Study On Effects Of Surfactants On Ammonia Nitrogen Mass Transfer In Buffer System Of High Concentrations Of Ammonia Nitrogen Wastewater

At present, with the high development of economy, the environment load is more and moreserious. The state pays more attention to environmental protection of enterprise, and has madeeven more strict environmental regulations, especially for waste water that can cause seriousenvironmental pollution. Ammonia nitrogen as a serious contaminants damaging water, isdischarged in the wastewater largely and can cause water eutrophication. For the highconcentration of ammonia nitrogen wastewater, pretreatment methods are mainly the evaporationmethod, the stripping method and the chemical precipitation method. The most common methodis ammonia evaporation method, whose efficiency is low and consume large amounts of steam. Itis high energy consumption and low efficiency processing. The air-stripping method engendersthe second pollution. The Chemical precipitation method consumes too much reagent andoperating costs. The product MAP is difficult to be effectively use.The coal gas stripping method is promising to replace the ammonia evaporation method totreat surplus ammonia wastewater in coking plant. This paper based on the coal gas strippingmethod to research effect of surfactants on ammonia mass transfer in buffer system of highconcentration of ammonia wastewater. This paper through the research of ammonia nitrogenwastewater buffer system and alkali adding process, makd use of a lot of volatile ammonia inammonia wastewater and reduce the62%of alkali consumption. The paper studied low airvelocity strip ammonia nitrogen wastewater system, established the ammonia mass transfermodel, and deduced the total ammonia liquid mass transfer coefficient and temperature relations:KL=8.3×10^-12e^0.051T. The study of effect of surfactants on ammonia mass transfer screened themixed fluorine carbon type surfactants, which improved2%of ammonia mass transfer quantity.Then, this paper extended the mechanism research to the pilot test, designed and manufactureda composite desorption tower of coal gas stripping ammonia nitrogen, which has fourpolypropylene packing and three sieve plates. The diameter is0.6m. The orthogonalexperiments detruded the best conditions: pH is11.5, adding alkali at meso-position, the gas toliquid ratio is400, the wastewater temperature is90oC, the gas temperature is70oC, thesurfactant dosage is15mg/L. At this time, the ammonia nitrogen removal efficiency is92.8%,alkali consumption is8Kg/m³.According to the research results, this paper makes the technical and economic analysis. Foran annual capacity of1million tons of coking plant, the coal gas stripping method can save857.5million a year in consist of the ammonia evaporation method and only increase a gasblower’s based investment. Thus it can be seen that the coal gas stripping method has a greateconomy, energy saving and industrialization prospect.