Leachate sludge,a byproduct of municipal solid waste leachate treated through biochemical processes,is characterized by high water content(761.1%)and significant organic matter content(71.2%).Cement that is commonly u...Leachate sludge,a byproduct of municipal solid waste leachate treated through biochemical processes,is characterized by high water content(761.1%)and significant organic matter content(71.2%).Cement that is commonly used for solidifying leachate sludge has shown limited effectiveness.To address this issue,an alkali-activated ground-granulated blast-furnace slag(GGBS)geopolymer blended with polypropylene fibers was developed to solidify leachate sludge.Moreover,unconfined compressive strength(UCS),immersion,as well as X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and scanning electron microscope(SEM)tests were conducted to investigate the solidification effect and mechanism of the GGBS-based geopolymer and fibers on leachate sludge.The results showed that:the 28-d UCS of the solidified sludge with 20%and 30%GGBS is 0.35 MPa and 1.85 MPa,and decreases to 0.18 MPa and 1.13 MPa,respectively,after soaked in water for 28 d.Notably,the UCS of the solidified sludge with 30%GGBS satisfied the strength requirement of roadbed materials.Polypropylene fibers significantly enhanced the strength,ductility and water stability of the solidified sludge,with an optimal fiber content of 0.3%.Alkali-activated GGBS geopolymer generated three-dimensional,cross-linked geopolymeric gels within the solidified sludge,cementing sludge particles and filling intergranular pores to form a stable cementitious structure,thereby achieving effective solidification.Furthermore,incorporating polypropylene fibers improved the bonding and anchoring effect between fiber and solidified sludge,constrained lateral deformation of the solidified sludge,restricted crack propagation,and enhanced engineering performance of the solidified leachate sludge.展开更多
Rare earth elements(REEs) were extracted from phosphogypsum(PG) using an indirect leaching method that produces CaCO_(3).The carbonation process transforms PG into CaCO_(3),and a potential source of value is the(NH_(4...Rare earth elements(REEs) were extracted from phosphogypsum(PG) using an indirect leaching method that produces CaCO_(3).The carbonation process transforms PG into CaCO_(3),and a potential source of value is the(NH_(4))_(2)SO_(4) fertilizer.The calcium carbonate byproduct is rich in REEs that are originally present in PG.Calcium carbonate,a byproduct of PG carbonation and a rich source of REEs,could dissolve in nitric acid to produce a calcium nitrate leach solution that contains RE nitrate.Subsequently,the most widely used solvent extraction technique can make use of an environmentally benign nitrate ionic liquid.Cyphos IL 101(trihexyl(tetradecyl)phosphonium chloride) is transformed into trihexyl(tetradecyl)phosphonium nitrate([P_(66614)][NO_(3)]) ionic liquid by adding 2.5 mol/L potassium nitrate.The extraction examinations were tested by equilibration of 2 mL of [P_(66614)][NO_(3)] with 2 mL of a synthetic solution of 1000 mg/L of individual La,Ce,and Nd to gain the optimal extraction conditions.The high extraction efficiency of La,Ce,and Nd was gained by stirring a 1/1 aqueous/organic phase ratio and 3 mol/L NH_(4)NO_(3)(as salting out) at 800 r/min for 40 min at 50℃ to decrease the viscosity of [P_(66614)][NO_(3)].The La(Ⅲ),Ce(Ⅲ),and Nd(Ⅲ) stripping efficiencies were examined from their loaded [P_(66614)][NO_(3)] ionic liquid by 1/1 A/O ratio of acidified water,800 r/min stirring speed,and 25℃.After nine cycles,the extraction and stirring efficiency for the La,Ce,and Nd drop to about 80%.The extraction and stripping parameters are applied to the RE leachate from PG to gain the RE oxide with an assay of 92.67%.展开更多
Conventional hydrometallurgy recycling process for treating wasted lithium-ion batteries(LIBs)typically results in the consumption of large amounts of corrosive leachates.Recent research on reusable leachate is expect...Conventional hydrometallurgy recycling process for treating wasted lithium-ion batteries(LIBs)typically results in the consumption of large amounts of corrosive leachates.Recent research on reusable leachate is expected to significantly improve the economic and environmental benefits,but is usually limited to specific and unique chemical reactions which could only apply to one type of metal elements.Herein,we report the co-extraction of multiple metal elements can be extracted without adding precipitates by mixed crystal co-precipitation,which enables the reusability of the leachate.We show that an oxalic acid(OA):choline chloride(ChCl):ethylene glycol(EG)type DES leachate system can leach transition metals from wasted LiNi_(x)Co_(y)Mn_(1-x-y)O_(2)(NCM)cathode materials with satisfactory efficiency(The time required for complete leaching at 120℃ is 1.5 h).The transition metals were then efficiently extracted(with a recovery efficiency of over 96%for all elements)by directly adding water without precipitants.Noteworthy,the leachate can be efficiently recovered by directly evaporating the added water.The successful realization of reusability of leachate for the synergistic extraction of multiple elements relies on the regulation of the mixed crystal co-precipitation coefficient,which is realized by rationally design the reaction condition(composition of leachate,temperature and time)and induces the extraction of originally soluble manganese element.Our strategy is expected to be generally applicable and highly competent for industrial applications.展开更多
Bioremediation has gained significant attention due to its potential to remove azo dyes.However,the challenges microor-ganisms face in surviving when azo dyes are the sole carbon source limit its widespread applicatio...Bioremediation has gained significant attention due to its potential to remove azo dyes.However,the challenges microor-ganisms face in surviving when azo dyes are the sole carbon source limit its widespread application.This study aimed to improve the biodegradation of azo dyes by utilizing Baijiu distiller’s grains leachate(BDGL)as a co-substrate.The experimental results demon-strated that BDGL significantly enhanced Providencia rettgeri’s ability to degrade the model pollutant Acid Black 210(AB210),achieving a decolorization efficiency of 94.5%.This may be attributed to the nutrient-rich composition of BDGL,which includes ethanol and protein,providing a favorable substrate for bacterial growth and activity.The higher biomass and increased activities of azoreductase and quinone oxidoreductase in the BDGL group further supported these findings.Additionally,this method demonstra-ted broad-spectrum degradation of azo dyes(Direct Red 5B,Acid Red 73,and Congo Red)with different structures,highlighting its potential applicability.Metabolite assays combined with transcriptomics analyses revealed that the expression of functional genes re-lated to redox reactions,azo bond cleavage,and hydrolysis increased under the co-metabolic conditions of BDGL,resulting in stronger reducing power that further mineralized the dye into smaller metabolites.Our study offers a practical strategy for the simulta-neous treatment of dye-containing wastewater and Baijiu distiller’s grains,with significant environmental and industrial applications.展开更多
