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.
Some clogging occurs in most MBR systems regardless of membrane module type or geometry. Prevention or control measures are typically considered at the system design level and during operation. Examples include fine screening of raw wastewater and rescreening of mixed liquor. But even with adequate pre-treatment, clogging can still occur and require remediation protocols and/or specialist equipment.
The integrated fixed-film activated sludge membrane bioreactor (IFAS-MBR): comparison with a regular MBR for nutrient removal
The IFAS-MBR process is less well explored than the MBBR-MBR configuration. It is of interest to establish the performance of the IFAS-MBR when challenged with a variable influent C/N ratio, since this affects both nutrient removal and the emission of N2O – a highly active greenhouse gas (GHG).
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.
Changes to the design and operation of MBR membrane modules have led to improved energy efficiency − but energy consumption is the most significant cost and contributor to environmental impact during MBR operation. The case study plant at Kaarst-Nordkanal highlights the impact of on-site installation of an AD process on the key parameters of energy consumption and the associated greenhouse gas emissions.
The arguments surrounding the precise target sludge (or mixed liquor suspended solids, MLSS) concentration to use when running an MBR are pretty well developed but what is it that ultimately sets the solids concentration range?