Landfills are the most widely used method for municipal solid waste (MSW) disposal method in China. However, these facilities have caused serious groundwater contamination due to the leakage of ...leachate. This study, analyzed 32 scientific papers, a field survey and an environmental assessment report related to groundwater contamination caused by landfills in China. The groundwater quality in the vicinity of landfills was assessed as “very bad” by a comprehensive score (FI) of 7.85 by the Grading Method in China. Variety of pollutants consisting of 96 groundwater pollutants, 3 organic matter indicators, 2 visual pollutants and 6 aggregative pollutants had been detected in the various studies. Twenty-two kinds of pollutants were considered to be dominant. According to the Kruskal-Wallis test and the median test, groundwater contamination differed significantly between regions in China, but there were no significant differences between dry season and wet season measurements, except for some pollutants in a few landfill sites. Generally, the groundwater contamination appeared in the initial landfill stage after five years and peaked some years afterward. In this stage, the Nemerow Index (PI) of groundwater increased exponentially as landfill age increased at some sites, but afterwards decreased exponentially with increasing age at others. After 25years, the groundwater contamination was very low at selected landfills. The PI values of landfills decreased exponentially as the pollutant migration distance increased. Therefore, the groundwater contamination mainly appeared within 1000m of a landfill and most of serious groundwater contamination occurred within 200m. The results not only indicate that the groundwater contamination near MSW landfills should be a concern, but also are valuable to remediate the groundwater contamination near MSW landfills and to prevent the MSW landfill from secondary pollutions, especially for developing countries considering the similar situation of MSW disposal.
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•96 groundwater pollutants, 2 visual and 7 aggregative pollutants were detected.•Groundwater quality was “very bad” in the vicinity of landfills in China.•Groundwater contamination differed significantly between regions in China.•Groundwater contamination trend coincided with change of leachate quality.•Groundwater contamination decreased exponentially as migration distance increases.
Leachate generation is a major problem for municipal solid waste (MSW) landfills and causes significant threat to surface water and groundwater. Leachate can be defined as a liquid that passes ...through alandfill and has extracted dissolved and suspended matter from it. Leachate results from precipitation entering the landfill from moisture that exists in the waste when it is composed. This paper presents the results of the analyses of leachate treatment from the solid waste landfill located in Borg El Arab landfill in Alexandria using an aerobic treatment process which was applied using the mean of coagulation flocculation theory by using coagulant and accelerator substances for accelerating and improving coagulation and flocculation performance.
The main goal of this study is to utilize a natural low cost material “as an accelerator additive to enhance the chemical treatment process using Alum coagulant and the accelerator substances were Perlite and Bentonite. The performance of the chemical treatment was enhanced using the accelerator substances with 90mg/l Alum as a constant dose. Perlite gave better performance than the Bentonite effluent. The removal ratio for conductivity, turbidity, BOD and COD for Perlite was 86.7%, 87.4%, 89.9% and 92.8% respectively, and for Bentonite was 83.5%, 85.0%, 86.5% and 85.0% respectively at the same concentration of 40mg/l for each.
Leachate produced from hazardous waste landfills (HWLs) is toxic and contain high concentration of refractory organics, ammoniacal-nitrogen, heavy metals, inorganic salts and organo-chloro compounds. ...Various Advanced Oxidation Processes (AOPs) have been developed in last few decades for efficiently treating the landfill leachate and many are still under development. Researchers have reviewed the performance of conventional AOPs for treating leachate produced from municipal solid waste landfills (MSWLs) but as this leachate is entirely different in characteristics from HWL leachate, these studies are not very useful when it comes to management of HWL leachate; also, specific studies focused on HWL leachate are rarely available. Present study critically reviews various AOPs involving ozone, UV radiation, hydrogen peroxide, electrocoagulation and electrochemical oxidation for their mechanism, treatment efficacy, advantages and limitations with a focus on HWL leachate. A brief review of emerging AOPs like wet air oxidation, hydrodynamic cavitation and ultrasound assisted AOPs is also discussed. This study also aims to identify the AOP which is user friendly, capable to treat the HWL leachate efficiently, discourage the use of chemicals and can be operated at ambient temperature and pressure. After thorough review of different AOPs, Electrocoagulation appears to be a very promising and effective AOP involving in-situ generation of coagulants and converting the organic pollutants in simpler and noble compounds like carbon dioxide and water. Electrocoagulation can be considered as one of the greener and cleaner technology for treatment of HWL leachate, which on optimization can result in a reduction of COD up to 60% along with considerable decrease in metal content in range of 70%–90% and has further potential of improvement and research.
