Optimization of Bioflocculant production from municipal sewage sludge by Aspergillus niger using Response Surface Methodology

Abstract

Abstract The production of sewage sludge is an environmental challenge in the steel industry, particularly from the point of view of water recycling and iron recovery. It contains large amounts of iron oxides, calcium, magnesium, and silicon oxides. In this study, the selective deposition rate of iron oxide in sludge in the presence of a bioflocculant produced by Aspergillus niger was investigated. The effects of several key parameters, including nitrogen concentration, carbon concentration, pH, and temperature, were investigated using the response surface method in a central composite design. The results were analyzed using analysis of variance (ANOVA). The optimum conditions for sludge deposition (91.3%) and iron oxide recovery (72.3%) were achieved at a growth time of 96 hours, a municipal wastewater extract concentration of 1.0 g/L, a pH of 5.9, and a temperature of 18°C. It can be concluded that the bioflocculant produced by A. niger could be used as an environmentally friendly reagent for iron recovery and to increase the efficiency of water recycling from steel industry sludge.