible.

5.1 Filtration processes

There are six commercially used membrane separation processes; Microfiltration (MF),

Ultrafiltration (UF), Nanofiltration (NF), Reverse Osmosis (RO), Dialysis, and Electrodialysis

(ED). Membrane processes can be classified based on membrane separation size and

mechanism, membrane material and configuration, or separation driving forces used.

Membrane processes utilize set terminology to discuss membrane performance. The rate of

fluid transfer across the membrane is referred to as the flux, and has units of kg/m²h.The

pressure experienced across the membrane is referred to as the trans-membrane pressure

(TMP). The fluid that passes through the membrane is the permeate, while the flow retained by

the membrane is the retentate.

Separations based on membrane pore size include MF (0.1- 0.2 μm),UF (0.002 – 0.1

μm), and NF (0.0001 – 0.001 μm). The ranges are not strictly defined and some overlap exists.

These three types of filtration rely on a sieving action to remove particulate matter. All four



varieties of membranes rely on hydrostatic pressure differences to drive the separation process.

Microfiltration or Ultrafiltration is the most commonly used membrane size in wastewater and

MBR treatment. Microfiltration is able to remove protozoa, bacteria and turbidity, while UF

has the added benefit of virus removal).

5.2 Membrane materials

Membranes are made from either organic polymers or ceramic materials. Polymers

offer the advantage of low cost production but may contain natural variations in pore size, and

are prone to fouling and degradation. Ceramic membranes offer excellent quality and durability

but are economically unfeasible for large scale operations, although they may be well suited for

industrial applications (Scott and Smith, 1996). All of the commercial MBR manufacturers use

polymeric MF membranes. Table lists the most common types of polymer materials used to

construct membranes. Polymeric membranes are manufactured in several forms, the most

common types for MBR are hollow fiber and plate and frame.

TABLE 1: Polymer Membrane Materials and Characteristics

Material Advantages Disadvantages

Polypropylene Low cost

High pH range tolerance

No chlorine tolerance

Expensive cleaning

Chemicals required

Polyvinylidene fluoride High chlorine tolerance

Simple cleaning chemicals

Cannot sustain pH>10

Polyether Sulphone and

Polysulphone

Chlorine tolerance

Reasonable cost

Brittle material requires

support or flow inside to

outside

Polyacrylonitrile Low cost, typically used for

UF membranes

Less chemically resistant than

PVdF

Cellulose Acetate Low cost Narrow pH range

Biologically active

5.3 Membrane integrity

Monitoring membrane integrity is necessary for all processes. Membrane breakage or



Degradation can lead to the loss of physical separation and possible contamination of the

effluent. Membrane integrity can be monitored by particle counters or pressure decay testing

(PDT). PDT is the preferred method due to its reliability and increased accuracy. In PDT the

membrane module is pressurized to a high pressure and monitored for leaks, the PDT is

sensitive enough to detect the breakage of a single fibre.

5.4 Membrane fouling

Membrane fouling is the largest concern in the design of membrane and MBR systems.

Membrane fouling can be due to particulate build-up, chemical contamination or precipitation.

Particulate fouling occurs as matter in the wastewater collects on the surface of the membrane.

As the layer builds up the membrane pores can be blocked reducing the flux through the

membrane and increasing the TMP. Particulate matter can foul membranes by either plugging

or narrowing the pores or through the formation of a cake layer on the surface. Membrane

fouling can be controlled through the use of periodic maintenance back-flushing and chemical

cleans in place (CIP). Back-flushing is completed by reversing the flow of air or water through

the membrane to unclog the pores. If the membrane is heavily fouled a chemical clean may be

necessary. Sodium hydroxide and surfactant solution is the most common chemical used for

cleaning, but other chemicals such as citric acid, chlorine, hydrogen peroxide, or aluminium

bifluoride may be used depending on manufacturer’s guidelines. Long term fouling due to the

precipitation of manganese of silica has been observed in some instances, but can generally be

reversed with cleaning.

In membrane bioreactors several additional steps are taken to reduce fouling due to the

high suspended solids in the retentate. Coarse bubble aeration is introduced at the bottom of

hollow fiber membranes and travels vertically along their length. This has a two-fold purpose

of aerating the wastewater and vibrating the membrane fibers to remove particulate matter,

increasing the time between cleanings. The membranes are operated near critical flux to

minimize fouling and in a periodic fashion, with a back-flush every 5 to 15 minutes.

