Study On The Start-up And Operation Of Partial Nitrification-anammox In Actual Landfill Leachate Treatment Project

Environmental pollution and shortage of resources are two major problems facing human beings.When nitrogen from various sewage enters water,it will not only cause water environmental pollution,but also lead to further shortage of water resources.Therefore,in the 12th five-year plan of China,ammonia nitrogen hes been taken as the total amount of pollution control.While in the 13th five-year plan,total nitrogen has been listed as the key treatment object.Landfill leachate is a typical wastewater with high ammonia nitrogen.And nitrogen removal is the focus and difficulty of landfill leachate treatment.This study used partial nitrification-anaerobic ammonia oxidation(anammox)process for the treatment of landfill leachate,characterized by the COD concentration of 3000-5500 mg/L,ammonia nitrogen and total nitrogen between 1000-3000 mg/L,C/N ratio between 1.5 and 3.0,and pH of 8.0 to 8.5.We designed the pretreatment,biochemical treatment and flocculation process,calculated and designed the main body of the"hydrolytic acidizing tank-UASB-aerobic tank-the secondary sedimentation tank"biochemical treatment unit.During commissioning,parameters such as water inflow,reflux ratio,sludge reflux,pH of each reactor and dissolved oxygen in aerobic tank were controlled.In the later period of the commissioning,the water inflow was controlled at 100 m~3/d,and the reflux ratio was 1:1.Finally,the COD concentration of the effluent of the aerobic tank is about 1500 mg/L.The ammonia nitrogen concentration does not exceed 30 mg/L and the total nitrogen concentration is 300-400mg/L.The COD removal rate of biochemical treatment system is around 67%.The removal rate of ammonia nitrogen has been kept at 99%and the total nitrogen removal rate is around 80%.The dissolved oxygen was gradually reduced to 2.0mg/L in the aerobic tank and the pH of the inlet water was controlled to 8.5.The aerobic tank mainly experienced partial nitrification and nitrite was accumulated to 200mg/L,with the accumulation rate up to 78%.Sludge loss in aerobic tank indirectly promoted nitrite oxidizing bacteria(NOB)with a long cycle of panning generation.The results of the microbial DNA detection indicated that the species abundance of AOB in aerobic tank was more than 10 times that of NOB.The inlet water of the hydrolytic acidizing tank was 100m~3/d with the reflux ratio was 1:1 and the pH was around 8.5.Anaerobic ammonia-oxidation(ammox)was successfully started in the hydrolytic acidizing tank without adding organic carbon source.The contribution rate of anammox to total nitrogen removal in the hydrolytic acidizing tank varies with the change of the C/N ratio of water intake and the contribution range is 35-67%.In the actual landfill leachate treatment project,by controlling the inflow,reflux ratio,pH and DO,the partial nitrification-ANAMMOX process was successfully conducted.