Landfill leachates with different ages(mature leachate,11 years;semi-mature leachate,5 years;fresh leachate,under operation) were collected from Laogang Refuse Landfill,Shanghai to characterize the colloid size distri...Landfill leachates with different ages(mature leachate,11 years;semi-mature leachate,5 years;fresh leachate,under operation) were collected from Laogang Refuse Landfill,Shanghai to characterize the colloid size distribution and variations of leachate.These leachates were separated using micro-filtration and ultra-filtration into specific size fractions,i.e.,suspended particles(SP)(>1.2μm) ,coarse colloids(CC)(1.2-0.45μm) ,fine colloids(FC)(0.45μm,5 kDa/1 kDa molecular weight(MW) ) ,and dissolved organic matters(DM,<5 kDa/1 kDa MW) .The specific colloids in each size fraction were quantified and characterized through chemical oxygen demands(COD) ,total solid(TS) ,pH,NH4+-N,total organic carbon(TOC) and fixed solid(FS) .It was found that COD,NH4+-N and TS in leachate decreased significantly over ages,while pH increased.The dissolved fractions(<5 kDa/1 kDa) dominated(over 50%) in three leachates in terms of COD,and the organic matter content in dissolved fraction of leachates decreased and the inorganic matter increased as the disposal time extended,with the TOC/COD ratio 30%-7%.Dissolved fractions decreased from 82%to 40%in terms of TOC as the disposal time extended,suggested that the organic matter remained in leachate would form into middle molecular weight substances during the degradation process.展开更多
Population development of key groups of anaerobic and aerobic bacteria involved in municipal refuse decomposition under laboratory landfill bioreactors with and without leachate recycle and inoculation was measured si...Population development of key groups of anaerobic and aerobic bacteria involved in municipal refuse decomposition under laboratory landfill bioreactors with and without leachate recycle and inoculation was measured since modeling municipal refuse was landfilled in bioreactors for about 210 days. Hydrolytic fermentative bacteria (HFB), hydrogen producing acetogenic bacteria (HPAB), methane producing bacteria (MPB), sulfate reducing bacteria (SRB), anaerobic and aerobic cellulolytic bacteria and denitrabacteria were enumerated by the most probable number technique. The results showed that the dominant microorganism groups were the methanogenic bacteria including hydrolytic fermentative, hydrogen producing acetogenic and methane producing bacteria. They were present in fresh refuse but at low values and positively affected by leachate recycle and refuse inoculation. The amounts of HFB or HPAB in digesters D4 and D5 operated with inoculation and leachate recycle reached their maximum values of 10 10 -10 12 cells/g dry refuse for HFB or 10 5-10 6 cells/g dry refuse for HPAB on day 60, in digester D3 operated with leachate recycle on day 120 for HFB (10\+9 cells/g dry refuse) or on day 90 for HPAB (10\+5 cells/g dry refuse), and in digesters D1 and D2 on day 210 for HFB (10 9 cells/g dry refuse) or on day 90 for HPAB (10 4-10 6 cells/g dry refuse). The population of methane producing bacteria in digesters D4 and D5 sharply increased on days 60 and 90 respectively, however in digesters D1, D2 and D3 on day 120. Leachate recycle and inoculation changed the cellulolytic microorganisms composition of refuse ecosystem, the higher amounts of anaerobic cellulolytic bacteria were measured in digesters D4 and D5 (10 7 cells/g dry refuse), followed by digesters D3 (10 6 cells/g dry refuse), D2 or D1(10 4 cells/g dry refuse). However, the amounts of aerobic cellulolytic bacteria were much lower than that of anaerobic cellulolytic bacteria. And it was higher in digester D3 than those in digesters D1, D2, D4 and D5 The amounts of SRB and denitrabacteria were also higher in digester D5 than those in digesters D1, D2, D3 and D4 Refuse decomposition could be accelerated by leachate recycle and inoculation in the view of microorganism development.展开更多
A field-scale aged refuse(AR) biofilter constructed in Shanghai Refuse Landfill,containing about 7000 m3 aged refuse inside,was evaluated for its performance in the treatment of landfill leachate. This AR biofilter ca...A field-scale aged refuse(AR) biofilter constructed in Shanghai Refuse Landfill,containing about 7000 m3 aged refuse inside,was evaluated for its performance in the treatment of landfill leachate. This AR biofilter can be divided into three stages and can manage 50 m3 landfill leachate per day. The physical,chemical,and biological characteristics of AR were analyzed for evaluating the AR biofilter as leachate treatment host. The results revealed that over 87.8%-96.2% of COD and 96.9%-99.4% of ammonia nitrogen were removed by the three-stage AR biofilter when the influent leachate COD and ammonia nitrogen concentration were in the range 5478-10842 mg/L and 811-1582 mg/L,respectively. The final effiuent was inodorous and pale yellow with COD and ammonia nitrogen below 267-1020 mg/L and 6-45 mg/L,respectively. The three-stage AR biofilter had effcient nitrification but relative poor denitrification capacity with a total nitrogen(TN) removal of 58%-73%. The external temperature of AR biofilter did not influence the total ammonia nitrogen removal significantly. It was concluded that the scale-up AR biofilter can work very well and can be a promising technology for the treatment of landfill leachate.展开更多
