Landfill Leachate Management Research Articles

A comprehensive review of landfill leachate treatment technologies

The management of landfill leachate presents a significant environmental challenge, necessitating a comprehensive and dynamic treatment approach. This comprehensive review delves into the critical issue of landfill leachate treatment, exploring its environmental impact, treatment technologies, regulatory frameworks, and the path towards sustainable management practices. This review explores the complexities of landfill leachate, emphasizing the need for sustainable waste management practices to safeguard environmental health. Our analysis highlights the evolution of conventional and advanced treatment technologies designed to mitigate these risks, focusing on membrane technologies, advanced oxidation processes, and the promising potential of emerging techniques such as adsorption and biological nutrient removal. These technologies are evaluated for their efficiency, cost implications, and sustainability impacts, underscoring the challenges and opportunities within the current landscape of leachate treatment. The review aims to provide insights into designing efficient and effective treatment systems through a detailed analysis of conventional and advanced treatment methods. By examining a case study in Changsha City, the effectiveness of a comprehensive treatment system integrating various technologies is demonstrated. The review underscores the interconnectedness of human activities, environmental health, and waste management, emphasizing the importance of a holistic approach. It stresses the continuous improvement of leachate treatment technologies and the adoption of sustainable practices to reduce the environmental footprint of landfills. Ultimately, it calls for integrating multiple treatment processes, economic considerations, and readiness to address future challenges in landfill leachate treatment, contributing to the advancement of sustainable waste management practices.

Development of a floating constructed wetland for landfill leachate treatment and its potential to remove recalcitrant organic matter

The development of simple and economical treatment technologies for the removal of recalcitrant organic matter is required to achieve long-term and sustainable treatment of landfill leachates in tropical regions. In this study, we evaluated the fundamental properties required to develop the floating constructed wetland (FCW), which consists of a buoyant planting unit made of foamed glass and cattails. The results showed that foamed glass alone can be used as a planting substrate for cattails. Treatment of a synthetic landfill leachate by a lab-scale FCW demonstrated that the test system effectively and continuously removed recalcitrant organic matter, whereas the control system did not. This removal by FCW was shown to proceed through nearly equal contributions from adsorption and potential biological processes. Furthermore, the effect of introducing an FCW in an actual waste landfill site in Thailand was simulated using the parameters obtained from this study. The simulation indicated that the introduction of the FCW into the stabilisation pond was effective in reducing both leachate volume and recalcitrant organic matter. It is important to determine how much of the stabilisation pond should be covered with the FCW for cost-effectiveness. The FCW is expected to contribute to improving long-term, sustainable, and appropriate management of landfill leachate in tropical developing countries.

The Relationship between Waste Management Practices and Human Health: New Perspective and Consequences

Waste management, an integral aspect of modern life, exerts a profound influence on both public health and the environment. While existing research explores the environmental impact of various waste management practices, there is a paucity of studies investigating the direct health effects on humans from these practices. This article aims to address this gap by examining the intricate interplay between specific waste management strategies, such as open burning or landfill leachate management, and their potential to cause respiratory illnesses, birth defects, or other health problems in urban areas. Drawing from existing knowledge and recent research, it underscores the imperative of adopting an integrated waste management approach that harmonizes environmental preservation and health considerations. Furthermore, the review spotlights emerging technologies and innovative methodologies that hold promise in mitigating potential health hazards associated with conventional waste management practices. It accentuates the intricate connection between waste management and human health, underscoring the need for holistic strategies that encompass both community welfare and environmental sustainability. This paper advocates for sustainable waste management approaches that not only alleviate health concerns but also promote resource recovery and community engagement. Policymakers, urban planners, and stakeholders are encouraged to collaborate in the adoption of effective waste management methods that safeguard both the environment and human health. By recognizing the intrinsic link between environmental and health issues, a harmonized approach can be forged to address them.

Global perspective of municipal solid waste and landfill leachate: generation, composition, eco-toxicity, and sustainable management strategies.

