Operation of a vertical algal biofilm enhanced raceway pond for nutrient removal and microalgae-based byproducts production under different wastewater loadings.

In this study, a vertical-algal-biofilm-enhanced raceway pond (VAB-enhanced raceway pond) was designed and assessed for wastewater treatment and algal biomass production under different nutrient loading rates. Results indicated that the maximum removal capacity of the system was accordingly 7.52, 6.76 and 0.11 g·m·day for COD, TN and TP, under which the wastewater effluent concentration could be respectively reduced from 106.00, 92.71 and 1.48 mg/L to 43.5, 11.03 and 0.46 mg/L in continuous mode. Meanwhile, about 7.47-10.10 t·ha·year of lipid, 14.85-23.01 t·ha·year of protein and 10.69-14.20 t·ha·year of carbohydrate could be produced from the algae by the system in large scale. The corresponding estimated stoichiometric-methane-potential and biodiesel production of the harvested biomass was 21,471-29,136 m·ha·year and 0.57-1.15 t·ha·year, respectively. The findings of this study demonstrate the feasibility of using VAB-enhanced raceway pond for economically and cost-effectively recovery of nutrients from the wastewater via algal-based byproducts production.