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
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
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
As the global electric vehicle market continues to grow,the recycling of Li-ion battery (LIB) becomes more important worldwide and the resynthesis of cathode materials would be the most value-added recycling approach ...As the global electric vehicle market continues to grow,the recycling of Li-ion battery (LIB) becomes more important worldwide and the resynthesis of cathode materials would be the most value-added recycling approach taking into account limited metal resources.Although resynthesized homogenous LiNi_(x)Co_(y)Mn_(z)O_(2)(NCM) from spent LIB leachate shows comparable battery performance to pristine NCM from virgin materials,there is general concern in its cycling performance.Here,we synthesize core–shell(CS) Ni-rich NCM,which consists of Ni-rich NCM as the core and NCM derived from the original or purified leachate of spent LIBs as the shell.Resynthesized CS Ni-rich NCM exhibits improved rate capability resulting from expanded interslab thickness in the NCM structure.CS Ni-rich NCM from purified LIB leachate shows improvement in cycling performance and thermal stability.It specifically delivers a capacity retention of 86.6%at a high temperature after 80 cycles compared to that (75.0%) of pristine CS Ni-rich NCM.These improvements are caused by a relatively high Mg content on the shell and the widespread distribution of Al through the CS structure.CS Ni-rich NCM derived from spent LIB leachate provides a new alternative approach to conventional LIB recycling methods,which would utilize efficiently limited metal resources for the sustainable LIB production.展开更多
Groundwater contamination near landfills is commonly caused by leachate leakage,and permeable reactive barriers(PRBs)are widely used for groundwater remediation.However,the deactivation and blockage of the reactive me...Groundwater contamination near landfills is commonly caused by leachate leakage,and permeable reactive barriers(PRBs)are widely used for groundwater remediation.However,the deactivation and blockage of the reactive medium in PRBs limit their long-term effectiveness.In the current study,a new methodology was proposed for the in situ regeneration of PRB to remediate leachate-contaminated groundwater.CO_(2)coupled with oxidants was applied for the dispersion and regeneration of the fillers;by injecting CO_(2)to disperse the fillers,the permeability of the PRB was increased and the oxidants could flow evenly into the PRB.The results indicate that the optimumfiller proportion was zero-valent iron(ZVI)/zeolites/activated carbon(AC)=3:8:10 and the optimum oxidant proportion was COD/Na_(2)S_(2)O_(8)/H_(2)O_(2)/Fe^(2+)=1:5:6:5;the oxidation system of Fe^(2+)/H_(2)O_(2)/S_(2)O_(8)^(2−)has a high oxidation efficiency and persistence.The average regeneration rate of zeolites was 72.71%,and the average regeneration rate of AC was 68.40%;the permeability of PRB also increased.This technology is effective for the remediation of landfills in China that have large contaminated areas,an uneven pollutant concentration distribution,and a long pollution duration.The purification mode of long-term adsorption and short-time in situ oxidation can be applied to the remediation of long-term high-concentration organically polluted groundwater,where pollution sources are difficult to cut off.展开更多
In this study,vine pruning wastes(VPW)were used as raw material to develop an alternative activated carbon(VPW-AC)for adsorbing and concentrating rare earth elements cerium(Ce(Ⅲ))and lanthanum(La(Ⅲ))from synthetic a...In this study,vine pruning wastes(VPW)were used as raw material to develop an alternative activated carbon(VPW-AC)for adsorbing and concentrating rare earth elements cerium(Ce(Ⅲ))and lanthanum(La(Ⅲ))from synthetic and real leachate solutions.The Ce and La adsorption studies evaluated the effects of VPW-AC dosage,pH,contact time,rare earth initial concentration,and temperature.The VPW-AC adsorbent was subjected to many physicochemical characterization methods to correlate and understand its adsorptive performance.The characterization data indicate a carbonaceous adsorbent with a specific surface area of 467 m^(2)/g.Zeta potential indicates a material with a negatively charged surface at a pH higher than 3.1,which is extremely beneficial to cations removal.For both rare earths elements(REEs),the adsorption capacity increases with the increase of the pH,reaching its maximum at pH 4-6.The kinetic data are well fitted by Avrami-fractional o rder,while the Liu model agreeably fits equilibrium data.The maximum adsorption capacities for Ce(Ⅲ)and La(Ⅲ)are 48.45 and 53.65 mg/g at 298 K,respectively.The thermodynamic studies suggest that the adsorption process is favorable,spontaneous,and exothermic for both REEs.Pore filling,surface complexation,and ion exchange are the dominant mechanisms.Finally,the VPW-AC was subjected to the recovery of REEs from real phosphogypsum leachate,and it is proved that it can be successfully used to recover REEs in a real process.展开更多
