Effect of transient sodium chloride shock loads on the performance of submerged membrane bioreactor

Membrane bioreactor (MBR) is a promising technological option to meet water reuse demands. Though MBR provides effluent quality of reusable standard, its versatility to shock loads remains unexplored. The present study investigates the robustness of MBR under sodium chloride shock load (5–60 g/L) conditions. A bench scale aerobic submerged MBR (6 L working volume) with polyethylene hollow fiber membrane module (pore size 0.4 μm) was operated with synthetic wastewater at steady state OLR of 3.6 gCOD/L/d and HRT of 8 h. This resulted in 99% TSS removal and 95% COD and TKN removal. The COD removal during the salt shock load was in the range of 84–64%. The TSS removal showed maximum disturbance (88%) with a corresponding decrease in biomass MLVSS by 8% at 60 g/L shock. TKN removal was reduced due to inhibition of nitrification with increasing shock loads. It took about 4–9 days for the MBR to regain its steady state performance.