[Study on efficiency of nitrogen and phosphorus removal by algal biofilm]

Cultivating algal biofilm on nitrogen (N) and phosphorus (P) in waters presents an alternative to control eutrophication. Under laboratory conditions, efficiency on nitrogen and phosphorus removal from synthetic wastewater, secondary effluent and eutrophic lake water by algal biofilm was assessed. Algal biofilm was mainly composed of blue-green algal species Oscillatoria princeps. During a 5-day treatment, for synthetic wastewater, secondary effluent and eutrophic lake water, removal rates of TN were 57.1%, 94.5% and 93.8%, respectively, removal rates of TP were 93%, 73% and 79%, respectively. The dried algal production were 3.7 - 7.2 g x m(-2)x d(-1), and the TKN and TP of algal biomass were 5.7% - 7.2% and 0.78% - 2.44%, respectively. Recovery of nutrients in harvested algal biomass accounted for about 20% - 39% for N and 65% - 82% for P.