Municipal solid waste(MSW)is an important destination for abandoned plastics.During the waste disposal process,large plastic debris is broken down into microplastics(MPs)and released into the leachate.However,current ...Municipal solid waste(MSW)is an important destination for abandoned plastics.During the waste disposal process,large plastic debris is broken down into microplastics(MPs)and released into the leachate.However,current research only focuses on landfill leachates,and the occurrence of MPs in other leachates has not been studied.Therefore,herein,the abundance and characteristics of MPs in three types of leachates,namely,landfill leachate,residual waste leachate,and household food waste leachate,were studied,all leachates were collected from the largest waste disposal center in China.The results showed that the average MP abundances in the different types of leachates ranged from(129±54)to(1288±184)MP particles per liter(particlesL1)and the household food waste leachate exhibited the highest MP abundance(p<0.05).Polyethylene(PE)and fragments were the dominant polymer type and shape in MPs,respectively.The characteristic polymer types of MPs in individual leachates were different.Furthermore,the conditional fragmentation model indicated that the landfilling process considerably affected the size distribution of MPs in leachates,leading to a higher percentage(>80%)of small MPs(20–100 lm)in landfill leachates compared to other leachates.To the best of our knowledge,this is the first study discussing the sources of MPs in different leachates,which is important for MP pollution control during MSW disposal.展开更多
Leachate from a sanitary landfill site in Chengdu, China is treated using a hybrid-UASB reactor at pilot scale. H2S, resulting from the anaerobic bioconversion process of sulfate-reducing bacteria（SRB）, inhibits the...Leachate from a sanitary landfill site in Chengdu, China is treated using a hybrid-UASB reactor at pilot scale. H2S, resulting from the anaerobic bioconversion process of sulfate-reducing bacteria（SRB）, inhibits the growth and activity of methane-producing bacteria（MPB）and poses serious problems of pollution, so FeCl3is used for H2S removal. The results show that the system performs well in the treatment process. COD removal generally increases with the increase in the organic loading rate（OLR）, while the sulfate removal decreases slowly. As the OLR is higher than 7 kgCOD/（m3·d）, both COD and sulfate removal tend to be stable. When the reactor is operated at the design load of 9 kgCOD/（m3·d）, COD and sulfate removal remain about 79% and 91%, respectively. At the same time, the percentage of COD removed by SRB（CODSRB）also decreases from 8.9% to 4.0%. With FeCl3 addition, COD removal increases to 83%, while sulfate removal and CODSRBfurther decrease to 89% and 1.89%, respectively. According to the mass balance, nearly 82% of the sulfur is prevented from converting into H2S. Moreover, when the FeCl3 dosage is more than 1.6 g/L leachate, H2S can be removed totally from the biogas. Therefore, the application of FeCl3 for H2S removal in leachate treatment using the UASB reactor is very suitable and viable.展开更多
Landfill is the major disposal route of municipal solid waste（MSW） in most Asian countries. Leachate from landfill presents a strong wastewater that needs intensive treatment before discharge. Direct recycling was p...Landfill is the major disposal route of municipal solid waste（MSW） in most Asian countries. Leachate from landfill presents a strong wastewater that needs intensive treatment before discharge. Direct recycling was proposed as an effective alternative for leachate treatment by taking the landfill as a bioreactor. This process was proved not only considerably reducing the pollution potential of leachate, but also enhancing organic degradation in the landfill. However, as this paper shows, although direct leachate recycling was effective in landfilled MSW with low food waste fraction （3.5%, w/w）, it failed in MSW containing 54% food waste, as normally noted in Asian countries. The initial acid stuck would inhibit methanogenesis to build up, hence strong leachate was yielded from landfill to threaten the quality of receiving water body. We demonstrated the feasibility to use an assisted bioreactor landfill, with a well-decomposed refuse layer as ex-situ anaerobic digester to reducing COD loading in leachate. By doing so, the refuse in simulated landfill column （2.3 m high） could be stabilized in 30 weeks while the COD in leachate reduced by 95%（61000 mg/L to 3000 mg/L）. Meanwhile, the biogas production was considerably enhanced, signaling by the much greater amount and much higher methane content in the biogas.展开更多
This study was conducted to measure the impact of a municipal solid waste landfill on groundwater quality around Njelianparamba, a solid waste dumping site in Kozhikode district, Kerala state, India. One of the major ...This study was conducted to measure the impact of a municipal solid waste landfill on groundwater quality around Njelianparamba, a solid waste dumping site in Kozhikode district, Kerala state, India. One of the major problems associated with dumping of municipal solid waste landfill is the release of leachate and its impact on surrounding groundwater. In this study, physico-chemical and bacteriological parameters of groundwater samples collected from the region surrounding the leachate area during the pre- and post-monsoon seasons were analysed. The majority of the groundwater samples contained contaminants at a level beyond the permissible limit set by the Bureau of Indian Standards for drinking water quality. The Geographic Information System software of the Environmental Systems Research Institute, (USA) ArcMap 10.1 was used to prepare spatial distribution maps of different parameters and Leachate Pollution Index and Water Quality Index in the study area were applied to assess the overall quality of groundwater. Characterisation of leachate and groundwater samples revealed that, water in the domestic wells has been deteriorated in response to the percolation of leachate. Additionally spatial and correlation analysis revealed that contamination was present maximum within 300 m radius around the landfill site.展开更多
Electrolytic manganese residue leachate(EMRL)contains plenty of Mn^(2+) and NH_(4)^(+)-N,and phosphogypsum leachate(PGL)contains large amounts of PO_(4)^(3-)-P and F^(-).Traditional methods of EMRL and PGL discharge c...Electrolytic manganese residue leachate(EMRL)contains plenty of Mn^(2+) and NH_(4)^(+)-N,and phosphogypsum leachate(PGL)contains large amounts of PO_(4)^(3-)-P and F^(-).Traditional methods of EMRL and PGL discharge could seriously damage the ecological environment.In this study,an innovative method for cooperative removal Mn^(2+),NH_(4)^(+)-N,PO_(4)^(3-)-P,F^(-)from PG and POFT was studied.The result showed that Mn^(2+),PO_(4)^(3-)-P and F^(-)were mainly removed in forms of Mg_(3)Si_(4)O_(10)(OH)_(2),Mn_(3)O_(4),Mn_(3)(PO_(4))_(2),Mg_(3)(PO_(4))_(2),CaSO_(4)·2H_(2)O,MnF_(2),MnOOH and Ca_(2)P_(2)O_(7)·2H_(2)O,when LG-MgO was used to adjust the pH value of the system to 9.5,and the volume ratio of EMRL and PGL was 1:4,as well as reaction for 1 h at 25℃.NH_(4)^(+)-N was mainly removed by struvite precipitate,when the molar ratio of N:Mg:P was 1:3:2.4.The concentrations of Mn^(2+),NH_(4)^(+)-N and F^(-)were lower than the integrated wastewater discharge standard.The concentration of PO_(4)^(3-)-P decreased from 254.20 mg/L to 3.21 mg/L.This study provided a new method for EMRL and PGL cooperative harmless treatment.展开更多
