NITROGEN AND PHOSPHORUS REMOVAL FROM WASTEWATER BY THE MICROALGAE BIOFILM

摘要

Wastewater reuse is an important approach to resolving the water crisis and reducing water pollution. However, the water from municipal wastewater treatment plants is not conducive for reuse as the contents of nitrogen and phosphorus in secondary effluents are relatively high. Algae biofilm is an eco-friendly approach suitable for advanced treatment to remove nitrogen and phosphorus from wastewater. This work investigates the potential of Oedogonium sp.biofilm systems for the nitrogen and phosphorus removal from synthetic wastewater. The effect of glucose, initial pH and Fe~(3+) ions on the nitrogen and phosphorus removal are investigated. The results are present as follows: Oedogonium sp.biofilm systems can remove nitrogen and phosphorus effectively. The main mechanism of nitrogen and phosphorus removal is algae assimilation. (1) Glucose concentration had a great effect on the removal of nitrogen, the higher the glucose concentration, the higher the TN removal rate. Totally, the optimum glucose concentration was 200 mg/L, under which the nitrogen and phosphorus removal efficiency reached 76.8% and 82.7%, respectively. (2) The initial pH of the wastewater had little effect on the absorption of nitrogen while had a great effect on the absorption of phosphorus. When the initial pH = 5.0-8.0, the NH_4~+-N, TN and TP removal rate reached 97.0%, 97.0% and 96.0%, respectively. (3) Fe~(3+) had little effect on nitrogen and phosphorus removal. The NH_4~+-N removal rate was about 99.0% and TN removal rate increased slightly with the increase of Fe~(3+) concentration. While the Fe~(3+) concentration was 3 mg/L, the TP removal rate was the highest of 98.0%.