Abstract

Microalgae are promising candidates for the nutrient removal in tertiary treatment of domestic wastewater. In this study, batch experiments were carried out to investigate the effects of five different kinds of nitrogen sources (NaNO₃, urea, NaNO₂, NH₄Cl and glycine) on the growth characteristics and nutrient removal properties of a freshwater cyanobacterium, Synechococcus sp. PCC7942. Among the nitrogen sources, the order of specific growth rate (r) of the microalga was NH₄-N>NO₃-N>NO₂-N>urea-N>glycine-N, while that of chlorophyll yield coefficients was glycine-N>NO₃-N>NO₂-N>NH₄-N>urea-N. With nitrate, nitrite and glycine as nitrogen source, total nitrogen (TN) and total phosphorus (TP) could be removed efficiently. However, final cell density and nutrient removal efficiency were relatively low when urea or ammonium was used as nitrogen source.

Key words: Synechococcus sp., growth characteristics, chlorophyll a content, nutrient removal property, nitrogen source.