Population growth combined with the rising standard of living of people around the world is the reason for the ever-increasing production of waste which management is costing states a lot of money for its disposal. Am...Population growth combined with the rising standard of living of people around the world is the reason for the ever-increasing production of waste which management is costing states a lot of money for its disposal. Among available waste treatment techniques, landfill is one of the most promoted waste management techniques with the emergence of the bioreactor concept. However, the control of biodegradation parameters in order to accelerate waste stabilization is an important issue. For environmental and economic reasons, the technique of leachate recirculation by injection into the waste is increasingly used to improve the degradation of landfilled waste. The injection of leachate is possible using vertical boreholes, horizontal pipes, infiltration ponds or a combination of these. Indeed, moisture is the main factor in waste degradation and biogas production. The migration of leachate to the bottom of the landfill creates low moisture in the upper areas of the landfill reducing the growth of microbial populations. This results in low or no biogas production. The main objective of the present work is to develop a numerical model of leachate recirculation by injection into the waste to rewet the waste and restart biological activity. The analysis of the results shows that the diffusion of the wet front increases with time and depth. The lateral widening of the wet front is slow in relation to the progression of the wet front towards the bottom of the waste cell. This indicates the predominance of gravity effects over diffusion phenomena. The results reveal that the distributed re-injection is the best mode of leachate recirculation because the moisture distribution on the whole waste mass is totally satisfactory and the biogas generation is more important. Leachate recirculation campaigns should be done periodically to rewet the waste, boost microbial activity and hope for a quicker stabilization of the landfill.展开更多
Activity development of key groups of enzymes involved in municipal refuse decomposition was measured in laboratory landfill bioreactors with and without leachate recycling and inoculation for about 210 days. The resu...Activity development of key groups of enzymes involved in municipal refuse decomposition was measured in laboratory landfill bioreactors with and without leachate recycling and inoculation for about 210 days. The results showed that the enzymes (amylase, protease, cellulase, lipase and pectinase) were present in fresh refuse but at low values and positively affected by leachate recycling and refuse inoculation. The total average of cellulase activity in digesters D3 operated with leachate recycling but no inoculation, D4 and D5 operated with leachate recycling and inoculation was much higher than that in digesters D1 and D2 without leachate recycling and inoculation by 88%—127%, 117%—162% and 64%—98%. The total average of protease activity was higher in digester D4 than that in digesters D1, D2, D3 and D5 by 63%, 39%, 24% and 24%, respectively, and the positive effect of leachate recycling and inoculation on protease activity of landfilled refuse mainly was at the first two months. The total average of amylase activity was higher in digesters D3, D4 and D5 than that in digesters D1 and D2 by 83%—132%, 96%—148% and 81%—129%. During the early phase of incubation, the stimulatory effect of inoculation on lipase activity was measured, but refuse moisture was the main factor affecting lipase activity of landfilled refuse. The inoculation, initial and continuous inoculation of microorganisms existing in leachate, was the mainly stimulatory factor affecting pectinase activity of landfilled refuse.展开更多
Refuse in landfills becomes stabilized as organic matter in refuse degrades and soluble inorganic substances dissolve during their long term stabilization process. In this paper, this process is also referred to as mi...Refuse in landfills becomes stabilized as organic matter in refuse degrades and soluble inorganic substances dissolve during their long term stabilization process. In this paper, this process is also referred to as mineralization process and the resultant stabilized refuse referred to as aged refuse. Aged refuse contains a wide spectrum and huge quantity of microorganisms with strong decomposition capability for refractory organic matter present in some wastewater such as leachate. In this study, aged refuse excavated from 2 to 10 years old closed landfill compartments in Shanghai Refuse Landfill is characterized in terms of particulate distribution by screening, total nitrogen, total phosphorus, biodegradable matter. The approaches for redevelopment of both land and aged refuse in the stabilized landfills are proposed.展开更多
An UASB+Anoxic/Oxic(A/O)system was introduced to treat a mature landfill leachate with low carbon-to-nitrogen ratio andhigh ammonia concentration.To make the best use of the biodegradable COD in the leachate,the denit...An UASB+Anoxic/Oxic(A/O)system was introduced to treat a mature landfill leachate with low carbon-to-nitrogen ratio andhigh ammonia concentration.To make the best use of the biodegradable COD in the leachate,the denitrification of Nox--N in therecirculation effuent from the clarifier was carried out in the UASB.The results showed that most biodegradable organic matters wereremoved by the denitrification in the UASB.The NH4+-N loading rate(ALR)of A/O reactor and operational temperature was 0.28-0.60 kg NH4+-N/(m3·d)and 17-29°C during experimental period,respectively.The short-cut nitrification with nitrite accumulationeffciency of 90%-99%was stabilized during the whole experiment.The NH4+-N removal effciency varied between 90%and 100%.When ALR was less than 0.45 kg NH4+-N/(m3·d),the NH4+-N removal effciency was more than 98%.With the influent NH4+-Nof 1200-1800 mg/L,the effuent NH4+-N was less than 15 mg/L.The shortcut nitrification and denitrification can save 40%carbonsource,with a highly effcient denitrification taking place in the UASB.When the ratio of the feed COD to feed NH4+-N was only 2-3,the total inorganic nitrogen(TIN)removal effciency attained 67%-80%.Besides,the sludge samples from A/O reactor were analyzedusing FISH.The FISH analysis revealed that ammonia oxidation bacteria(AOB)accounted for 4%of the total eubacterial population,whereas nitrite oxidation bacteria(NOB)accounted only for 0.2%of the total eubacterial population.展开更多