The main objective of the study was to investigate the characteristics of dissolved organic matter （DOM） in leachate with different landfill ages through the chemical, spectroscopic, and elemental analysis. Humic ac...The main objective of the study was to investigate the characteristics of dissolved organic matter （DOM） in leachate with different landfill ages through the chemical, spectroscopic, and elemental analysis. Humic acid （HA）, fulvic acid （FA）, and hydrophilic （HyI） fractions were isolated and purified by the XAD-8 resin combined with the cation exchange resin method. The analytical results of fluorescence excitation-emission matrix spectroscopy （EEMs） revealed that the fluorescence peaks were protein-like fluorescence for young landfill leachate, while the fluorescence peaks for medium and old landfill leachate were humic-like and fulvic-like fluorescence, respectively. Elemental analysis showed that carbon, hydrogen, and nitrogen content decreased with landfill age, while the oxygen content increased. Moreover, the nitrogen content in these isolated fractions followed： HA 〉 HyI 〉 FA. The results of elemental analysis, FT-IR, and fluorescence EEMs also confirmed that aromatic carbons and portions of aliphatic functional groups were more abundant in leachate samples with increasing landfill age.展开更多
The nitrite accumulation in the denitrification process is investigated with sequencing batch reactor （SBR） treating pre-treated landfill leachate in anoxic/anaerobic up-flow anaerobic sludge bed I（UASB）. Nitrite ...The nitrite accumulation in the denitrification process is investigated with sequencing batch reactor （SBR） treating pre-treated landfill leachate in anoxic/anaerobic up-flow anaerobic sludge bed I（UASB）. Nitrite accumulates obviously at different initial nitrate concentrations （64.9,54.8,49.3 and 29.5 mg·L^-1 ） and low temperatures, and the two break points on the oxidation-reduction potential （ORP） profile indicate the completion of nitrate and nitrite reduction. Usually, the nitrate reduction rate is used as the sole parameter to characterize the denitrification rate, and nitrite is not even measured. For accuracy, the total oxidized nitrogen （nitrate ＋ nitrite） is used as a measure, though details characterizing the process may be overlooked. Additionally, batch tests are conducted to investigate the effects of C/N ratios and types of carbon sources on the nitrite accumulation during the denitrification. It is observed that carbon source is sufficient for the reduction of nitrate to nitrite, but for further reduction of nitrite to nitrogen gas, is deficient when C/N is below the theoretical critical level of 3.75 based on the stoichiometry of denitrification. Five carbon sources used in this work, except for glucose, may cause the nitrite accumulation. From experimental results and cited literature, it is concluded that Alcaligene species may be contained in the SBR activated-sludge system.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 impro...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 supematant 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/（m^3.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℃）. More than 98.3% TN was removed through complete denitrification in UASB 1 and SBR. In addition, temperature had a significant effect 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
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 ...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
In this study,a denitrification(DN)–partial nitritation(PN)–anaerobic ammonia oxidation(Anammox)system for the efficient nitrogen removal of mature landfill leachate was built with a zone-partitioning self-reflux bi...In this study,a denitrification(DN)–partial nitritation(PN)–anaerobic ammonia oxidation(Anammox)system for the efficient nitrogen removal of mature landfill leachate was built with a zone-partitioning self-reflux biological reactor as the core device,and the effects of changes in seasonal temperature on the nitrogen removal in non-temperature-control environment were explored.The results showed that as the seasonal temperature decreased from 34℃to 11.3℃,the total nitrogen removal rate of the DN-PN-Anammox system gradually decreased from the peak value of 1.42 kg/(m^(3)·day)to 0.49 kg/(m^(3)·day).At low temperatures(<20℃),when the nitrogen load(NLR)of the system is not appropriate,the fluctuation of high NH_(4)^(+)-N concentration in the landfill leachate greatly influenced the stability of the nitrogen removal.At temperatures of 11℃–15℃,the NLR of the system is controlled below 0.5 kg/(m^(3)·day),which can achieve stable nitrogen removal and the nitrogen removal efficiency can reach above 96%.The abundance of Candidatus Brocadia gradually increased with the decrease of temperature.Nitrosomonas,Candidatus Brocadia and Candidatus Kuenenia as the main functional microorganisms in the low temperature.展开更多
Anaerobic ammonium oxidation （ANAMMOX） technology has potential technical superiority and economical efficiency for the nitrogen removal from landfill leachate, which contains high-strength ammonium nitrogen （NH4^...Anaerobic ammonium oxidation （ANAMMOX） technology has potential technical superiority and economical efficiency for the nitrogen removal from landfill leachate, which contains high-strength ammonium nitrogen （NH4^＋-N） and refractory organics. To complete the ANAMMOX process, a preceding partial nitritation step to produce the appropriate ratio of nitrite/ammonium is a key stage. The objective of this study was to determine the optimal conditions to acquire constant partial nitritation for landfill leachate treatment, and a bench scale fixed bed bio-film reactor was used in this study to investigate the effects of the running factors on the partial nitritation. The results showed that both the dissolved oxygen （DO） concentration and the ammonium volumetric loading rate （Nv） had effects on the partial nitritation. In the controlling conditions with a temperature of 30±1℃, Nv of 0.2-1.0 kg NH4＋-N/（m^3·d）, and DO concentration of 0.8-2.3 mg/L, the steady partial nitritation was achieved as follows： more than 94% partial nitritation efficiency （nitrite as the main product）, 60%-74% NH4^＋-N removal efficiency, and NO2^--N/NH4^＋-N ratio （concentration ratio） of 1.0-1.4 in the effluent.The impact of temperature was related to Nv at certain DO concentration, and the temperature range of 25-30℃ was suitable for treating high strength ammonium leachate. Ammonium-oxidizing bacteria （AOB） could be acclimated to higher FA （free ammonium） in the range of 122-224 mg/L. According to the denaturing gradient gel electrophoresis analysis result of the bio-film in the reactor, there were 25 kinds of 16S rRNA gene fragments, which indicated that abundant microbial communities existed in the bio-film, although high concentrations of ammonium and FA may inhibit the growth of the nitrite-oxidizing bacteria （NOB） and other microorganisms in the reactor.