Globally, more than 2 billion tonnes of municipal solid waste (MSW) are generated each year, with that amount anticipated to reach around 3.5 billion tonnes by 2050. On a worldwide scale, food and green waste contribute the major proportion of MSW, which accounts for 44% of global waste, followed by recycling waste (38%), which includes plastic, glass, cardboard, and paper, and 18% of other materials. Population growth, urbanization, and industrial expansion are the principal drivers of the ever-increasing production of MSW across the world. Among the different practices employed for the management of waste, landfill disposal has been the most popular and easiest method across the world. Waste management practices differ significantly depending on the income level. In high-income nations, only 2% of waste is dumped, whereas in low-income nations, approximately 93% of waste is burned or dumped. However, the unscientific disposal of waste in landfills causes the generation of gases, heat, and leachate and results in a variety of ecotoxicological problems, including global warming, water pollution, fire hazards, and health effects that are hazardous to both the environment and public health. Therefore, sustainable management of MSW and landfill leachate is critical, necessitating the use of more advanced techniques to lessen waste production and maximize recycling to assure environmental sustainability. The present review provides an updated overview of the global perspective of municipal waste generation, composition, landfill heat and leachate formation, and ecotoxicological effects, and also discusses integrated-waste management approaches for the sustainable management of municipal waste and landfill leachate.

A mixed blessing of influent leachate microbes in downstream biotreatment systems of a full-scale landfill leachate treatment plant

In landfill leachate treatment plants (LLTPs), the microbiome plays a pivotal role in the decomposition of organic compounds, reduction in nutrient levels, and elimination of toxins. However, the effects of microbes in landfill leachate influents on downstream treatment systems remain poorly understood. To address this knowledge gap, we collected 23 metagenomic and 12 metatranscriptomic samples from landfill leachate and activated sludge from various treatment units in a full-scale LLTP. We successfully recovered 1,152 non-redundant metagenome-assembled genomes (MAGs), encompassing a wide taxonomic range, including 48 phyla, 95 classes, 166 orders, 247 families, 238 genera, and 1,152 species. More diverse microbes were observed in the influent leachate than in the downstream biotreatment systems, among which, an unprecedented ∼30 % of microbes with transcriptional expression migrated from the influent to the biological treatment units. Network analysis revealed that 399 shared MAGs across the four units exhibited high node centrality and degree, thus supporting enhanced interactions and increased stability of microbial communities. Functional reconstruction and genome characterization of MAGs indicated that these shared MAGs possessed greater capabilities for carbon, nitrogen, sulfur, and arsenic metabolism compared to non-shared MAGs. We further identified a novel species of Zixibacteria in the leachate influent with discrete lineages from those in other environments that accounted for up to 17 % of the abundance of the shared microbial community and exhibited notable metabolic versatility. Meanwhile, we presented groundbreaking evidence of the involvement of Zixibacteria-encoded genes in the production of harmful gas emissions, such as N2O and H2S, at the transcriptional level, thus suggesting that influent microbes may pose safety risks to downstream treatment systems. In summary, this study revealed the complex impact of the influent microbiome on LLTP and emphasizes the need to consider these microbial characteristics when designing treatment technologies and strategies for landfill leachate management.

Bioaugmentation in Leachate Treatment: Enhancing Ammonia Nitrogen Elimination in US Landfills

Purpose: This research seeks to assess the quantitative effects of implementing bioaugmentation solutions within existing landfill leachate management systems. The study involves the analysis of different sites to gauge the influence on leachate composition, considering various industry management practices such as lagoons, tanks, sewer discharge, or off-site trucking. The primary objective is to examine changes in microbial communities within the leachate, specifically focusing on their impact on ammonia nitrogen elimination rates. The ultimate goal is to achieve lower levels of ammonia nitrogen before the discharge of leachate to publicly owned treatment works (POTW).Methodology: The research employs a comprehensive methodology that involves the examination of diverse landfill sites utilizing various industry management practices for leachate treatment. The analysis includes assessing leachate composition and the study evaluates effectiveness of bioaugmentation in enhancing ammonia elimination rates, considering different leachate treatment approaches and operating conditions. This involves a systematic comparison of outcomes across sites and management practices.Findings: The findings of this study indicate that bioaugmentation is an effective strategy for accelerating ammonia elimination rates in landfill leachate. The analysis reveals notable improvements in microbial communities, leading to reduced levels of ammonia nitrogen in the leachate prior to its discharge to POTW. The study highlights the versatility of bioaugmentation across different industry management practices, showcasing its potential benefits under varying operating conditions and treatment setups.Unique contributor to theory, policy and practice: Based on the study's outcomes, it is recommended that landfill operators and leachate management practitioners consider implementing bioaugmentation solutions to expedite ammonia elimination rates. The findings suggest that bioaugmentation is a cost-effective and fast-to-deploy solution that requires negligible capital expenditure. This approach has the potential to generate significant savings, especially in the face of a more stringent regulatory environment. The recommendations emphasize the adaptability and efficiency of bioaugmentation across a broad range of operating conditions within existing landfill leachate management infrastructure.