A combined process consisting of a short-cut nitrification (SN) reactor and an anaerobic ammonium oxidation upflow anaerobic sludge bed (ANAMMOX) reactor was developed to treat the diluted effluent from an upflow anae...A combined process consisting of a short-cut nitrification (SN) reactor and an anaerobic ammonium oxidation upflow anaerobic sludge bed (ANAMMOX) reactor was developed to treat the diluted effluent from an upflow anaerobic sludge bed (UASB) reactor treating high ammonium municipal landfill leachate.The SN process was performed in an aerated upflow sludge bed (AUSB) reactor (working volume 3.05 L),treating about 50% of the diluted raw wastewater.The ammonium removal efficiency and the ratio of NO 2 N to NOx-N in the effluent were both higher than 80%,at a maximum nitrogen loading rate of 1.47 kg/(m 3 ·day).The ANAMMOX process was performed in an UASB reactor (working volume 8.5 L),using the mix of SN reactor effluent and diluted raw wastewater at a ratio of 1:1.The ammonium and nitrite removal efficiency reached over 93% and 95%,respectively,after 70-day continuous operation,at a maximum total nitrogen loading rate of 0.91 kg/(m 3 ·day),suggesting a successful operation of the combined process.The average nitrogen loading rate of the combined system was 0.56 kg/(m 3 ·day),with an average total inorganic nitrogen removal efficiency 87%.The nitrogen in the effluent was mostly nitrate.The results provided important evidence for the possibility of applying SN-ANAMMOX after UASB reactor to treat municipal landfill leachate.展开更多
A comprehensive assessment of heavy metals and organic content was performed for leachates produced from a number of old and new landfills in Jordanover 9 month in efforts to set a framework for treatment regulations....A comprehensive assessment of heavy metals and organic content was performed for leachates produced from a number of old and new landfills in Jordanover 9 month in efforts to set a framework for treatment regulations. All leachates were basic (pH = 7 - 9) and have high electric conductivity and high organic contents (COD = 3000 - 500,000 mg/L, TOC= 500 - 21,000 mg/L). The organic content was inversely proportional to the age of landfill. Heavy metals analysis showed no significant threat of Co, Zn, Pb and Al in any site. Meanwhile, the concentrations of Cr, Mn, Ni, Cd and As were high, exceeding local and international standard limits. Typical physical, chemical and biological treatments can be employed to upgrade the leachates of the active Ghabawi and Akaider sites. Whereas for the high organic strength of Russeifeh, an adsorption treatment by activated carbon is recommended.展开更多
A two-stage upflow anaerobic sludge blanket(UASB) and sequencing batch reactor(SBR) system was introduced to treat landfill leachate for advanced removal of COD and nitrogen at low temperature.In order to improve the ...A two-stage upflow anaerobic sludge blanket(UASB) and sequencing batch reactor(SBR) system was introduced to treat landfill leachate for advanced removal of COD and nitrogen at low temperature.In order to improve the total nitrogen(TN) removal efficiency and to reduce the COD requirement for denitrification,the raw leachate with recycled SBR nitrification supernatant was pumped into the first-stage UASB(UASB1) to achieve simultaneous denitrification and methanogenesis.The results showed that UASB1 played an important role in COD removal and UASB2 and SBR further enhanced the nutrient removal efficiency.When the organic loading rates of UASB1,UASB2 and SBR were 11.95,1.63 and 1.29 kg COD/(m3·day),respectively,the total COD removal efficiency of the whole system reached 96.7%.The SBR acted as the real undertaker for NH4+-N removal due to aerobic nitrification.The system obtained about 99.7% of NH4+-N removal efficiency at relatively low temperature(14.9-10.9°C).More than 98.3% TN was removed through complete denitrification in UASB1 and SBR.In addition,temperature had a significant effiect on the rates of nitrification and denitrification rather than the removal of TN and NH4+-N once the complete nitrification and denitrification were achieved.展开更多
Organic micropollutants,with high toxicity and environmental concern,are present in the landfill leachate at much lower levels than total organic constituents (chemical oxygen demand (COD),biochemical oxygen demand (B...Organic micropollutants,with high toxicity and environmental concern,are present in the landfill leachate at much lower levels than total organic constituents (chemical oxygen demand (COD),biochemical oxygen demand (BOD),or total organic carbon (TOC)),and few has been known for their behaviors in different treatment processes.In this study,occurrence and removal of 17 organochlorine pesticides (OCPs),16 polycyclic aromatic hydrocarbons (PAHs),and technical 4-nonylphenol (4-NP) in landfill leachate in a combined anaerobic-membrane bioreactor (MBR) were investigated.Chemical analyses were performed in leachates sampled from different treatment processes,using solid-phase extraction and gas chromatography with electron capture detector and mass spectrometry.Concentrations of OCPs,PAHs,and 4-NP in the raw leachate were detected within the range from ND (not detected) to 595.2 ng/L,which were as low as only 10-7-10-5 percentage of TOC (at the concentration of 2,962 mg/L).The removal of 4-NP was mainly established in the MBR process,in agreement with removals of COD,BOD,and TOC.However,the removals of OCPs and PAHs were different,mainly achieved in the anaerobic process.High removal effciencies of both total organic constituents and organic micropollutants could be achieved by the combined anaerobic-MBR technology.The removal effciencies of total organic constituents were in the order of BOD (99%) > COD (89%) > TOC (87%),whereas the removal effciencies of investigated organic micropollutants were as follows: OCPs (94%) > 4-NP (77%) > PAHs (59%).展开更多
