Municipal Solid Waste Landfill Site Research Articles

Identification of prevalent leachate percolation of municipal solid waste landfill: a case study in India

Landfill leachate forms when waste-inherent water and percolated rainfall transfer are highly toxic, corrosive, acidic, and full of environmental pollutants. The release of leachate from municipal solid waste (MSW) landfill sites poses a severe hazard to human health and aquatic life. This study examined the impact of leachate from Delhi’s Ghazipur landfill on the nearby groundwater quality. Analysis of leachate samples was done to determine various parameters such as total dissolved solids (TDS), hardness, alkalinity, electrical conductivity, pH, BOD5, COD, nitrate, sulphate, chloride and iron, and presence of coliform bacteria. Significant dissolved elements (22,690–34,525 mg/L) were observed in the samples, indicated by the high conductivity value (1156–1405 mho/cm). However, a stable pH range (6.90–7.80) of leachate samples was observed due to high alkalinity concentrations between 2123 and 3256 mg/L. The inverse distance weighing (IDW) interpolation tool from QGIS 3.22.7 developed spatial interpolated models for each parameter across the Ghazipur area. The IDW interpolated graphs of various parameters over the whole study area confirmed these contaminations. In addition, leachate and groundwater samples were physio-chemically analyzed, and temporal fluctuation in landfill waste has also been studied. The temporal fluctuation results showed that when heat is produced, transmitted, and lost throughout the waste system, the maximum temperature position fluctuates over time. The findings of this study highlight the critical importance of landfill management in reducing groundwater contamination from MSW leachate.

Health risk assessment and characterization of PM2.5 bound bioaerosols at the municipal solid waste landfill site of Nagpur, India

Landfill being the reservoir of organic waste, serves as the most important source in the generation and emission of bioaerosols in the environment, and these bioaerosols have a significant impact on the environment and public health. In India, there are limited studies on the characterization of culturable bacteria and fungi in the bioaerosols originating from landfills. Therefore, the present study aimed to quantify and identify the bioaerosols and study their characteristics at a landfill site in Nagpur, India. The study describes the seasonal variation of PM2.5, PM2.5-associated bacteria and fungi in the landfill air, their molecular identification, antibiotic resistance, pathogenicity, dispersion and health risk assessment during winter and pre-monsoon seasons at the landfill site and surrounding residential sites in upwind and downwind directions. The study showed PM2.5 concentration was highest in the winter season (265.56 μg/m3) followed by the pre-monsoon season (173.1 μg/m3) at the landfill site. The culturable bioaerosol level was also significantly higher in winter (11056 CFU/m3) in comparison to pre-monsoon season (2244 CFU/m3) at the landfill site. Upon isolating and characterizing the microorganisms in the bioaerosols, some of the bacterial isolates, like Bacillus, Staphylococcus gallinarum, and Streptomyces speibonae were found to be resistant to chloramphenicol, netillin, nitrofurantoin, streptomycin etc. About 30% of the bacterial isolates were found to show β-hemolytic virulence activity. This indicated the presence of multi-drug resistant and potentially pathogenic bacteria in the bioaerosols over the landfill. The health risk assessment in adults indicated that the workers at the landfill site were at risk of bacterial aerosol in the winter season (hazard quotient i.e., HQ>1). The impact of bioaerosols on children needs to be investigated in the further studies and regular monitoring of bioaerosols is suggested to avoid any morbidity. To the best of our knowledge, this is the first study on the characterization of microorganisms from the bioaerosols over an open landfill site in India.

Effects of initial temperature and moisture content on heat generation during degradation of municipal solid waste

Heat generation from degradation of organic matter in municipal solid waste (MSW) often leads to increased landfill temperature. However, it is difficult to measure environmental heat loss in laboratory and field tests; therefore, little research has been conducted to evaluate heat generation during waste degradation under different initial temperatures and moisture contents. In this study, tests were conducted to investigate the effects of initial temperature and moisture content on heat generation during waste degradation. A simple formula for calculating heat generation was proposed. Within 200 h, the waste temperature decreased by about 70%, and lower initial moisture contents were associated with greater temperature decreases. The smallest temperature decrease of 47% and the greatest heat generation occurred when the initial temperature was 40 °C. The initial moisture content increased from 30% to 60% and the heat generation increased from 5% to 36%. The heat generation per unit mass of organic matter during the aerobic and anaerobic stages were 19.44–23.77 and 0.27–0.50 MJ·kg−1, respectively, indicating that the proposed formula for calculation of heat generated from waste degradation was reasonable. The results presented herein provide theoretical support for the prediction of heat generation and the recycling of heat resources in MSW landfill sites.

