Effects of the microalgae, sludge and activated carbon on the wastewater treatment with low organics (weak wastewater)

Abstract

In this study, for the first time, weak wastewater was remediated using biological treatment with microalgae–sludge cultivation combined with physical absorption by the activated carbon. The influences of each factor on the process efficiency have been studied in detail by statistical analysis. The experimental design was carried out using Taguchi arrangement. Chemical oxygen demand (COD) and biological oxygen demand (BOD) were measured as responses over 16 h of the treatment. It was found that the physical absorption was controlled the treatment with the highest contribution (> 71%). We show that the second and third ranks correspond to the microalgae and activated sludge, respectively. The optimal conditions to minimize COD were obtained at the activated carbon of 0.2 g/l, microalgae of 1 ml/l and activated sludge of 1 ml/l. Our study shows that the reductions in COD and BOD are more than 90% and 93%, respectively. The validity of the predicted mathematical model also has been confirmed by measuring the responses at the optimal conditions, resulting in low deviation. Therefore, the process that we studied in this paper can be utilized efficiently in wastewater treatment plants. Finally, we compare the results obtained from this method with other scenarios published, finding a good agreement.