Design of high-performance electro-driven nanofiltration membrane via facile co-deposition of pyrogallol and polyethyleneimine for sustainable resource recovery from landfill leachate concentrate

Conventional treatment methods of landfill leachate concentrate mainly focus on the degradation or removal of humic substance, which are prone to secondary pollution and fail to meet the requirements of current sustainable development. The key to sustainable management of landfill leachate concentrate is to precisely fractionate the existing humic substance and inorganic salts as individual resources. Here, electro-driven nanofiltration membranes were fabricated by sodium periodate inducing co-deposition of pyrogallol and polyethyleneimine on the loose polyamide-based nanofiltration substrate membranes as high-performance anion conducting membrane. The pyrogallol/polyethyleneimine composite coating layer endowed the electro-driven nanofiltration membranes with reduced surface negative charge and specific areal electric resistance for enhanced anion transfer. During the electro-driven nanofiltration process, the fabricated membrane with a 30-min co-deposition exhibited an extremely fast anion transfer rate and outstanding fractionation performance with 99.08 ​% humic substance recovery of 99.08 ​%. Particularly, the fabricated membrane showed stable separation capacity over an 8-cycle electro-driven nanofiltration operation, demonstrating a low fouling propensity. Our study sheds light on the strategy to fabricate high-performance electro-driven nanofiltration membranes via co-deposition of pyrogallol and polyethyleneimine, paving the way to sustainable treatment of landfill leachate concentrate.

The influence of combined treatment of municipal wastewater and landfill leachate on the spread of antibiotic resistance in the environment – A preliminary case study

Environmentally-friendly management of landfill leachate (LL) poses a challenge, and LL is usually co-treated with municipal wastewater in wastewater treatment plants (WWTPs). The extent to which the co-treatment of LL and municipal wastewater influences the spread of antibiotic resistance (AR) in the environment has not been examined to date. Two WWTPs with similar wastewater composition and technology were studied. Landfill leachate was co-treated with wastewater in one of the studied WWTPs. Landfill leachate, untreated and treated wastewater from both WWTPs, and river water sampled upstream and downstream from the wastewater discharge point were analyzed. Physicochemical parameters, microbial diversity, and antibiotic resistance genes (ARGs) abundance were investigated to determine the impact of LL co-treatment on chemical and microbiological contamination in the environment. Landfill leachate increased pollutant concentrations in untreated wastewater and river water. Cotreatment of LL and wastewater could affect the abundance and diversity of microbial communities and the interactions between microbial species. Co-treatment also decreased the stability of microbial co-occurrence networks in the examined samples. The mexF gene was identified as a potential marker of environmental pollution with LL. This is the first study to explore the impact of LL on the occurrence of AR determinants in wastewater and rivers receiving effluents.

Towards effective recovery of humate as green fertilizer from landfill leachate concentrate by electro-neutral nanofiltration membrane

Under the environmental sustainability concept, landfill leachate concentrate can be up-cycled as a useful resource. Practical strategy for effective management of landfill leachate concentrate is to recover the existing humate as fertilizer purpose for plant growth. Herein, we designed an electro-neutral nanofiltration membrane to separate the humate and inorganic salts for achieving a sufficient humate recovery from leachate concentrate. The electro-neutral nanofiltration membrane yielded a high retention of humate (96.54 %) with an extremely low salt rejection (3.47 %), tremendously outperforming the state-of-the-art nanofiltration membranes and exhibiting superior promise in fractionation of humate and inorganic salts. With implementation of the pressure-driven concentration process, the electro-neutral nanofiltration membrane enriched the humate from 1756 to 51,466 mg∙L−1 at a fold of 32.6, enabling 90.0 % humate recovery and 96.4 % desalination efficiency from landfill leachate concentrate. Furthermore, the recovered humate not only exerted no phytotoxicity, but also significantly promoted the metabolism of red bean plants, serving as an effective green fertilizer. The study provides a conceptual and technical platform using high-performance electro-neutral nanofiltration membranes to extract the humate as a promising nutrient for fertilizer application, in view of sustainable landfill leachate concentrate treatment.

