Use of drinking water treatment residuals to control the internal phosphorus loading from lake sediments: Laboratory scale investigation

This work investigated a novel approach of reusing drinking water treatment residuals (WTRs) to reduce the internal P loading from lake sediments under varied levels of dissolve oxygen (DO) in laboratory scale. The results showed that although the internal P loading increased as the DO level decreasing, WTRs can significantly reduce the internal P loading under different DO levels; in particular, under high DO level (5–8 mg L−1), the internal P loading can be reduced by 100%. The results of P fractionation suggested that the retained-P by WTRs existed as the NaOH extractable P. The P nuclear magnetic resonance spectroscopy (31P NMR) analysis further demonstrated that the retained-P was the orthophosphate, orthophosphate monoesters, orthophosphate diesters and pyrophosphate. Moreover, application of WTRs had marginal effects on Fe and Al concentrations and pH of the overlaying water. Therefore, WTRs can be an ideal material for controlling the internal P loading for lake restoration in large scale.