Efficiency of the Combined Chemical Precipitation -Reduction Process to Remove Dye and Chromium from Industry Wastewater of Home Appliance

Industrial wastewater is one the most important pollutants of environment. This study aimed to evaluate the efficiency of the combined chemical precipitation-reduction process for removal of dye and chromium from wastewater of home appliance factories.
This experimental study was performed in laboratory scale on wastewater from the dying unit of the home appliance factory. The process used was a combination of the chemical precipitation-reduction process. Combine sampling was done and 214 samples were analyzed. COD, dye, and chromium were measured in samples. MgCl2, Polyaluminium Chloride (PAC), and FeCl3, cationic polymer and bentonite were used for chemical precipitation; and sodium meta bi sulfite was used for chemical reduction. Data were analysed by ANOVA and Tukey tests and by SPSS 16 software.
The results show that PAC had the highest color removal efficiency (90.92%). Also, the highest COD removal was related to the combination of magnesium chloride (1.4 mg/l), poly aluminum chloride (0.6 mg/l), and the coagulant aid cationic polymer (0.4 mg/l) with an efficiency of 89.11%. Moreover, total efficiency of the combined chemical precipitation and reduction process in chromium removal was 94%.
The chemical precipitation- reduction process as a pre-treatment method has high efficiency in removal of COD, dye and chrome from wastewater of home appliance factories.