Color and COD Reduction of Biotreated Complex Wastewater using Ozonation Process

Muhammad Saif Ur Rehman, Sajid Mehmood, Ayyaz Ahmad, Ameena Saeed, Tariq Mahmood

Abstract


This study was mainly focused to investigate the color and COD abatement kinetics of ozonation process for biotreated complex wastewater. An up-flow anaerobic filter reactor (UAFR) treated combined domestic and industrial wastewater was ozonated to improve the effluent quality. The efficacy of ozonation process was assessed in terms of color and COD removal. Ozonation process followed pseudo first order kinetics. It was found that decoloration rate constant (kd) and COD abatement rate constant (kcod) had observed two stages; the first stage with a greater efficiency and second with decreasing trend. However, both the color and COD rate constants had great dependence on ozonation time, pH and temperature. Ozone feed time showed a critical impact on reaction rate whereas values of both rate constants respectively grew almost doubled at pH 9 (0.39 min-1 and 0.15 min-1) than their values at pH 7 (0.21 min-1 and 0.07 min-1) as reaction was controlled by hydroxyl radicals. However elevated temperature showed insignificant impact on ozone performance. An ozonation time of 10 minutes, pH value of 7.6 and room temperature were found as optimal process variables on the basis of EE/O (Electrical energy required per order of pollutant) values. 


Keywords


Biotreated wastewater, Ozone, Color, COD

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