Anaerobic digested effluent phycoremediation by microalgae co-culture and harvesting by Moringa oleifera as natural coagulant

Abstract

Abstract In this study, a microalgal co-culture of Chlorella sp. and Scenedesmus sp. was cultivated in a photobioreactor (PBR). The microalgal biomass was then harvested by locally available and inexpensive natural coagulants, Moringa oleifera seed powder. Overall microalgal growth rate, biomass productivity, and nutrient efficiency have been analyzed. The linear correlation among the ammonia-N (NH3–N), orthophosphate (PO43), and microalgae concentration demonstrated that nitrogen and phosphorus removal had been dominated by microalgal assimilation. The experimental results suggested that the anaerobic reactor effluent was a useful substrate for microalgae growth. The maximum biomass productivity and growth rate was 0.12 g/L/d and 0.50 day−1, respectively, and almost 89 ± 1% of the nutrient was removed within 5 days. Besides, Moringa oleifera seed powder showed a very high microalgal biomass harvesting efficiency of 85%. Hence, it can be concluded that this cost-effective microalgae cultivation and harvesting method could tailor a promising phycoremediation application worldwide.