6. MBR SYSTEM CONFIGURATIONSMBR systems can be classified into two major categories according to the location of

the membrane component.

6.1 Submerged or Immersed MBR



In the submerged MBR process, the membrane is submerged directly in the aeration

tank. By applying low vacuum or by using the static head of the mixed liquor, effluent is

driven through the membrane leaving the solids behind.

6.2 External / Sidestream MBR

In the external MBR, the mixed liquor is pumped from the aeration tank to the

membrane at flow rates that are 20-30 times the product water flow to provide adequate shear

for controlling solids accumulation at the membrane surface. The high cost of pumping makes

EMBR system impractical for full scale municipal wastewater treatment plants.

Fig 5:Immersed membrane bioreactor

Fig 6:sidestream membrane bioreactor



TABLE 2 – Comparison of External and Internal Membrane Based MBR System Configuration.

Comparative Factor External MBR Systems Internal MBR Systems

Membrane area

Requirement

Characterized by higher flux and therefore lower membrane area requirement.

Lower flux but higher membrane packing density (i.e., membrane area per unit volume).

Space or Footprint

Requirements

Higher flux membranes with bioreactor operating at higher VSS concentration and skidded assembly construction, results in, compact system.

Higher membrane packing density and operation at bioreactor VSS concentration of 10 g/l or greater translates to compact system.

Bioreactor and Membrane Component Design and Operation

Dependency

Bioreactor can be designed and operated under optimal conditions including those to achieve biological N and P removal, if required.

Design and operation of bioreactor and membrane compartment or tank are not independent. High membrane tank recycle required (e.g., recycle ratio 4) to limit tank VSS concentration build-up.

Membrane Performance

ConsistencyLess susceptible to changing wastewater and biomass characteristics.

More susceptible to changing wastewater and biomass characteristics requiring alteration in membrane cleaning strategy and/or cleaning frequency.

Recovery of Membrane

PerformanceOff-line cleaning required every 1 to 2 months. Simple, automated procedure normally requiring less than 4 hours.

Off-line “recovery” cleaning required every 2 to 6 months. A more complex procedure requiring significantly more time and manual activity, at least on occasion may be required (i.e., physical membrane cleaning).



Membrane Life or Replacement Requirements

Results to-date imply an operating life of 7 years or more can be achieved with polymerics prior to irreversible fouling. Operating life of ceramics much longer.

Results to-date imply an operating life of 5 years may be possible prior to irreversible fouling and/or excessive membrane physical damage.

Full Scale Application

StatusConventional membrane based systems have a very long track record. Few non- conventional systems in operation in the U.S.

Full scale application widespread in the

U.S.

Economics Non-conventional designs translate to comparable power costs. Comparable capital cost at least at lower wastewater feed rates (e.g., approaching 1893 m3/day).

Power and capital cost advantage at higher wastewater feed rates.

7. DESIGN FEATURES

7.1 Pre-treatment

To reduce the chances of membrane damage, wastewater should undergo a high level of

debris removal prior to the MBR. Primary treatment is often provided in larger installations,

although not in most small to medium sized installations, and is not a requirement. In addition,

all MBR systems require 1- to 3-mm-cutoff fine screens immediately before the membranes,

depending on the MBR manufacturer. These screens require frequent cleaning. Alternatives for

reducing the amount of material reaching the screens include using two stages of screening and

locating the screens after primary settling.

7.2 Membrane Location

MBR systems are configured with the membranes actually immersed in the biological

reactor or, as an alternative, in a separate vessel through which mixed liquor from the

biological reactor is circulated.



7.3 Membrane Configuration

MBR manufacturers employ membranes in two basic configurations: hollow fiber

bundles and plate membranes. Siemens/U.S.Filter’s Memjet and Memcor systems, GE/Zenon’s

ZeeWeed and ZenoGem systems, and GE/Ionics’ system use hollow-fiber, tubular membranes

configured in bundles. A number of bundles are connected by manifolds into units that can be

readily changed for maintenance or replacement. The other configuration, such as those

provided by Kubota/Enviroquip, employ membranes in a flat-plate configuration, again with

manifolds to allow a number of membranes to be connected in readily changed units. Screening

requirements for both systems differ: hollow-fibre membranes typically require 1- to 2-mm

screening, while plate membranes require 2- to 3-mm screening.