中国生活垃圾填埋场的水文地质分类及与地下水污染物迁移的关联性

中国生活垃圾填埋场的水文地质分类及与地下水污染物迁移的关联性

Characterization and Process Optimization for Enhanced Production of Polyhydroxybutyrate (PHB)-Based Biodegradable Polymer from Bacillus flexus Isolated from Municipal Solid Waste Landfill Site.

In recent years, there has been a growing interest in bio-based degradable plastics as an alternative to synthetic plastic. Polyhyroxybutyrate (PHB) is a macromolecule produced by bacteria as a part of their metabolism. Bacteria accumulate them as reserve materials when growing under different stress conditions. PHBs can be selected as alternatives for the production of biodegradable plastics because of their fast degradation properties when exposed to natural environmental conditions. Hence, the present study was undertaken in order to isolate the potential PHB-producing bacteria isolated from the municipal solid waste landfill site soil samples collected from the Ha'il region of Saudi Arabia to assess the production of PHB using agro-residues as a carbon source and to evaluate the growth of PHB production. In order to screen the isolates for producing PHB, a dye-based procedure was initially employed. Based on the 16S rRNA analysis of the isolates, Bacillus flexus (B. flexus) accumulated the highest amount of PHB of all the isolates. By using a UV-Vis spectrophotometer and Fourier-transform infrared spectrophotometer (FT-IR), in which a sharp absorption band at 1721.93 cm-1 (C=O stretching of ester), 1273.23 cm-1 (-CH group), multiple bands between 1000 and 1300 cm-1 (stretching of the C-O bond), 2939.53 cm-1 (-CH3 stretching), 2880.39 cm-1 (-CH2 stretching) and 3510.02 cm-1 (terminal -OH group), the extracted polymer was characterized and confirmed its structure as PHB. The highest PHB production by B. flexus was obtained after 48 h of incubation (3.9 g/L) at pH 7.0 (3.7 g/L), 35 °C (3.5 g/L) with glucose (4.1 g/L) and peptone (3.4 g/L) as carbon and nitrogen sources, respectively. As a result of the use of various cheap agricultural wastes, such as rice bran, barley bran, wheat bran, orange peel and banana peel as carbon sources, the strain was found to be capable of accumulating PHB. Using response surface methodology (RSM) for optimization of PHB synthesis using a Box-Behnken design (BBD) proved to be highly effective in increasing the polymer yield of the synthesis. With the optimum conditions obtained from RSM, PHB content can be increased by approximately 1.3-fold when compared to an unoptimized medium, resulting in a significant reduction in production costs. Thus, isolate B. flexus is a highly promising candidate for the production of industrial-size quantities of PHB from agricultural wastes and is capable of removing the environmental concerns associated with synthetic plastics from the industrial production process. Moreover, the successful production of bioplastics using a microbial culture provides a promising avenue for the large-scale production of biodegradable and renewable plastics with potential applications in various industries, including packaging, agriculture and medicine.

An Integrated GIS-AHP Approach for Municipal Solid Waste Landfill Siting in Srikakulam District, Andhra Pradesh

The availability of land for proper waste disposal is one of the most important and emerging potential challenges in most big cities. Although some attempts are being made to minimize and recover garbage, landfill disposal continues to be the dominant method of waste disposal. An improper landfill site can negatively impact the environment, the economy, and the environment. Thus, it should be carefully chosen, taking into consideration both rules and standards from other sources. To examine all aspects of this study, an integration of the “Geographic Information System (GIS)” and the “Analytic Hierarchy Process (AHP)” was incorporated for land-fill site selection. Various parameters were examined to make decisions about landfill site selection. These parameters included slope, elevation, soil texture, LULC, surface water, groundwater table, road network, historical areas, and residential areas. An analytic-hierarchy process was used to determine the relative importance of each parameter, and a final site suitability map was created. With an equal interval classification method, the final index model was categorized into four categories, which included “unsuitable”, “less suitable”, “moderately suitable” and “suitable”. As a result, 30.28% of the study area was less suitable, 28.49% was moderately suitable, 12.39% was suitable, and 28.84% of the study area was unsuitable for landfilling.

