Study And Application Of Partial Nitrification And Denitrification In Treatment Of Mature Landfill Leachate

Landfill leachate is a kind of high concentration organic wastewater with high ammonia nitrogen and low carbon nitrogen ratio.If the traditional nitrification denitrification and denitrification process is adopted directly,it has the problems of high energy consumption,large carbon input and low denitrification efficiency.In view of the current situation,this project use partial nitrification and denitrification coupled ANAMMOX to treat leachate in a small scale,and carries on the process transformation and upgrading in a leachate treatment plant to realize the pilot application.The process modification is to replace the original ammonia stripping pretreatment process by partial nitrification and denitrification,and then continue the treatment with the standard EGSB anaerobic biorereactor,AO-MBR and NF processes and then discharge the nanotubes.At present,partial nitrification and denitrification can be used in pilot applications up to 200 t/d,equivalent to the size of a small sewage treatment plant.The partial nitrification and denitrification coupled ANAMMOX treatment system for the mature waste leachate was operated in the laboratory for 120 days.In the SBR pool the DO was controlled for 0.5?1 mg·L^-1,and the aeration reaction lasted for 19 hours.In System of the average water quality of ammonia nitrogen concentration of 2497.07 mg·L^-1,average water TN was 2600.12 mg·L^-1,SBR the partial nitrification and denitrification of ammonia nitrogen average removal rate of about 62%,the average removal rate of TN is about 16.45%,the average rate of nitrosation is about 86%,the water and the ratio of nitrate nitrogen and ammonia nitrogen basic maintain between 0.8?1.4,SBR stable partial nitrification and denitrification reaction effluent at the same time the basic meet the requirements of subsequent ANAMMOX into the water.The average ammonia nitrogen load of the system is about 0.99 kg·m^-3·d^-1,and the average total nitrogen load of the system is about1.04kg·m^-3·d^-1,and the average COD of the is 4033.45mg·L^-1.The average removal rate of ammonia nitrogen of the whole system is 99.21%,the average removal rate of total nitrogen is 91.61%,and the average removal rate of COD is 64.88%.AO-SBR was used as a pilot test for mature landfill leachate pretreatment in place of ammonia stripping after the partial nitrification and denitrification treatment in the laboratory achieved good results.The system operated for 190 days.When the mass concentration of ammonia nitrogen in the water was 1000?3000 mg·L^-1,the ammonia nitrogen treatment reached more than 80%,and the nitrification rate remained stable above 95%.Methanol is used to supplement COD of raw water to improve the carbon nitrogen ratio of raw water.When the carbon nitrogen ratio of inlet water is 1.8,the removal rate of total nitrogen reaches about 50%.The results of typical cyclic nitrogen balance analysis showed that the total nitrogen load removed by the partial nitrification and denitrification paths accounted for 74.8%and 13.5%of the total nitrogen removal loads respectively.The AO-SBR partial nitrification and denitrification as the mature landfill leachate pretreatment process can meet the inlet water requirements of the subsequent process process,and the final effluent can meet the nanotubes standard.The operating cost of the landfill leachate pretreatment process is reduced by about 30%compared with ammonia stripping.The partial nitrification and denitrification process is technically and economically feasible to replace the ammonia stripping process for landfill leachate pretreatment.In the experiment,the sludge of the partial nitrification and denitrification pilot system was studied.The results showed that MLSS?MLVSS?the ratio of MLSS and MLVSS of sludge in the SBR tank after acclimation was finally stable at about 5000?6000 mg·L^-1,2000?3000 mg·L^-1 and 0.4,respectively.SV₃₀ was maintained at 40?50%and SVI at 80?90m L·g^-1.The biodiversity of microorganisms in the partial nitrification and denitrification system was sequenced by 16s RNA high-throughput sequencing.The species diversity of SBR decreased after 190 days of operation.The analysis of phyla level microorganisms shows that the main phyla are denitrification related ones such as Proteobacteria,Chloroflexi and Bacteroidetes,among which the relative abundance of Proteobacteria is relatively large.Analysis at the microorganism level of the partial nitrification and denitrification system showed that the relative abundance of AOB bacteria in the SBR pool inoculation sludge increased from 0.27%to 2.2%on 190 day,and the proportion of NOB bacteria decreased from 0.2%in the inoculation sludge to less than 0.01%on 190 day,and the NOB bacteria were basically washed out.