Enhanced treatment of ceramic-tile industry wastewater was investigated by modified coagulation–flocculation process using combination of poly-aluminum chloride (PAC) with anionic (A300), cationic polymer (C270) and nonionic polymers. The effects of pH, PAC coagulant dose alone and with polymers dose in various combinations was studied by jar tests. To compare the removal efficiencies of turbidity, total suspended solids (TSS), chemical oxygen demand (COD), and color at different levels, we run multivariate analysis of variance. Regarding the economic evaluation, we applied the incremental cost-effectiveness ratio. PAC had the best performance in pH 7 and in optimal dose of 400 mg/L; so that removal efficiency of wastewater turbidity, TSS, COD and color were 99.63%, 99.7%, 47.5% and 50.38%, respectively. The best removal efficiency for wastewater turbidity, TSS, COD and color were 99.87%, 99.89%, 87.5% and 93.02%, respectively which were obtained by combination of anionic polymer (1.5 mg/L) with PAC (300 mg/L). Furthermore, with combination of PAC + anionic + non-ionic polymers, the removal efficiency for wastewater turbidity, TSS, COD and color were 99.93%, 99.94%, 88% and 94.57%, respectively. The imposed cost for treating one cubic meter of ceramic-tile wastewater treatment by PAC + anionic and PAC + anionic and non-ionic polymers in comparison with PAC alone was reduced to 22.96% and therefore economically more affordable for the tile industry wastewater treatment.

Background and Objectives: Boron is widely found in raw materials and wastewater of the tile industry and its removal from aquatic environments is very complex. The aim of this study was to remove boron from wastewater of ceramic tile industry using coagulation and flocculation-adsorption process. Materials and Methods:This was an experimental study. Initially, for the coagulation process, pH parameters between 5 to 11, concentrations of 150 to 450 mg/L of poly-aluminum chloride (PAC) and concentrations of 0.5 to 2.5 mg/L of anionic and cationic polymers were examined. Then, in the adsorption process, the effect of pH between 2 to 7 at contact times of 5 to 20 min was investigated. Finally, the data were analyzed using Pearson's correlation test. Results:The results showed that the percentage of boron removal by poly-aluminum chloride at the optimum pH equal 8 and the concentration of 400 mg/L was 35.7% and in combination with 1.5 and 2.5 mg/L anionic and cationic polymer, removal efficiency of 54.2 % (from 35 to 16 mg/L) was observed. Then, in the adsorption process with an optimum pH equal 5 and contact time of 15 minutes, removal efficiency of 50% (from 16 to 8 mg/L) was obtained. Examination of isotherms in the adsorption process showed that boron adsorption follows the Freundlich isotherm and first-degree kinetics. Conclusion:According to the results, the combined process of coagulation and flocculation with adsorption can be introduced as an effective process in boron removal.