Abstract: The piggery wastewater can provide sufficient nutrient for the growth of microalgae. However, high concentration of ammonium nitrogen in the piggery wastewater may inhibit the growth of microalgae. In order to solve this problem, the inhibition of ammonia on Desmodesmus sp. CHX1 growth was investigated in the wastewater with initial ammonium concentration of 350-900 mg·L^-1, as well as the elimination effects of aeration with carbon dioxide. Results showed that the growth of Desmodesmus sp. CHX1 was inhibited by ammonia, with the increment of biomass of only 0.08-0.13 g·L^-1 after 7 days of culturing. Aeration with carbon dioxide could alleviate the inhibition of ammonia, with biomass increment of 0.32-0.47 g·L^-1. Decreasing trends of pH were observed in the wastewater without aeration, with the reduction of 0.5. While the pH in the aeration condition increased by 1.50 first and then decreased by 0.40. The ammonium was removed by 3.76%-20.10% in the experiment conditions. These results demonstrated that high concentration of ammonium nitrogen inhibited the growth of Desmodesmus sp. CHX1. Aeration with carbon dioxide could improve the growth of Desmodesmus sp. CHX1 in the wastewater with high concentration of ammonium nitrogen.

Key words: microalgae, ammonium nitrogen, piggery wastewater, aeration, carbon dioxide