Study On Treatment Of Domestic Sewage By One-stage Autotrophic Nitrogen Removal In Upflow Double Layer Filler Reactor

Water eutrophication is one of the most important reasons for shortage of water resources in China.High efficient biological nitrogen removal technology has become a research foucs.At present,China has promulgated a more stringent urban sewage discharge standard,which has higher requirements for the effluent concentration of nitrogen than before.The traditional nitrification-denitrification process has many disadvantages,such as additional carbon source and high aeration energy consumption.The one-stage autotrophic nitrogen removal process based on anaerobic ammonia oxidation greatly reduces the energy consumption required by aeration,and does not need to add organic carbon source,and the surplus sludge yield is low.According to the disadvantages of the previous single stage autotrophic nitrogen removal reactor filler,this study developed a upflow double layer filler reactor,and explored its starting process,and the effect of low ammonia nitrogen concentration and backwash on strengthening starting operation.On this basis,the nitrogen removal efficiency of the reactor was investigated under the conditions of low ammonia nitrogen concentration,room temperature and different proportion of fillers.Using the pretreated sewage as influent,removal efficiency of the reactor treated with the was investigated,and the change of the denitrification pathway in different stage domestic sewage s and the influence factors were analyzed,and the effect of the internal circulation ratio on the performance of the system was also discussed.The start-up of one-stage autotrophic nitrogen removal process in upflow double layer filler reactor were successfully established after 139 days.The removal rate of ammonia nitrogen reached 98.3%and the total nitrogen removal rate reached 75.1%.Backwashing can effectively wash out NOB bacteria,and the system can recover quickly,which is beneficial to the stable operation of the reactor.Low concentration organic matter（60mg/L）can enhance the start-up of one-stage autotrophic nitrogen removal and has a beneficial effect on the improvement of nitrogen removal.The removal rate of ammonia nitrogen was slightly lower,but the total nitrogen removal rate increased to84.4%,and the total nitrogen removal load reached 0.15 kgN·（m³·d）^-1,respectively.The total nitrogen removal rate and total nitrogen removal load of the reactor reached 88.7%and 0.14 kgN·（m³·d）^-1,respectively,at room temperature and low ammonia nitrogen concentration.Increasing inflow load and backwash is beneficial to restore and maintain stable operation.The NOB in the reactor was effectively inhibited and the nitrogen removal performance was good.Without adding organic matter into influent,the reactor with higher proportion of zeolite filling can resist the adverse effects of changing aeration regulation.After backwashing,denitrifying bacteria also get more growth and proliferation space,resulting in a lower△NO₃^--N/△NH₄⁺-N ratio.On the basis of the above research,the removal efficiency of the reactor treated with domestic sewage was investigated.The ammonia nitrogen concentration in the effluent was maintained at 2⁴mg/L,and the average total nitrogen removal rate was83%.The total nitrogen removal load reaches 0.14 kgN·（m³·d）^-1,and the effluent reaches domestic sewage standard.Under the condition of high influent C/N,the structure of double layer fillers and long SRT may be the reason why the system can maintain high nitrogen removal performance.Under domestic sewage conditions,the proportion of nitrogen removal via anammox has reduced,but anaerobic ammonia oxidation is still the main nitrogen removal pathway in the system,and the denitrification process contributes to the increase of total nitrogen removal rate.