Effects of Microalgae on the Removal of Nutrients from Wastewater: Various Concentrations of Chlorella vulgaris

The aim of this paper is to evaluate the efficiency of nutrients removal by Chlorella vulgaris (C. vulgaris). The study is comprised of five different fractions, having different quantities of C. vulgaris. From the batch reactor operations it was observed that increasing the content of C. vulgaris in the wastewater caused an apparent increase of removal rates in biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), NH3-N and PO4-P. More quantitatively, increasing C. vulgaris content from 1 to 10 g/L caused an increase of removal rate of BOD from 80.41% to 82.92%; COD from 78.33% to 82.30%; TN from 81.04% to 84.81%; TP from 32.26% to 36.12%; NH3-N from 96.90% to 97.26%; and PO4-P from 44.76% to 48.71%. Moreover, run 4 fractions (6 g/L in wastewater) possessed a better removal rate than the other four fractions studied. The results also indicated that TN and NH3-N were more effectively removed than TP and PO4-P. The optimal ratio of C. vulgaris density and orthophosphate concentration caused an enhancement of removal efficiency.