| Sanitary landfill of refuse is a kind of commonly used methods of garbagedisposal at home and abroad, but the produced landfill leachate is harmful to theenvironment, removing the high concentration ammonia nitrogen in leachate to meetthe discharge standard is difficult, this experiment mainly studied the productiveapplication of short-cut biological nitrogen removal in the two-stage anaerobic/oxicbiochemical system,and the influence of dissolved oxygen, ammonia nitrogen load,organic load and hydraulic retention time on this process.After about two months of inoculation and domestication, biochemical systemachieves stable full nitrification and denitrification.The ammonia nitrogen removalrate is97.98%in the first contact oxidation tank; the two aerobic pool remove43.31%and18.37%of the total COD respectively, the residual concentration of biodegradableCOD is448.53mg/L, the effluent can meet the discharge standard after treated by thesubsequent Fenton oxidation process;the second-stage anaerobic tank should be addedcarbon with the proportion of COD/NO3--N=4.7, denitrification can remove99.49%ofthe NO3--N, total nitrogen removal efficiency is84.44%.By reducing the dissolved oxygen concentration to1.5mg/L, good shortcutnitrification and denitrification can be achieved in the first contact oxidation tank. Atthis time, the average ammonia nitrogen removal rate of the first contact oxidationtank is94.82%, lower than the rate in period of full nitrification and denitrificationwhich is97.98%, the effluent nitrite nitrogen concentration is306.97mg/L, nitriteaccumulation rate gets an average of74.29%. The effluent COD concentration of thefirst contact oxidation tank is689.33mg/L,30mg/L higher than the period of fullnitrification and denitrification.Effects of various factors on short-cut nitrification and denitrification are:(1)DO concentrations are the main factors affecting shortcut nitrification,when the DO is1.5mg/L, the shortcut nitrification is stable in the first contact oxidation tank,theammonia nitrogen removal rate can be94.53%, nitrite accumulation rate is74.29%,lower DO will reduce ammonia nitrogen removal rate,higher DO will cutdown nitrite accumulation rate;(2) The ammonia nitrogen load has great effect on theammonia nitrogen removal rate,when the influent ammonia concentration is400~500mg/L, ammonia nitrogen removal rate is94.82%in the first aerobic tank, the ammonia nitrogen and total nitrogen of the final effluent can meet the standard onlywhen the influent total nitrogen concentration of the second-stage aerobic tank is lessthan70mg/L;(3) The COD has important implications for maintaining the state andquantity of aerobic microbes and the denitrification in Anaerobic pond, when theinfluent COD concentration is1000~1100mg/L, the operation of this aerobic tank isstable;the second anaerobic pool should be dosed carbon source in the proportion ofC/NOx--N=4.0,thus the total nitrogen removal efficiency is87.46%,it saves15%carbon dosage compared with the full nitrification and denitrification; the operation ofthe second aerobic tank is stable when its influent concentration of COD is600~1000mg/L;(4) The hydraulic retention time(HRT) primarily affects the ammonianitrogen removal rate of the first aerobic tank,when the influent ammoniaconcentration is400~500mg/L, it is more favourable for stable and effective short-cutnitrification and denitrification when HRT is longer than66h, avoid long HRT leadingto the disintegration of biofilm in aerobic pool.High ammonia nitrogen concentration of raw water has great effects onbiochemical systems, large amount of carbon sources are needed for thedenitrification, and the leachate treatment capacity is relatively small, pretreatment byammonia stripping is relatively workable improvement.Finally, with the Monod equation and the conservation of mass, as well as thedefinition of ammonia-oxidizing bacteria’s yield coefficient, the dynamic equations ofthe utilization rate that ammonia nitrogen was used and the growth ofammonia-oxidizing bacteria are solved respectively. |
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