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 and high ammonia concentration. To make the best use of the biodegradable COD in the leaehate, t...An UASB＋Anoxic/Oxic （A/O） system was introduced to treat a mature landfill leachate with low carbon-to-nitrogen ratio and high ammonia concentration. To make the best use of the biodegradable COD in the leaehate, the denitrifieation of NOx^--N in the reeireulation effluent from the elarifier was carried out in the UASB. The results showed that most biodegradable organic matters were removed by the denitrifieation in the UASB. The NH4^＋-N loading rate （ALR） of A/O reactor and operational temperature was 0.28- 0.60 kg NH4^＋-N/（m^3-d） and 17-29℃ during experimental period, respectively. The short-cut nitrification with nitrite accumulation efficiency of 90%-99% was stabilized during the whole experiment. The NH4^＋-N removal efficiency varied between 90% and 100%. When ALR was less than 0.45 kg NH4^＋-N/（m^3.d）, the NH4^＋-N removal efficiency was more than 98%. With the influent NH4^＋-N of 1200-1800 mg/L, the effluent NH4^＋-N was less than 15 mg/L. The shortcut nitrification and denitrifieation can save 40% carbon source, with a highly efficient denitrifieation 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 efficiency attained 67%-80%. Besides, the sludge samples from A/O reactor were analyzed using FISH. The FISH analysis revealed that ammonia oxidation bacteria （AOB） accounted for 4% of the total eubaeterial population, whereas nitrite oxidation bacteria （NOB） accounted only for 0.2% of the total eubaeterial population.展开更多
A system consisting of a two-stage up-flow anaerobic sludge blanket （UASB）, an anoxic/aerobic （A/O） reactor and a sequencing batch reactor （SBR）, was used to treat landfill leachate. During operation, denitrific...A system consisting of a two-stage up-flow anaerobic sludge blanket （UASB）, an anoxic/aerobic （A/O） reactor and a sequencing batch reactor （SBR）, was used to treat landfill leachate. During operation, denitrification and methanogenesis took place simultaneously in the first stage UASB, and the effluent chemical oxygen demand （COD） was further removed in the second stage UASB. Then the denitrification of nitrite and nitrate in the returned sludge by using the residual COD was accomplished in the A/O reactor, and ammonia was removed via nitrite in it. Last but not least, the residual ammonia was removed in SBR as well as nitrite and nitrate which were produced by nitrification. The results over 120 d （60 d for phase I and 60 d for phase II） were as follows： when the total nitrogen （TN） concentration of influent leachate was about 2500 mg/L and the ammonia nitrogen concentration was about 2000 mg/L, the shortcut nitrification with 85%-90% nitrite accumulation was achieved stably in the A/O reactor. The TN and ammonia nitrogen removal efficiencies of the system were 98% and 97%, respectively. The residual ammonia, nitrite and nitrate produced during nitrification in the A/O reactor could be washed out almost completely in SBR. The TN and ammonia nitrogen concentrations of final effluent were about 39 mg/L and 12 mg/L, respectively.展开更多
A field-scale aged refuse （AR） biofilter constructed in Shanghai Refuse Landfill, containing about 7000 m^3 aged refuse inside, was evaluated for its performance in the treatment of landfill leachate. This AR biofil...A field-scale aged refuse （AR） biofilter constructed in Shanghai Refuse Landfill, containing about 7000 m^3 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 m^3 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 infiuent leachate COD and ammonia nitrogen concentration were in the range 5478-10842 mg/L and 811-1582 mg/L, respectively. The final effluent 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 efficient 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
In this study, a full-scale internal circulation（IC） reactor coupled with an external circulation system was developed to treat high-strength leachate from a municipal solid waste（MSW）incineration plant, in which ...In this study, a full-scale internal circulation（IC） reactor coupled with an external circulation system was developed to treat high-strength leachate from a municipal solid waste（MSW）incineration plant, in which anaerobic sludge granulation was intensively investigated. Results showed that the IC reactor achieved excellent treatment performance under high organic loading rates（OLR） of 21.06–25.16 kg chemical oxygen demand（COD）/（m3？ day）. The COD removal efficiency and biogas yield respectively reached 89.4%–93.4% and 0.42–0.50 m3/kg COD.The formation of extracellular polymeric substances（EPS） was closely associated with sludge granulation. Protein was the dominant component in sludge EPS, and its content was remarkably increased from 21.6 to 99.7 mg/g Volatile Suspended Solid（VSS） during the reactor operation. The sludge Zeta potential and hydrophobicity positively correlated with the protein/polysaccharide ratio in EPS, and they were respectively increased from-26.2 m V and 30.35% to-10.6 m V and 78.67%, which was beneficial to microbial aggregation. Three-dimensional fluorescence spectroscopy（3 D-EEM） and Fourier transform infrared spectroscopy（FT-IR）analysis further indicated the importance of protein-like EPS substances in the sludge granulation. Moreover, it was also found that the secondary structures of EPS proteins varied during the reactor operation.展开更多
To study the characteristics of stabilization in semi-aerobic landfill, large-scale simulated landfill was constructed based on the semi- aerobic landfill theory. Consequently, the concentrations of chemical oxygen de...To study the characteristics of stabilization in semi-aerobic landfill, large-scale simulated landfill was constructed based on the semi- aerobic landfill theory. Consequently, the concentrations of chemical oxygen demand （COD）, ammonia nitrogen, and nitrite nitrogen, and the pH value in leachate, as well as the component contents of landfill gas composition （methane, carbon dioxide, and oxygen） in landfill were regularly monitored for 52 weeks. The restflts showed that COD and ammonia concentrations declined rapidly and did not show the accumulating rule like anaerobic landfill, and remained at about 300 and 100 mg/L, respectively, after 48 weeks. Meanwhile, the descending rate reached 98.9% and 96.9%, respectively. Nitrate concentration increased rapidly after 24 weeks and fluctuated between 220-280 mg/L after 43 weeks. The pH values were below 7 during the first 8 weeks and after that leachates appeared to be alkaline. Carbon dioxide was the main composition in landfill gas and its concentration remained at a high level through the whole stabilization process. The average contents of carbon dioxide, oxygen, and methane varied between 19 vol.%-28 vol.%, 2 vol.%-8 vol.%, and 5 vol.%-13 vol.%, respectively. A relative equilibrium was reached after 48 weeks. The highest temperature in the landfill chamber could amount to 75.8 degrees centigrade.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.52078142).
