Chemical treatment and reuse applications for latex paint industry wastewater

摘要

Latex paint industries in Peru produce high volumes of wastewater discharges. This wastewater shows high concentration of suspended solids (5,000 ppm), COD 1,000 ppm and bacterial content ( 100,000 CFU/mL). This study describes a suitable treatment technology for latex paint industry wastewater that allows treated water reuse in latex paint production. Treatment of these effluents consisted on a physicochemical treatment, using aluminium polychloride (PAC) as coagulant and anionic polyacrylamide (PAM) as flocculant. Process worked with 3 m(3)/h treatment flow in following doses: 1,200 ppm PAC and 2 ppm PAM, and hydraulic retention time of 5 h. Clarified water, after disinfection treatment with sodium hypochlorite (10 ppm and 1 h of contact), met the following standards: TSS = 12 ppm, TDS = 680 ppm, free chlorine = 0.6 ppm, pH = 7.3 and bacterial content lower than 1,000 CFU/mL. Three types of acrylic latex paintings with treated water, and quality standards such as pH, viscosity, and density fell within the quality limits, were produced. Up to 56 % of raw wastewater production was obtained and wastewater recycling is a profitable activity due to the economic savings.