Analysis The Quality And Research Advanced Treatment Of Coal Gasification Wastewater

Usually, coal gasification wastewater with high concentration of phenolic contaminates is treated by three steps: The pretreatment, the biochemical treatment, and the advanced treatment. After three steps, the wastewater can be reused or discharged. In the process of wastewater treatment, it is still lack of systematic and effective method for the analysis and characterization of the key pollutants. In addition, due to the biochemical treatment of residual existing wastewater of organic material is chemically stable and biological toxicity strong, the advanced treatment was not effectively and might have a high cost. In view of the above problems, the analysis method of the key pollutants of coal gasification wastewater was studied in this paper, and the optimization of several kinds of advanced treatment methods were carried out.In this paper, the accuracy of determination of total phenols by Direct Bromine Method during gasification wastewater pretreatment was analyzed, and the effects of different components to measurement results were investigated. This work established the method of solid phase extraction and identified the analysis conditions of GC-MS. And the changes of water quality during the biochemical process were analyzed, including the wastewater before biochemical treatment, anaerobic and aerobic treatment tank effluent, as well as the depth of processing coagulating sedimentation tank effluent process water. Furthermore, the content of the 16 kinds of PAHs in gasification wastewater were analyzed and the results showed that the highest naphthalene concentration up to 1.685 ?g/L. The concentration of Phenanthrene, fluoranthene, pyrene, benzo(a) anthracene were all more than 0.2 ?g/L.The advanced treatment of biochemical wastewater was studied with the methods of Fenton oxidation, coagulation and sedimentation-Fenton oxidation, respectively. Coagulating sedimentation analysis of the experimental comparison alumen, ferric sulfate, PAC and PFS four kinds of flocculation settling results, the results revealed that the performance of PFS was best. After treatment, COD dropped to 92.4 mg/L, emoval rates were 60.17%, the removal rates of color and turbidity of wastewater were 66.9% and 96.83%, respectively. Using single factor experiment method and response surface methodology analyzed the effect of pH, H2O2 dosing concentration, the molar ratio of H2O2 and Fe2+, and time on Fenton oxidation. The best conditions of the oxidation were pH=3.33, the concentration of H2O2 dosage was 1146.17 mg/L, H2O2:Fe2+=3.24, reaction time was 60 min. Under the conditions, the COD removal rate could approach 65.36%. Advanced treatment by sedimentation-Fenton oxidation, after settling flocculation with PFS as the coagulant, under the conditions of the initial pH=3.5, H2O2 concentration was 300 mg/L, H2O2:Fe2+=4:1, reaction time was 40 min. COD dropped to 28 mg/L and removal efficiency was 87.93%. Reduced the difficulty of waste water recycling.