Growth and nutrient removal properties of a freshwater microalga Scenedesmus sp LX1 under different kinds of nitrogen sources

Microalgae have received much attention for the inorganic nutrient removal in tertiary treatment of domestic wastewater. Effect of different kinds of nitrogen sources on the growth and nitrogen/phosphorus removal properties of a newly isolated freshwater microalga. Scenedesmus sp. LX1, from a low-nutrient environment condition was studied and reported in this paper. The order of specific growth rate of the microalga with different nitrogen sources was NH4-N > urea-N >NO3-N. With nitrate or urea as nitrogen source, the microalga could grow well and remove both nitrogen and phosphorus efficiently (90% nitrogen and nearly 100% phosphorus were removed). However, with ammonium as the nitrogen source, the maximum algal density was relatively low, and the nitrogen and phosphorus removal efficiencies were as low as 31.1% and 76.4%, respectively. This was caused by the inhibitory effect of algal culture's acid pH due to H. releasing from NH4+ during algal cultivation process. (C) 2009 Elsevier B.V. All rights reserved.