Advanced Treatment Technology Of Late Landfill Leachate Based On Co-metabolism

Late landfill leachate is an organic wastewater containing a large amount of refractory organics and high concentrations of ammonia nitrogen,and it is difficult to be effectively treated by biological methods.Usually,physico-chemical method is used as pretreatment of biochemical method,or physico-chemical method is used for advanced treatment of biochemical effluent,but the combination processes tend to be costly and subject to secondary pollution.Therefore,many new biological treatment technologies have emerged.Co-metabolism technology can cost-effectively degrade refractory organic matter,but this technology is rarely used to treat refractory organics in late landfill leachate.In this paper,co-metabolism technology is applied to the advanced treatment of landfill leachate.The results show that:?1?Adding starch,glucose and oxalic acid can promote the degradation of refractory organic matter in late landfill leachate.The degradation process of refractory organic matter accords with the first-order reaction kinetics.Among them,oxalic acid is the most effective co-metabolism matrix,and the optimal dosage is 50 mg/L.The addition of co-metabolism substrate effectively promoted the degradation of fulvic acid-like components in late landfill leachate.?2?When no substrate was added,the total COD removal rate of the UASB1+A/O+UASB2 system was 10.32%,and the total ammonia nitrogen removal rate was 52.16%.When oxalic acid was added,the total removal rate of COD in UASB1+A/O+UASB2 system was 24.67%,and the total removal rate of ammonia nitrogen was 63.63%.The COD removal rate of UASB2 reactor increased from 5.95% without substrate to 15.24% after adding oxalic acid,the addition of oxalic acid promoted the removal of refractory organics.Short-cut nitrification can also be achieved and maintained when DO in the aerobic section of A/O reactor is controlled at 1.5⁵.0 mg/L.UASB1+A/O+UASB2 system can remove the refractory components of fulvic acid-like in late landfill leachate,but the degradation effect of humic acid-like components is not obvious.?3?The diversity and abundance of microorganisms in the UASB2 reactor increased after the addition of the oxalic acid substrate.The bacteria associated with degradable organic matter in UASB2 reactor,such as Petrimonas?Macellibacteroides?Proteiniclasticum and Tissierella gradually decreased or even disappeared after adding oxalic acid.After adding oxalic acid,the bacteria related to the degradation of refractory organic matter,such as norank-c-Bacteroidetes-vadinHA17?unclassified-fcoriobacteriaceae? Lentimicrobium?Limnobacter?Clostridium_sensu_stricto₁ become relatively abundant bacteria in UASB2 reactor.The refractory organic matter in late landfill leachate is degraded under the combined action of these bacteria.