文摘Leachate sludge,a byproduct of municipal solid waste leachate treated through biochemical processes,is characterized by high water content(761.1%)and significant organic matter content(71.2%).Cement that is commonly used for solidifying leachate sludge has shown limited effectiveness.To address this issue,an alkali-activated ground-granulated blast-furnace slag(GGBS)geopolymer blended with polypropylene fibers was developed to solidify leachate sludge.Moreover,unconfined compressive strength(UCS),immersion,as well as X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and scanning electron microscope(SEM)tests were conducted to investigate the solidification effect and mechanism of the GGBS-based geopolymer and fibers on leachate sludge.The results showed that:the 28-d UCS of the solidified sludge with 20%and 30%GGBS is 0.35 MPa and 1.85 MPa,and decreases to 0.18 MPa and 1.13 MPa,respectively,after soaked in water for 28 d.Notably,the UCS of the solidified sludge with 30%GGBS satisfied the strength requirement of roadbed materials.Polypropylene fibers significantly enhanced the strength,ductility and water stability of the solidified sludge,with an optimal fiber content of 0.3%.Alkali-activated GGBS geopolymer generated three-dimensional,cross-linked geopolymeric gels within the solidified sludge,cementing sludge particles and filling intergranular pores to form a stable cementitious structure,thereby achieving effective solidification.Furthermore,incorporating polypropylene fibers improved the bonding and anchoring effect between fiber and solidified sludge,constrained lateral deformation of the solidified sludge,restricted crack propagation,and enhanced engineering performance of the solidified leachate sludge.
文摘Rare earth elements(REEs) were extracted from phosphogypsum(PG) using an indirect leaching method that produces CaCO_(3).The carbonation process transforms PG into CaCO_(3),and a potential source of value is the(NH_(4))_(2)SO_(4) fertilizer.The calcium carbonate byproduct is rich in REEs that are originally present in PG.Calcium carbonate,a byproduct of PG carbonation and a rich source of REEs,could dissolve in nitric acid to produce a calcium nitrate leach solution that contains RE nitrate.Subsequently,the most widely used solvent extraction technique can make use of an environmentally benign nitrate ionic liquid.Cyphos IL 101(trihexyl(tetradecyl)phosphonium chloride) is transformed into trihexyl(tetradecyl)phosphonium nitrate([P_(66614)][NO_(3)]) ionic liquid by adding 2.5 mol/L potassium nitrate.The extraction examinations were tested by equilibration of 2 mL of [P_(66614)][NO_(3)] with 2 mL of a synthetic solution of 1000 mg/L of individual La,Ce,and Nd to gain the optimal extraction conditions.The high extraction efficiency of La,Ce,and Nd was gained by stirring a 1/1 aqueous/organic phase ratio and 3 mol/L NH_(4)NO_(3)(as salting out) at 800 r/min for 40 min at 50℃ to decrease the viscosity of [P_(66614)][NO_(3)].The La(Ⅲ),Ce(Ⅲ),and Nd(Ⅲ) stripping efficiencies were examined from their loaded [P_(66614)][NO_(3)] ionic liquid by 1/1 A/O ratio of acidified water,800 r/min stirring speed,and 25℃.After nine cycles,the extraction and stirring efficiency for the La,Ce,and Nd drop to about 80%.The extraction and stripping parameters are applied to the RE leachate from PG to gain the RE oxide with an assay of 92.67%.
基金supported by The National Natural Science Foundation of China(No.52262030)Natural Science Research Project of Guizhou Provincial Department of Education(No.[2022]041).
文摘Conventional hydrometallurgy recycling process for treating wasted lithium-ion batteries(LIBs)typically results in the consumption of large amounts of corrosive leachates.Recent research on reusable leachate is expected to significantly improve the economic and environmental benefits,but is usually limited to specific and unique chemical reactions which could only apply to one type of metal elements.Herein,we report the co-extraction of multiple metal elements can be extracted without adding precipitates by mixed crystal co-precipitation,which enables the reusability of the leachate.We show that an oxalic acid(OA):choline chloride(ChCl):ethylene glycol(EG)type DES leachate system can leach transition metals from wasted LiNi_(x)Co_(y)Mn_(1-x-y)O_(2)(NCM)cathode materials with satisfactory efficiency(The time required for complete leaching at 120℃ is 1.5 h).The transition metals were then efficiently extracted(with a recovery efficiency of over 96%for all elements)by directly adding water without precipitants.Noteworthy,the leachate can be efficiently recovered by directly evaporating the added water.The successful realization of reusability of leachate for the synergistic extraction of multiple elements relies on the regulation of the mixed crystal co-precipitation coefficient,which is realized by rationally design the reaction condition(composition of leachate,temperature and time)and induces the extraction of originally soluble manganese element.Our strategy is expected to be generally applicable and highly competent for industrial applications.
基金supported by the National Key Re-search and Development Project of China(No.2023YFC3108400).
