Dissertation > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Wastewater treatment and utilization

Research on Catalytic Wet Peroxide Oxidation for Treatment of Semi-Coking Wastewater

Author YaoZuo
Tutor MaXiaoXun
School Northwestern University
Course Chemical Engineering
Keywords Catalytic wet hydrogen peroxide Activated carbon catalyst Semi-coking wastewater CODcr removal
CLC X703
Type Master's thesis
Year 2013
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The northwest of Shaanxi Province has abundant coal resources, the major coalfields is the Jurassic non-caking and weakly caking coal, with low ash, low phosphorus, low sulfur, high calorific characteristics, this coal is a good low-temperature carbonization coal. Low temperature carbonization coke production is a greater industry in the northwest of Shaanxi Province. Because of the backward production technology, the low-temperature carbonization production process has produced a lot of waste water, waste gas and waste, they are seriously pollutes the environment, this has become one of the key challenges need to be resolved in northern Shaanxi energy and chemical base construction.Semi-coking wastewater composition is more complex, it containing phenolic compounds, cyanide, heterocyclic compounds and other organic substances, it is highly toxic polluting organic wastewater。 Semi-coking wastewater’s composition is similar to coking wastewater, in addition to the concentration of sulfur cyanide and cyanide, the former COD, phenol concentration of ammonia were higher than the latter. Currently, domestic semi-coking production industry used biological treatment of semi-coking wastewater, but it did not meet the national emission standards. Semi-coking wastewater contains a lot of organic matter, it is more difficult to handle than the coking wastewater, so, studies on how to remove the pollutants in semi-coking wastewater is significant.In this thesis, it take the semi-coking wastewater for the study. It proposed using catalytic wet peroxide oxidation for treatment of semi-coking wastewater. Catalytic Wet Oxidation of Technology (CWPO) is a way to efficiently handle high concentration organic wastewater technology. The technology mainly relies on H2O2as oxidant, it make the reaction can be carried out under atmospheric pressure at room temperature, the H2O2decomposition with strong oxidizing free radicals.In this way, majority of organic wastewater are easily oxidized with a higher oxidation rate, so it has a broad application prospects. As the key of catalytic wet peroxide oxidation, catalyst is particularly important. This article prepared catalyst by impregnation method, and use it to handle coke semi-coking wastewater. Discuss the influence factors on removal of organic pollutants. The conclusions were as follow:1. In order to discuss the catalyst carrier and the main active ingredient, different catalysts had prepared:5%Fe/X (X=Ac, A1203),5%X/Ac (X=Fe, Cu, Mn, Zn), use catalytic wet peroxide oxidation method to treat phenol analog wastewater,after compare the treatment effect, select the activated carbon as the carrier, Fe-based active ingredients.2. In order to evaluate the activity of the catalyst, the catalyst has be prepared by changing various factors, use catalytic wet peroxide oxidation method to treat phenol analog wastewater, The experimentally derived concentration of impregnating solution with0.1mol/L, the calcination temperature was350℃, baking time was3h optimum as the best conditions for the catalyst preparation.3. Characterize the catalysts and observe the specific surface area and load conditions.4. Research on Catalytic Wet Peroxide Oxidation for treatment of Semi-Coking wastewater, by the way of orthogonal experiment, determine the degree of influence of each factor (catalyst dosage, H2O2dosage, reaction temperature, initial pH value), and then through a single factor optimized way to further define the optimum process parameters.The results showed that:(1) When the catalyst dosage is less than30g/L, with the increase in catalyst dosage, the CODcr removal rate and color removal rate are increases. But when the catalyst is increased to more than30g/L time, the CODcr removal and color removal will not continue to increase but appear to downward trend. So, choosing the optimal catalyst dosage is30g/L.(2) When the H2O2dosage is25ml/L, the CODcr removal rate of semi-coking wastewater of87.5%, color removal rate of90%, when the H2O2dosage continues to increase, color removal rate and CODcr are slow increases,when increasing the dosage of45ml/L CODcr removal rate reached a maximum of94.7%. Therefore, choosing the optimal dosage of H2O2was45ml/L.(3) When the pH is between3to5, the CODcr removal and color removal is relatively large, when the pH is3,CODcr to rate reached91.7%, color removal rate reached96percent, are maximums, so choose the most excellent pH is3. (4) As the reaction temperature increases, CODcr removal rate and color removal rate increases slowly, owing to when the temperature increases the removal rate is increased very slowly. Taking into account the economic, selecting the optimal reaction temperature is room temperature to30℃.5. Though gas chromatography-mass spectrometry Organic (GC-MS) analysis of the process of catalytic wet hydrogen peroxide oxidation of coke wastewater treatment organic matter degradation, and the reactions were detected before and after the removal of organic matter compared treatment effect.The results of this study on semi-coking wastewater treatment has a certain practical significance, and provides a lot of basic data and theoretical guidance for the actual operation of coke wastewater treatment

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