Study On Efficacy Of Nitrogen Removal And Microbiological Mechanism In Bioreactor Landfill

Leachate recirculation resulted in the accumulation of organic acid and ammonia nitrogen in bioreactor landfill, and even led to the final leachate ammonia nitrogen concentrations higher than that of conventional landfill, the external treatment of leachate to remove ammonia nitrogen which not only might result additional costs and operational challenges, but also might affect refuse well decomposed. In this paper, landfill was combined with leachate treatment as one system and leachate recirculation landfill system (Ri) was regarded as reference. Based on nitrification and denitrification principle, aerobic, anoxic and anaerobic zones were linked by leachate and one cluster system (R2) composed by nitrification bioreactor, denitrification bioreactor and methanogenic bioreactor was formed. Nitrogen removal efficacy and microbiological mechanism were studied. The main results of this paper were as folio wings:(1) The chemical oxygen demand (CODcr) concentration in R1 decreased from 5200 mg/L to 637.4 mg/L, and the removal of CODcr stabilized about 80%.(2) The removal of CODcr and ammonia nitrogen in R2 was much better than that in R1, furthermore, the stability of R2 was better than that of R1. The ammonia nitrogen concentration of R2 gradually reduced from 58.56 mg/L to zero by the day 127, when the ammonia nitrogen concentration in R1 was still at 100.9 mg/L. And also the CODcr concentration in R2 rapidly dropped to 79.68 mg/L by the day 127, while that in R1 was still at 637.4 mg/L.(3) The removal of total nitrogen of landfill in R2 was better than that of landfill in R1. Although initial total nitrogen of landfill in R2 was more than that in R[(the concentration of total nitrogen in R2 and R1 were 7639 mg TN /g dry refuse,6628 mg TN /g dry refuse, respectively), when the experiment was terminated, the total nitrogen concentration of landfill in R2 and R1 were 479 mg TN/g dry refuse and 396 mg TN/g dry refuse, respectively.(4) The biological environment in R2 was positively influenced the growth andpropagation of denitrifying bacteria. The denitrifying bacteria population in R2 was always 1-3 orders more than that in R1. The denitrifying bacteria population in R2 was up to 4.39 X 10~11 cells/g dry refuse, and by the day 124 was 7.51 X 105 cells/g dry refuse, while the denitrifying bacteria population in R1 was only 9.34 X 109 cells/g dry refuse, and by the day 124 was 8.65 X104 cells/g dry refuse .