文摘Bioremediation has gained significant attention due to its potential to remove azo dyes.However,the challenges microor-ganisms face in surviving when azo dyes are the sole carbon source limit its widespread application.This study aimed to improve the biodegradation of azo dyes by utilizing Baijiu distiller’s grains leachate(BDGL)as a co-substrate.The experimental results demon-strated that BDGL significantly enhanced Providencia rettgeri’s ability to degrade the model pollutant Acid Black 210(AB210),achieving a decolorization efficiency of 94.5%.This may be attributed to the nutrient-rich composition of BDGL,which includes ethanol and protein,providing a favorable substrate for bacterial growth and activity.The higher biomass and increased activities of azoreductase and quinone oxidoreductase in the BDGL group further supported these findings.Additionally,this method demonstra-ted broad-spectrum degradation of azo dyes(Direct Red 5B,Acid Red 73,and Congo Red)with different structures,highlighting its potential applicability.Metabolite assays combined with transcriptomics analyses revealed that the expression of functional genes re-lated to redox reactions,azo bond cleavage,and hydrolysis increased under the co-metabolic conditions of BDGL,resulting in stronger reducing power that further mineralized the dye into smaller metabolites.Our study offers a practical strategy for the simulta-neous treatment of dye-containing wastewater and Baijiu distiller’s grains,with significant environmental and industrial applications.
基金supported by the National Key Research and Development Program of China(2023YFC3711600)the National Natural Science Foundation of China(22076045 and 22376066)the Shanghai Talent Development Funding,and the Shanghai Youth Talent Support Program.
文摘Municipal solid waste(MSW)is an important destination for abandoned plastics.During the waste disposal process,large plastic debris is broken down into microplastics(MPs)and released into the leachate.However,current research only focuses on landfill leachates,and the occurrence of MPs in other leachates has not been studied.Therefore,herein,the abundance and characteristics of MPs in three types of leachates,namely,landfill leachate,residual waste leachate,and household food waste leachate,were studied,all leachates were collected from the largest waste disposal center in China.The results showed that the average MP abundances in the different types of leachates ranged from(129±54)to(1288±184)MP particles per liter(particlesL1)and the household food waste leachate exhibited the highest MP abundance(p<0.05).Polyethylene(PE)and fragments were the dominant polymer type and shape in MPs,respectively.The characteristic polymer types of MPs in individual leachates were different.Furthermore,the conditional fragmentation model indicated that the landfilling process considerably affected the size distribution of MPs in leachates,leading to a higher percentage(>80%)of small MPs(20–100 lm)in landfill leachates compared to other leachates.To the best of our knowledge,this is the first study discussing the sources of MPs in different leachates,which is important for MP pollution control during MSW disposal.
文摘Leachate from a sanitary landfill site in Chengdu, China is treated using a hybrid-UASB reactor at pilot scale. H2S, resulting from the anaerobic bioconversion process of sulfate-reducing bacteria（SRB）, inhibits the growth and activity of methane-producing bacteria（MPB）and poses serious problems of pollution, so FeCl3is used for H2S removal. The results show that the system performs well in the treatment process. COD removal generally increases with the increase in the organic loading rate（OLR）, while the sulfate removal decreases slowly. As the OLR is higher than 7 kgCOD/（m3·d）, both COD and sulfate removal tend to be stable. When the reactor is operated at the design load of 9 kgCOD/（m3·d）, COD and sulfate removal remain about 79% and 91%, respectively. At the same time, the percentage of COD removed by SRB（CODSRB）also decreases from 8.9% to 4.0%. With FeCl3 addition, COD removal increases to 83%, while sulfate removal and CODSRBfurther decrease to 89% and 1.89%, respectively. According to the mass balance, nearly 82% of the sulfur is prevented from converting into H2S. Moreover, when the FeCl3 dosage is more than 1.6 g/L leachate, H2S can be removed totally from the biogas. Therefore, the application of FeCl3 for H2S removal in leachate treatment using the UASB reactor is very suitable and viable.
文摘Landfill is the major disposal route of municipal solid waste（MSW） in most Asian countries. Leachate from landfill presents a strong wastewater that needs intensive treatment before discharge. Direct recycling was proposed as an effective alternative for leachate treatment by taking the landfill as a bioreactor. This process was proved not only considerably reducing the pollution potential of leachate, but also enhancing organic degradation in the landfill. However, as this paper shows, although direct leachate recycling was effective in landfilled MSW with low food waste fraction （3.5%, w/w）, it failed in MSW containing 54% food waste, as normally noted in Asian countries. The initial acid stuck would inhibit methanogenesis to build up, hence strong leachate was yielded from landfill to threaten the quality of receiving water body. We demonstrated the feasibility to use an assisted bioreactor landfill, with a well-decomposed refuse layer as ex-situ anaerobic digester to reducing COD loading in leachate. By doing so, the refuse in simulated landfill column （2.3 m high） could be stabilized in 30 weeks while the COD in leachate reduced by 95%（61000 mg/L to 3000 mg/L）. Meanwhile, the biogas production was considerably enhanced, signaling by the much greater amount and much higher methane content in the biogas.
文摘This study was conducted to measure the impact of a municipal solid waste landfill on groundwater quality around Njelianparamba, a solid waste dumping site in Kozhikode district, Kerala state, India. One of the major problems associated with dumping of municipal solid waste landfill is the release of leachate and its impact on surrounding groundwater. In this study, physico-chemical and bacteriological parameters of groundwater samples collected from the region surrounding the leachate area during the pre- and post-monsoon seasons were analysed. The majority of the groundwater samples contained contaminants at a level beyond the permissible limit set by the Bureau of Indian Standards for drinking water quality. The Geographic Information System software of the Environmental Systems Research Institute, (USA) ArcMap 10.1 was used to prepare spatial distribution maps of different parameters and Leachate Pollution Index and Water Quality Index in the study area were applied to assess the overall quality of groundwater. Characterisation of leachate and groundwater samples revealed that, water in the domestic wells has been deteriorated in response to the percolation of leachate. Additionally spatial and correlation analysis revealed that contamination was present maximum within 300 m radius around the landfill site.
