Study On Influence Of A New Packing On Ammonia Nitrogen Removal From High Strength Ammonia Wastewater By Gas Stripping And Desorption Method

Most coke plants adopt steam stripping as a pretreatment method to remove ammonianitrogen, and then activated sludge method to treat coking wastewater. But this combinedprocess still has the problem that the concentration of discharged ammonia nitrogen cannotalways meets the national emission standard. So it has become an important study subject todevelop an economical and effective ammonia nitrogen treatment technology. Coal gas strippingmethod is a promising method to treat surplus ammonia wastewater in coking plant and toreplace ammonia stripping with water steam which consumes large amounts of energy.Firstly, effect of the wastewater temperature T and pH, surfactant dosage, gas-liquid ratio onstripping efficiency has been researched to remove ammonia nitrogen from simulated wastewaterthrough orthogonal experimental of air stripping method. Secondly，paper researched the effectof three packings with different specific surface area on ammonia nitrogen removal. Throughorthogonal experimental of air stripping method, the effect of the wastewater temperature T andpH, surfactant dosage, gas-liquid ratio on stripping efficiency has been researched. it wasconcluded that:(1) the important order of relevant favors influencing the removal rate ofammonia-nitrogen was pH> gas-liquid ratio n> ammonia temperature T> surfactant dosage p.(2)The best operating condition was pH=11.5, gas-liquid ratio n=250:1, surfactant dosagec=20mg/L, ammonia temperature T=80℃.(3) The best removal rate of ammonia-nitrogen was71.82%with the pall ring tower. With the packing tower of packing I and II, the best removalrate of ammonia-nitrogen was66.44%and73.78%separately.(4) Removal rate ofammonia-nitrogen reached73.37%with packing II through single factor experiment, when themodified condition was pH=11.5, gas-liquid ratio n=250:1, surfactant dosage c=20mg/L,ammonia temperature T=75℃.With pilot equipment of coal gas stripping process, finally, Influence of palling andcombined packing II on ammonia removal from residual ammonia has been studied. Throughorthogonal experiment of coal gas stripping, combined packing II showed a better performancethan pall ring. For combined packing II, it was concluded that:(1) The important order ofrelevant favors influencing the removal rate of ammonia was wastewater pH> wastewatertemperature T> gas-liquid ratio n> coal gas temperature t> surfactant dosage p.(2) The bestoperating condition, in which ammonia-nitrogen removal rate was94.24%, was pH=11.5,n=350:1, p=20mg/L, T=85℃, t=55℃.Taking a coke plant of annual production of1million tons as an example, the investmentand cost analysis of coal gas tripping process was made: The cost of wastewater treatment, ofwhich72%was alkali consumption, was23.4yuan. So it has a great potential to lower the costof wastewater treatment by reducing alkali consumption.