Efficacy of Chitosan Derived from Tahong (Perna viridis) Shells in Treating Swine Biogas Digester Effluent

Chitosan, a natural linear biopolyaminosaccharide, is a non-toxic and environmentally friendly coagulant derived through the deacetylation of chitin, a major component of Tahong (Perna viridis) shells. This study evaluates the efficacy of chitosan in modifying the physicochemical properties of treated swine biogas digester effluent under varying chitosan dosages (8 g/L and 10 g/L) and agitation speeds (30 rpm and 50 rpm). The extracted chitosan powder exhibited high deacetylation, quantified at 74.65%. The untreated swine biogas digester effluent displayed the following properties: pH 7.34, COD 704 mg/L, BOD 338 mg/L, phosphate 81.54 mg/L, nitrate 138.75 mg/L, TDS 2027 mg/L, and TSS 2355 mg/L. Optimal treatment conditions were observed at a dosage of 8 g/L and an agitation speed of 30 rpm, yielding effluent properties of pH 8.30, COD 1499.00 mg/L, BOD 348.33 mg/L, phosphate 2.28 mg/L, nitrate 64.93 mg/L, TDS 2950.67 mg/L, and TSS 25.33 mg/L. Comparative analysis against the Department of Environment and Natural Resources (DENR) Class C water standards revealed significant improvements in BOD, phosphate, and nitrate levels, with p-values of 0.000. Conversely, the differences in pH and TSS were not statistically significant, with p-values of 0.141 and 0.199, respectively.