Application of integrated sequence of air stripping, coagulation flocculation, electrocoagulation and adsorption for sustainable treatment of municipal landfill leachate

Leachate generated from landfill is required to be treated by simple, fast, economic and environmentally sustainable methods before being discharged to the environment since it is considered as a highly pollutant wastewater. The aim of this research work is to check the potential treatability of integrated sequence of air stripping, coagulation flocculation, electrocoagulation and adsorption method for leachate generated from an uncontrolled municipal solid waste landfill site complying with legal discharge standard. At optimum retention period of 36 hours air stripping method exhibited a maximum removal of 96.87% of NH 4 -N, 74.5% of BOD 5 , 52.78% of COD, 8.7% of Hg and 18.43% of Pb from raw leachate at normal pH and air flow rate of 10 L/min. The application of optimized CF process using FeCl 3 as coagulant of dosage 3.09 mg/L resulted a maximum removal of 84.20% of BOD 5 , 57.67% of COD and 46.2% of Hg at pH 5.22. Following CF process EC process was adopted with Fe electrode and optimized by CCD of response surface methodology. At optimum pH 7.46, current density 3.13 mA/cm 2 and electrolysis time 24.83 min the maximum removal was recorded as 51.1% COD and 91.92% Hg. EDAX analysis confirmed the presence of Hg in the precipitates of ECP. Finally fixed bed column adsorption study using chitosan beads resulted in 98.11% of Hg removal. The integrated treatment sequence resulting an overall removal of 96.87% of NH 4 -N, 95.97% of BOD 5 , 90.23% of COD, and 99.93% of Hg which is sufficient enough to reduce pollutants of raw leachate below discharge standards at overall costs of USD 0.036/L. • Integrated sequence of multiple physicochemical treatment methods were used to reduce pollution load from raw municipal landfill leachate. • Process variables of electrocoagulation method were optimized by center composite design of response surface methodology. • EDAX confirmed the removal of Hg by electrocoagulation process using iron electrodes. • Low cost chitosan beads were used for adsorption. • The leachate discharge standard in inland surface water was achieved at nominal cost.

Determination of risk of spontaneous waste ignition and leachate quality for open municipal solid waste dumpsite

The waste receiving capacity of most municipal solid waste (MSW) landfill sites in India is exhausted, resulting in the formation of larger waste heaps. In the majority of Indian cities, these old waste heaps are prone to frequent smoldering and ignition resulting into fires. In this study, the potential risk of spontaneous ignition of landfilled waste at landfill surface was analyzed based on the physico-chemical characteristics of waste, carbon monoxide (CO) levels, landfill surface temperature (LST). The leachate pollution index was also determined to analyze the leachate quality for three different seasons (monsoon, pre-monsoon and post-monsoon). The regression analysis was carried out to understand the thermal properties (smoldering temperature, smoldering time, ignition temperature etc.) of MSW. The results showed that old waste has a higher tendency to undergo ignition compared to fresh waste. It has also been observed that the lower MC of old waste samples in the range of 3.4% and 18.2% is the most likely cause of early smoldering (106.6–109.5 °C) and ignition (198.6–208.4 °C) of old waste. In pre-monsoon season, CO concentrations for sub-surface (10–30 cm depth) smoldering events (SSE) were observed to be between ∼ 150 to 200 ppm. This CO level substantially dropped to 10 ± 1 ppm in the post-monsoon season. The estimation of the leachate pollution index (LPI) showed an index score of 27.35, 30.47 and 10.71 for pre-monsoon, monsoon and post-monsoon seasons, respectively. The determination of CO levels, increased LST and physico-chemical properties of landfilled waste will greatly assist in the abatement of environmental pollution arising from landfill fires.

Comparison of AHP and TOPSIS methods in municipal solid waste landfill site selection of Songhor County

Comparison of AHP and TOPSIS methods in municipal solid waste landfill site selection of Songhor County

Environmental risk assessment and factors influencing heavy metal concentrations in the soil of municipal solid waste landfills.