7.4 System Operation

All MBR systems require some degree of pump-ing to force the water flowing through

the membrane. While other membrane systems use a pressurized system to push the water

through the membranes, the major systems used in MBRs draw a vacuum through the

membranes so that the water outside is at ambient pressure. The advantage of the vacuum is

that it is gentler to the membranes; the advantage of the pressure is that throughput can be

controlled. All systems also include techniques for continually cleaning the system to maintain

membrane life and keep the system operational for as long as possible. All the principal

membrane systems used in MBRs use an air scour technique to reduce buildup of material on

the membranes. This is done by blowing air around the membranes out of the manifolds. The

GE/Zenon systems use air scour, as well as a back-pulsing technique, in which permeate is

occasionally pumped back into the membranes to keep the pores cleared out. Back-pulsing is

typically done on a timer, with the time of pulsing accounting for 1 to 5 percent of the total

operating time.

7.5 Downstream Treatment

The permeate from an MBR has low levels of suspended solids, meaning the levels of

bacteria, BOD, nitrogen, and phosphorus are also low. Disinfection is easy and might not be

required, depending on permit requirements.

The solids retained by the membrane are recycled to the biological reactor and build up

in the system. As in conventional biological systems, periodic sludge wasting eliminates sludge



buildup and controls the SRT within the MBR system. The waste sludge from MBRs goes

through standard solids-handling technologies for thickening, dewatering, and ultimate

disposal. Hermanowicz et al. (2006) reported a decreased ability to settle in waste MBR

sludges due to increased amounts of colloidal-size particles and filamentous bacteria. Chemical

addition increased the ability of the sludges to settle. As more MBR facilities are built and

operated, a more definitive understanding of the characteristics of the resulting biosolids will be

achieved. However, experience to date indicates that conventional biosolids processing unit

operations are also applicable to the waste sludge from MBRs.

7.6 Membrane Care

The key to the cost-effectiveness of an MBR system is membrane life. If membrane life is

curtailed such that frequent replacement is required, costs will significantly increase.

Membrane life can be increased in the following ways:

Good screening of larger solids before the membranes to protect the membranes

from physical damage.

Throughput rates that are not excessive, i.e., that do not push the system to the

limits of the design. Such rates reduce the amount of material that is forced into the

membrane and thereby reduce the amount that has to be removed by cleaners or that

will cause eventual membrane deterioration.

Regular use of mild cleaners. Cleaning solutions most often used with MBRs

include regular bleach (sodium) and citric acid. The cleaning should be in accord

with manufacturer-recommended maintenance protocols.

7.7 Membrane Guarantees

The length of the guarantee provided by the membrane system provider is also important in

determining the cost-effectiveness of the system. For municipal wastewater treatment, longer

guarantees might be more readily available com-pared to those available for industrial systems.

Zenon offers a 10-year guarantee; others range from 3 to 5 years. Some guarantees include cost

prorating if replacement is needed after a certain service time. Guarantees are typically

negotiated during the purchasing process. Some manufacturers’ guarantees are tied directly to

screen size: longer membrane warranties are granted when smaller screens are used.



8. WORKING THEORYNormally, systems are built with two different compartments.

The first section is the screening stage where the wastewater enters the unit. In this area;

heavy solids are first separated subsequently traversing to another compartment which houses

the membranes. The initial screening is of high importance, as the larger molecules (scum and

grit) will not trap the surface of the membrane and lead to fouling.

In the second compartment, the biological process takes place involving vigorous

agitation, coming from air bubbles generated from a blower system. This acts to scour and

clean the surface of the membrane to prevent buildup of material on the and also to provide

sufficient oxygen concentration for biological action that supports growth of bacteria

Depending on how the system is designed to ensure efficient air to water oxygen transfer, the

household MBR is capable to support up to 4000ppm of MLSS level while large-scale

industrial wastewater treatment plant bioreactor scan handle up to 20000ppm.

