城市生活垃圾晚期渗滤液中氨氮的常温短程去除

Both “two-stage upflow anaerobic sludge blanket (UASB) +anoxic/oxic(A/O)” system and “one stage UASB+A/O” system were successively introduced to treat a leachate containing relatively low concentration of organics and high concentration of ammonia from a mature landfill site.The “two-stage UASB+A/O” system was used firstly.The denitrification of the return effluent was carried out in the first stage UASB (UASB1).The nitrification took place in the A/O reactor.The results showed that most biodegradable organic matter was removed in the UASB1,so “one stage UASB+A/O” system was used in the second phase experiment.The NH+4-N loading rate of A/O reactor and operation temperature were 0.28—0.60 kg NH+4-N·m-3·d-1 and 17—29℃,respectively.The COD removal efficiency and the final effluent COD were 50%—70%,1000—1500 mg·L-1,respectively.Short-cut nitrification with 90%—99% of nitrite accumulation efficiency took place in the system.The NH+4-N removal efficiency varied between 90% and 100%.When NH+4-N loading rate was less than 0.45 kg NH+4-N·m-3·d-1,the NH+4-N removal efficiency was more than 98%,and effluent NH+4-N was below 15 mg·L-1.When the ratio of the feed COD to feed NH+4-N concentrations was 2—3,the total inorganic nitrogen (TIN) removal efficiency was 70%—80%.The sludge samples from A/O reactor were analyzed by using fluoresence in situ hybridization (FISH).The FISH analysis showed that ammonia oxidation bacteria (AOB) were 4% of the eubacteria,meanwhile nitrite oxidation bacteria (NOB) were less than 0.2% of the eubacteria.