基金Project(2018YFC1903500)supported by the National Key Research and Development Program of ChinaProject(52174386)supported by the National Natural Science Foundation of ChinaProject(2021YFH0058)supported by the Science and Technology Plan Project of Sichuan Province,China。
文摘Electrolytic manganese residue leachate(EMRL)contains plenty of Mn^(2+) and NH_(4)^(+)-N,and phosphogypsum leachate(PGL)contains large amounts of PO_(4)^(3-)-P and F^(-).Traditional methods of EMRL and PGL discharge could seriously damage the ecological environment.In this study,an innovative method for cooperative removal Mn^(2+),NH_(4)^(+)-N,PO_(4)^(3-)-P,F^(-)from PG and POFT was studied.The result showed that Mn^(2+),PO_(4)^(3-)-P and F^(-)were mainly removed in forms of Mg_(3)Si_(4)O_(10)(OH)_(2),Mn_(3)O_(4),Mn_(3)(PO_(4))_(2),Mg_(3)(PO_(4))_(2),CaSO_(4)·2H_(2)O,MnF_(2),MnOOH and Ca_(2)P_(2)O_(7)·2H_(2)O,when LG-MgO was used to adjust the pH value of the system to 9.5,and the volume ratio of EMRL and PGL was 1:4,as well as reaction for 1 h at 25℃.NH_(4)^(+)-N was mainly removed by struvite precipitate,when the molar ratio of N:Mg:P was 1:3:2.4.The concentrations of Mn^(2+),NH_(4)^(+)-N and F^(-)were lower than the integrated wastewater discharge standard.The concentration of PO_(4)^(3-)-P decreased from 254.20 mg/L to 3.21 mg/L.This study provided a new method for EMRL and PGL cooperative harmless treatment.
文摘The main objective of the study was to investigate the characteristics of dissolved organic matter （DOM） in leachate with different landfill ages through the chemical, spectroscopic, and elemental analysis. Humic acid （HA）, fulvic acid （FA）, and hydrophilic （HyI） fractions were isolated and purified by the XAD-8 resin combined with the cation exchange resin method. The analytical results of fluorescence excitation-emission matrix spectroscopy （EEMs） revealed that the fluorescence peaks were protein-like fluorescence for young landfill leachate, while the fluorescence peaks for medium and old landfill leachate were humic-like and fulvic-like fluorescence, respectively. Elemental analysis showed that carbon, hydrogen, and nitrogen content decreased with landfill age, while the oxygen content increased. Moreover, the nitrogen content in these isolated fractions followed： HA 〉 HyI 〉 FA. The results of elemental analysis, FT-IR, and fluorescence EEMs also confirmed that aromatic carbons and portions of aliphatic functional groups were more abundant in leachate samples with increasing landfill age.
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The nitrite accumulation in the denitrification process is investigated with sequencing batch reactor （SBR） treating pre-treated landfill leachate in anoxic/anaerobic up-flow anaerobic sludge bed I（UASB）. Nitrite accumulates obviously at different initial nitrate concentrations （64.9,54.8,49.3 and 29.5 mg·L^-1 ） and low temperatures, and the two break points on the oxidation-reduction potential （ORP） profile indicate the completion of nitrate and nitrite reduction. Usually, the nitrate reduction rate is used as the sole parameter to characterize the denitrification rate, and nitrite is not even measured. For accuracy, the total oxidized nitrogen （nitrate ＋ nitrite） is used as a measure, though details characterizing the process may be overlooked. Additionally, batch tests are conducted to investigate the effects of C/N ratios and types of carbon sources on the nitrite accumulation during the denitrification. It is observed that carbon source is sufficient for the reduction of nitrate to nitrite, but for further reduction of nitrite to nitrogen gas, is deficient when C/N is below the theoretical critical level of 3.75 based on the stoichiometry of denitrification. Five carbon sources used in this work, except for glucose, may cause the nitrite accumulation. From experimental results and cited literature, it is concluded that Alcaligene species may be contained in the SBR activated-sludge system.
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 supematant 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/（m^3.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℃）. More than 98.3% TN was removed through complete denitrification in UASB 1 and SBR. In addition, temperature had a significant effect 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 Natural Science Foundation of China(No.51938010)the Suzhou Science and Technology Plan Project-Minsheng Project(No.SS201804-02)+1 种基金National Key Research and Development Programme of China(No.2016YFC 0401103)the Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment。
文摘In this study,a denitrification(DN)–partial nitritation(PN)–anaerobic ammonia oxidation(Anammox)system for the efficient nitrogen removal of mature landfill leachate was built with a zone-partitioning self-reflux biological reactor as the core device,and the effects of changes in seasonal temperature on the nitrogen removal in non-temperature-control environment were explored.The results showed that as the seasonal temperature decreased from 34℃to 11.3℃,the total nitrogen removal rate of the DN-PN-Anammox system gradually decreased from the peak value of 1.42 kg/(m^(3)·day)to 0.49 kg/(m^(3)·day).At low temperatures(<20℃),when the nitrogen load(NLR)of the system is not appropriate,the fluctuation of high NH_(4)^(+)-N concentration in the landfill leachate greatly influenced the stability of the nitrogen removal.At temperatures of 11℃–15℃,the NLR of the system is controlled below 0.5 kg/(m^(3)·day),which can achieve stable nitrogen removal and the nitrogen removal efficiency can reach above 96%.The abundance of Candidatus Brocadia gradually increased with the decrease of temperature.Nitrosomonas,Candidatus Brocadia and Candidatus Kuenenia as the main functional microorganisms in the low temperature.
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).
文摘Anaerobic ammonium oxidation （ANAMMOX） technology has potential technical superiority and economical efficiency for the nitrogen removal from landfill leachate, which contains high-strength ammonium nitrogen （NH4^＋-N） and refractory organics. To complete the ANAMMOX process, a preceding partial nitritation step to produce the appropriate ratio of nitrite/ammonium is a key stage. The objective of this study was to determine the optimal conditions to acquire constant partial nitritation for landfill leachate treatment, and a bench scale fixed bed bio-film reactor was used in this study to investigate the effects of the running factors on the partial nitritation. The results showed that both the dissolved oxygen （DO） concentration and the ammonium volumetric loading rate （Nv） had effects on the partial nitritation. In the controlling conditions with a temperature of 30±1℃, Nv of 0.2-1.0 kg NH4＋-N/（m^3·d）, and DO concentration of 0.8-2.3 mg/L, the steady partial nitritation was achieved as follows： more than 94% partial nitritation efficiency （nitrite as the main product）, 60%-74% NH4^＋-N removal efficiency, and NO2^--N/NH4^＋-N ratio （concentration ratio） of 1.0-1.4 in the effluent.The impact of temperature was related to Nv at certain DO concentration, and the temperature range of 25-30℃ was suitable for treating high strength ammonium leachate. Ammonium-oxidizing bacteria （AOB） could be acclimated to higher FA （free ammonium） in the range of 122-224 mg/L. According to the denaturing gradient gel electrophoresis analysis result of the bio-film in the reactor, there were 25 kinds of 16S rRNA gene fragments, which indicated that abundant microbial communities existed in the bio-film, although high concentrations of ammonium and FA may inhibit the growth of the nitrite-oxidizing bacteria （NOB） and other microorganisms in the reactor.
