Study On High Efficiency Denitrification Of Landfill Leachate Based On Short - Cut Nitrification And Denitrification Process

As people living standard gradually improve and environmental standards areincreasingly strict, the national environmental protection bureau in2008clearlystipulated landfill leachate of ammonia nitrogen and total nitrogen emission standard,since people actively develop new biological denitrification theory and technologyresearch.At present, the most studied new biological denitrification technology includeanaerobic ammonia oxidation, simultaneous nitrification denitrification and shortcutnitrification and denitrification technology. Among them, the new type of shortcutnitrification and denitrification denitrification technology has save carbon source,reducing oxygen, reduce area, decrease the sludge quantity, etc, has been paidattention by researchers.In this paper, we basically researched the low C/N ratio and high concentrationorganic waste landfill leachate for shortcut nitrification and denitrificationdenitrification process, the main research results are as follows：1. In within less than a short residence time(15h)range, Lead denitrification A/Oprocess system COD removal efficiency is78.13%, ammonia nitrogen removalefficiency is91.67%, total nitrogen removal rate is52.67%; O/A process systemCOD removal rate is70.44%, ammonia nitrogen removal rate is81.56%. totalnitrogen removal rate is42.35%. pollutants degradation efficiency is below thanA/O process, It explains that the A/O process denitrification effect is better thanO/A process.2. Low C/N ratio landfill leachate shortcut nitrification and denitrificationdenitrification research results show that：1) Best DO concentration of implementation of shortcut nitrification anddenitrification is0.8-1.0mg/L, best pH range is in8.46-8.68and8.22-8.45inA pool and O pool, and in the best conditions, NO2￣-N concentration can bereached165.3mg/L and200.3mg/L in A pool and O pool, and accumulationrate are52.38%and59.63%respectively.2) when influent COD concentration is from1000mg/L to1350mg/L,⊿COD/⊿TN average value is from1.53to1.98, shortcut nitrification anddenitrification process is realizied. When influent COD concentration isabout1900mg/L,⊿COD/⊿TN average value is around2.85, it promotesthe realization of shortcut nitrification and denitrification, but the trend ofComplete nitrification and denitrification begin to be occurred. It explainsthat increase appropriate organic matter is unhelpful to realize shortcutnitrification and denitrification. 3. The results of high concentration organic waste landfill leachate shortcutnitrification and denitrification denitrification operation show that:1) After system stability, COD, ammonia nitrogen and total nitrogendegradation efficiency is high in EGSB-A/O-MBR process system, the averageremoval rate of effluent COD was96.53%. the average effluent ammonianitrogen removal rate reached95.5%, the average effluent TN removal rateis92.6%.2) Load increase stage, with influent ammonia concentration increasedgradually, nitrite nitrogen accumulation is gradually increasing. After thesystem is stable, the effluent NO2￣-N accumulation rate of aerobic Iandaerobic II are increased to67.9%and70.2%, respectively, It explains thatsystem achieves stable shortcut nitrification.3) When NH+-14-N average concentration is1475.8mg·Lin original leachate,total alkalinity is7000~9500mg·L-1, denitrification produce alkalinity5268.6mg·L-1in anoxic pool, and it accumulates10487mg·L-1alkalinity, thisprovides enough alkalinity for nitrification process and promotes shortcutnitrification.4. Dynamics research results of pollutants degradation in the process system ofanaerobic-denitrification-nitrification show that:1) In the process of aerobic degradation: In certain temperature range, thetemperature effect on ammonia nitrogen removal is not large, the maximumremoval rate rmaxand saturation constant KSare not more than5%, but theremoval rate of COD is strongly influenced by temperature, the biggestremoval rate rmaxincreases by19%, but saturated constant KSreduces by39%.2) In the process of anaerobic degradation: The total of nitrogen removal rateis greatly influenced by temperature, when the temperature is33℃, themaximum removal rate rmaxis higher25%than it is25℃,but saturationconstant KSreduces by10%; The effects of temperature on the COD removalrate is smaller when aerobic, the maximum removal rate rmaxonly increasesby2%, saturation constant KSreduces by7%, inhibition constant increases by39%.3) In the process of anaerobic degradation: When the temperature from25℃increases to33℃, the maximum removal rate rmaxincreases by10%andsaturated constant decreases32%, It explains that appropriatly increasingthe temperature can obviously reduce the inhibition of concentration onCOD removal rate.5. Dynamics research results of pollutant degradation in Nitrification and denitrification process system show that:1) Intermittent flow degradation: In the condition of25℃, COD removal rate ris0.09(mg·L-1)0.2·h-1in the nitrification phase, and the removal rate r is12.5%higher than that of denitrification stage. It explains that nitrificationeffect on COD removal is greater than the denitrification phase on CODremoval; NH+4-N removal rate r is0.08(mg·L-1) h–1in denitrification stage,and it equals the removal rate of nitrification phase. It explains thatdenitrification stage has also certain influence on NH+4-N removal; TNremoval rate r is0.06(mg·L-1) h–1in nitrification phase, and it is higher50%than denitrification stage. It explains that nitrification stage has a largerinfluence on TN removal.2) Continuous flow degradation: In the condition of25℃, Denitrificationphase COD removal rate constant k is0.0679(mg·L-1)-0.2·h-1, it is10.13timesof nitrification phase rate constant, It explains that denitrification stage hada large influence on COD removal rate constant; NH+4-N rate constant k is0.0731(mg·L–1)-0.35·h-1in nitrification stage, the difference withdenitrification phase NH+4-N rate constant k is2%. It explains that two stageshad small influence on NH+4-N removal rate constant k; TN rate constant k is0.0687(mg·L–1)-0.35·h-1in nitrification phase, the difference withdenitrification phase TN rate constant k is only3.6%, It explains that twostages had small influence on TN removal rate constant.6. In the EGSB-A/O-MBR process system, the study results of the bacteriacommunity structure characteristics on anaerobic sludge, anoxic sludge andaerobic sludge show that:1) Anaerobic sludge can achieve more than25kinds of bacterial species,among them, the number of Thauera sp. MZ1T is the largest, at22.6%.Thauera sp species has the function of aromatic organic compoundsdegradation. And it indicates that anaerobic sludge is mainly of the organicmatter degradation bacteria.2) In denitrification sludge, there are more than23kinds of bacterial species,among them, the Thauera sp is the largest number of bacterial species, is upto65%, the important of denitrifying bacteria in the anoxic reactor, whichhas the denitrification ability. It shows that denitrifying bacteria is mainlycomposed in anoxic sludge.3) Nitrification sludge bacterial species can reach21species, among them,the Nitrosospira fungus belongs to the most abundant, at55%, followed byNitrosomonas bacteria genera. The two types of bacteria respectively arenitrosation spirillum group and nitrosation of bacterium, namely ammonia oxidizing bacteria(AOB), which is conductive to the accumulation of nitratenitrogen and shortcut nitrification. At the same time, A lot of Nitrospina alsoexist in aerobic sludge, namely nitrite oxidizing bacteria(NOB).