Treatment Of Wastewater With Low C/N Ratio And High Ammonia Nitrogen Concentration By Entrapped Ammonia-oxidizing Bacteria

Some industries like synthetic ammonia industry and Coking industry tend to discharge high concentrated ammonia-nitrogen waste water into the environment.The most common ammonia-nitrogen waste water treatment is the biological treatment.In most cases,ammonia-nitrogen nitrify relies on the Autotrophic ammonia oxidizing bacteria which has its tolerance threshold;the activity of the bacteria depends on the concentration of ammonia-nitrogen.Unlike autotrophic ammonia oxidizing bacteria,Heterotrophic ammonia-oxidizing bacteria has better tolerance towards high concentrated ammonia-nitrogen water.In addition,microorganism embedding immobilization can enhance the bacteria's tolerance of toxicant because it boost the functional microbial biomass and reduce the embedded body damage from the external inhibitory substance.At present,embedding immobilization still need to optimize due to some problems like the reduction of the microorganism activity or the mechanical strength is not ideal.This research aims to inspect the ammonia-nitrogen removal effect by treating low C/N ratio sewage water with enriched Heterotrophic ammonia-oxidizing bacteria and optimized embedding immobilization technical.This research use high-throughput sequencing technology analyzing the effect of raising ammonia nitrogen concentration on the both embedding and unembedding microbial community.The main results are as follows:?1?In the test,influent pH is controlled to 8,and the temperature is 30±1?in constant aeration?1.5 L/min?5 h,microbial community reach stable short-range nitration and enrich bacteria through 28 d acclimation in SBR reactor.Nitrite accumulation rate is above 90%,and the ammonia nitrogen removing ratio reach to93%.Ammonia nitrogen sludge load achive 0.15 kgN?kgMLSS·d???2?The result of the high-throughput detection shows that Proteobacteria is the dominant bacterial community,the ratio of the Comamonas is up to 25.4%,which indicate the full acclimatization of the microorganisms.?3?The PVA-SA Freeze-thaw method,after modification by activated carbon,is optimized according to five targets?balling,adhesion conditions,mechanical strength,mass transfer performance,and ammonia nitrogen removing ratio?.At last,adopt:PVA9%,SA0.9%,activated carbon 0.4%,package mud quantity rate 3:2,freeze thawing time 72 h,the concentration of stationary liquid is 3%Ca?NO₃?₂ solution.?4?The high-throughput sequencing method analyze the stable embedded culturing sludge and stable unembedded culturing sludge separately,finding out that the microbial diversity index experience a decline in the embedded system,and Paracoccus become the dominant bacteria community.Embedding method can increase the TN removal ratio and is good for the conversion from NH₃-N to nitrite,thus,the method will lead to the rise of the removal rate of ammonia nitrogen.?5?The treatment of the low C/N ratio high ammonia concentration wastewater is using the optimized embedding method under the index like the ammonium-nitrogen removal rate and nitrite accumulation rate.The optimal operating condition is obtained:temperature 28±1?,DO 5 mg/L,pH is 8.When influent ammonia-nitrogen concentration of artificial simulated waste water is 500 mg/L,the standing time is 6 hours,and the optimal effluent ammonium-nitrogen removal rate is 70%,the accumulation rate of nitrite is above 90%.