Chemical treatment and reuse applications for latex paint industry wastewater

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.