An experimental bio-column composed of aged refuse was installed around the exhaust pipe as a new way to mitigate methane in refuse landfill.One of the objectives of this work was to assess the effect of aged refuse t...An experimental bio-column composed of aged refuse was installed around the exhaust pipe as a new way to mitigate methane in refuse landfill.One of the objectives of this work was to assess the effect of aged refuse thickness in bio-column on reducing CH 4 emissions.Over the study period,methane oxidation was observed at various thicknesses,5 cm (small size),10 cm (middle size) and 15 cm (large size),representing one to three times of pipeline diameters.The middle and large size both showed over 90% methane conversion,and the highest methane conversion rate of above 95% occurred in the middle-size column cell.Michaelis-Menten equation addressed the methanotrophs diffusion in different layers of the bio-columns.Maximum methanotrophic activity (V max) measured at the three thicknesses ranged from 6.4 × 10 3 to 15.6 × 10 3 units,and the half-saturation value (K M) ranged from 0.85% to 1.67%.Both the highest V max and K M were observed at the middle-size of the bio-column,as well as the largest methanotrophs population,suggesting a significant efficiency of methane mitigation happened in the optimum zone with greatest affinity and methanotrophic bacteria activities.Therefore,bio-column is a potential style for methane abatement in landfill,and the aged refuse both naturally formed and artificially placed in the column plays a critical role in CH 4 emission.展开更多
Excessive leachate levels in landfills can be a major triggering mechanism for translational failure. The scope of this paper is to present the development of the calculation methods for limit equilibrium analysis of ...Excessive leachate levels in landfills can be a major triggering mechanism for translational failure. The scope of this paper is to present the development of the calculation methods for limit equilibrium analysis of translational failure of landfills and the effects of parametric variation on the factor of safety (FS) of landfills under different leachate buildup conditions. During the development of the calculation methods, 4 leachate buildup conditions are considered. The FS for an interface with high friction angle and low apparent cohesion generally drops much more quickly when leachate levels are increased than that for an interface under inverse conditions. The critical interface of a multilayer liner system with the lowest FS for the entire waste mass can shift from one to another with changes in the leachate levels. The different interfaces of a multilayer liner will have different FS-values under different leachate buildup conditions.展开更多
This paper presents a study on the biotic/abiotic conditions of the S?o Giácomo sanitary landfill, located near the city of Caxias do Sul, Brazil, through statistical analysis of fourteen physic-chemical data set...This paper presents a study on the biotic/abiotic conditions of the S?o Giácomo sanitary landfill, located near the city of Caxias do Sul, Brazil, through statistical analysis of fourteen physic-chemical data sets for the leachate, produced in the garbage dump site over a long period of years. Different chemometric methods are used in the statistical analysis. For example, the correlations between the variables, related to the degraded organic matter and biological activity, are determined by means of multivariate methods. The results highlight that BOD, COD, VTS, FTS and TS give information on the anaerobic degradation of the organic matter contained in the cells, and suggest that the greater the contribution of the variables with positive weights in PC1 the greater the level of organic matter degradation. The variables TN, Amon Nit. and alkalinity are related to the biological activity and determine the potency of the variables in relation to time. The greater the contribution of the variables related to organic degradation the greater the values in PC2 and the lesser the potency of these variables, whose influence is greater in the second stage of anaerobic degradation. The variables of PC2 is important plans of the contamination of the leached in the bodies hídrics.展开更多
The landfill of municipal solid waste(MSW) could be regarded as denitrification reactor and involved in ammonia nitrogen biological removal process. In this research, the process was applied to municipal solid waste c...The landfill of municipal solid waste(MSW) could be regarded as denitrification reactor and involved in ammonia nitrogen biological removal process. In this research, the process was applied to municipal solid waste collected in Shanghai, China, which was characterized by high food waste content. The NH + 4 removal efficiency in the system of SBR nitrifying reactor followed by fresh and matured landfilled waste layer in series was studied. In the nitrifying reactor, above 90% of NH + 4 in leachate was oxidized to NO - 2 and NO - 3. Then high concentrated NO - 2 and NO - 3 were removed in the way of denitrification process in fresh landfilled waste layer. At the same time, degradation of fresh landfilled waste was accelerated. Up to the day 120, 136.5 gC/(kg dry waste) and 17.9 gN/(kg dry waste) were converted from waste layer. It accounted for 50.15% and 86.89% of the total carbon and nitrogen content of preliminary fresh waste, which was 4.42 times and 5.17 times higher than that of reference column respectively. After filtering through matured landfilled waste, BOD 5 concentration in leachate dropped to below 100 mg/L, which would not affect following nitrification adversely. Because the matured landfilled waste acted as a well methanogenic reactor, 23% of carbon produced accumulatively from fresh landfilled waste degradation was converted into CH 4.展开更多
