The Study Of Effectson Treating Sewage With Peroxides

With the growth of population and the improvement of people’s living standards, China’s total water consumption and per capita water consumption is increasing, also and the amount of sewage discharge. But the sewage treatment capacity of sewage treatment plant is limited, resulting that sewage treatment was not standard or discharged in environment directly, which easily lead to lake eutrophication nearby. Therefore the sewage problem should be taken seriously. Peroxides, such as Ca O₂, have been widely used in environmental remediation for its resistance of release oxygen and oxidation, the advantage is significant effect and operate simply. So this article chosen severics peroxide（CaO₂, MgO₂, ZnO₂） to treatment sewage. By contralling different treatment conditions（stirring, the amount of peroxide, peroxide type and processing time） when peroxide treat sewage, to evaluat the impact of DO, COD, TN and TP and other indicators of sewage, determining the appropriate conditions; by the experiments of oxidation of the methylene blue solution to prove the presence of the system of Fe²⁺/ peroxide can occur Fenton reaction and to determine the optimal Fe²⁺/peroxide molar ratio. Finally we studied the effects of peroxide treated sewage with the presence of Fe²⁺, Learn the removal mechanism of COD whit system of Fe²⁺/peroxide treating sewage. to provide a theoretical basis of treating sewage. The conclusion is as follows:（1） When dealt sewage with CaO₂, DO and TP had significant changes. DO increased significantly and even be supersaturated, DO could be adequate for 24 h when added 0.4g/L CaO₂ in water with static process, the amount of O₂ in water increased with the quality of CaO₂, MgO₂ and ZnO₂ released oxygen was significantly lower than CaO₂ under the same conditions, the total mount of oxygen also lower than CaO₂.The removal of TP was obvious, basically completed removaling within 1h, mainly because of the removal of phosphate. CaO₂, MgO₂ and ZnO₂ treated wastewater with the same molar amount under the same experimental conditions instirring conditions, the removal efficiency of TP was 78%, 68.6%, 53.6%;（2） When dealt sewage with CaO₂, TN and COD had a little change by CaO₂ and MgO₂, do not with ZnO₂. CaO₂ and MgO₂ treated wastewater with the same molar amount under the same experimental conditions, the removal of ammonia in water was 23.5% and 21.3%, the greater amount of CaO₂ and MgO₂ and the longer of processing time, the greater the ammonia removal was; no matter how to change the conditions, removal of COD is not ideal, the best removal rate is only 15.3%.（3） Under the catalysis of Fe²⁺, the peroxide could produce a advanced oxidizer, HO?. The optimum ratio of Fe²⁺/peroxide systems is 1/2.CaO₂ generated most HO? at the same molar amount of peroxide under the same conditions, Fe²⁺/CaO₂ system could have Fenton reaction under a wide pH range, Fe²⁺/ZnO₂ system and Fe²⁺/MgO₂ system could produce large amounts of HO? at a pH of 5 or below.（4） The removal of COD on treatmen with Fe²⁺/peroxide Fenton system sewage was more ideal, the removal rate range 60% to 76%, the removal of COD under with Fe²⁺/ peroxide system was higher than Fe²⁺ alone, but Fenton flocculation also plays a dominant role, it could be effectively performance by controlling the initial pH of the sewage.