Reducing Sediment and Phosphorus in Tributary Waters with Alum and Polyacrylamide.

This article presents a study which states that inflow to the Salton Sea in California, is predominately nutrient-rich agricultural wastewater, which has led to eutrophication. The watershed generates $1.3 billion in agricultural commodities per year. Alum and/or polyacrylamide (PAM) are commonly used in municipal wastewater treatment to remove phosphorus and solids, and then the sludge is collected and disposed. The charge of the polymer and the type of suspended solids in the wastewater influence the degree of flocculation and settling rate. Cationic polymers directly adsorb to the negative surfaces of the clay particles, anionic polymers adsorb through cation-bridging, and nonionic polymers form floc by attaching to the clay surfaces through van der Waals forces. Turbidity reductions were measured in the jar tests to determine the removal efficiency of phosphorus-laden sediment in the tributaries. The PAM treatments resulted in turbidity measurements lower than the control throughout the experiment, showing the PAM was capable of settling suspended solids at higher speeds.