基金supported by the State Key Laboratory of Pollution Control and Resource Reuse Foundation(No.PCRRF09008)the Key Project of Science and Technology Commission of Shanghai Municipality (No.08Dz1202800)
文摘Landfill leachates with different ages(mature leachate,11 years;semi-mature leachate,5 years;fresh leachate,under operation) were collected from Laogang Refuse Landfill,Shanghai to characterize the colloid size distribution and variations of leachate.These leachates were separated using micro-filtration and ultra-filtration into specific size fractions,i.e.,suspended particles(SP)(>1.2μm) ,coarse colloids(CC)(1.2-0.45μm) ,fine colloids(FC)(0.45μm,5 kDa/1 kDa molecular weight(MW) ) ,and dissolved organic matters(DM,<5 kDa/1 kDa MW) .The specific colloids in each size fraction were quantified and characterized through chemical oxygen demands(COD) ,total solid(TS) ,pH,NH4+-N,total organic carbon(TOC) and fixed solid(FS) .It was found that COD,NH4+-N and TS in leachate decreased significantly over ages,while pH increased.The dissolved fractions(<5 kDa/1 kDa) dominated(over 50%) in three leachates in terms of COD,and the organic matter content in dissolved fraction of leachates decreased and the inorganic matter increased as the disposal time extended,with the TOC/COD ratio 30%-7%.Dissolved fractions decreased from 82%to 40%in terms of TOC as the disposal time extended,suggested that the organic matter remained in leachate would form into middle molecular weight substances during the degradation process.
基金TheNationalNaturalScienceFoundationofChina (No .5 980 80 12 )andZhejiangProvince (No .5 9912 7)
文摘Population development of key groups of anaerobic and aerobic bacteria involved in municipal refuse decomposition under laboratory landfill bioreactors with and without leachate recycle and inoculation was measured since modeling municipal refuse was landfilled in bioreactors for about 210 days. Hydrolytic fermentative bacteria (HFB), hydrogen producing acetogenic bacteria (HPAB), methane producing bacteria (MPB), sulfate reducing bacteria (SRB), anaerobic and aerobic cellulolytic bacteria and denitrabacteria were enumerated by the most probable number technique. The results showed that the dominant microorganism groups were the methanogenic bacteria including hydrolytic fermentative, hydrogen producing acetogenic and methane producing bacteria. They were present in fresh refuse but at low values and positively affected by leachate recycle and refuse inoculation. The amounts of HFB or HPAB in digesters D4 and D5 operated with inoculation and leachate recycle reached their maximum values of 10 10 -10 12 cells/g dry refuse for HFB or 10 5-10 6 cells/g dry refuse for HPAB on day 60, in digester D3 operated with leachate recycle on day 120 for HFB (10\+9 cells/g dry refuse) or on day 90 for HPAB (10\+5 cells/g dry refuse), and in digesters D1 and D2 on day 210 for HFB (10 9 cells/g dry refuse) or on day 90 for HPAB (10 4-10 6 cells/g dry refuse). The population of methane producing bacteria in digesters D4 and D5 sharply increased on days 60 and 90 respectively, however in digesters D1, D2 and D3 on day 120. Leachate recycle and inoculation changed the cellulolytic microorganisms composition of refuse ecosystem, the higher amounts of anaerobic cellulolytic bacteria were measured in digesters D4 and D5 (10 7 cells/g dry refuse), followed by digesters D3 (10 6 cells/g dry refuse), D2 or D1(10 4 cells/g dry refuse). However, the amounts of aerobic cellulolytic bacteria were much lower than that of anaerobic cellulolytic bacteria. And it was higher in digester D3 than those in digesters D1, D2, D4 and D5 The amounts of SRB and denitrabacteria were also higher in digester D5 than those in digesters D1, D2, D3 and D4 Refuse decomposition could be accelerated by leachate recycle and inoculation in the view of microorganism development.
基金supported by the Ministry of Education of China (No. 305005)the Science and Technology Commission of Shanghai Municipality (No. 05DZ12003).
文摘A field-scale aged refuse(AR) biofilter constructed in Shanghai Refuse Landfill,containing about 7000 m3 aged refuse inside,was evaluated for its performance in the treatment of landfill leachate. This AR biofilter can be divided into three stages and can manage 50 m3 landfill leachate per day. The physical,chemical,and biological characteristics of AR were analyzed for evaluating the AR biofilter as leachate treatment host. The results revealed that over 87.8%-96.2% of COD and 96.9%-99.4% of ammonia nitrogen were removed by the three-stage AR biofilter when the influent leachate COD and ammonia nitrogen concentration were in the range 5478-10842 mg/L and 811-1582 mg/L,respectively. The final effiuent was inodorous and pale yellow with COD and ammonia nitrogen below 267-1020 mg/L and 6-45 mg/L,respectively. The three-stage AR biofilter had effcient nitrification but relative poor denitrification capacity with a total nitrogen(TN) removal of 58%-73%. The external temperature of AR biofilter did not influence the total ammonia nitrogen removal significantly. It was concluded that the scale-up AR biofilter can work very well and can be a promising technology for the treatment of landfill leachate.
