The Inves tigation of Using Biological and Chemical Oxidation Combination Effect on Wast ewater Treatment

Recently, the use of hybrid techniques is taken into consideration in wastewater treatment to achieve a high efficiency and effective removal of contaminants especially for resistant contaminants. In this research, the process of a combination of chemical oxidation by ozone and biological oxidation by aerobic attached growth bioreactor in the different modes for treating of wastewater were studied. At first, the performance of aerobic biological reactor was alone studied. Synthetic wastewater (sodium acetate as carbon source and ammonium chloride as a source of nitrogen) with the initial COD of 300 mg/L and the ratio of carbon to nitrogen of 10 was used. The results showed that there is a complete nitrification in bioreactor and COD removal efficiency is 89%. When using ozone oxidation before biotreatment, it was seen that the efficiency of COD removal increased to 94.0% and TSS was achieved to 75 mg/L in output. In the next step, the ozonation was used after biotreatment and it was observed that COD removal efficiency increased to 97.0% and the amount of TSS also decreased to 35 mg/L in output. In the final step, ozonation was used simultaneously before and after biotreatment as pretreatment as well as final treatment. In this mode, the results showed that the efficiency of COD removal in the output of the system increased to 98.3% and the value of TSS was declined to 20 mg/L.