•Necessity of AOPs for treating leachate from hazardous waste landfill.•Mechanism of various AOPs along with their limitations critically reviewed.•Extensive datasheet compiled for leachate treatment efficiency of various AOPs.•AOPs: Research hot spot to treat hazardous waste landfill leachate.•Electrocoagulation: A cleaner process comparative to chemical based AOPs.
The municipal solid waste landfill (MSWL) is an important source of microplastics (MPs) and a huge bioreactor for plastic-degrading microorganisms (PDM). However, the spatiotemporal distribution and ...degradation mechanisms of MPs in MSWLs are unclear. Therefore, they were studied using the samples drilled in a sanitary landfill (SL) and an non-sanitary landfill (NSL). The results showed that there were a lot of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyurethane (PU), Polyamide (PA), Polyethylene terephthalate (PET) and Polyvinyl chloride (PVC) in the landfill, and their abundance ranged from 0 to 80 items/g. The MPs surface gradually faded, became rough and even yielded cracks and holes with the landfill depth and age increase. The tiny-size MPs (< 100 µm) were the most abundant and their amount significantly increased from 28.14% to 49.13% in SL and from 24.54% to 59.51% in NSL, respectively, while large-size MPs were significantly reduced from the top to the bottom. Lysinibacillus (0.21%~67.87%) and Bacillus (0.10%~67.00%) were the dominate PDMs in SL and Candidatus_Caldatribacterium (5.06%~73.48%) was the dominate in NSL. The PE degradation was closely related to Candidatus_Cloacimonas (r = 0.688*) and Candidatus_Caldatribacterium (r = 0.680*); PS and PA were closely related to Candidatus_Contubernalis (r = 0.595*~0.705*) and PVC was closely related to Candidatus_Caldatribacterium (r = 0.547*). In addition to physical and chemical effects, biological effects can also promote the MPs formation in MSWLs.
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•MPs abundance was increased with landfill depth.•The amount of < 100 µm MPs were significantly increased with landfill depth.•MPs surface gradually faded, became rough and yielded cracks with landfill depth.•Lysinibacillus(0.21%~67.87%) and Bacillus(0.10%~67.00%) were the dominate PDMs in SL.•Candidatus_Caldatribacterium(5.06%~73.48%) was the dominate PDMs in NSL.
Landfill sites are regarded as sources of volatile compounds (VOCs) and odors emitted to the atmosphere. Surface emissions of VOCs and odors were investigated in a rural domestic waste landfill site ...located in southwest China. A total of 76 chemical compounds belonging to 3 chemical families were identified and quantified. The total number of VOCs (TVOC) detected ranged from 18.1 to 806.3 mg/m3, while odorous gases and greenhouse gases ranged from 0.4 to 21.2 and 0–100.5 mg/m3, respectively. High emissions were found in the air surrounding the leachate storage pool (LSP) and dumping area (DPA). The dominant species of VOCs were hexaldehyde, m-xylene, propylene oxide, acetophenone, and 2-butanone. The traceability analysis showed that the odors and VOCs diffused to the downwind boundary mainly came from the DPA and LSP. According to the olfactory effect analysis and cancer risk assessment, the main odor-causing gaseous pollutants were hydrogen sulfide, propionic acid, styrene, and 2-pentanone, while benzene, trichlorethylene, and 1,3-butadiene were the dominant carcinogens. This study provides new insights into the emission characteristics, olfactory effects, and cancer risks of VOCs and odors emitted from rural domestic solid waste landfill sites.
