The challenge posed by micropollutants and pathogens has been the subject of considerable interest over the past few decades. Our online event 'Discussing membrane technology: micropollutants and pathogens' event was held on 14 April 2021, in which Simon Judd and Graeme Pearce hosted a discussion with 30 delegates worldwide on the subject.
Features - Process biology
Ragging is a type of clogging, where clogging relates to agglomeration of solids in the membrane tank. In the case of ragging, the filament solids from textile materials join together to form long rags or braids. These rags, which may contain filaments no more than a few mm in length, are mechanically stable in the mixed liquor and can block the inlet channels of the membrane module and/or wrap themselves around the infrastructure of the membrane tank – including the aerators.
Disinfection by MBRs. Unlike regular physical membrane filtration, virus removal by MBRs is not limited to simple size exclusion. Adsorption onto the sludge solids and the membrane cake layer (as well as the membrane itself) represent important removal mechanisms, as well as removal by predation (the feeding on the pathogens by other higher organisms).
Designing and managing wastewater treatment plants using CAE software − the LynxASM1 modelling and simulation tool
Ever more versatile and sophisticated options for designing and managing plants are being developed. And as the new CAE tools become more accessible and widespread, suppliers continue to develop and refine the tools, so the reliability of their predictions increases – promoting further take-up.
MBR membranes are prone to fouling generally, and biofouling in particular, by organic matter originating from the microbial cells. These biofoulants vary in concentration with the activated sludge characteristics, such as the mixed liquor suspended solids (MLSS) concentration and solids retention time (SRT) (and so the food/microorganism (F/M) ratio), as well as the feedwater chemistry.
MBRs use more energy compared with classical activated sludge (CAS) because the aeration requirements are greater. Aeration is needed both for the biological and membrane tanks for degrading the organics and scouring the membrane respectively. Typically, aeration energy consumption accounts for 70–80% of total energy used for the municipal wastewater treatment process, with 40–60% consumed by the process biology.