Algae-based treatment of a landfill leachate pretreated by coagulation-flocculation

Landfill leachate (LL) management is an urgent issue at recently closed Sisdol Landfill Site (SLS) used to dispose of solid waste generated in Kathmandu (Nepal) as untreated leachate is flowing directly to the nearby Kolpu River causing environmental and health concerns. This study aims to assess the potential of algae-based treatment of LL pretreated by optimized coagulation-flocculation (CF) for the removal of conventional pollutants such as biological oxygen demand (BOD5), chemical oxygen demand (COD), ammonia, nitrate, and phosphate. Response Surface Methodology (RSM) was used to optimize the operating variables (dose and pH) during the pretreatment of leachate by the CF process using ferric chloride (FeCl3.7H2O), alum (Al2(SO4)3.6H2O) and commercial poly aluminium chloride (PAC) as coagulants using a jar test apparatus. The pretreated LL was subjected to algal treatment using the mixed microalgae culture isolated and enriched from the wastewater collection pond and grown in artificial light. The combined physicochemical and algal treatment of LL from SLS achieved 62.93–72.43%, 74.93–75.55% and 87.58–93.40% and 73.63–86.73% removal for COD, BOD5, ammonium-nitrogen and phosphate, respectively. Thus, this research has proven the feasibility of a combined physiochemical and algae-based treatment of LL and also offers an exciting alternative to current treatment practices for LL.

A Critical Review on the Microbial Ecology of Landfill Leachate Treatment Systems

Sanitary landfilling is still considered worldwide as one of the most common methods applied for the management of the municipal solid waste. As a consequence, vast amounts of landfill leachate are generated annually, which are characterized by variability in physicochemical composition, owing to the stabilization process that occurs over the years. However, sustainable management of landfill leachate is a challenging issue, due to diverse chemical composition and high concentration in heavy metals and xenobiotics. Despite the fact that several studies have been reported on the biotreatment of landfill leachate, only in recent years has the microbial composition in such systems have been examined. In the present review, the key role of the microbial ecology involved in depurification and detoxification of landfill leachate in activated sludge and anaerobic systems is interpreted and ecological considerations influencing landfill leachate treatment are stated. Apart from the assessment of landfill toxicity on certain model organisms, this work provides an extensive overview on microbial communities performing key biological processes during landfill leachate treatment, including nitrification-denitrification, anammox and anaerobic digestion. Moreover, microbial aspects affecting nutrient removal efficiency in such biosystems are discussed.

Impact, Mitigation Strategies, and Future Possibilities of Nigerian Municipal Solid Waste Leachate Management Practices: A Review

Landfills and solid waste disposal facilities have historically been the most common point sources of pollution with the potential to release contamination leachate plumes into the environment. Waste disposal is one of the biggest problems that the world is facing. In man’s everyday life, he produces waste materials which, if not properly managed, can affect health and environment. The seepage of landfill leachate into groundwater tables and aquifer systems significantly creates a possible danger and threat to human health and environment at large and remains a subject of concern in Nigeria and other parts of the world. This paper provides a review of existing approaches to leachate treatment in Nigeria and current practices across the globe, depicts the impact on environmental implications, documented previous findings, challenges and mitigation measures, and future perspectives of landfill leachate management in Nigeria, and compares with global practice of leachate management. In Nigeria, there are only a few standard techniques of landfill leachate treatment. This resulted in severe environmental impacts that threaten human life, especially in the north-eastern part of the country. Vector-borne and water-related illnesses such as cholera, Dengue, Diarrhoea, Trachoma, typhoid, malaria etc, have become a major source of concern resulting from the leaching effect from landfills. Advanced treatment methods, including membrane filtration, trickling filters, and Batch and Sequencing-Batch Reactors (SBR) are used in some of the cities and private organizations in Nigeria. Most researchers in Nigeria have stressed the necessity to utilise efficient, cost-effective technology in landfill wastewater treatment. Despite this, landfill leachate has continued to have severe effects in Nigeria and the situation seems to be escalating, requiring further study.

