Long term trials with membrane bioreactor for enhanced wastewater treatment coupled with compact sludge treatment -pilot Henriksdal 2040, results from 2020
Stockholm’s wastewater treatment plant (WWTP) in is currently retrofitting from a conventional activated sludge process to a new membrane bioreactor (MBR) process. It also includes new treatment steps for sludge handling. Stockholm Vatten och Avfall (SVOA) and IVL have since 2014 conducted long-term MBR studies in pilot scale at the R&D facility Hammarby Sjöstadsverk. This report present results from the pilot operation during 2020.
The MBR-pilot was continuously operated at a higher inflow than the design average flow. The average effluent concentration of nitrogen and phosphorus met the effluent requirements of the future WWTP also this year. A low consumption of phosphorus precipitation chemicals could be achieved mainly due to a high Bio-P activity. The pilot showed that glycerol can be a good temporary carbon source at Henriksdal WWTP during startup.
Like previous years, the membranes in membrane tank 1 (MT1) was cleaned with oxalic acid and the membranes in MT2 with citric acid. Several tests to optimize the chemical consumption for membrane cleaning were performed. Recovery cleanings (RC) of the membranes were performed twice in 2020.
In the sludge pilot, a thermophilic and a mesophilic hydraulic retention time (HRT) crash test showed stable performance down to 4 days HRT.
The overall resource consumption in the pilot showed that the optimization of phosphorus precipitation and membrane cleaning chemicals resulted in a significantly lower dosing than design values for the future Henriksdal WWTP.