A complete unit usually comes equipped with a backflush system whereby discharged

wastewater will now move counter flow from the permeate side back again to the system to

dislodge trapped material accumulating on the surface During this process, air scouring will

still continue to run to help increase removal efficiency.

Fig 7: Working theory



Fig 8: Schematic diagram of the Membrane Bioreactor

9. WATER RECLAMATION

The use of MBR technology for reclamation is a rapidly expanding application. MBR

technology is well suited for reuse treatment due to its small footprint and relatively easy

operation. Small MBR systems can be designed to pull wastewater directly from the sewer at

the remote points of reuse, eliminating the need for large central treatment plants and

redistribution. MBR effluent is ideal for further treatment by reverse osmosis. The high quality

of the MBR permeate allows increased RO flux with reduced fouling. Following RO treatment

the water generally meets or exceeds all drinking water standards and may be even higher in

quality than virgin water. Despite the high water quality public acceptance within the US is

difficult. Studies have suggested that a hierarchy of acceptable use exists.



Treatment Reuse Hierarchy:

1. Forest Irrigation

2. Forage Crop Irrigation

3. Food Crop Irrigation

4. Park and Garden Irrigation

5. Livestock Watering

6. Cooling

7. Industrial Cleaning

8. Industrial Process

9. Fishery Use

10. Recreational Water Supplies

11. Public Grey Water

12. Public Drinking Water

In many cases the public fears are unfounded or irrational as “de-facto” reuse of

drinking water supplies occurs already, often with less treatment than direct reuse designed

systems. In areas with ample water supplies the reuse of economic cost of wastewater reuse

cannot usually be justified. In areas with water scarcity such as Singapore, which relies on

Malaysia to supply it’s water the reuse of water is highly accepted. Reused water is sold under

the name NeWater and all wastewater treatment plants are being retrofitted with MF, RO and

UV systems for production.



TABLE 3: Typical MBR Effluent Quality

S.NO. PARAMETERS UNITS VALUES

1. BOD mg/l <2

2. TSS mg/l <1

3. Ammonical nitrogen as

NH3-N

mg/l <0.5

4. Nitrogen as TKN mg/l <1

5. Fecal coliform count MPN/100ml <2

6. pH 6.8-7.8

10. APPLICATIONS OF MEMBRANE BIOREACTOR:

10.1 Applications in municipal wastewater treatment

MBR systems were initially used for municipal wastewater treatment, primarily in the

area of water reuse and recycling. Compactness, production of reusable water, and trouble-free

operation made the MBR an ideal process for recycling municipal wastewater in water and

space limited environments. the development of less expensive submerged membranes made

MBRs a real alternative for high flow, large scale municipal wastewater applications. Over

1,000 MBRs are currently in operation around the world with approximately 66% in Japan, and

the remainder largely in Europe and North America. Out of these installations, about 55% use

submerged membranes while the rest have external membrane modules.

10.2 Applications in industrial wastewater treatment

High organic loadings and very specific and difficult to treat compounds are two major

characteristics of industrial waste streams that render alternative treatment techniques such as

the MBR desirable. Since, traditionally wastewater with high COD content was treated under

anaerobic conditions, initial attempts of MBR applications for industrial wastewater were in the

field of anaerobic treatment.



10.3 Applications in fields of landfill leachate, sludge digestion, And human excrement

In addition to municipal and industrial wastewater treatment, MBRs have been utilized

in a number of other areas. One such area is the treatment of landfill leachates. Landfill

leachates usually contain high concentrations of organic and inorganic compounds.

Conventionally, the treatment of leachates involves a physical, biological, or membrane

filtration process (or a combination of them). MBR systems have been successfully utilized

with an additional treatment step for inorganics and heavy metal removal, such as reverse

osmosis (RO). Several industrial scale plants, combining a MBR and a reverse osmosis system,

are presently operated.

The MBR system was also used in the treatment of human excreta in domestic

wastewater. These applications, also known as night soil treatment systems, were typified by

the high strength of the waste and the need for on-site treatment. The

MBR system replaced a rather complex set of treatment systems which incorporated

denitrification, coagulation, filtration, and activated carbon treatment. Another application of

the MBR is in the area of sludge treatment. Conventionally, sludge stabilization in wastewater

treatment plants is achieved by a single pass, anaerobic digester. Since the HRT and the SRT

are identical in these systems, the capacity is limited and long solid retention times are required

for effective solids destruction.

