Influences of Nutrient Concentrations in Treated Effluent on Lipid Content in Indigenous Microalgae

摘要

Several studies have focused on microalgae cultivation with treated effluent in wastewater treatment plants for energy production. It is important to comprehend lipid content in microalgae for high energy production. We investigated temporal change of lipid content in indigenous microalgae against variations of nutrient concentration in treated effluent and analyzed the effects of light irradiance on the lipid accumulation. We cultivated indigenous algae with 30 L of actual treated effluent before chlorination by batch mode. Experimental results showed that in the case when inorganic nitrogen (IN) was abundant in treated effluent, increase of lipid content from 6.6 to 9.1% was observed for 4 hours under light irradiation, which corresponded to decrease of IN from 8.90 to 6.80 mg-N/L. Therefore, it was revealed that microalgae rapidly accumulated lipid in response to the decrease in IN. Meanwhile, there was little change in lipid content under the condition that IN was depleted. In the case when IN increased from 8.73 to 12.4 mg-N/L by chemical addition, the lipid content in indigenous algae also did not change. Based on the result, it was suggested that IN increase have little influences on the lipid accumulation.