Optimization Study On The Degradation Condition Of Butyric Acid By Catalytic Wet Air Oxidation Over Mn-Ce Catalyst

Landfill leachate produced in the process of municipal landfill will cause harmful danger to the environment and the public health for its highly organic concentrated, highly toxic and refractory of biological. The composition of the pollutants in the leachate is complex, with which COD can reach 70000mg/L, BOD5 reach 38000mg/L and Ammonia-nitrogen over 1700mg/L, while the highest concentration in the heavy metal pollutants is Fe, Pb etc. Generally organic compounds of landfill leachate include aromatics, alkanes, alkenes, organic acid, ester, alcohol, ketones and aldehyde etc. Now, the treatment of high concentration refractory organic wastewater has become a major issue to be resolved in the field of environmental protection at home and abroad. Catalytic Wet Air Oxidation (CWAO) was proved to be the effective way with greater advantages. CWAO is a physicochemical treatment method. Under the high temperature and high pressure, it used liquid oxygen or air as oxidant, and the catalyst was added to oxide the dissolved or suspended organic compounds or the reduced inorganics in liquid phase. In this process, complex organic compounds are mostly oxidized into carbon dioxide and water without producing NOX, SO2, HCl, dioxins, furans and fly ash. Its advantages are highly purification efficiency, fast processing speed, no secondary pollution, simple process and less covering. Main factors of CWAO are systematic temperature, catalysts dosage, reaction time, the initial concentration and initial oxygen partial pressure. The different value of the experimental conditions could lead to the different impact to the results, and it also determines the degradation effect of the CWAO technology. So it is very important to choose the high efficiency and economical experimental conditions.With the development of the community, the application of mathematics is more extensive, and there has been many crossed subjects and all the science technology show trend of mathematics. Mathematics has been widely applied in the natural sciences, engineering technology, the economy, population, education, management, and other fields of social sciences. It is considered useful to carry out environmental work with the method that collated and analyzed the environmental data, researched the mutual relations for the various factors of environment, revealed inherent laws of environmental system, forecast the changeable trend of environmental system with the basic theory and calculation method of mathematics. Adopting mathematics mean that it begin from the problems of real life to carry through translation of mathematics, to establish mathematical model, to calculate mathematical model and use the results to the original problems.In this paper, the butyric acid was used as simulated solutions of landfill leachate, according to the research on the factors which include the reaction temperature, pressure, the amount of catalyst, undiluted concentration, reaction time etc, and the experimental data of degradation the butyric acid by CWAO, the mathematical model of the heating and reaction process were established. The reaction process model was optimized to ensure the operating parameters of the minimum operating costs using the optimization criteria, while the limited conditions were that the undiluted concentration of TOC was 200mg/L-1200mg/L, the amount of catalyst was 0.25g~1.25g, reaction temperature was 160℃~240℃, reaction pressure was 0.5Mpa~2.5Mpa.The Mn-Ce complex oxides catalysts was prepared by the complexation process of citric acid, and selected different standard numerical value of the main influence factors (the initial concentration of butyric acid, catalysts dosage, systematic temperature, initial oxygen partial pressure) which were based on the experimental schemes. Then the residue of TOC under the different conditions was gained according to the experiment that the degradation of butyric acid using CWAO which used TOC as degrading standard.First, based on the data in the heating process of the degradation of the CWAO of butyric acid, the relationship of degradation efficiency and four main factors (the initial concentration of butyric acid, catalysts dosage, systematic temperature, initial oxygen partial pressure) was analyzed and a mathematics model about the effects of main factors on the TOC degradation rate was established according to regression analysis method. Analysis of variance was used for the mathematics model. Furthermore, established model was validated and adjusted in order to reach the higher credibility. Based on the data which comes from the reaction process of CWAO experimental, same methods as mentioned above was used to establish the mathematics model describing the effect of single factor and the four main factors on the TOC degradation rate. Also this mathematics model was validated and adjusted in order to reach the higher credibility.Secondly, the final goal of this study is to obtain the minimum expense of experiment (E), that is to obtain optimum value of four influencing factors (catalysts dosage, systematic temperature, original oxygen partial pressure, reaction time), under the condition of accordance with the TOC degradation efficiency. Using the extremism method of optimization theory and software Lingo to solve the optimization model of the CWAO process for butyric acid degradation, the obtained cost of experiment is 1.9957RMB which is obviously lower than the initial values according to obtain the butyric acid for 0.5L which concentration is 450.3 mg/L, while the concentration of TOC is 9.92 mg/L, catalysts dosage is 0.25 g, systematic temperature is 240℃, initial oxygen partial pressure is 0.5 Mpa, and reaction time is 68min.Results showed that mathematics model can describe the law of main factors (the initial concentration of butyric acid, catalysts dosage, systematic temperature, initial oxygen partial pressure) effecting on the degradation of the CWAO of butyrate acid. Furthermore, optimizing and calculating of the model could obtain the satisfactory result for the best economy condition. Therefore, mathematical simulation on the degradation of CWAO process of butyrate acid can forecast and optimize experimental result, decrease the waste, save time. It is significant for the experiment.