Study On Treatment Of Ammonia Wastewater By Catalytic Wet Air Oxidation Process

With the development of industry and agriculture, the discharge of ammoniaincreased greatly, ammonia wastewater became one of the main pollutants that woulddo harm to humans, animals and break nature balance. At present, physicochemicalprocess coupled with biologic process was generally used to treat the highconcentration ammonia wastewater, but it covered wide floor area and had a complexprocess, what's more, the efficiency is low. In contrast to, catalytic wet airoxygenation (CWAO) developed in last years has a high activity, when the noblemetal was take as the catalyst. But the high cost of noble metal limits its large-scaleindustrial use. In the dissertation, a low cost and high activity catalyst was try tofound to eliminate the ammonia in wastewater.Based on the goal, the main work as follows:1. The preparation and characterization of the catalyst for treatment of NH3-Nwastewater by CWAO.(1) The Cu, Mn and Ce oxide compound catalyst was prepared. Based on thetheory of catalyst-oxidation, the CuO was selected as the main activity of catalyst.When it is compounded with different metal oxide such as Ni, Co, Mn and Zn, theCu-Mn compound catalyst showed a superior performance that the percentagedecrease of NH3-N increase from 45.2% to 59.1% in contrast to single componentCuO. What's more, the adding of electron-promoter in CuO and Mn oxide catalystincreases sharply the percentage decrease of NH3-N to 91%. Meanwhile thedissolution of cu was limited obviously.(2) The effect of carrier on the efficiency of catalyst was investigated. The resultshows the carrier which pore size distribution between 6-10nm is more suitable to thetreatment of NH3-N than the other.(3) The proportion of the component was optimized, the calcinations temperatureand hold time were investigated as a function of catalyst performances with thespecial catalyst optimized. iABSTRACT2. Operation condition was investigated for treatment of NH3-N by CWAO.(1) The effect of reaction temperature, partial pressure of oxygen and pH valueon the percentage decrease was studied, the optimal catalytic oxidation condition: T=255℃, PO2=4.2MPa, pH =10.8, time=150 min. And at least 98.5% of ammonia(C0=1023mg·L-1) was decomposed.(2) The reaction kinetic equation was fitted by the experiment data. It meet theclass I kinetic model. Meanwhile the stability of catalyst was studied. Under thecontinuous 1000 minutes, the percentage decrease of NH3-N (C0=980mg·L-1) wasover 90%.3. The experiment investigation of the industrial coking wastewaterThe coking wastewater (from Ma Gang coking factory) was treated under thecondition as follows: T=255℃, PO2=4.2Mpa and pH=12, the decomposition ofammonia (C0=3114mg·L-1) could be achieved to 98.2% and COD (C0=7640mg·L-1)could be achieved to 97.5%. So the self-made catalyst has a promising future infurther industrial use.