Biological Phosphorus Removal Using a Biofilm Membrane Reactor: Operation at High Organic Loading Rates

Abstract

This research describes Biological Phosphorus Removal at Organic Loading Rates from 5 to 30 g COD/m2·d using a laboratory scale Sequencing Batch Biofilm Membrane Reactor. The reactor was fed with synthetic wastewater based on sodium acetate with a COD:N:P ratio of 20:5:1. An average PO4-P removal of 72% was observed when the organic load was kept under 15 gCOD/m2·d. Maximum PO4-P removal of 85% was associated with a consumption rate of 700 mgPO4-P/m2·d. Increasing with the organic load, the PO4-P released during the anaerobic phase averages 40% over the influent concentration, showing a maximum value of 107%. Throughout the experiments, overall COD removal rates were above 90%, and the COD uptake during the anaerobic phase ranged between 60 and 80% for organic loading rates under 15 gCOD/m2·d. Simultaneous nitrification and dentrification took place during the transition from aerobic to anaerobic conditions at the beginning of every cycle. Average transformation rates between 0.6 to 2.0 gNH4-N/m2·d and 0.3 to 1.2 gNO3-N/m2·d were observed for organic loading rates under 15 gCOD/m2·d, corresponding to average NH4-N removal rates between 50 and 70%. Average effluent NO3-N ranged between 1.5 and 10.6 mg/l. Phosphorus contents of the biofilm based on dry mass ranged between 4.2 and 5.2%.