Research On The Nitrification Of One-step Autotrophic Ammonia Removal Process

Traditional biological nitrogen removal process utilzes the organic carbon aselectron donor in the denitrification phase, which is not favor to treat the low C/Nwastewater for the shortage of organic carbon. The methods, such as deliveringmethanol, which may bring to much energy waste and high operation cost etc inpractice. All this is much far away from the sustaining-development aim of wastewatertechnologies. One-step autotrophic nitrogen removal process, which means theexperiment is carried out in one reactor and no extra organic carbon is affixed, has theadvantages of facility, high efficiency and low energy requirement. In this dissertationthe experiment on treatment of mid-low ammonia concentration synthetic wastewaterwas carried out to get the optimized operation conditions and explore the possiblemechanism of one-step autotrophic nitrogen removal process.The experiment was carried out in four SBR reactors to compare to get the bestoperation condition of one-step autotrophic nitrogen removal process, and used ordinaryaerobic sludge and anaerobic sludge as the inoculation sludge and the synthetic mid-lowammonia concentration wastewater as nitrogen resource. The results showed that on theconditions of temperature 30±2℃, ammonia concentration 80～120mg/l, DO 0.8～1.0mg/l, hydraulic retention time 24h and FA 1.0 mgNH₃/l, the steady nitrification canbe reached after 125 days, nitrification accumulation rate was 76.9% averagely, andnitrogen removal rate was about 40% after the 180^th day and the sludge load was0.20kgNH₄⁺ -N/kgMLSS·d .The representative sludge characteristic of heterotrophic bacteria being washed outand autotrophic bacteria accumulating was occurrence of the bacilliform sludge, but thesludge was petallike when the steady nitrification was set up and part nitrogen removalfunction was reached. The bacteria separation experiments now showed that the amountratio of nitrosomonas and nitrifier was 41.5, which was 155 times higher than the ratioof them in the inoculation sludge.The possible mechanism of one-step autotrophic nitrogen removal process may bethe combination of Nitrification and Anammox, which is deduced from the operation ofthe process and bacteria separation study.