Optimization of Natural Coagulants to Treat Aquaculture Industry Effluent
摘要
The effluent from fish farm is not toxic and can be recovered for watering plants, and nutrients recovered from sludge can be used as fertiliser. In this study, two kinds of natural coagulants (palm pith and watermelon rinds), which are alternatives to chemical coagulation, were used as eco-friendly, low-cost coagulants. Two parameters, namely, coagulant concentration and water pH, were optimised using response surface methodology (RSM) to determine the responses in terms of turbidity, total suspended solid and total dissolved solids. The optimum conditions by the central composite design (CCD) model for the maximum removal efficiency of turbidity, total suspended solids (TSS) and total dissolved solids (TDS) were obtained at the coagulant concentration of 100 mg/L and pH of 6.7 for palm pith and pH of 7.9 for watermelon rinds. The results from the RSM showed maximum removal efficiencies for turbidity, TSS and TDS were 98.8%, 76.5% and 7.5%, respectively, for palm pith and 91.6%, 86.8% and 8.2%, respectively, for watermelon rinds. The two natural coagulants according to CCD demonstrated that the experimental data fit quadratic polynomial models. The validation was run with optimum conditions, and the results showed less than 5% error. The application of natural coagulants in treating fish farm effluent by coagulation–flocculation process is promising and can be used to recover biomass as fertiliser.