The environmental risk assessment and the factors influencing heavy metals (HM) in the soil at the municipal solid waste landfill sites (MSWLs) were studied by literature review, field survey, and statistical methods. The results indicated that the dominant HM contamination in the soil at the MSWLs was caused by chromium (Cr) with the Nemero index values (PI) from 22.7 to 44.3 and zinc (Zn) with the PI from 0.7 to 9.8. There were significant differences in the Cr, mercury (Hg), lead (Pb), Zn, and arsenic (As) concentrations between soil samples from sanitary and non-sanitary landfills (NSLs) where HM contamination (PI=10.9) was more obvious. As (CRAAs=2.35×10-4) and cadmium (Cd) (CRACd=1.45×10-4) posed potential carcinogenic health effects. The soil Cd concentration had a significant negative correlation (r=-0.476**) with the landfill age. The soil As concentration had a significant positive correlation (r=0.472**) with rainfall in NSLs. There were significant differences in the As (P=0.042) and copper (Cu) (P=0.042) concentrations between soil samples from the surrounding areas of MSWLs and the base where soil had higher HM concentrations. For the efficient prevention of HM ecological risk, a scientific site selection, undamaged coverage and anti-seepage systems, standardized management, and ongoing monitoring are required.

Retarding performance of the vadose zone for nitrogen pollutants derived from municipal solid waste landfills in the red bed zone

Nitrogen pollutants such as ammonia and nitrates cause soil and groundwater contamination at municipal solid waste landfill (MSWL) sites due to leachate leakage. Here, the migration of nitrogen pollutants in the vadose zone of the red bed (VZRB) at a MSWL site was studied by static adsorption batch experiments and one-dimensional simulated migration experiments. The results indicated that the soil in the red bed did not adsorb nitrates. Chemical adsorption and monolayer adsorption of the soil played dominant roles during ammonia adsorption in the VZRB, which was best fitted by the pseudo-second-order kinetic equation (RNH4+2 = 0.99) and the Langmuir model. The ammonia adsorption capacity of the soil was the highest (Qm = 2.041 mg·g−1) at 318 K. It was due to the endothermic and non-spontaneous chemical adsorption of ammonia, whose enthalpy change (ΔH) reached 20.995 kJ·mol−1 and Gibbs free energy ranged from 8.469 to 8.706 kJ·mol−1. Chloride penetration tests indicated that the diffusion coefficient and migration speed reached 0.0515 cm2·h−1 and 0.0833 cm·h−1, respectively, in the clay layer under the MSWL sites. The average hysteresis diffusion coefficients of ammonia in the simulated soil columns leached by ammonium chloride solution (SSCAC) and by the leachate from MSWL (SSCL) were 1.129 and 1.400, respectively. After the leaching experiments, the clay pore structure was saturated, and the specific surface area decreased. The absorption peak intensities of clay functional groups, including carboxyl, alkyne, and hydroxyl groups, were reduced. The ammonia content in the soil of SSCAC decreased from the top (14.51 mg·kg−1) to the bottom (3.14 mg·kg−1) and in the SSCL from 24.96 mg·kg−1 to 5.05 mg·kg−1, respectively. Thus, the impermeable clay layer and VZRB helped in retardation of ammonia leakage from MSWL sites. This was due to the blockage of seepage, ammonia mechanical filtration, ammonia monolayer chemical adsorption, and the reaction between the functional groups and ammonia in the VZRB underneath the MSWL sites.

Quantification of landfill gas emissions and energy production potential in Tirupati Municipal solid waste disposal site by LandGEM mathematical model

The present key challenges the world is currently facing are the environmental pollution, climate change and energy crisis. The anthropogenic emissions of carbon dioxide due to burning of fossil fuels for energy production and other greenhouse gas emissions are considered unsustainable, and whole world is having a paradigm shift towards the renewable energy. The one of the major contributor of the greenhouse gases like methane, carbon dioxide are the municipal solid waste landfill sites. The landfill sites contains nearly 50–60% of organic contents, and they undergo anaerobic decomposition with a help microbes in the waste dumps contribute to the higher percent of methane emissions. There is now enhanced public awareness on sustainable products, and commodities usage in their daily needs, hence the global warming can be slowed down and devise an environmentally sound sustainable society. The present study aimed to provide a methodology to quantify the amount of methane and carbon-di-oxide emitted from the Tirupati municipal solid waste dumpsite using LandGEM3.02 model and empirical equation to estimate the renewable energy potential. The method provided was simple and more accurate having higher efficiency in predicting the landfill emissions and subsequently the energy potential. The study shows that the energy emission potential are maximum to the waste with a higher fraction of biodegradable organic content. Therefore, the method can be implemented in all the landfills by the policy makers to predict the methane emissions and control the greenhouse gas emissions by sequestering the methane and carbon dioxide optimally for energy production.•Landfill gases are a primary constituent in greenhouse gases and has potential for energy production.•The results from this study showed an abundant quantity of methane and carbon dioxide are emitted from tripathi landfill site.•The study concludes that methane can be extracted and used as alternative source of sustainable energy.

