Membrane Bioreactor Technology
Clarifiers in conventional water and wastewater treatment systems, clarifiers occupy a significant proportion of a treatment facility’s land area because they are designed on the basis of surface loading. An approach to making a treatment facility more compact could be to replace its clarifiers with an alternative technology. Filtration could be one such alternative. However, conventional granular media filtration technology would not be able to stand up to the rigours of solids-liquid separation where the suspended solids content is measured in terms of thousands of mg/L instead of hundreds. A possible alternative to granular media filtration is membrane filtration. In principle, a membrane bioreactor can attain a high sludge concentration that would lead to higher treatment capacity and result in potentially very significant reductions in land area requirement. However, a reactor with a high treatment capacity is often much more difficult to stabilize and it is
harder to maintain its stability during operation. The membrane bioreactor is a relatively untested technology for sewage treatment. As a result, relatively little information is available relating to the design and operation protocols for membrane bioreactors. The lack of information is particularly severe with respect to its application in a tropical region. Furthermore, the direct applicability of information, available in the literature, to the tropical environment is questionable.
The Wastewater Biotreatment Group (WBG) at the Department of Civil Engineering, NUS, has been conducting a research project to investigate the operational characteristics and performance of a membrane Sequencing Batch Reactor (SBR) system for treating high strength wastewater. The main emphases of the project are to study the effect of operation protocol on membrane fouling and to
harder to maintain its stability during operation. The membrane bioreactor is a relatively untested technology for sewage treatment. As a result, relatively little information is available relating to the design and operation protocols for membrane bioreactors. The lack of information is particularly severe with respect to its application in a tropical region. Furthermore, the direct applicability of information, available in the literature, to the tropical environment is questionable.
The Wastewater Biotreatment Group (WBG) at the Department of Civil Engineering, NUS, has been conducting a research project to investigate the operational characteristics and performance of a membrane Sequencing Batch Reactor (SBR) system for treating high strength wastewater. The main emphases of the project are to study the effect of operation protocol on membrane fouling and to investigate the possibility of operating the membrane bioreactor as a high cell density reactor as well as to determine the consequential changes in microbial morphology and yields. It is also intended to sutdy the potential of reclaiming the treated water for non-potable usage by assessing the microbiological quality of the treated effluent.
The results obtained thus far suggest that the membrane bioreactor consistently achieves a Chemical Oxygen Demand (COD) removal efficiency of 98.5% for 5 months of continuous operation (Fig. 1). It was observed that increase in the feed concentration did not affect the overall COD removal efficiency of the system.
With the encouraging results obtained from the membrane SBR system, WBG is planning to carry out a continuous flow version of the MBR. This new series of studies will likely be jointly carried out with at least one industrial partner. This project was carried out in collaboration with Assoc Prof SL Ong and Asst Prof JY Hu.
Contact Person: Assoc Prof WJ Ng
Tel: 8742172/2102, Fax: 7791635
Email: cvengwj@nus.edu.sg