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 and high ammonia concentration. To make the best use of the biodegradable COD in the leaehate, the denitrifieation of NOx^--N in the reeireulation effluent from the elarifier was carried out in the UASB. The results showed that most biodegradable organic matters were removed by the denitrifieation in the UASB. The NH4^＋-N loading rate （ALR） of A/O reactor and operational temperature was 0.28- 0.60 kg NH4^＋-N/（m^3-d） and 17-29℃ during experimental period, respectively. The short-cut nitrification with nitrite accumulation efficiency of 90%-99% was stabilized during the whole experiment. The NH4^＋-N removal efficiency varied between 90% and 100%. When ALR was less than 0.45 kg NH4^＋-N/（m^3.d）, the NH4^＋-N removal efficiency was more than 98%. With the influent NH4^＋-N of 1200-1800 mg/L, the effluent NH4^＋-N was less than 15 mg/L. The shortcut nitrification and denitrifieation can save 40% carbon source, with a highly efficient denitrifieation 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 efficiency attained 67%-80%. Besides, the sludge samples from A/O reactor were analyzed using FISH. The FISH analysis revealed that ammonia oxidation bacteria （AOB） accounted for 4% of the total eubaeterial population, whereas nitrite oxidation bacteria （NOB） accounted only for 0.2% of the total eubaeterial population.
基金supported by the Project of Beijing Natural Science Foundation (No. 8091001)the National Natural Science Foundation of China (No. 50978003)+1 种基金the Higher Learning under the Jurisdiction of Beijing Municipality (No. PHR20090502)the State Key Laboratory of Urban Water Resource and Environment (HIT) (No.QAK200802)
文摘A system consisting of a two-stage up-flow anaerobic sludge blanket （UASB）, an anoxic/aerobic （A/O） reactor and a sequencing batch reactor （SBR）, was used to treat landfill leachate. During operation, denitrification and methanogenesis took place simultaneously in the first stage UASB, and the effluent chemical oxygen demand （COD） was further removed in the second stage UASB. Then the denitrification of nitrite and nitrate in the returned sludge by using the residual COD was accomplished in the A/O reactor, and ammonia was removed via nitrite in it. Last but not least, the residual ammonia was removed in SBR as well as nitrite and nitrate which were produced by nitrification. The results over 120 d （60 d for phase I and 60 d for phase II） were as follows： when the total nitrogen （TN） concentration of influent leachate was about 2500 mg/L and the ammonia nitrogen concentration was about 2000 mg/L, the shortcut nitrification with 85%-90% nitrite accumulation was achieved stably in the A/O reactor. The TN and ammonia nitrogen removal efficiencies of the system were 98% and 97%, respectively. The residual ammonia, nitrite and nitrate produced during nitrification in the A/O reactor could be washed out almost completely in SBR. The TN and ammonia nitrogen concentrations of final effluent were about 39 mg/L and 12 mg/L, respectively.
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 m^3 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 m^3 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 infiuent leachate COD and ammonia nitrogen concentration were in the range 5478-10842 mg/L and 811-1582 mg/L, respectively. The final effluent 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 efficient 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.
基金supported by the National Natural Science Foundation of China(Nos.21506076,51678279 and 51508230)the National Science and Technological Support of China(No.2014BAC25B01)
文摘In this study, a full-scale internal circulation（IC） reactor coupled with an external circulation system was developed to treat high-strength leachate from a municipal solid waste（MSW）incineration plant, in which anaerobic sludge granulation was intensively investigated. Results showed that the IC reactor achieved excellent treatment performance under high organic loading rates（OLR） of 21.06–25.16 kg chemical oxygen demand（COD）/（m3？ day）. The COD removal efficiency and biogas yield respectively reached 89.4%–93.4% and 0.42–0.50 m3/kg COD.The formation of extracellular polymeric substances（EPS） was closely associated with sludge granulation. Protein was the dominant component in sludge EPS, and its content was remarkably increased from 21.6 to 99.7 mg/g Volatile Suspended Solid（VSS） during the reactor operation. The sludge Zeta potential and hydrophobicity positively correlated with the protein/polysaccharide ratio in EPS, and they were respectively increased from-26.2 m V and 30.35% to-10.6 m V and 78.67%, which was beneficial to microbial aggregation. Three-dimensional fluorescence spectroscopy（3 D-EEM） and Fourier transform infrared spectroscopy（FT-IR）analysis further indicated the importance of protein-like EPS substances in the sludge granulation. Moreover, it was also found that the secondary structures of EPS proteins varied during the reactor operation.
文摘To study the characteristics of stabilization in semi-aerobic landfill, large-scale simulated landfill was constructed based on the semi- aerobic landfill theory. Consequently, the concentrations of chemical oxygen demand （COD）, ammonia nitrogen, and nitrite nitrogen, and the pH value in leachate, as well as the component contents of landfill gas composition （methane, carbon dioxide, and oxygen） in landfill were regularly monitored for 52 weeks. The restflts showed that COD and ammonia concentrations declined rapidly and did not show the accumulating rule like anaerobic landfill, and remained at about 300 and 100 mg/L, respectively, after 48 weeks. Meanwhile, the descending rate reached 98.9% and 96.9%, respectively. Nitrate concentration increased rapidly after 24 weeks and fluctuated between 220-280 mg/L after 43 weeks. The pH values were below 7 during the first 8 weeks and after that leachates appeared to be alkaline. Carbon dioxide was the main composition in landfill gas and its concentration remained at a high level through the whole stabilization process. The average contents of carbon dioxide, oxygen, and methane varied between 19 vol.%-28 vol.%, 2 vol.%-8 vol.%, and 5 vol.%-13 vol.%, respectively. A relative equilibrium was reached after 48 weeks. The highest temperature in the landfill chamber could amount to 75.8 degrees centigrade.