A spatial decision support system for municipal solid waste landfill sites (case study: The Mazandaran Province, Iran).

Landfilling is an inevitable step for the municipal solid waste (MSW) management system in developing countries. This article presents a Spatial Decision Support System (SDSS) that was developed for the monitoring of municipal landfills and siting the new places for waste disposal at Mazandaran province, south of Caspian Sea, Iran. The effective criteria and evaluation constraints were chosen according to the Iran waste management law. The ArcGIS 10.4.1 software was used for creating a geospatial database and the analytic hierarchy process (AHP) was used for ranking the criteria. By integrating the criteria, a suitability map was generated into four categories: high suitability, moderate suitability, low suitability and illegal areas. Using ArcGIS online, the maps were shared on a website that was specifically designed for this purpose. The decision-makers can check online the laws, the effective criteria and the results of spatial analysis for optimal siting. Also, the results of environmental evaluations for active landfills have been provided. Given the characteristics of active landfills and the optimal sites for the possible development, the SDSS can provide a mutually beneficial relationship between the experts, decision-makers and stakeholders to decide about the priority of actions required for the relocation of landfills, site closure or emergency care.

Landfill Siting Evaluation Using GIS and Multi-Criteria Decision-Making Method: A Case Study: Dammam Municipal Solid Waste Landfill

Waste landfills are a prominent global issue that does not concern a country without the other because of its long-term effects especially in the environmental aspect. As these pose an environmental threat to water, air and soil; and directly affect human life and health. Accordingly, this research uses the integration of Geographic Information Systems (GIS) and Multi-Criteria Decision-Making (MCDM) approaches to assess the location of the municipal solid waste dump in Dammam, which was established in (2000AD) twenty years ago, due to the lack of recent studies assessing the current status of the landfill and whether it is in a suitable location and keeps pace with the population and urbanization increase in the region. For this purpose, the researchers are using the tools and techniques of GIS to evaluate eight criteria on the study area. The required standards were directed to the landfill site and transformed into maps that represent the most important economic, social, environmental, geological, geomorphological and Public Acceptance standards. These standards have been processed using the tools of spatial and statistical analyses. Analytic Hierarchy Process (AHP) is implemented in geographical information system for building the suitable cartographic model, and thus allowed to determine the suitable degree of Dammam municipal solid waste landfill site in light of the study criteria. The study concluded that the current landfill site achieves a good degree of suitability, as it achieved 63% measured against the quality standards set by the study, and that the current landfill site conforms to most of the criteria in this study to a good degree. But it violates two standards, which are distance from wells standard and distance between landfill and the center of waste generation standard.

Applicability of Recycled Soil Mixed with Bentonite and Polymer as a Waste Landfill Liner

Waste landfill liner has been developed with a variety of materials, but the landfill liner and cover material have not been developed in consideration of the local conditions. In order to build a cost effective municipal solid waste (MSW) landfill site, it is necessary to develop technology that utilizes materials suitable for local characteristics as liner. The purpose of this study is to develop an amended compacted clay liner (CCL) by proportionally mixing construction waste soil called “recycled soil” with small amount bentonite powder as well as polymer powder. Permeability and strength characteristics of recycled soil-bentonite mixture were analyzed through laboratory test and then compare this mixture with characteristics of marine clay-bentonite mixture. The characteristics of strength and permeability were analyzed by applying different mixing ratios with adjustment of polymer and bentonite ratios in consideration of its proportion of bentonite’s weight to improve economic efficiency and increase the strength of recycled soil-bentonite mixture. Finally, the proper mixing ratio of recycled soil-4% bentonite-0.28% polymer mixture was determined considering economical efficiency. The mixture was confirmed to be suitable as lining material based on the results of dry shrinkage test, free swelling test, and soil contamination test. In this study, it is proposed the mixing ratio of recycled soil, bentonite, and polymer as a minimum ratio that satisfies the standard of hydraulic conductivity(1 × 10−7 cm/sec) on the waste management law and unconfined compressive strength (500 kPa) on the specification of construction of waste landfill liner.

