Study On The Removal Of Nitrogen Of Polluted River By Bio-contact Oxidization Process

In order to provide a technical support for treatment of the key Tiao Zi River andreduce total nitrogen concentration of Liao River and its tributaries, this paper studiedBio-contact oxidation process treating simulated Tiao Zi River, which was the mainpollution source of the Liao River important tributaries-ZhaoSuTai River.Taking diluted domestic waste water as the influent and using gravel and lava asthe carrier of microorganism to design the reactors. Reactor was started-up in thelow-temperature. By adjusting the water flow, aeration rate, reactor length and stepfeed ratio during operation, the hydraulic load, DO concentration, removal load ofpollutants, removal rate of ammonia, TN, COD were studied to eventually develop anew contact oxidation reactor.Started the batch training firstly and continuous training30days under thecondition of the water temperature of11¹6℃, the removal rate of COD andNH₄⁺-N, TN was stable at80%and70%,50%respectively, so the system was startedup successfully. The biofacies were steady and the reactor was adaptable to changes inwater quantity and quality.The ability to resist load shock was good, and the wholeprocess was without excess sludge. During setting up period, temperature, theconcentration of DO, the hydraulic load and COD volume load had an affect on theremoval of COD and NH4⁺-N. In order to keep good ability to remove pollutants, theconcentration of DO should be maintained at5⁶mg/L, the hydraulic load should bemaintained at5⁷m³/m³/d and COD volume load should be maintained at0.6¹.0kgCOD/m³/d. During running period, the average removal rates of COD wasstable and the average removal rates of TN was increased from40%to70%afterstep-feeding, which proved that step-feed mode was conducive to the removal ofTN.COD volume load and the total nitrogen load had an affect on the removal ofCOD and total nitrogen with a negative correlation. Increasing the length of thereactor can effectively improve the removal efficiency and capacity of COD and TN.The right step feed ratios of three-step feeding reactor and four-step feeding reactorwas1:2:3and4:2:1:1. The removal efficiency of four-step feeding reactor was betterthan three-step feeding reactor. What’s more, four-step feeding reactor couldeffectively save the aeration. When the step feed ratio of the three-step feeding reactor was1:1:1and the aeration rate was maintained at5m³/h, the average removal rate ofNH₄⁺-N was stable at70%and the average removal rate of TN was stable at40%.The experiment had achieved some valuable data, which provided a technicalsupport for Tiao Zi River treatment.