Evaluation of the Devilfish (Pterygoplichthys spp.) Natural Coagulant as a Treatment for the Removal of Turbidity in Fish Farm Wastewater

This study evaluated using a devilfish (Pterygoplichthys spp.) natural coagulant to remove the turbidity in fish farm wastewater. A combined experimental design of mixture-process under a cubic × linear model was selected to evaluate the effectiveness of the natural coagulant and two chemical coagulants (ferric sulfate and aluminum sulfate). An analysis of variance (ANOVA) and an optimization analysis were performed to determine the model significance and the optimal treatment conditions (optimal dose and mixture proportion). The results showed that a turbidity removal efficiency of 30% is achieved using a dose of 200 mg/L of natural coagulant. However, the coagulation treatment could be feasible when it is used as an optimal coagulant with a dose of 93 mg/L with a mixture proportion of 11% natural coagulant and 89% aluminum sulfate to achieve turbidity removal efficiency > 98%. ANOVA results showed that the model is significant (p-value < 0.0001), and the lack of fit is not required (p-value > 0.05). Therefore, a combined reduced special cubic × linear model accurately describes the observed data. These results support the use of devilfish meal as a natural coagulant. However, its use is more feasible as a coagulant aid in wastewater treatment. Graphical abstract: [Figure not available: see fulltext.]