10.4 Nitrate removal in drinking water

Denitrification and removal of natural organic matter are two main treatment

requirements for drinking water. Nitrate is the most common groundwater contaminant in

North America and world-wide. Nitrate is a stable and highly soluble nitrogen species, easily

transported and accumulated in groundwater systems. These properties, coupled with increased

anthropogenic discharges of nitrogen containing compounds from point and non-point sources,

have resulted in elevated nitrate concentrations in ground and surface waters. Non-point

sources may have a larger impact on ground water and are associated with agricultural and

livestock practices and residential septic tank effluents.

Nitrates can be removed either biologically or by physicochemical treatment techniques

such as reverse osmosis, ion exchange, and electrodialysis. Natural organic matter can be

treated biologically or through activated carbon adsorption. Biological removal of nitrates and

organic matter is receiving more attention due to the complete conversion of nitrate into

nitrogen gas and relative ease of operation (Falk 2002). Conventional physico-chemical



treatment methods only concentrate nitrate into solutions which still require disposal. In typical

biological denitrification processes, however, post treatment processes such as sand filtration,

activated carbon adsorption, and disinfection are required to remove biological entities and

excess organic matter and colour. The number of post-treatment processes can be significantly

reduced by using a MBR for biological denitrification. All biological entities as well as some

dissolved organic matter will be retained in the bioreactor while long denitrifying culture

retention times and short hydraulic retention times can be maintained.

11. LIMITATIONS

The primary disadvantage of MBR systems is the typically higher capital and operating

costs than conventional systems for the same through-put.

O&M costs include membrane cleaning and fouling control, and eventual membrane

replacement.

Energy costs are also higher because of the need for air scouring to control bacterial

growth on the membranes. In addition, the waste sludge from such a system might have

a low settling rate, resulting in the need for chemicals to produce biosolids acceptable

for disposal (Hermanowicz et al. 2006). Fleischer et al. 2005 have demonstrated that

waste sledges from MBRs can be processed using standard technologies used for

activated sludge processes.



12. CONCLUSION

The membrane bioreactor technology has great potential in wide ranging applications including

municipal and industrial wastewater treatment, groundwater and drinking water abatement,

solid waste digestion, and odour control.

The technical feasibility of this process has been demonstrated through a number of pilot and

bench scale research studies. Full scale systems are operational in various parts of the world

and substantial growth in the number and size of installations is anticipated for the near

future.

The MBR process is already considered as a viable alternative for many waste treatment

challenges and with water quality issues firmly placed into the forefront of public debate, ever

tightening discharge standards and increasing water shortages will further accelerate the

development of this technology.

Agricultural activities and related industries constitute a potential source of pollution to the

environment. Waste from intensive livestock operations and wastewater generated by the

food processing industry are two streams characterized by high organic and nutrient strength.

Multiple treatment processes are normally required to ameliorate the waste to levels

acceptable for on-site reuse or direct discharge to surface water.

MBRs offer a proven alternative due to their ability to handle high organic loadings and wide

fluctuations in flow and strength. Activated sludge scrubbing may also be able to be

incorporated into these systems for odour control and air pollution management.

High quality effluent produced by the MBR would provide pathogen and bacteria control and

assist the facility in complying with strict environmental regulations. It would also allow

extensive process optimization through internal water recycle and significantly reduce

dependence to municipal waste treatment facilities or to the availability of crop land for waste

application.



13. REFERENCES

Adham, S., P. et al. 2001. Feasibility of the membrane bioreactor process for water

reclamation. Water Science and Technology 43(10): 203-209.

BCC. (2011). Membrane bioreactors: global markets. BCC Report MST047C. March

2011.

Fane, A. G. (1996) Membranes for Water Production and Wastewater Reuse.

Desalination., 106, 1.

George Crawford et al (2001) The Evolution of Membrane Bioreactor System Designs

for Wastewater Treatment. IWA Sept 2001.

Gupta, K.et al. (1994) Membrane Biological Reactor System for Treatment of Oily

Wastewaters. Water Environment Research, 66 (2), pp.133-139.


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MEMBRANE BIOREACTORS