Fouling of landfill leachate,a biofilm formation process on the surface of the collection system,migration pipeline and treatment system causes low efficiency of leachate transportation and treatment and increases cos...Fouling of landfill leachate,a biofilm formation process on the surface of the collection system,migration pipeline and treatment system causes low efficiency of leachate transportation and treatment and increases cost for maintenance of those facilities.In addition,landfill leachate fouling might accumulate pathogens and antibiotic resistance genes(ARGs),posing threats to the environment.Characterization of the landfill leachate fouling and its associated environmental behavior is essential for the management of fouling.In this study,physicochemical and biological properties of landfill leachate fouling and the possible accumulation capacity of pathogens and ARGs were investigated in nitrification(aerobic condition)and denitrification(anaerobic condition)process during landfill leachate biological treatment,respectively.Results show that microbial(bacterial,archaeal,eukaryotic,and viral)community structure and function(carbon fixation,methanogenesis,nitrification and denitrification)differed in fouling under aerobic and anaerobic conditions,driven by the supplemental leachate water quality.Aerobic fouling had a higher abundance of nitrification and denitrification functional genes,while anaerobic fouling harbored a higher abundance of carbon fixation and methanogenesis genes.Both forms of leachate fouling had a higher abundance of pathogens and ARGs than the associated leachate,suggesting the accumulation capacity of fouling on biotic pollutants.Specifically,aerobic fouling harbored three orders of magnitude higher multidrug resistance genes mex D than its associated leachate.This finding provides fundamental knowledge on the biological properties of leachate fouling and suggests that leachate fouling might harbor significant pathogens and ARGs.展开更多
This review highlights the importance of recovering valuable metals from spent Li-ion battery(LIB)cathodes through the resynthesis of cathode active materials(CAMs).The resynthesis process of CAMs,a promising recyclin...This review highlights the importance of recovering valuable metals from spent Li-ion battery(LIB)cathodes through the resynthesis of cathode active materials(CAMs).The resynthesis process of CAMs,a promising recycling method that directly produces CAM precursors from LIB leachate,is explored.This process encompasses six key steps,including pretreatment,leaching,purification,adjustment of metal concentrations,precursor synthesis,and sintering.The review also investigates the potential introduction of impurity elements during CAM resynthesis and provides tolerance levels for these impurities based on thorough reference analysis.Additionally,it addresses challenges related to the commercialization of the resynthesis process.Notably,this review represents the first comprehensive assessment of CAM resynthesis,including the systematic evaluation of 12 impurity elements(Fe,Li,Al,Cu,C,P,F,Na,Cl,S,Mg,and Zn).Overall,this comprehensive review is poised to support the commercial development of resynthesized CAMs by offering valuable guidelines for managing impurities and streamlining the purification process.展开更多
Convenience rice has become widely popular due to its easy availability for cooking. This study investigated the starch structure and composition of leachate and the microstructure of reheated convenience rice using n...Convenience rice has become widely popular due to its easy availability for cooking. This study investigated the starch structure and composition of leachate and the microstructure of reheated convenience rice using novel processing technologies: super-heated steaming(SHS), auto-electric cooking(AEC), and pressurized-steam cooking(PSC). Additionally, the effect of two different target water contents(58% and 63%) was also evaluated. The PSC_63% sample had the highest total solids and amylopectin amount in the leachate. The amylopectin amount in the leachate differed significantly based on the targeted water content. Morphological characterization revealed that the swelling of starch and the coated layer on the surface of rice grains were most pronounced in the PSC_63% sample due to the pressure processing. The textural hardness of the AEC_58% sample was much higher than that of the other samples. The PSC_63% sample had the highest textural adhesiveness value, which can be attributed to the highest amylopectin amount in the leachate. Sensory characterization showed that the PSC_63% sample had the highest glossiness, whiteness, moistness, and overall acceptability. The principal component analysis score plots presented substantial differences in the leachate and textural and sensory characteristics of reheated convenience rice among the different processing technologies.展开更多
