MBR-17: Anaerobic Membrane Bioreactors for domestic wastewater treatment
CU |
07/2006 - 06/2009 |
The demand of higher wastewater treatment efficiencies and restrictions on sludge disposal poses a significant challenge to wastewater companies as the energy cost associated to these have increased exponentially. Therefore significant efforts in finding alternative processes for sludge treatment and sludge reduction are being made. Membrane bioreactors represent a specific subset of bioreactor technology where the membrane replaces alternative means of solids retention such as a gravity sedimentation tank. As an effectm the hydraulic and sludge retention times become completely decoupled, providing greater operational flexibility and the potential to intensify the biological process.
The combination of anaerobic biological treatment with membranes has proven to be an effective technology for the treatment of high strength industrial wastewaters, due to the absence of aeration costs, and the lower sludge productions as compared to aerobic processes. For instance, typical sludge retention times for aerobic MBRs employed in the treatment of domestic wastewaters are between 15 and 25 days while for high strength wastewaters at much higher organic loading rates, SRT in the range 25-70 days have been applied in anaerobic systems. By considering anaerobic MBRs for the treatment of low strength wastewaters it is not only possible to reduce the energy costs associated to aeration but also the operating costs related to sludge treatment or disposal as the few existing studies have shown how the SRT as high as 150 to 200 days have been employed.
The main aim of this project is to study the feasibility of anaerobic MBRs for the treatment of domestic sewage through the comparison of the performance of this system with that of an AE MBR. Direct comparison of effluent qualities and fouling propensities will be used to ascertain the energy and mass balances in both systems