Growth of Scenedesmus dimorphus in swine wastewater with versus without solid-liquid separation pretreatment

Abstract

Scenedesmus dimorphus was cultivated in raw and pretreated swine wastewater (SW) with 6-L photobioreactors (PBRs) to investigate the effect of solid-liquid separation on algal growth. The same aerated PBRs containing no algae were used as control. Moderate COD and nitrogen removal from the SW was achieved with the algal PBRs. However, compared to the control reactors, they offered no consistent treatment boost. Improved algal growth occurred in the pretreated SW, as measured by maximum algal cell count (3202 +/- 275 x 10(6) versus 2286 +/- 589 x 10(6) cells L-1) and cell size. The enhanced algal growth in the pretreated SW resulted in relatively high nitrogen (5.7 %) and organic matter contents in the solids harvested at the end of cultivation experiments, with similar to 25.6 % of nitrogen in the SW retained in the solids and similar to 9.1 % absorbed by algae. The pretreatment also resulted in elevated phosphorus removal. This study is anticipated to foster the development of microalgae-based SW treatment processes.