
Ongoing
oagulant addition is used widely in both conventional and membrane-based water treatment as an essential aid to floc formation and is also recognized to assist greatly in reducing the extent of trans-membrane pressure (TMP) build-up in submerged membrane bioreactor treatment of wastewaters . Coagulant addition may also assist in removal of phosphorus in treatment of wastewaters and is also recognized to aid the dewatering of the highly gelatinous sludge that is typically produced in submerged membrane bioreactor wastewater treatment.
Despite the apparent advantages, there has been only limited investigation of the impact of coagulant choice and dosing conditions on nutrient removal, membrane fouling and excess sludge dewatering in SMBR treatment of wastewaters. One reason for the limited research undertaken to date in this area relates to the complexity of the SMBR system and the variety of reactions that can occur on addition of a coagulant to a membrane bioreactor.
Some of the unanswered questions are:
The objective of this project is to improve nutrient removal, minimise membrane fouling and aid the dewatering of excess sludge in hybrid coagulation/submerged membrane bioreactor (MBR) treatment of wastewater by:
Judicious use of both laboratory-based and pilot-scale experimentation using both synthetic and real wastewaters coupled with advanced mineral characterisation techniques (EXAFS, SAED, HRTEM) combined with systems-based kinetic modelling will assist greatly in elucidating the key processes operating in hybrid coagulation/submerged membrane bioreactor (C/SMBR) systems.
The project commenced in July 2010. A wide range of coagulant dosing
conditions were tested using three small scale membrane bioreactors located at UCMST and one pilot scale MBR at Sydney Water’s Bondi Sewage Treatment Plant.
Upon the completion in 2014, the project succesfuly derived operating protocols for membrane bioreactors that allow the development of cost effective operating methods. Novel cleaning strategies that are far more effective than traditional cleaning protocols used in MBR plants have also developed. Superior performance of membranes modified with the in-house developed antimicrobial additives was maintained during long-term pilot plant studies using brackish river water. The number of required backwashes for the modified membrane was an order of magnitude less than the control. Additionally trans-membrane pressure for the modified membrane was significantly lower. Membrane performance was also tested when the feed was spiked with bacteria and modified membrane performed significantly better than control. We found insignificant depletion of antimicrobial active component from modified membrane during long-term pilot plan studies.
Beijing Origin Water Technology
Tsinghua University
Sydney Water
Water Research Australia
ARC Linkage Grant LP100100056