Optimizing Condition for of Struvite Precipitation as Pre-treatment of Swine Wastewater

This study developed a novel pre-treatment of swine wastewater through a stirring precipitation process of struvite formation that could trim down the pollutants loaded, and thus enhance the efficiency of further treatment. The major focus was on optimizing the quantitative factors influencing the struvite precipitation, e.g., P/Mg/N ratio of chemicals, pH value, stirring speed, temperature, and reaction time. The pH and amount of chemicals being added in the wastewater were the key factors influencing the precipitation of struvite. Results of our experiment indicated that a P:Mg:N ratio of 1:1:1.2 and pH 10.0 were the optimal conditions. Under these conditions, the removal efficiency of NH4+-N was 87%; and it brought down residual PO43--P to the lowest concentration of 30.2 mg/L in the swine wastewater. We conclude that pre-treatment of swine wastewater by struvite precipitation could be economical and highly beneficial for enhancing the efficiency of a wastewater treatment facility, compared to the traditional approach of struvite precipitation as post-treatment through anaerobic processing