Evaluation of natural organic matter release from alum sludge reuse in wastewater treatment and its role in P adsorption

Abstract

Risks evaluation of alum sludge reuse is the first step to promote its popularization in wastewater treatment engineering, such as alum sludge-based constructed wetland. The present study, for the first time, is focusing on evaluating the concern of natural organic matter (NOM) leakage from the alum sludge. A series of lab-scale trials including static tests, column tests and sequencing batch reactor (SBR) trials were designed and conducted to assess the potential NOM release from the alum sludge and its behavior on the effect of phosphorus adsorption. The results have demonstrated that alkaline condition, fine particle size of alum sludge and P adsorption could induce more NOM leakage where the quantity of leakage has particularly strong positive relation with P adsorbed. NOM was believed to be an important replacement for P adsorption in ligand exchange process. Moreover, alum sludge has the function of pH neutralization via ligand exchange between OH− and NOM, which could benefit to wastewater treatment, such as nitrification. Overall, the NOM release was not a big concern.