文摘Population growth combined with the rising standard of living of people around the world is the reason for the ever-increasing production of waste which management is costing states a lot of money for its disposal. Among available waste treatment techniques, landfill is one of the most promoted waste management techniques with the emergence of the bioreactor concept. However, the control of biodegradation parameters in order to accelerate waste stabilization is an important issue. For environmental and economic reasons, the technique of leachate recirculation by injection into the waste is increasingly used to improve the degradation of landfilled waste. The injection of leachate is possible using vertical boreholes, horizontal pipes, infiltration ponds or a combination of these. Indeed, moisture is the main factor in waste degradation and biogas production. The migration of leachate to the bottom of the landfill creates low moisture in the upper areas of the landfill reducing the growth of microbial populations. This results in low or no biogas production. The main objective of the present work is to develop a numerical model of leachate recirculation by injection into the waste to rewet the waste and restart biological activity. The analysis of the results shows that the diffusion of the wet front increases with time and depth. The lateral widening of the wet front is slow in relation to the progression of the wet front towards the bottom of the waste cell. This indicates the predominance of gravity effects over diffusion phenomena. The results reveal that the distributed re-injection is the best mode of leachate recirculation because the moisture distribution on the whole waste mass is totally satisfactory and the biogas generation is more important. Leachate recirculation campaigns should be done periodically to rewet the waste, boost microbial activity and hope for a quicker stabilization of the landfill.
文摘Activity development of key groups of enzymes involved in municipal refuse decomposition was measured in laboratory landfill bioreactors with and without leachate recycling and inoculation for about 210 days. The results showed that the enzymes (amylase, protease, cellulase, lipase and pectinase) were present in fresh refuse but at low values and positively affected by leachate recycling and refuse inoculation. The total average of cellulase activity in digesters D3 operated with leachate recycling but no inoculation, D4 and D5 operated with leachate recycling and inoculation was much higher than that in digesters D1 and D2 without leachate recycling and inoculation by 88%—127%, 117%—162% and 64%—98%. The total average of protease activity was higher in digester D4 than that in digesters D1, D2, D3 and D5 by 63%, 39%, 24% and 24%, respectively, and the positive effect of leachate recycling and inoculation on protease activity of landfilled refuse mainly was at the first two months. The total average of amylase activity was higher in digesters D3, D4 and D5 than that in digesters D1 and D2 by 83%—132%, 96%—148% and 81%—129%. During the early phase of incubation, the stimulatory effect of inoculation on lipase activity was measured, but refuse moisture was the main factor affecting lipase activity of landfilled refuse. The inoculation, initial and continuous inoculation of microorganisms existing in leachate, was the mainly stimulatory factor affecting pectinase activity of landfilled refuse.
基金TheNationalNaturalScienceFoundationofChina (No .2 97770 19)theExcellentYouthFoundationofChinaEducationMinistry
文摘Refuse in landfills becomes stabilized as organic matter in refuse degrades and soluble inorganic substances dissolve during their long term stabilization process. In this paper, this process is also referred to as mineralization process and the resultant stabilized refuse referred to as aged refuse. Aged refuse contains a wide spectrum and huge quantity of microorganisms with strong decomposition capability for refractory organic matter present in some wastewater such as leachate. In this study, aged refuse excavated from 2 to 10 years old closed landfill compartments in Shanghai Refuse Landfill is characterized in terms of particulate distribution by screening, total nitrogen, total phosphorus, biodegradable matter. The approaches for redevelopment of both land and aged refuse in the stabilized landfills are proposed.
基金Project supported by the National Natural Science Foundation of China (No. 50238050)the Hi-Tech Research and Development Program (863) of China (No. 2002AA649250).
基金Project supported by the National Natural Science Foundation of China(No.50521140075)the Funding Project for Academic Human Resource Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality(PHR(IHLB))the international cooperationproject financed by Beijing Municipal Science and Technology Commission.
文摘An UASB+Anoxic/Oxic(A/O)system was introduced to treat a mature landfill leachate with low carbon-to-nitrogen ratio andhigh ammonia concentration.To make the best use of the biodegradable COD in the leachate,the denitrification of Nox--N in therecirculation effuent from the clarifier was carried out in the UASB.The results showed that most biodegradable organic matters wereremoved by the denitrification in the UASB.The NH4+-N loading rate(ALR)of A/O reactor and operational temperature was 0.28-0.60 kg NH4+-N/(m3·d)and 17-29°C during experimental period,respectively.The short-cut nitrification with nitrite accumulationeffciency of 90%-99%was stabilized during the whole experiment.The NH4+-N removal effciency varied between 90%and 100%.When ALR was less than 0.45 kg NH4+-N/(m3·d),the NH4+-N removal effciency was more than 98%.With the influent NH4+-Nof 1200-1800 mg/L,the effuent NH4+-N was less than 15 mg/L.The shortcut nitrification and denitrification can save 40%carbonsource,with a highly effcient denitrification taking place in the UASB.When the ratio of the feed COD to feed NH4+-N was only 2-3,the total inorganic nitrogen(TIN)removal effciency attained 67%-80%.Besides,the sludge samples from A/O reactor were analyzedusing FISH.The FISH analysis revealed that ammonia oxidation bacteria(AOB)accounted for 4%of the total eubacterial population,whereas nitrite oxidation bacteria(NOB)accounted only for 0.2%of the total eubacterial population.
