Impact Of Hydraulic Load And Recirculation Frequency On N₂O Emissions From Semi-aerobic Bioreactor Landfill

Semi-aerobic bioreactor landfill, which makes the nitrification and denitrification occurred at the same reactor by leachate recirculation and air injection has an effective nitrogen removal and faster waste stabilization. However nitrous oxide(N2O) as the main ozone-depleting substances, which has a great global warming potential will be inevitable produced during the nitrification and denitrfication process in the system.Study have showen that recirculation hydraulic load and the recirculation frequency have a great effect on the removal of leachate and waste stabilization process,while the influence of recirculation hydrogen load and the recirculation frequency on N2 O emissions from semi-aerobic bio-reactor landfill are not known. This paper is focued on leachate quality index(p H、COD、VFA、NH4+-N、TN,etal) and the production characteristics and influencing factors of N2 O by establishing semi-aerobic bioreactors in different recirculation hydraulic load and different recirculation frequency. The main conclusions were obtained as follows:1. The production chareacteristic of N2 O indifferent recirculation hydraulic load had the same trend,they all showed high at the initial period,then decread to a low level for a long time,then rised at a high level quickly at the later period,then decread at a low level but still remain at a high level. Statistical analysis showed the recirculation hydraulic load had an impact on the average concentration of N2 O, the average concentration of N2 O were 1546±2673 ppm,1789±3088 ppm,1800±2968 ppm recpectively when the recirculation hydraulic load were16.25 L/(m2·d),48.75 L/(m2·d)and32.50 L/(m2·d).2. The main influencing factors which resulting in N2 O production were different at different recirculated hydraulic load. At 16.25 L/(m2·d)recirculated hydraulic load:NH4+-N、VFA were the maim influencing factors which resulting in N2 O producing. At 32.50 L/(m2·d)recirculated hydraulic load:NH4+-N、ORP were the maim influencing factors. At 48.75 L/(m2·d)recirculated hydraulic load:NO3--N、NH4+-N were the main influencing factors.3. The production chareacteristic of N2 O indifferent recirculation frequency have the same trend with the recirculation hydraulic load. In Semi-aerobic bioreactor landfill, when Recirculation frequency was one time per day, the average concentration of N2 O was at middle level. When the recirculation frequency was two times per day, the average concentration of N2 O was the highest(3499±5830 ppm). At one time in two days, the average concentration of N2 O was minimum(1800±2968 ppm).4. The main influencing factors which resulting in N2 O production were different at different recirculated frequency. At one time per day:NH4+-N、ORP were the maim influencing factors which resulting in N2 O producing. At two times per day:NO3--N、NO2--N were the maim influencing factors. At one time in two days:NO3--N was the maim influencing factors.