Study Of Influence Factors On Landfill Leachate Treatment By Catalytic Wet Air Oxidation

Landfill leachate, which water especially rainwater through solidwaste in landfill produces by taking away inorganic and organicdecomposition intermediate and the end products, is a kind of harmfulwastewater containing high concentration organic compounds. Thereare a lot of organic pollutants, many kinds of heavy metals and highlyconcentrated ammonia and nitrogen in landfill leachate. The pollutantdensity ranges of landfill leachate produced in different locations,seasons, and times of filling landfill are wide. So the fit treatmentsshould be adopted according to the various landfill leachate. At present,the treatments of landfill leachate mainly include biological methodsand physical-chemical methods. Because of its easy manipulation, lowfunctioning cost and ripe techniques, biological methods are widelyapplied. However, the highly dense ammonia and nitrogen in landfillleachate strongly check microbial activation. Landfill leachate must bepretreated to be beneficial to the follow-up in biological methods.Physical-chemical methods are good to treat organic wastewater that ishard to treat by biological methods and the organic composition whoserelative molecular weight is small, but its treatment cost iscomparatively high. So finding the treatment that is not limited by thespecific property of water quality in landfill leachate becomes one ofhot issues of researching treatment techniques of landfill leachate athome and abroad. Wet air oxidation (WAO) is the abbreviation for wetair oxidation), growing in 1950s, is an advanced oxidation techniquethat is suitable to treat waste water which is highly dense, poisonous,harmful and hard to biodegrade. Compared with the traditionalbiological methods, WAO has such merits as high efficiency intreatment and land occupation, no second pollution and production ofactive mud. The technique is widely used in treating waste water of oil,chemical industry and pharmaceutical industry, city mire, activecarbon regeneration. It has aroused general concern that suitablecatalyst is added in the traditional WAO technology to reduce theneeded temperature and pressure of reaction, improve the ability ofoxidation decomposition, shorten the time, prevent equipments fromcorroding, cut down the cost and raise elimination rate of COD andNH3-N. The thesis is about treating the landfill leachate in a landfill byadopting CWAO (CWAO is the abbreviation for catalytic wet airoxidation) technique and using Co/Bi as catalyst. Based on theelimination efficiency of COD and TOC in the process, the factorssuch as temperature, oxygen partial pressure, the initial density and pHvalue of landfill leachate and oxidant amounts are examined separatelyon their effects towards the efficiency of treatment on landfill leachateby CWAO. Meanwhile, the dynamics law of landfill leachatedecomposition under the influence factors is discussed according tothe experimental data in order to found the technological conditions oflandfill leachate decomposition by CWAO.Among the various influence factors in decomposing landfillleachate by CWAO, the removal rate of TOC in the landfill leachateincreases with the increase of the temperature, the dose of the catalystand the oxygen partial pressure with the former two factors havingmore obvious effects. The result of catalytic reaction affected byoxygen partial pressure at different temperatures shows that the effectof oxygen partial pressure was not obvious at high temperaturebecause the temperature increase makes contribution to expediting thereaction rate. In the process of research into the influence of reactionsolution concentration and the pH on decomposing landfill leachate byCWAO, with the increase of the reaction solution concentration, thedecomposition reaction rate of the organic compounds increases whilethe removal rate of the organic compounds decreases. The initial pHvalue of reaction liquid tremendously and complicatedly affectslandfill leachate decomposition by CWAO. With the increase of theinitial PH value, the removal rate of TOC appears increasing at firstand then decreasing gradually after reaching the peak value.Elovich equation describes the dynamics process of decomposingTOC in landfill leachate by CWAO under various factors.Experimental data is simulated well and the decomposition reactionrate is obtained. By comparing the decomposition rate resulting fromdifferent influence factors, the influence of different factors ondecomposition can be understood similarly, which accords with theprevious conclusion.In order to study whether organic pollutant in landfill leachatetreatment by CWAO reach the discharge standard of national waste...