基金supported by the Special Fundof State Key Joint Laboratory of Environment Simulation and Pollution Control,China (No. 08Y03ESPCT)the Key Projects in the National Science & Technology Pillar Program in the Eleventh Five-Year Plan Period of China(No. 2006BACl9B01)
文摘A combined process consisting of a short-cut nitrification (SN) reactor and an anaerobic ammonium oxidation upflow anaerobic sludge bed (ANAMMOX) reactor was developed to treat the diluted effluent from an upflow anaerobic sludge bed (UASB) reactor treating high ammonium municipal landfill leachate.The SN process was performed in an aerated upflow sludge bed (AUSB) reactor (working volume 3.05 L),treating about 50% of the diluted raw wastewater.The ammonium removal efficiency and the ratio of NO 2 N to NOx-N in the effluent were both higher than 80%,at a maximum nitrogen loading rate of 1.47 kg/(m 3 ·day).The ANAMMOX process was performed in an UASB reactor (working volume 8.5 L),using the mix of SN reactor effluent and diluted raw wastewater at a ratio of 1:1.The ammonium and nitrite removal efficiency reached over 93% and 95%,respectively,after 70-day continuous operation,at a maximum total nitrogen loading rate of 0.91 kg/(m 3 ·day),suggesting a successful operation of the combined process.The average nitrogen loading rate of the combined system was 0.56 kg/(m 3 ·day),with an average total inorganic nitrogen removal efficiency 87%.The nitrogen in the effluent was mostly nitrate.The results provided important evidence for the possibility of applying SN-ANAMMOX after UASB reactor to treat municipal landfill leachate.
基金Supported by the National Natural Science Foundation of China （50978003）, the Natural Science Foundation of Beijing （8091001）, the Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality （PHR 20090502）, and the State Key Laboratory of Urban Water Resource and Environment （HIT） （QAK200802）.
文摘A comprehensive assessment of heavy metals and organic content was performed for leachates produced from a number of old and new landfills in Jordanover 9 month in efforts to set a framework for treatment regulations. All leachates were basic (pH = 7 - 9) and have high electric conductivity and high organic contents (COD = 3000 - 500,000 mg/L, TOC= 500 - 21,000 mg/L). The organic content was inversely proportional to the age of landfill. Heavy metals analysis showed no significant threat of Co, Zn, Pb and Al in any site. Meanwhile, the concentrations of Cr, Mn, Ni, Cd and As were high, exceeding local and international standard limits. Typical physical, chemical and biological treatments can be employed to upgrade the leachates of the active Ghabawi and Akaider sites. Whereas for the high organic strength of Russeifeh, an adsorption treatment by activated carbon is recommended.
基金supported by the National Natural Science Foundation of China (No.50978003)the Beijing Natural Science Foundation (No.8091001)+1 种基金the Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality (No.PHR20090502)the State Key Laboratory of Urban Water Resource and Environment (No.QAK200802)
文摘A two-stage upflow anaerobic sludge blanket(UASB) and sequencing batch reactor(SBR) system was introduced to treat landfill leachate for advanced removal of COD and nitrogen at low temperature.In order to improve the total nitrogen(TN) removal efficiency and to reduce the COD requirement for denitrification,the raw leachate with recycled SBR nitrification supernatant was pumped into the first-stage UASB(UASB1) to achieve simultaneous denitrification and methanogenesis.The results showed that UASB1 played an important role in COD removal and UASB2 and SBR further enhanced the nutrient removal efficiency.When the organic loading rates of UASB1,UASB2 and SBR were 11.95,1.63 and 1.29 kg COD/(m3·day),respectively,the total COD removal efficiency of the whole system reached 96.7%.The SBR acted as the real undertaker for NH4+-N removal due to aerobic nitrification.The system obtained about 99.7% of NH4+-N removal efficiency at relatively low temperature(14.9-10.9°C).More than 98.3% TN was removed through complete denitrification in UASB1 and SBR.In addition,temperature had a significant effiect on the rates of nitrification and denitrification rather than the removal of TN and NH4+-N once the complete nitrification and denitrification were achieved.
基金the National Natural Science Foundation of China (No.50538090)the National Basic Research Program (973) of China (No.2007CB407301)ST Program of Beijing Municipality (No.D0706007040291-01).
