Study On Nitrogen Removal Characteristics Of Single-Stage Nitrogen Removal Reactor

With the rapid development of industry and human activities,a large amount of nitrogen is discharged into nature,which breaks the balance of nitrogen cycle in nature,and brings great harm to human health and the natural environment.There are many problems in the traditional nitrogen removal process,such as low efficiency,high energy consumption,easily causing secondary pollution.In order to treat the wastewater with high ammonia nitrogen efficiently and economically,it is very important to develop a stable,efficient and low energy-consumption biological nitrogen removal process.Single-Stage Nitrogen Removal Using Anammox and Partial Nitritation(SNAP)process is a new biological nitrogen removal technology for high efficiency and economy,compared with the traditional biological process,can save more than half of the amount of nitrification oxygen demand and all the denitrification COD demand.SNAP is the frontier and hot research topic in biological nitrogen removal process.However,the process is faced with many problems,such as long period of sludge culture,and easy to be affected by water quality.The research investigated on the influence of temperature,salinity and the effect of landfill leachate and other key water quality factors on SNAP process in an up-flow reactor,metabolism dynamics were also analyzed.And microbial community structure of reactor was analyzed using high-throughput sequencing technology.A highly reactive nitrifying sludge was inoculated into a stable Anaerobic Ammonium Oxidation(Anammox)reactor then control aeration,and the start-up of the SNAP reactor was realized.On this basis,through the control of the operating conditions,the reactor achieved a peak load in a short time,and quantitatively analyzed the characteristics and activity of the sludge.It was found that the SNAP reaction was successfully carried out after 35 days,and the total nitrogen load was stable at 0.72 kg-N/m3/day,and the removal rate was maintained above 65%.On the 125th day,the SNAP reactor reached the peak load,the load reached more than 1.15 kg-N/m3/day,and the removal rate of NH4+-N remained above 90%.Microscopic analysis of the packed sludge showed that a large number of Anammox bacteria were successfully enriched.Batch experiments showed that the ratio of sludge consumption NH4+-N、NO2--N、and produced NO3--N by 1:1.117:0.168,is close to the theoretical value,the removal of total nitrogen in the reactor is indeed the result of the interaction of ammonia oxidation and Anammox process.Based on the SNAP reactor in different periods,different positions of sludge high-throughput sequencing analysis showed that the micro aeration environment,SNAP bioreactor has been formed to adapt to the microbial community structure of the combined action of several strains of nitrogen removal:lateral aerobic nitrification,anaerobic ammonia oxidation inside.The proportion of Anammox bacteria in the mold increased with the increase of operation time,which was the main reason for the increase of nitrogen removal efficiency.The proportion of Candidatus Brocadia belongs to 18.9%,which is the dominant bacteria in SNAP reactor,and a certain amount of Candidatus Kuenenia exists.The microbial community structure is gradually complicated from start to stabilization.After successful start-up,the proportion of Proteobacteria and moulds associated with denitrification reached more than 49%.With the operation of the reactor,the biofilm structure of the packed sludge biofilm appeared "stratification",and the inner community structure was purer than that of the outer side.The symbiosis of bacteria can promote the growth and enrichment of functional bacteria(Anammox bacteria and so on).The actual water quality,such as temperature,salinity,pH,landfill leachate and so on,had a significant effect on the SNAP reaction.The effect of water quality on SNAP process was analyzed by using continuous flow reactor combined with sequencing batch reactor.The results showed that temperature had an obvious effect on the activity of Anammox and AOB bacteria,and keeping the optimum temperature played an important role in obtaining high efficiency SNAP reaction.The SNAP reaction system can resist and adapt to 10g/L and lower salinity shock,The pretreatment of landfill leachate has irreversible inhibition on the pollutant removal capacity of SNAP system,the removal rate of ammonia nitrogen and total nitrogen in the system is maintained at 60%,and the removal of COD is limited,which is about 10%.The maximum specific rate of degradation of NH4+-N was 2.821 mg/(g·h)and the semi saturation constant Ks was 125.486 mg/L by measuring the related parameters of the model.Extreme acid shock can bring about an un recoverable effect on nitrogen removal capacity of SNAP system.This paper studies the startup of the SNAP reactor and its operating characteristics,understand the effects of different water conditions on the SNAP process,the start-up and operation conditions of SNAP process,provides a theoretical basis and technical guidance for the practical application of SNAP technology.