In this study,to efficiently remove Pb(Ⅱ) from aqueous environments,a novel L-serine-modified polyethylene/polypropylene nonwoven fabric sorbent(NWF-serine)was fabricated through the radiation grafting of glycidyl me...In this study,to efficiently remove Pb(Ⅱ) from aqueous environments,a novel L-serine-modified polyethylene/polypropylene nonwoven fabric sorbent(NWF-serine)was fabricated through the radiation grafting of glycidyl methacrylate and subsequent L-serine modification.The effect of the absorbed dose was investigated in the range of 5–50 kGy.NWF-serine was characterized by Fourier transform infrared spectroscopy,thermogravimetric analysis,and scanning electron microscopy.Batch adsorption tests were conducted to investigate the influences of pH,adsorption time,temperature,initial concentration,and sorbent dosage on the Pb(Ⅱ) adsorption performance of NWF-serine.The results indicated that Pb(Ⅱ) adsorption onto NWF-serine was an endothermic process,following the pseudo-second-order kinetic model and Langmuir isotherm model.The saturated adsorption capacity was 198.1 mg/g.NWF-serine exhibited Pb(Ⅱ) removal rates of 99.8% for aqueous solutions with initial concentrations of 100 mg/L and 82.1% for landfill leachate containing competitive metal ions such as Cd,Cu,Ni,Mn,and Zn.Furthermore,NWF-serine maintained 86% of its Pb(Ⅱ) uptake after five use cycles.The coordination of the carboxyl and amino groups with Pb(Ⅱ) was confirmed using X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis.展开更多
Dump sites pose a significant threat to groundwater resources due to the possibility of leachate leakage into the aquifer.This study investigated the impact of leachate on groundwater quality in the southwest region o...Dump sites pose a significant threat to groundwater resources due to the possibility of leachate leakage into the aquifer.This study investigated the impact of leachate on groundwater quality in the southwest region of Zanjan City,Iran,where groundwater is utilized for drinking,agricultural,and industrial purposes.We analyzed 18 parameters of dump site leachate,including physicochemical,heavy metals,and bacterial properties,alongside 13 groundwater samples.Sampling was conducted twice,in November 2020 and June 2021,within a five-kilometer radius of the Zanjan dump site.We utilized the Leachate Pollution Index(LPI)to evaluate potential groundwater contamination by leachate leakage from nearby dumpsite.Additionally,due to the predominant agricultural activities in the study area,various indices were employed to assess groundwater quality for agricultural purposes,such as Sodium Adsorption Ratio(SAR),Soluble Sodium Index(SSI),Kelly Ratio(KR),and Permeability Index(PI).Our analysis revealed no observed contamination related to leachate in the study area according to the LPI results.However,with the persistent pollution threat,implementing sanitary measures at the dump site is crucial to prevent potential impacts on groundwater quality.Moreover,the assessment of groundwater quality adequacy for irrigation yielded satisfactory results for SAR,KR,and PI indices.However,during both the dry(November 2020)and wet seasons(June 2021),the SSP index indicated that 80%of the samples were not classified as excellent,suggesting groundwater may not be suitable for agriculture.Overal,our qualitative study highlights the significant impact of the dry season on groundwater quality in the study area,attributed to elevated concentration levels of the investigated parameters within groundwater sources during the dry season.展开更多
Fecal coliform bacteria such as Escherichia coli (E. coli) are one of the main sources of groundwater pollution. An assessment of the transport and Persistence of E. coli in poultry litter amended Decatur silty Clay s...Fecal coliform bacteria such as Escherichia coli (E. coli) are one of the main sources of groundwater pollution. An assessment of the transport and Persistence of E. coli in poultry litter amended Decatur silty Clay soil and Hartsells Sandy soil was conducted using soil columns and simulated groundwater leaching. Enumeration of initial E. coli was determined to range from 2.851 × 10<sup>3</sup> to 3.044 × 10<sup>3</sup> CFU per gram of soil. These results have been used in a batch study to determine the persistence rate of E. coli in Decatur silty Clay soil and Hartsells Sandy soil. Results prove that E. coli survival growth rate increases for clay soil later than and at a higher rate than sandy soil. The column study has determined that E. coli was transported at a rate of 3.7 × 10<sup>6</sup><sup> </sup>CFU for Decatur silty loam and 6.3 × 10<sup>6</sup><sup> </sup>CFU for Hartsells sandy per gram of soil. Further, linear regression analysis predictions show higher porosity and soil moisture content affect transport, and Hartsells sandy soil has higher transport of E. coli due to its higher porosity and lower volumetric water content.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
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.