文摘Organic micropollutants,with high toxicity and environmental concern,are present in the landfill leachate at much lower levels than total organic constituents (chemical oxygen demand (COD),biochemical oxygen demand (BOD),or total organic carbon (TOC)),and few has been known for their behaviors in different treatment processes.In this study,occurrence and removal of 17 organochlorine pesticides (OCPs),16 polycyclic aromatic hydrocarbons (PAHs),and technical 4-nonylphenol (4-NP) in landfill leachate in a combined anaerobic-membrane bioreactor (MBR) were investigated.Chemical analyses were performed in leachates sampled from different treatment processes,using solid-phase extraction and gas chromatography with electron capture detector and mass spectrometry.Concentrations of OCPs,PAHs,and 4-NP in the raw leachate were detected within the range from ND (not detected) to 595.2 ng/L,which were as low as only 10-7-10-5 percentage of TOC (at the concentration of 2,962 mg/L).The removal of 4-NP was mainly established in the MBR process,in agreement with removals of COD,BOD,and TOC.However,the removals of OCPs and PAHs were different,mainly achieved in the anaerobic process.High removal effciencies of both total organic constituents and organic micropollutants could be achieved by the combined anaerobic-MBR technology.The removal effciencies of total organic constituents were in the order of BOD (99%) > COD (89%) > TOC (87%),whereas the removal effciencies of investigated organic micropollutants were as follows: OCPs (94%) > 4-NP (77%) > PAHs (59%).
基金supported by the Hi-Tech Research and Development Program (863) of China (No.2007AA06Z349)
文摘An experimental bio-column composed of aged refuse was installed around the exhaust pipe as a new way to mitigate methane in refuse landfill.One of the objectives of this work was to assess the effect of aged refuse thickness in bio-column on reducing CH 4 emissions.Over the study period,methane oxidation was observed at various thicknesses,5 cm (small size),10 cm (middle size) and 15 cm (large size),representing one to three times of pipeline diameters.The middle and large size both showed over 90% methane conversion,and the highest methane conversion rate of above 95% occurred in the middle-size column cell.Michaelis-Menten equation addressed the methanotrophs diffusion in different layers of the bio-columns.Maximum methanotrophic activity (V max) measured at the three thicknesses ranged from 6.4 × 10 3 to 15.6 × 10 3 units,and the half-saturation value (K M) ranged from 0.85% to 1.67%.Both the highest V max and K M were observed at the middle-size of the bio-column,as well as the largest methanotrophs population,suggesting a significant efficiency of methane mitigation happened in the optimum zone with greatest affinity and methanotrophic bacteria activities.Therefore,bio-column is a potential style for methane abatement in landfill,and the aged refuse both naturally formed and artificially placed in the column plays a critical role in CH 4 emission.
文摘Excessive leachate levels in landfills can be a major triggering mechanism for translational failure. The scope of this paper is to present the development of the calculation methods for limit equilibrium analysis of translational failure of landfills and the effects of parametric variation on the factor of safety (FS) of landfills under different leachate buildup conditions. During the development of the calculation methods, 4 leachate buildup conditions are considered. The FS for an interface with high friction angle and low apparent cohesion generally drops much more quickly when leachate levels are increased than that for an interface under inverse conditions. The critical interface of a multilayer liner system with the lowest FS for the entire waste mass can shift from one to another with changes in the leachate levels. The different interfaces of a multilayer liner will have different FS-values under different leachate buildup conditions.
文摘This paper presents a study on the biotic/abiotic conditions of the S?o Giácomo sanitary landfill, located near the city of Caxias do Sul, Brazil, through statistical analysis of fourteen physic-chemical data sets for the leachate, produced in the garbage dump site over a long period of years. Different chemometric methods are used in the statistical analysis. For example, the correlations between the variables, related to the degraded organic matter and biological activity, are determined by means of multivariate methods. The results highlight that BOD, COD, VTS, FTS and TS give information on the anaerobic degradation of the organic matter contained in the cells, and suggest that the greater the contribution of the variables with positive weights in PC1 the greater the level of organic matter degradation. The variables TN, Amon Nit. and alkalinity are related to the biological activity and determine the potency of the variables in relation to time. The greater the contribution of the variables related to organic degradation the greater the values in PC2 and the lesser the potency of these variables, whose influence is greater in the second stage of anaerobic degradation. The variables of PC2 is important plans of the contamination of the leached in the bodies hídrics.
文摘The landfill of municipal solid waste(MSW) could be regarded as denitrification reactor and involved in ammonia nitrogen biological removal process. In this research, the process was applied to municipal solid waste collected in Shanghai, China, which was characterized by high food waste content. The NH + 4 removal efficiency in the system of SBR nitrifying reactor followed by fresh and matured landfilled waste layer in series was studied. In the nitrifying reactor, above 90% of NH + 4 in leachate was oxidized to NO - 2 and NO - 3. Then high concentrated NO - 2 and NO - 3 were removed in the way of denitrification process in fresh landfilled waste layer. At the same time, degradation of fresh landfilled waste was accelerated. Up to the day 120, 136.5 gC/(kg dry waste) and 17.9 gN/(kg dry waste) were converted from waste layer. It accounted for 50.15% and 86.89% of the total carbon and nitrogen content of preliminary fresh waste, which was 4.42 times and 5.17 times higher than that of reference column respectively. After filtering through matured landfilled waste, BOD 5 concentration in leachate dropped to below 100 mg/L, which would not affect following nitrification adversely. Because the matured landfilled waste acted as a well methanogenic reactor, 23% of carbon produced accumulatively from fresh landfilled waste degradation was converted into CH 4.
