Advanced treatment of liquid swine manure using physico-chemical treatment

Abstract

In this study, liquid swine manure was treated by physico-chemical treatment, including coagulation, flocculation, and sedimentation followed by an oxidation step as a polishing treatment at a bench-scale level. A superabsorbent polymer (SAP) and a mineral and salt formulation able to generate molecular iodine were used as coagulant and oxidant agents, respectively. The results indicated that SAP at a concentration of 1.25g/L was able to reduce 32% of the initial total suspended solids (TSS) in experiments using supernatant at its natural pH. Following the SAP application, 82% of initial ammonia (NH3), 78% of initial total organic carbon (TOC), and 93% of the total coliforms were reduced using 40mg/L of free iodine. In experiments performed with diluted supernatant (five-fold dilution), it was found that SAP at a concentration of 0.5g/L was capable of reducing 80% of the initial TSS in experiments at pH 11. A leaching study was conducted to assess the safety of sludge disposal. From the leaching tests using non-diluted supernatant, it was found that 24% of the chloride (Cl−) and 50% of the phosphate (PO43−) ions retained in the sludge leached to the ultrapure water after 48h. Potential contamination due to leaching of NH3, nitrite (NO2−) and nitrate (NO3−) was found to be statistically insignificant.