plSSN : 0374-8111 | elSSN : 2287-8815
plSSN : 0374-8111 | elSSN : 2287-8815
plSSN : 0374-8111elSSN : 2287-8815
Comparative Study on the Treatment Efficiency of Natural and SyntheticCoagulants for Recirculating Aquaculture System (RAS) Effluent Treatment
김승리·이재건·운성천1·박정환2*
국립부경대학교 수산생물학과, 1서울대학교 지구환경과학부, 2어번대학교 수산양식 및 수생과학과
This study evaluated natural polymer coagulants and polyaluminum chloride (PAC) for the removal of suspended solids from recirculating aquaculture system (RAS) effluents. Synthetic wastewater (TSS?4,000 mg·L-1) was prepared using sedimentation-tank solids. Chitosan, alginate, an alginate-Ca composite, starch, cationic starch, and PAC were evaluated as coagulants. Jar tests were conducted at 150 rpm for 2 min, 40 rpm for 10 min followed by 30 min of settling. The supernatant total suspended solids (TSS), turbidity, total dissolved solids (TDS), chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) levels were measured. The optimal dosing was determined primarily by TSS reduction, with COD, TN, and TP used as secondary criteria. When the performance plateaued, the minimum effective dose was selected. PAC achieved strong TSS and turbidity removal, but increased TDS, raising concerns about residual aluminum and increased ionic strength. At similar doses, chitosan provided solids and turbidity control comparable to that of PAC. It also consistently reduced COD and TP and lowered TDS, suggesting that it is a biodegradable, low-toxicity coagulant with minimal residuals. The alginate-Ca composite improved over alginate alone but had practical limitations owing to the added process complexity and cost. In contrast, starch-based coagulants exhibited low efficiencies under these conditions. Overall, chitosan emerged as the most feasible eco-friendly alternative to PAC for RAS effluent treatment.
Recirculating aquaculture system, Effluent treatment, Coagulation-flocculation, Natural polymer coagulants, Polyaluminum chloride