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•VOCs, odors, and greenhouse gases showed a site-related variation.•High emissions of VOCs were found in the areas of dumping and leachate treatment.•Oxygenated compounds were the main category of concern in VOCs.•H2S, propionic acid, styrene and 2-pentanone were the main gases causing odor.•Benzene, trichlorethylene, and 1,3-butadiene were the dominant carcinogens.
Landfill sites are sources of gaseous volatile compounds. The dumping area (LDA) and leachate storage pool (LSP) of two typical rural domestic waste landfill sites in north China (NLF) and southwest ...China (SLF) were investigated. We found that 45, 46, 61 and 68 volatile organic compounds (VOC) were present in the air of NLF-LDA, NLF-LSP, SLF-LDA, and SLF-LSP, respectively. And there were 27, 29, 35 and 37 kinds of odorous compounds being detected. Oxygenated compounds (>48.88%), chlorinated compounds (>6.85%), and aromatics (>5.46%), such as organic acid, 1-chlorobutane, and benzene, were the most abundant compounds in both landfills. The SLF-LDA had the highest olfactory effect, with a corresponding total odor activity value of 29,635.39. The ozone-formation potential analysis showed that VOCs emitted from SLF landfills had significantly higher potential for ozone formation than those from NLF landfills, with ozone generation potentials of 166.02, 225.86, 2511.82, and 1615.99 mg/m3 for the NLF-LDA, NLF-LSP, SLF-LDA, and SLF-LSP, respectively. Higher chronic toxicity and cancer risk of VOCs were found in the SLF according to method of Risk Assessment Information System. Based on the sensitivity analysis by the Monte Carlo method, concentrations of benzene, propylene oxide, propylene, trichloroethylene, and N-nitrosodiethylamine, along with exposure duration, daily exposure time, and annual exposure frequency, significantly impacted the risk levels. We provide a scientific basis, which reflects the need for controlling and reducing gaseous pollutants from landfills, particularly rural residential landfills, which may improve rural sanitation.
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•Identification and impact assessment of VOCs generated from two landfill sites.•Main VOCs types that escaped from two landfills are oxygenated compounds.•Types and relative abundance of VOCs released presented regional variations.•Olfactory effects are significant in the northern landfill.•Higher chronic toxicity and cancer risk of VOCs were found in southern landfill.
Since municipal solid waste (MSW) landfill harbours miscellaneous wastes, pollutants and microorganisms, it gradually becomes a huge potential reservoir for breeding antibiotic resistance genes ...(ARGs). The objective of this study was to determine the prevalence and diversity of ARGs associated with various mobile genetic elements (MGEs) in MSW landfill leachates. The relationship of ARGs with leachate characteristics was also studied to explore the influence of landfill age. Seven sulfonamides (sulfapyridine, sulfadiazine, sulfathiazole, sulfamethoxazole, sulfamerazine, sulfamethazine and sulfaquinoxaline), three encoded ARGs (sul-I, sul-II and sul-III) and four types of MGEs (plasmids, transposons, integrons and insertion sequences) were quantified in leachates with landfill ages ranging from 3 months–6 years. ARGs increased to an absolute concentration of 106 copies/μL and were positively correlated (p < 0.05) to MGEs. Significant correlations (p < 0.05) were also discovered among ARGs and the increasing humic acids, heavy metals (Zn, Cu and Co) and antibiotics (except for sulfathiazole and sulfaquinoxaline), implying landfilling might contribute to the enrichment of ARGs in the long-term. Non-target full scans revealed the role of persistent unknown compounds in stimulating the ARGs dissemination. Overall, this study demonstrates the exacerbation of ARGs pollution in landfill environment and a detailed delineation of the complex inter-relationships between ARGs and the substances harbouring in landfills is badly required.
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•ARGs copies increase with the age of MSW landfill leachates.•ARGs copies positively correlate to antibiotics, heavy metals and MGEs.•MGEs in landfills facilitate the prolonged HGT in dissemination of ARGs.•Non-target full scans reveal the role of unknown compounds in promoting ARGs.•Humic acids plays the vital role in stimulating ARGs in the long-term.