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.
基金supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (2023R1A2C100571511,RS-2023-00254424)the Ministry of Education(2020R1A6A1A03038540)。
文摘As the global electric vehicle market continues to grow,the recycling of Li-ion battery (LIB) becomes more important worldwide and the resynthesis of cathode materials would be the most value-added recycling approach taking into account limited metal resources.Although resynthesized homogenous LiNi_(x)Co_(y)Mn_(z)O_(2)(NCM) from spent LIB leachate shows comparable battery performance to pristine NCM from virgin materials,there is general concern in its cycling performance.Here,we synthesize core–shell(CS) Ni-rich NCM,which consists of Ni-rich NCM as the core and NCM derived from the original or purified leachate of spent LIBs as the shell.Resynthesized CS Ni-rich NCM exhibits improved rate capability resulting from expanded interslab thickness in the NCM structure.CS Ni-rich NCM from purified LIB leachate shows improvement in cycling performance and thermal stability.It specifically delivers a capacity retention of 86.6%at a high temperature after 80 cycles compared to that (75.0%) of pristine CS Ni-rich NCM.These improvements are caused by a relatively high Mg content on the shell and the widespread distribution of Al through the CS structure.CS Ni-rich NCM derived from spent LIB leachate provides a new alternative approach to conventional LIB recycling methods,which would utilize efficiently limited metal resources for the sustainable LIB production.
文摘Groundwater contamination near landfills is commonly caused by leachate leakage,and permeable reactive barriers(PRBs)are widely used for groundwater remediation.However,the deactivation and blockage of the reactive medium in PRBs limit their long-term effectiveness.In the current study,a new methodology was proposed for the in situ regeneration of PRB to remediate leachate-contaminated groundwater.CO_(2)coupled with oxidants was applied for the dispersion and regeneration of the fillers;by injecting CO_(2)to disperse the fillers,the permeability of the PRB was increased and the oxidants could flow evenly into the PRB.The results indicate that the optimumfiller proportion was zero-valent iron(ZVI)/zeolites/activated carbon(AC)=3:8:10 and the optimum oxidant proportion was COD/Na_(2)S_(2)O_(8)/H_(2)O_(2)/Fe^(2+)=1:5:6:5;the oxidation system of Fe^(2+)/H_(2)O_(2)/S_(2)O_(8)^(2−)has a high oxidation efficiency and persistence.The average regeneration rate of zeolites was 72.71%,and the average regeneration rate of AC was 68.40%;the permeability of PRB also increased.This technology is effective for the remediation of landfills in China that have large contaminated areas,an uneven pollutant concentration distribution,and a long pollution duration.The purification mode of long-term adsorption and short-time in situ oxidation can be applied to the remediation of long-term high-concentration organically polluted groundwater,where pollution sources are difficult to cut off.
基金Project supported by the Brazilian National Council for Scientific and Technological Development/CNPq(405982/2022—4,303992/2021-2)。
文摘In this study,vine pruning wastes(VPW)were used as raw material to develop an alternative activated carbon(VPW-AC)for adsorbing and concentrating rare earth elements cerium(Ce(Ⅲ))and lanthanum(La(Ⅲ))from synthetic and real leachate solutions.The Ce and La adsorption studies evaluated the effects of VPW-AC dosage,pH,contact time,rare earth initial concentration,and temperature.The VPW-AC adsorbent was subjected to many physicochemical characterization methods to correlate and understand its adsorptive performance.The characterization data indicate a carbonaceous adsorbent with a specific surface area of 467 m^(2)/g.Zeta potential indicates a material with a negatively charged surface at a pH higher than 3.1,which is extremely beneficial to cations removal.For both rare earths elements(REEs),the adsorption capacity increases with the increase of the pH,reaching its maximum at pH 4-6.The kinetic data are well fitted by Avrami-fractional o rder,while the Liu model agreeably fits equilibrium data.The maximum adsorption capacities for Ce(Ⅲ)and La(Ⅲ)are 48.45 and 53.65 mg/g at 298 K,respectively.The thermodynamic studies suggest that the adsorption process is favorable,spontaneous,and exothermic for both REEs.Pore filling,surface complexation,and ion exchange are the dominant mechanisms.Finally,the VPW-AC was subjected to the recovery of REEs from real phosphogypsum leachate,and it is proved that it can be successfully used to recover REEs in a real process.
