The Study On Heterogeneous Catalytic Oxidation At Low Temperature And Atmospheric Pressure In Coking Wastewater Treatment

With the rapid development of industrial technology and expanding the production scale, different to contain high concentrations of non-biodegradation organic pollutants and ammonia nitrogen compounds, suspended by the increasing number of industrial wastewater, these pollutants pose a special threat to the environment. Organic wastewater of high concentrations dispersion,high levels of pollutants,less water,treatment process complicated,high costs in investment and operating and inconvenience in management.Due to the high concentration of organic wastewater emissions caused water pollution,deterioration of the ecological environment,threats to human health problems and obstacles related to industrial development. Currently, the situation is particularly serious in developing countries, including China. The wastewater often contain the chemical composition which is inhibited microbial normal activities, or contain very stable microbial normal digestion of pollutants, which is hard to be normal digestion wastewater decomposition of pollutants. For example, the pharmaceutical mother liquor containing antibiotics; the presence of various stable substances hydrocarbon residue in petrochemical industry; the black liquor contained lignin which is difficult to degradation; high concentrations of the dye wastewater contained stability of the dye components. If using conventional methods for decontamination of biological, physical or chemical purification difficult or impossible to meet the technical and economic requirements. Therefore, such high concentrations industrial wastewater purification technologies for environmental protection at this stage become a problem that needs to be solved urgently.Coking wastewater is coking coal coke, coking coal gas purification products and the recovery process focusing on the oils containing high concentrations of phenols and refractory wastewater, including gas condensate from the beginning of the cold water separation, benzole section of the water, finally cold gas cleaning and gas scrubber water of gas stations, for his complex, organic matter is mainly industrial wastewater. The wastewater contains dozens of inorganic and organic compounds, in inorganic compounds, mainly by the large number of salt,sulfur,sulfide and cyanide; The organic compounds in addition to phenol, there are single and multi-ring aromatic ring compounds, nitrogen, sulfur, oxygen heterocyclic compounds. In coking wastewater, CODCr, NH3-N and volatile pollutants are high concentrations, these pollutants have tremendous harm to human beings,crops and aquatic products, it must be able to deal with emissions.In general, coking wastewater must be pretreated,secondary treatment and advanced treatment before discharge. The pretreated method of coking wastewater is anaerobic acidification,gas flotation,coagulation and advanced Oxidation,etc; Many secondary treatment, such as biochemistry, physics, chemistry, and other physical and chemical methods; The advanced treatment technologies of coking wastewater are chemical oxidation,add chlorination in the turning point,flocculation and sedimentation supplemented by chlorination and adsorption filters supplemented by ion exchange, etc. However, the most commonly used method in coking wastewater is after oil removal grease traps and more than 2 flotation tank aeration of biological treatment, then through oxidation pond or adsorption drainage treatment.As coking wastewater has higher CODCr, higher chroma ,and contains many difficult biological pollutants, after these pollutants full into the aeration tanks will not only affect the normal biological treatment effects, but also add load CODCr, the purpose of this study is to use wet catalytic oxidation under low-temperature and atmospheric pressure as coking wastewater pretreatment, the difficult biochemical oxidation of organic pollutants in wastewater will be oxidated, thus benefiting the order of the biological treatment.Based on the wet hydrogen peroxide catalytic oxidation technology, we use heterogeneous catalytic oxidation technology at low-temperature and atmospheric pressure for applied research. Compared to other catalytic oxidation technology, the tests will be active catalyst to a porous solid catalyst, preparation of the heterogeneous catalysts. Use efficient heterogeneous catalysts to catalytic oxidant to produce high oxidizing free radicals, and at low temperature and atmospheric pressure—a more moderate conditions, high activity of free radicals on the oxidative degradation of organic pollutants, ultimately to carbon dioxide and water degradation of organic pollutants.Thorough the catalyst system of screening tests, found copper and manganese metal components catalyst for the removal of CODCr and NH3-N are both better than the other components catalyst, as active catalyst, copper and manganese can provide better oxidant to produce higher catalytic activity of the radical oxidation. Both carbon catalyst and modified bentonite catalyst have greater surface adsorption. Organic pollutants are adsorbed on the active site, deformation and generate activation complex, thus reducing the activation energy and accelerate the speed of the chemical reaction. In addition, modified bentonite and activated carbon catalyst itself is adsorption properties, can adsorbe organic pollutants to a certain extent, thus resorted to reduce the concentration of organic pollutants in water, but the adsorption of the organic extremely limited capacity, catalytic oxidation is dominated. Meanwhile, there is a comparison of the two catalyst for evaluation.Through experiments determined the modified bentonite catalyst superior to the activated carbon catalyst. Through a series of experiments at the low temperature and atmospheric pressure conditions, determine the catalytic oxidation optimal reaction conditions of the modified bentonite catalyst, an analysis of the effects of each factor. Better reaction conditions: temperature of 60℃, pH value of 3, the catalyst for the use of volume fraction of 26%,oxidation volume fraction of 5% and the reaction time is 2h.After the installation of catalytic oxidation reactor modified bentonite and activated carbon were a catalyst to fill, through continuous reaction of the catalyst in the reaction dynamics of the low-temperature and atmospheric pressure conditions, investigated the efficacy and feasibility of catalytic oxidation at low-temperature and atmospheric pressure. The experimental results show that the removal of pollutants in the continuing decline with the passage of time, but when the reaction time is 72 hours ,the removal of CODCr and NH3-N is also above 50% and 40%,proved the feasibility of practice.The author of this article was obtained through the experiment at low temperature and atmospheric pressure conditions to meet the heterogeneous catalyst, at the same time, through a series of experiments on the properties of liquid metals activity concentration,pH,temperature,amount of catalyst,oxidant concentration and reaction time for the analysis of the impact of such factors, the low temperature oxidation of refractory wastewater to determine the best reaction conditions, Dynamic response to determine the practical application of the heterogeneous catalytic oxidation technology effectiveness and feasibility at low temperature and atmospheric pressure. This study has opened a new wastewater treatment study for the way. Not only made the new catalyst to meet the low temperature and atmospheric pressure, but also determined the atmospheric heterogeneous catalytic oxidation technology practicality, the application of catalytic oxidation technology will provide a valuable experimental basis.