Characteristics and health effects of potentially pathogenic bacterial aerosols from a municipal solid waste landfill site in Hamadan, Iran.

The aim of this study was to evaluate the potential pathogenic bacterial aerosols produced from the municipal solid waste landfill site and its health risk assessment in the Hamadan city at west of Iran. In this study, air samples were collected every month during spring and summer at six locations including the active zone, leachate collection pond, infectious waste landfill, upwind, closure landfill, and downwind using the Andersen impactor. Spatial and seasonal variations of the potential pathogenic bacterial aerosols were detected. Also, Health risk associated were estimated based on the average daily dose rates (ADD) of exposure by inhalation. The mean concentration of potentially pathogenic bacterial aerosols were 468.7 ± 140 CFU m- 3 1108.5 ± 136.9 CFU m- 3 detected in the active zone in spring and summer, respectively. Also, there was a significant relationship between meteorological parameters and bacterial concentration (p < 0.05). The predominant potential pathogenic bacterial identified in the spring were Proteus mirabilis, Streptococcus sp., and Pseudomonas sp., while in summer were Pseudomonas sp., Staphylococcus aureus, and Escherichia coli. The hazard quotient (HQ) in both seasons were less of 1. Bacteria were spread throughout the landfill space, but their maximum density was observed around the active zone and leachate collection pond. This study highlights the importance of exposure to potential pathogenic bacterial aerosols in the summer and its adverse effects, especially in the MSW landfill site active zone. Finally, controlled exposure can reduce the health hazard caused by the potential pathogenic bacterial aerosols.

A novel mathematical modelling for simulating the spread of heavy metals in solid waste landfills

Municipal solid waste (MSW) landfills create the environmental pollutions due to problems related to toxins, leachate, and greenhouse gas, which are the growing environmental concerns, especially in developing countries. This paper presents a novel mathematical modelling for simulating the spread of heavy metals in soil layers in the MSW landfills. A new mathematical modelling procedure is studied for deriving the governing equation which describes the time varying concentration of pollutants in the leachate in a 3-dimensional (3D) space of soil layers. A Finite Element Method (FEM) based algorithm is then constructed to solve numerically the governing equation over time in 3D space for effectively analyzing the variation of pollutants concentrations. Finally, the applicability and advantages of the proposed novel method are demonstrated through the case study with soil samples collected from the actual MSW landfill. The successfully developed algorithm can be applied to model and predict the spread of different heavy metals in the MSW landfill sites; and to develop effective solutions and policies for solid waste classification and management, in order to minimise the negative impacts from the potential risk of the toxic heavy metal pollutions, soil contaminations and groundwater pollutions in the areas nearby the MSW landfill.

Potential Environmental and Human Health Risks Caused by Antibiotic-Resistant Bacteria (ARB), Antibiotic Resistance Genes (ARGs) and Emerging Contaminants (ECs) from Municipal Solid Waste (MSW) Landfill.

The disposal of municipal solid waste (MSW) directly at landfills or open dump areas, without segregation and treatment, is a significant concern due to its hazardous contents of antibiotic-resistant bacteria (ARB), antibiotic resistance genes (ARGs), and metal resistance genes (MGEs). The released leachate from landfills greatly effects the soil physicochemical, biological, and groundwater properties associated with agricultural activity and human health. The abundance of ARB, ARGs, and MGEs have been reported worldwide, including MSW landfill sites, animal husbandry, wastewater, groundwater, soil, and aerosol. This review elucidates the occurrence and abundance of ARB, ARGs, and MRGs, which are regarded as emerging contaminants (ECs). Recently, ECs have received global attention because of their prevalence in leachate as a substantial threat to environmental and public health, including an economic burden for developing nations. The present review exclusively discusses the demands to develop a novel eco-friendly management strategy to combat these global issues. This review also gives an intrinsic discussion about the insights of different aspects of environmental and public health concerns caused due to massive leachate generation, the abundance of antibiotics resistance (AR), and the effects of released leachate on the various environmental reservoirs and human health. Furthermore, the current review throws light on the source and fate of different ECs of landfill leachate and their possible impact on the nearby environments (groundwater, surface water, and soil) affecting human health. The present review strongly suggests the demand for future research focuses on the advancement of the removal efficiency of contaminants with the improvement of relevant landfill management to reduce the potential effects of disposable waste. We propose the necessity of the identification and monitoring of potential environmental and human health risks associated with landfill leachate contaminants.