A comprehensive investigation of toxicity and pollution potential of municipal solid waste landfill leachate.

It is evident from the literature that research on the treatment of leachate generated from municipal solid waste (MSW) landfills has been a focus area of environmental management. However, the available information is discrete because most studies have reported only one or a couple of aspects of either closed or active MSW landfill leachate treatment. Hence, this investigation has focused on comprehensive attributes of both closed landfill leachate (CLL) and active landfill leachate (ALL), including generation, characterisation, and toxicity assessment to quantify and establish their pollution potential. The results indicated that CLL generation is higher (188.59 m3/d) than ALL (49.53 m3/d). The concentrations of principal physical, chemical, and biological constituents and concomitant leachate pollution index were higher in CLL (33.20) than in ALL (26.65). Furthermore, the germination indices of CLL (57.48) and ALL (79.14) and tail DNA damage of CLL (56.49%) and ALL (23.8%) ratified greater phytotoxicity and genotoxicity potential, respectively of CLL over ALL. The reasons for the variations in the generation, characteristics, and toxicity of CLL and ALL were discussed in detail. Evaluation of the commonly used landfill leachate treatment methods through the analytical hierarchy process confirmed that the activated sludge process and Fenton oxidation process are the most and least preferred treatment methods. The comprehensive investigation of CLL and ALL have established their pollution potential and the inevitable necessity for their treatment. The findings of this investigation will serve as a ready reference for researchers from academia and industry who work on the monitoring, treatment, and management of landfill leachate.

Electrochemical oxidation of landfill leachate using boron-doped diamond anodes: pollution degradation rate, energy efficiency and toxicity assessment.

Electrochemical oxidation (EO), due to high efficiency and small carbon footprint, is regarded as an attractive option for on-site treatment of highly contaminated wastewater. This work shows the effectiveness of EO using three boron-doped diamond electrodes (BDDs) in sustainable management of landfill leachate (LL). The effect of the applied current density (25-100mAcm-2) and boron doping concentration (B/C ratio: 500ppm, 10,000ppm and 15,000ppm) on the performance of EO was investigated. It was found that, of the electrodes used, the one most effective at COD, BOD20 and ammonia removal (97.1%, 98.8% and 62%, respectively) was the electrode with the lowest boron doping. Then, to better elucidate the ecological role of LLs, before and after EO, cultivation of faecal bacteria and microscopic analysis of total (prokaryotic) cell number, together with ecotoxicity assay (Daphnia magna, Thamnocephalus platyurus and Artemia salina) were combined for the two better-performing electrodes. The EO process was very effective at bacterial cell inactivation using each of the two anodes, even within 2h of contact time. In a complex matrix of LLs, this is probably a combined effect of electrogenerated oxidants (hydroxyl radicals, active chlorine and sulphate radicals), which may penetrate into the bacterial cells and/or react with cellular components. The toxicity of EO-treated LLs proved to be lower than that of raw ones. Since toxicity drops with increased boron doping, it is believed that appropriate electrolysis parameters can diminish the toxicity effect without compromising the nutrient-removal and disinfection capability, although salinity of LLs and related multistep-oxidation pathways needs to be further elucidated.

Biofuel production from fruit and vegetable market waste and mature landfill leachate by an active filter-anaerobic digestion integrated system

• The sustainable management of landfill leachate (LL) is particularly problematic. • Anaerobic digestion (AD) is suitable for producing a sustainable biofuel. • Pre-treated LL is used for integration of NH 3 -N in AD of market waste. • The addition of granular activated carbon (GAC) was tested during AD. • GAC allowed a 14% increase of methane yield that reached 0.302 NL/gVS added . The management of municipal solid wastes represents one of the biggest challenges for the actual implementation of the circular economy. While the main “dry” fractions (such as plastics and paper) can be easily recycled, treatments for both the valorisation of the organic waste and for the disposal of leachate (produced by the landfilling of unsorted municipal waste) often turn out to be inadequate and expensive. Particularly, the leachate management is a critical issue since the mature landfill leachate (MLL) must be treated for decades even after the landfill closure. In this study, an innovative approach is proposed and it consists in an integrated system of active filters and anaerobic reactors for the simultaneous treatment of both waste streams (i.e., organic waste and MLL). Firstly, bio-refractory compounds (e.g., metals) present in MLL are removed by filtration on active materials (i.e., zero valent iron (ZVI) and granular activated carbon (GAC) or ZVI and Lapillus mixtures). The so-treated MLLs are then used as nutrient solutions for the anaerobic digestion (AD) of market wastes (MW) to optimize the C/N ratio. Moreover, during the anaerobic digestion, granular active carbon (GAC) is added in some reactors along with the feeding solution (substrate and pre-treated MLLs) to retain possible refractory or toxic compounds and to facilitate microorganisms’ activities by promoting the direct interspecies electron transfer mechanism. MLLs, used as nutrient solutions, lead to a stable AD of MW with a methane yield of about 0.260 NL/gVS added . GAC is proved to be also efficient in the enhancement of the methane production as higher methane yields (about 0.302 NL/gVS added ) are obtained in reactors where it is added as a supplement.