基金supported by the National Natural Science Foundation of China (Nos.52000016 and 51578642)the Major program of Science and Technology of Anhui Province (No.202103a07020016)。
文摘Fouling of landfill leachate,a biofilm formation process on the surface of the collection system,migration pipeline and treatment system causes low efficiency of leachate transportation and treatment and increases cost for maintenance of those facilities.In addition,landfill leachate fouling might accumulate pathogens and antibiotic resistance genes(ARGs),posing threats to the environment.Characterization of the landfill leachate fouling and its associated environmental behavior is essential for the management of fouling.In this study,physicochemical and biological properties of landfill leachate fouling and the possible accumulation capacity of pathogens and ARGs were investigated in nitrification(aerobic condition)and denitrification(anaerobic condition)process during landfill leachate biological treatment,respectively.Results show that microbial(bacterial,archaeal,eukaryotic,and viral)community structure and function(carbon fixation,methanogenesis,nitrification and denitrification)differed in fouling under aerobic and anaerobic conditions,driven by the supplemental leachate water quality.Aerobic fouling had a higher abundance of nitrification and denitrification functional genes,while anaerobic fouling harbored a higher abundance of carbon fixation and methanogenesis genes.Both forms of leachate fouling had a higher abundance of pathogens and ARGs than the associated leachate,suggesting the accumulation capacity of fouling on biotic pollutants.Specifically,aerobic fouling harbored three orders of magnitude higher multidrug resistance genes mex D than its associated leachate.This finding provides fundamental knowledge on the biological properties of leachate fouling and suggests that leachate fouling might harbor significant pathogens and ARGs.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(Ministry of Science and ICT(RS-2023-00254424)Ministry of Education(2020R1A6A1A03038540))。
文摘This review highlights the importance of recovering valuable metals from spent Li-ion battery(LIB)cathodes through the resynthesis of cathode active materials(CAMs).The resynthesis process of CAMs,a promising recycling method that directly produces CAM precursors from LIB leachate,is explored.This process encompasses six key steps,including pretreatment,leaching,purification,adjustment of metal concentrations,precursor synthesis,and sintering.The review also investigates the potential introduction of impurity elements during CAM resynthesis and provides tolerance levels for these impurities based on thorough reference analysis.Additionally,it addresses challenges related to the commercialization of the resynthesis process.Notably,this review represents the first comprehensive assessment of CAM resynthesis,including the systematic evaluation of 12 impurity elements(Fe,Li,Al,Cu,C,P,F,Na,Cl,S,Mg,and Zn).Overall,this comprehensive review is poised to support the commercial development of resynthesized CAMs by offering valuable guidelines for managing impurities and streamlining the purification process.
基金supported by the High Value-added Food Technology Development Program in Korea (Grant No. 323002-4)the Korea Institute of Planning and Evaluation for Technology in Food, Agriculture and Forestry, Republic of Korea。
文摘Convenience rice has become widely popular due to its easy availability for cooking. This study investigated the starch structure and composition of leachate and the microstructure of reheated convenience rice using novel processing technologies: super-heated steaming(SHS), auto-electric cooking(AEC), and pressurized-steam cooking(PSC). Additionally, the effect of two different target water contents(58% and 63%) was also evaluated. The PSC_63% sample had the highest total solids and amylopectin amount in the leachate. The amylopectin amount in the leachate differed significantly based on the targeted water content. Morphological characterization revealed that the swelling of starch and the coated layer on the surface of rice grains were most pronounced in the PSC_63% sample due to the pressure processing. The textural hardness of the AEC_58% sample was much higher than that of the other samples. The PSC_63% sample had the highest textural adhesiveness value, which can be attributed to the highest amylopectin amount in the leachate. Sensory characterization showed that the PSC_63% sample had the highest glossiness, whiteness, moistness, and overall acceptability. The principal component analysis score plots presented substantial differences in the leachate and textural and sensory characteristics of reheated convenience rice among the different processing technologies.
