Avaliação da redução da carga orgânica de um efluente industrial contendo compostos orgânicos de uma indústria de resinas por coagulação-floculação com Policloreto de alumínio e Poliacrilamida não-catiônica

Abstract

Wastewater generated in the synthetic resin industry represents a major environmental challenge due to the presence of recalcitrant organic compounds, such as toluene, xylene, butanol, and formaldehyde residues, which contribute to high concentrations of organic matter and low biodegradability. These characteristics limit the efficiency of conventional biological treatments, making the application of physicochemical processes ecessary for their proper conditioning. In this context, the present study evaluated the efficiency of coagulation-flocculation using polyaluminum chloride (PAC) combined with non-cationic polyacrylamide in reducing the Chemical Oxygen Demand (COD) and turbidity of an effluent from a synthetic resin industry. Twelve bench-scale tests were performed, evaluating different dosages of PAC and polyacrylamide, as well as the influence of wastewater temperature on the process. The results demonstrated that temperature exerted a significant influence on floc formation, with higher coagulation efficiency observed at temperatures above 25 °C. Under the best experimental condition, a 60% reduction in COD and 97.87% reduction in turbidity were achieved, highlighting the efficiency of the process in organic matter removal and effluent clarification. Formaldehyde removal was limited, with a maximum reduction of 15.18%, indicating that a significant fraction of the compound remained dissolved in the treated effluent. The results indicate that coagulation-flocculation with PAC and non-cationic polyacrylamide constitutes a promising alternative for the pretreatment of complex industrial effluents, contributing to the reduction of the organic load, improvement of the physical characteristics of the wastewater, and the enhancement of subsequent treatment stages, given the effluent's characterization.