Sequential Batch Membrane BioReactor treating saline wastewater

A sequential batch membrane bioreactor treating high strength salinity wastewater has been investigated. The salt effects on carbon and nutrient removal, fouling behaviour as well as biomass kinetics have been analysed. Salinity was increased at step of 2 g NaCl L-1 per week. The total COD removal efficiency was high (93%) along the entire experimental campaign. However, the biological contribution on the COD removal efficiency was reduced with the increase of salinity. The lowest nitrification removal efficiency (63%) was obtained at 10 g NaCl L-1 salinity due to the lower nitrifier activity. Regarding membrane fouling, the irreversible cake deposition was the predominant fouling mechanism along the experimentation period. Despite the increase of salinity, soluble microbial product concentration was negligible likely due to the low food microorganisms ratio. Respirometric batch tests have showed an high stress effect due to salinity, with a significant reduction of the respiration rates (from 8.85 mgO2 L-1 h-1 to 4 mgO2 L-1 h-1).