Degradation Efficiency Of Two Bacteria For Two Characteristic Organic Matters In Landfill Leachate

Sanitary landfilling is nowadays the most common way to treat municipal solid wastes?MSW?.So the heavily polluted leachates,generated from the landfill,present various organic pollutants which are difficult to be eliminated with the normal wastewater treatment process.The removal of organic materials based on chemical oxygen demand?COD?,biological oxygen demand?BOD?from leachate is the usual prerequisite before discharging the leachates into natural waters.In order to pursue a new way to eliminate the dissolved organic matters in the leachate,we studied the degradation characteristics of two Arthrobacter sp.for diethyl phthalate?DEP?and1-naphthol respectively,one of which is the main organic matter in the leachate,the other is more difficult to be decomposed comparatively.One Arthrobacter sp.for the degradation of 1-naphthol was inoculated in a bio-reacter to treat the landfill leachate collected from Huaihua municipal landfill plant.The main results obtained are as follows:?1?The prime pollutant parameters of leachate are COD and NH₃-N,according to the analysis of the leachate from Huaihua landfill plant,and the biodegradability is low withBOD/COD ratio 0.10-0.18.The heavy metal concentrations in the leachate didn't exceed the discharging standard except for Hg and Pb,which exceeded the discharging standard slightly.Fifty seven organic matters in the leachate were identified by GC-MS,and the primary organics included alcohols,esters and alkanes.The three organics of highest concentration were thexyl alcohol 29.2%,Diethyl phthalate 14.23%,4-chloro-2-ethyl-1,3-propane 11.1%.?2?An Arthrobacter sp.was isolated which can utilize diethyl phthalate as the sole carbon source and was named as lxy-1.The best temperature and pH for lxy-1 to degrade DEP are 25-35?and 7.0-8.0 respectively.The degradation of DEP keep well with first order kinetics epuation at 200mg/L-400 mg/L concentration.The average half-life of degradation of DEP by lxy-1 was 6.56 hour,and about 96.5%of DEP?500mg/L?was degraded within 48 hours.Metal ions Ba,Ca,Fe,Mn and Cu in leachate had impacts on the growth of Arthrobacter sp.lxy-1 and DEP degradation differently with various concentrations.Especially Cu can kill Arthrobacter sp.lxy-1 with0.01mmol/L concentration.Ammonia nitrogen of 840mg/L can restrain Arthrobacter sp.lxy-1.The decomposition intermediates of DEP were identified as mono-ethyl phthalate?MEP?and phthalate acid?PA?by GC-MS ways.The pathway of DEP degradation was:DEP to MEP and then to PA before mineralization.?3?Another Arthrobacter sp.was isolated which can utilize 1-naphthol as the sole carbon source and was named as JY5-1.The best temperature and pH for JY5-1 to degrade 1-naphthol are 25-35?and 7.0-8.0 respectively.The degradation of1-naphthol keep well with first order kinetics epuation at 200mg/L-400 mg/L concentration.The average half-life of degradation of 1-naphthol by JY-1 was 8.34 hour,and about 85.5%of1-naphthol?250mg/L?was degraded within 48 hours.Metal ions Cu can kill Arthrobacter sp.JY5-1 above 0.1mmol/L concentration.Ammonia nitrogen of 560mg/L can restrain the growth of Arthrobacter sp.JY5-1.?4?Substrate extensive-adaptability experiment showed that Arthrobacter sp.JY5-1 could degrade thexyl alcohol,1-naphthol,DEP,4-chloro-2-ethyl-1,3-propane,and 1-chloro-3-ethoxy propane,which were the characteristic organic matters in the leachate.But Arthrobacter sp.lxy-1 could not degrade 1-naphthol.JY5-1 and lxy-1could not survive in the raw landfill leachate,which would kill them.After coagulation pre-treatment,the organics in leachate can be partly degraded by JY5-1 and lxy-1,and JY5-1 showed the better efficiency that reached 66.4%COD removal rate within 48hour.Operation data of the bio-reacter showed that COD removal rate with single bacterium was lower than that inoculated by mixed bacteria of JY5-1 and activated sludge.COD removal rate of leachate pretreated by Fenton oxidation reached 82.3%in the stable operated bio-racter inoculated by mixed bacteria under 48 hour of the hydraulic restrain time.