Study On Reuse Of Purified Water Of Petrochemical By Fenton Process And Micro-electrolysis Process

In the current increasing of water resources consumption and wastewater discharge pollution increasingly serious, the recycling of industrial waste water has become the key project of Chinese green economy. Petrochemical is one of China’s major industries, waste water generated in its existence is known as "purified water", obtained from pretreatment of petrochemical wastewater, is of high value of reuse. In order to reuse "purified water" as the circulating cooling water, the paper is focused on treatment effect of COD removal and biodegradability enhance to "purified water" by Fenton oxidation, micro-electrolysis reduction and combined technics, and designed a technical process. The main results are as follows:By water quality analysis, it was found that "purified water" have a certain biodegradability, after eight days of aerobic oxidation, COD can be treated from 1600 mg / L down to 500 mg / L.Using aerobic effluent as the target wastewater to study the optimum conditions of Fenton oxidation, and identified the optimal reaction parameters. Specifically, the COD removal efficiency could reach 79.7% and the B/C increased by 0.27 to 0.58, when H2O2 quantity was 6.34 ml/L, mole ratio of H2O2 to Fe2+ was 5, pH value was 4, temperature was 30°C and operating time was 2h. The aerobic effluent can obtain a higher biodegradability again. Confirmed by GC-MS analysis, the water samples with Fenton treatment containing benzoic acid, quinoxaline and other residual organic pollutants. It was not detected in the water samples which has been treated by Fenton, indicating that Fenton oxidation can remove refractory organic compounds with efficiency.Micro-electrolysis reduction process to treat the aerobic effluent was studied, the results indicated that the optimal ratio of iron and carbon was 3:1, the optimal pH value was 4, suitable reaction time was 2 hour. However, the COD removal rate of aerobic effluent is about 20%, which was not high after the treatment by micro-electrolysis.The removal rate of COD is 38.2% when we use biochemical process to treat the Fenton oxidation treated wastewater. The rate declines to 32.7% if we treat the microelectrode reduction treated wastewater. Ultrasound vibration can improve the removal efficiency by 20% averagely when combined with Fenton oxidation or microelectrode reduction, biodegradability of the waste water is also improved. The combined process of Fenton oxidation and biochemical treatment shows impressive treatment ability and practical value. Quality of the effluent can achieve the standard of industrial reuse water stably if we use biodegradation-Fenton oxidation-biological oxidation process to treat the wastewater.