•The MSW generation is related to social index, economic index and population index.•The Grey Relational Analysis method can improve the prediction performance accuracy.•The GRA-LSTM model precisely ...and accurately predict the MSW generation in Beijing.•Advice for urban development are proposed from the MSW source and the MSW disposal.
Achieving accurate prediction of the Municipal Solid Waste (MSW) generation is essential for the sustainable development of the city. This paper selects Beijing as the research object, building a neural network model based on Grey Relational Analysis and Long and Short-Term Memory (GRA-LSTM), and choosing 14 influencing factors of MSW generation as the input indicators, to realize the effective prediction of MSW generation. Then this study obtains the landfill area in Beijing by using the aforementioned prediction results and the calculation formula of the landfill. Firstly, the GRA method is used to sort the influencing factors of the MSW generation for obtain the key influencing indexes. Secondly, the LSTM model is used to learn features of the key influencing indexes. Finally, the area of Beijing landfill is estimated by the calculation formula of landfill area. The results show that, first of all, the MAPE value of the GRA-LSTM combined model established in this paper is 7.3, and the prediction performance of this model is better than the other seven structural methods. Secondly, the area demand for landfills in Beijing shows an upward trend. At last, this paper put forward relevant suggestions to achieve sustainable urban development and deal with the increase in the MSW generation and the demand for landfills.
This study focused on the removal of sulphur compounds from a high-strength leachate of a hazardous industrial waste landfill. Firstly, sulphides (0.5 g L−1) and sulphites (2.5 g L−1) were catalytic ...oxidised at natural pH (8.7). Air or H2O2 were applied as oxidants and metals present in the leachate were used as catalysts. Distinct air flow rates and H2O2:sulphur molar ratios were tested. Concentrations of sulphide and sulphite lower than 1.0 mg L−1 (emission limit value - ELV) were obtained after 5-h oxygenation or 1-min peroxidation under the best conditions, i.e. air flow rate of 1 Lair Lleachate−1 min−1 and H2O2:sulphur stoichiometric ratio. Aeration was considered unsafe since >33 volatile organic compounds (VOCs) and hydrogen sulphide (H2S) were released to the atmosphere. Thus, only the H2O2-oxidised leachate pursued treatment. Sulphates (13 g L−1) were removed by chemical precipitation as ettringite or barite applying different reactants contents and pH values. Without pH correction, sulphate contents below 2.0 g L−1 (ELV) were achieved using a Ca2+:Al3+:SO42− molar ratio of 12:4:3 (2-fold stoichiometry) and a Ba2+:SO42− molar ratio of 1.0:1.0 (1-fold stoichiometry). The analysis of precipitates by X-ray diffraction (XRD) showed a three-phase ettringite (only 67% corresponding to ettringite itself) and single-phase barite. Barite precipitation proved to be more appealing since a value-added product was obtained and, furthermore, less reactants were required. After sulphur compounds removal using H2O2-driven catalytic oxidation and chemical precipitation through barite, the leachate was suitable for biological treatment, despite the high salinity, and a high fraction of the organic load (46%) could be biologically oxidised.
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•First study on desulphurization of a hazardous industrial waste landfill leachate.•Sulphur compounds discharge requirements attained by oxidation and precipitation.•Immediate removal of 100% sulphides/sulphites by H2O2-driven catalytic oxidation.•Release of VOCs and H2S during O2-driven catalytic oxidation.•Production of pure barite with added-value by sulphate chemical precipitation.
The article presents an overview of ways of solving the problem of dusting of raw materials and fine-grained waste collected on landfills. The specific physicochemical properties of loose materials ...and unfavorable atmospheric conditions are responsible of heavy pollution of the environment by dust, posing a threat to human health. The types of materials that are potential sources of dust pollution are presented. The methods of eliminating and limiting dusty of loose powders, often used in industry, engineering, communal and emergency situations, are discussed. Examples of domestic and foreign solutions to prevent dusting and to protect the waste deposit from erosion are shown. In conclusion, existing safety techniques have been found to be effective in preventing dusting of raw materials and waste.
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