基金supported by the National Natural Science Foundation of China(Nos.11605275 and 11675247)。
文摘In this study,to efficiently remove Pb(Ⅱ) from aqueous environments,a novel L-serine-modified polyethylene/polypropylene nonwoven fabric sorbent(NWF-serine)was fabricated through the radiation grafting of glycidyl methacrylate and subsequent L-serine modification.The effect of the absorbed dose was investigated in the range of 5–50 kGy.NWF-serine was characterized by Fourier transform infrared spectroscopy,thermogravimetric analysis,and scanning electron microscopy.Batch adsorption tests were conducted to investigate the influences of pH,adsorption time,temperature,initial concentration,and sorbent dosage on the Pb(Ⅱ) adsorption performance of NWF-serine.The results indicated that Pb(Ⅱ) adsorption onto NWF-serine was an endothermic process,following the pseudo-second-order kinetic model and Langmuir isotherm model.The saturated adsorption capacity was 198.1 mg/g.NWF-serine exhibited Pb(Ⅱ) removal rates of 99.8% for aqueous solutions with initial concentrations of 100 mg/L and 82.1% for landfill leachate containing competitive metal ions such as Cd,Cu,Ni,Mn,and Zn.Furthermore,NWF-serine maintained 86% of its Pb(Ⅱ) uptake after five use cycles.The coordination of the carboxyl and amino groups with Pb(Ⅱ) was confirmed using X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis.
文摘Dump sites pose a significant threat to groundwater resources due to the possibility of leachate leakage into the aquifer.This study investigated the impact of leachate on groundwater quality in the southwest region of Zanjan City,Iran,where groundwater is utilized for drinking,agricultural,and industrial purposes.We analyzed 18 parameters of dump site leachate,including physicochemical,heavy metals,and bacterial properties,alongside 13 groundwater samples.Sampling was conducted twice,in November 2020 and June 2021,within a five-kilometer radius of the Zanjan dump site.We utilized the Leachate Pollution Index(LPI)to evaluate potential groundwater contamination by leachate leakage from nearby dumpsite.Additionally,due to the predominant agricultural activities in the study area,various indices were employed to assess groundwater quality for agricultural purposes,such as Sodium Adsorption Ratio(SAR),Soluble Sodium Index(SSI),Kelly Ratio(KR),and Permeability Index(PI).Our analysis revealed no observed contamination related to leachate in the study area according to the LPI results.However,with the persistent pollution threat,implementing sanitary measures at the dump site is crucial to prevent potential impacts on groundwater quality.Moreover,the assessment of groundwater quality adequacy for irrigation yielded satisfactory results for SAR,KR,and PI indices.However,during both the dry(November 2020)and wet seasons(June 2021),the SSP index indicated that 80%of the samples were not classified as excellent,suggesting groundwater may not be suitable for agriculture.Overal,our qualitative study highlights the significant impact of the dry season on groundwater quality in the study area,attributed to elevated concentration levels of the investigated parameters within groundwater sources during the dry season.
文摘Fecal coliform bacteria such as Escherichia coli (E. coli) are one of the main sources of groundwater pollution. An assessment of the transport and Persistence of E. coli in poultry litter amended Decatur silty Clay soil and Hartsells Sandy soil was conducted using soil columns and simulated groundwater leaching. Enumeration of initial E. coli was determined to range from 2.851 × 10<sup>3</sup> to 3.044 × 10<sup>3</sup> CFU per gram of soil. These results have been used in a batch study to determine the persistence rate of E. coli in Decatur silty Clay soil and Hartsells Sandy soil. Results prove that E. coli survival growth rate increases for clay soil later than and at a higher rate than sandy soil. The column study has determined that E. coli was transported at a rate of 3.7 × 10<sup>6</sup><sup> </sup>CFU for Decatur silty loam and 6.3 × 10<sup>6</sup><sup> </sup>CFU for Hartsells sandy per gram of soil. Further, linear regression analysis predictions show higher porosity and soil moisture content affect transport, and Hartsells sandy soil has higher transport of E. coli due to its higher porosity and lower volumetric water content.
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.
