Efficiency of Microalgae Scenedesmus in the Removal of Nitrogen from Municipal Wastewaters

Due to the high content of nitrogen in the municipal wastewaters, this study evaluated the efficiency of Scenedesmus as an important microalgae in the removal of nitrate from wastewaters and its application as an appropriate culture medium. As algae have high resistance to temperature and pH changes, they can absorb low concentrations of nutrients and need simple low-cost technology. Through photosynthesis, microalgae effectively stabilize carbon dioxide at a low cost, and the oxygen produced by the photosynthesis process can reduce the biochemical oxygen demand (BOD) of wastewaters. In this research, the chemical oxygen demand (COD), BOD, pH, total nitrogen (TN), and microalgae  density were measured in the samples within 14 days after sampling from the inlet and outlet of municipal wastewaters treatment plant.  
The results showed that nitrogen removal rate from the wastewaters at the laboratory conditions was 93% in the inlet and 85% in the outlet, which are higher in efficiency than those provided by other treatment processes. The microalgae can be used for the removal of nitrate and the production of algae biomass in municipal wastewaters processes before entering the natural environment.