نوع مقاله : مقاله پژوهشی
نویسندگان
1
Department of Water Sciences, Sho. C., Islamic Azad University, Shoushtar, Iran
2
Research Center for Water Science and Environmental, Department of Water Sciences, Sho.C., Islamic Azad University, Shoushtar, Iran
3
Department of Water Sciences, Water Science and Environmental Research Center, Sho. C., Islamic Azad University, Shoushtar, Iran.
4
Department of Water Sciences, Water Science and Environmental Research Center, Sho. C., Islamic Azad University, Shoushtar, Iran
5
Department of Environmental Health Engineering, Behbahan Faculty of Medical Sciences, Behbahan
10.22034/nawee.2026.584375.1226
چکیده
Objective: While SBR and hybrid SBR-AOP systems have been investigated for conventional wastewater treatment, their application and optimization for highly detergent-rich gray water presents unique challenges, such as biomass inhibition and low initial biodegradability (BOD5/COD ratio of 0.25). The distinct novelty of this study lies in the systematic configuration optimization and phase-duration management of an integrated SBR and UV/H2O2 system specifically tailored for gray water containing elevated detergent concentrations. Unlike traditional hybrid systems that apply chemical oxidation as a polishing step, this research evaluates and demonstrates the significant advantages of operating the UV/H2O2 process as a pre-treatment stage. This specific sequencing effectively breaks down non-biodegradable surfactants and mineralizes complex organic compounds prior to the biological stage, thereby enhancing the overall system efficiency to a COD removal rate of 97%.
Methods: Gray water with initial pollutant concentrations of 600 mg/L COD, 200 mg/L BOD, 4 mg/L TP, and 15 mg/L TKN was treated using an SBR system combined with UV/H₂O₂ chemical oxidation. Additionally, the potential of granular activated carbon (GAC) added during the SBR aeration phase to enhance pollutant removal was evaluated. Different chemical oxidation conditions were evaluated, and the effects of anaerobic pre-treatment and anaerobic phase duration were assessed.
Results: The SBR reduced BOD₅ to 40 mg/L and COD to 162 mg/L, while activated carbon had a limited effect. The optimal chemical oxidation conditions were 12 mg/L H₂O₂ and a reaction time of 3 hours. Under these conditions, the integrated system achieved removal efficiencies of 90.6% for COD, 85% for BOD, 82.5% for TP, and 65% for TKN. Chemical oxidation as a pre-treatment step improved the biodegradability of organic compounds by 6%. In addition, the inclusion of an anaerobic unit before aeration improved phosphorus removal, although extending the anaerobic phase beyond two hours provided no further benefit.
Conclusions: the integrated SBR and UV/H₂O₂ system is an effective method for treating gray water with high detergent concentrations, significantly reducing pollutant levels and improving biodegradability. The use of anaerobic pre-treatment can further enhance phosphorus removal, but longer anaerobic durations are not necessarily advantageous.
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