Factors influencing groundwater contamination near municipal solid waste landfill sites in the Qinghai-Tibetan plateau

Effective management of municipal solid waste (MSW) is essential for the conservation of ecosystems in the Qinghai-Tibetan Plateau (QTP). Considering the landfill is the major method of MSW management, the factors influencing groundwater contamination near MSW landfill sites in the QTP were studied, based on field investigations, environmental impact assessment, and meteorological and hydrogeological analyses. Results indicated that the groundwater was contaminated heavily by nitrate (PI = 7.5), particularly in the landfill without an anti-seepage system, followed by nitrite (PI = 3.5) and heavy metals including arsenic (PI = 4.1) and hexavalent chromium (PI = 2.8). Total hardness, total dissolved solids, nitrate, and lead in the groundwater near the investigated landfill sites were significantly different between the monsoon and the cold seasons. Both the rainfall infiltration and the leachate infiltration were considerably limited by environmental characteristics in the QTP, including high evaporation, low rainfall, and the presence of permafrost. Soil sample contamination near landfill sites was considered as moderate (28.6% of the soil samples) and moderate to heavy (71.4% of the soil samples), based on the geoaccumulation index of mercury. However, comparatively low generation and concentrations of leachate and good topsoil quality (PI = 0.84) reduced the quantity of pollutants infiltrating into the groundwater. The alkaline leachate (pH = 7.45–9.23) and soil (pH = 7.08–8.72) also considerably decreased the concentrations of contaminants dissolved in the infiltrated rainfall and leachate. Additionally, low groundwater level can delay preferential flow and enhance attenuation. Therefore, the groundwater contamination near the landfill sites was simply point pollution, which was influenced by leachate, soil, climate, and hydrogeology characteristics in the QTP. The anti-seepage system is a potential strategy for use in the prevention of groundwater contamination by MSW landfills in the QTP.

Real-time measurements of landfill atmospheric ammonia using mobile white cell differential optical absorption spectroscopy system and engineering applications

ABSTRACT The real-time measurement of atmospheric ammonia at municipal solid waste (MSW) landfills and adjacent areas is necessary for landfill management and the health of nearby residence. Continuous, fast, and real-time monitoring of landfill odor gases is a challenge, especially for ammonia. To our knowledge, this was the first study for the characteristics and seasonal variabilities of atmospheric ammonia at a whole landfill using a Mobile White cell Differential Optical Absorption Spectroscopy (MW-DOAS) system, which also simultaneously offers high sensitivity and fast response. Results show that atmospheric ammonia levels at various landfill areas were significantly dependent on the characteristics of areas, such as municipal solid waste-related areas, leachate-related areas, sludge-related areas, and fly ash-related area, the atmospheric ammonia peak or average level at the active leachate pool of the active MSW site was the highest among all areas of the whole landfill, and the ammonia concentrations at the closed MSW landfill sites were low and dependent on the ages. Moreover, it was found that the seasonal variabilities of ammonia concentrations at most of those areas were significantly dependent on the ambient temperature, and ambient temperature variation caused the atmospheric ammonia level at the active leachate pool and active MSW landfill site in the summer survey to raise 3.5 times and 5.58 times than in the winter survey, respectively. Implications: Continuous, fast, and real-time monitoring ambient ammonia at or nearby a landfill is critical for landfill operators and local EPAs. This study demonstrates that the mobile White cell Differential Optical Absorption Spectroscopy (MW-DOAS) system is an effective tool for real-time monitoring ambient ammonia of a whole landfill. The results in this article provided a guideline to the characteristics and seasonal changes of ambient ammonia at various types of areas of a whole landfill as well as the impact of age to ambient ammonia at the closed landfill areas.