Evaluation of Biocoagulant “Opuntia ficus-indica and Chitosan” to Improve the Removal of Contaminants in Dairy Effluents through Electrocoagulation

Abstract

The dairy industry is classified, worldwide, as one of the main wastewater-generating industries. The objective of the study was to evaluate the effect of parameters on the percentage of turbidity (TB) removal and chemical oxygen demand (COD), using as pretreatment a combined coagulation process using a biocoagulant composed of chitosan and Opuntia ficus-indica mucilage (OFI): chitosan-mucilage (Q-M from 1 to 9), and an electrocoagulation process with operational variables of biocoagulant dose (0.025, 0.05 y 0.1 g/L), current density (30, 40 y 50 mA/cm2), and time (10, 15 y 20 minutes). A monopolar glass reactor with aluminum electrodes was assembled by applying the response surface approach methodology. Additionally, using the Box–Behnken mathematical model for the removal of TB and COD, the effects and interactions of the factors and experimental design levels (considering control formulations using triplicates) were evaluated. An analysis of variance was performed to evaluate model responses and optimal conditions. The experimental results showed that the formulation of the compound biocoagulant Q-M-5 in doses of 0.99 g/L achieves 98.44% turbidity removal and 81.72% chemical oxygen demand removal. The dose of the compound biocoagulant has a significant positive effect as does the current density of 30 mA/cm2 and time of 19.05 min; that is, its efficiency in removing turbidity and chemical oxygen demand increases when using these parameters. It is concluded that the use of the biocoagulant composed of chitosan and Opuntia ficus-indica mucilage (Q-M-5) as the primary treatment of whey wastewater provides evidence for the literature, showing that it is also a low-cost, ecological, and easy-to-apply natural coagulant.