Treating high-strength saline piggery wastewater using the heterotrophic cultivation of Acutodesmus obliquus

Abstract

This study combined an algae treatment with post-ozonation for the robust treatment of piggery effluent in which high levels of organic constituents, inorganic nutrients, color, and salts remained. Due to a nearly complete light limitation resulting from a high level of color, the algae treatment was conducted with continuous O2 supplementation instead of using the combination of high lighting and CO2 injection. The microalga Acutodesmus obliquus KGE-17 showed tolerance to high salinity (up to 5.2% as chloride) and was capable of utilizing dissolved organics (1923mg-COD/(g-cell)(day)) under the heterotrophic growth conditions. The use of A. obliquus for remediation of piggery effluent also resulted in an operational simplicity in the simultaneous removal of nitrogen and phosphorus in a single treatment process, in contrast to conventional biological nutrient removal processes. Subsequent ozonation was successful in decolorizing the algae-treated wastewater and in improving the biodegradability of residual organics in post-treatment processes.