Removal of ammonia from wastewater effluent by chlorella vulgaris

Abstract

The capability of Chiarella vulgaristo remove nitrogen in the form of ammonia and/or ammonium ions from wastewater effluent in a local wastewater treatment plant (i.e., the Mill Creek Plant in Cincinnati, Ohio, U.S.A.) was studied. The wastewater effluent leaving the plant was found to include high concentrations of nitrogen (7.7±0.19 mg/L) (ammonia (NH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> ) and/or ammonium ion (NH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> )) and total inorganic carbon (58.6±0.28 mg/L) at pH 7, and to be suitable for growing Chiarella vulgaris. When Chiarella vulgariswas cultivated in a batch mode under a closed system, half of the nitrogen concentration was dramatically removed in 48 h after a 24-h lag-phase period. Total inorganic carbon concentration also concomitantly decreased during the rapid growth-phase. The total biomass weight gained during the entire cultivation period balanced out well with the total amount of inorganic carbon and nitrogen removed from the culture medium. These results indicate that wastewater can be synergistically used to polish residual nutrients in wastewater as well as to cultivate microalgae for biofuel production.