Application Of New Deep Denitrification Process In Garbage Leachate And Carbon Emission Analysis

Old landfill leachate is a typical high ammonia nitrogen wastewater,with high salinity,poor biochemistry,refractory degradation and easy fluctuation of water quality.Traditional landfill leachate treatment processes are costly and have a large carbon footprint.Based on the early study of our team,a partial nitrification denitrification（PN-D）coupled with sulfur autotrophic denitrification（S⁰AD）and membrane filtration system was used as the deep denitrification biochemical process to treat the landfill leachate in a landfill in Foshan.This study explore the treatment efficiency and stable operation mechanism of the process.The carbon emissions of the pilot scale PN-D-SAD-membrane treatment process,pilot scale and engineering scale of the traditional nitrification denitrification process were compared,the main conclusion of this study is as follows:（1）It took 40 days to start the short-range nitrification and denitrification pilot reactor by inoculated the fully nitrative and denitrification sludge in the NO.1 leachate treatment plant.Under the influent conditions of COD 10800～20000 mg/L,NH₄⁺-N2540～4000 mg/L,the daily treatment capacity gradually increased from 0.5 m³/d to 3m³/d,and the long-term stable operation lasted for 216 days.The removal rate of COD reached 83.39%,and the total nitrogen（TN）removal rate reached 95.72%.The analysis of microbial community structure showed that Nitrosomonas was the main functional species in the reactor,and the relative abundance increased from the initial2.34%to 12.76%.（2）The excess sludge of the short-range nitrated denitrification pilot reactor was used as the inoculated sludge of the pilot S⁰AD reactor.Then the reactor was successfully started with the sulfur filling ball as the biological carrier.Then,the coupling of PN-D-S⁰AD deep denitrification pilot reactor was successfully realized on 67_thday,and the TN removal rate of the S⁰AD reactor reached 65.89%.During stable operation,the TN sludge load and volume treatment load of the pilot reactor reached 0.1226 kg TN/（kg MLVSS·d）and 0.4345 kg TN/（m³·d）,respectively,which were significantly higher than the corresponding TN load of NO.1 landfill leachate treatment plant.（3）The effluent of S⁰AD reactor was used as the influent of the combined membrane process of MBR-NF.Finally,The average effluent from the MBR-NF membrane process NH₄⁺-N,NO₂^--N and NO₃^--N are 0 mg/L,20.2 mg/L and 2.9mg/L,respectively,The COD and TN average removal rate reached 99.3%and 64.9%,respectively.PN-D-S⁰AD-membrane process pilot reactor was stably operated for 135days.（4）A carbon emission model for high ammonia nitrogen wastewater treatment was established and applied to compare the pilot nitrogen denitrification process with the traditional denitrification process.The results show that the carbon emission of traditional complete nitrification and denitrification process and the pilot process are84.72 g O₂/t and 46.95 g O₂/t respectively.Energy consumption and biochemical reactions are the main carbon emission components.Biochemical reaction carbon emission is mainly constructed by heterotrophic denitrification and endogenous respiration.Aeration contributes the main energy consumption carbon emission.