Investigating phosphorus adsorption characteristics of sediment in a river reach receiving municipal tailwater: a response surface methodology

The Wangtang wastewater plant tailwater flowing into Chaohu Lake, China, is a major source of pollution, posing a serious threat to the lake's ecosystem. The purpose was to solve this problem by improving the sediment phosphorus (P) adsorption capacity, and a response surface methodology (RSM) was used to optimize sediment P adsorption conditions, providing a theoretical basis for managing P-contaminated watersheds.

Phosphorus adsorption kinetics and adsorption thermodynamics modeling were simulated for sediments from the Nanfei River, and the P adsorption potential of surface sediments was estimated. The effects of different environmental conditions on the sediment P adsorption capacity were investigated, and the optimal conditions for sediment P adsorption were determined by the RSM and verified by the orthogonal experiments.

The optimal conditions for surface sediment P adsorption were obtained from the RSM, as follows: the disturbance frequency of 138 rpm, the water column P concentration of 1.14 mg L⁻¹, the pH of 7.76, the ionic strength of 0.02 mol L⁻¹ and the water-soil ratio of 5.67:1, and the corresponding theoretical maximum removal rate of 89.19%.

The RSM was used to determine optimal conditions for sediment P adsorption, providing a theoretical basis for subsequent treatment and management of P pollution in the municipal tailwater receiving river reach.