Integrated Treatment at Laboratory Scale of a Mature Landfill Leachate via Active Filtration and Anaerobic Digestion: Preliminary Results

The management of mature landfill leachate (MLL) represents an increasingly crucial issue to tackle. In this study, the feasibility of an integrated treatment was investigated at the laboratory scale using synthetic leachate with the objective of maximizing the recovery of potentially useful compounds present in leachate (especially ammonia nitrogen). First, in order to remove heavy metals, active filtration of the MLL was carried out using zero-valent iron (ZVI) mixed with either lapillus or granular activated carbon (GAC). The average removal rates for the ZVI/lapillus and the ZVI/GAC filter were 33%, 85%, 66%, and 58% and 56%, 91%, 67%, and 75% for COD, Cu, Ni, and Zn, respectively. Then, pre-treated MLL was added during the anaerobic digestion (AD) of cellulose with the aim of providing bacteria with macro (i.e., ammonia nitrogen) and micro (e.g., residual heavy metals) nutrients. After 38 days, the best performance in terms of cumulative methane production (5.3 NL) and methane yield (0.26 NL/gVSadded on average) was recorded in the reactor fed with the lowest dosage (17.9 mL/d) of MLL pre-treated by the ZVI/lapillus filter. The main issue that emerged during AD was the possible inhibition of the process linked to an excessive presence of humic substances; however, in future experiments, this problem can be solved through an optimization of the management of the whole process. The residual digestate from AD, rich in nitrogen and humic substances, may be safely used for agriculture purposes, closing the cycle of MLL management.

Sustainable management of landfill leachate concentrate via nanofiltration enhanced by one-step rapid assembly of metal-organic coordination complexes

Sustainable treatment of the highly saline landfill leachate concentrate for application as green fertilizer calls for effective fractionation of the existing humic substances and inorganic salts; advanced selective nanofiltration membranes are proposed for this. One-step, rapid assembly of a tannic acid-Fe3+ coordination complex is a promising strategy to endow the membranes with an enhanced nanofiltration performance. In this study, a robust and homogeneous tannic acid-Fe3+ coordination complex layer was effectively coated onto the surface of a loose nanofiltration substrate in an extremely short time (15 s). After the coating of the tannic acid-Fe3+ coordination complex layer, the nanofiltration membrane showed a significantly reduced molecule weight cutoff (i.e., reduction from 601 to 279 Da) and thus enhanced selectivity towards humic substances. Specifically, the rejection to humic substances of the coated nanofiltration membrane increased from 95.31±0.54% to 99.32±0.18% with negligible rise in salt rejection, demonstrating an enhanced fractionation efficacy for humic substances and salts. Assisted by a diafiltration operation with the coated nanofiltration membrane, humic substances in the landfill leachate concentrate were effectively purified and extracted with 96.60% recovery. Particularly, the humic substances were linearly enriched by ca. 7.8 folds (i.e., from 1837 to 13970 mg·L−1) with a purity of 98.91% for potential application as liquid fertilizer. The one-step rapid tannic acid-Fe3+ coordination complex coating exhibits an impressive efficacy to engineer advanced nanofiltration membranes that could be applied at a large scale for sustainable resource extraction from landfill leachate concentrate.

Study on antibiotics, antibiotic resistance genes, bacterial community characteristics and their correlation in the landfill leachates.

This study aimed to investigate the contamination levels of antibiotics and antibiotic resistance genes (ARGs) in the landfill leachates and their correlations with the bacteria. Using HPLC-MS, quantitative PCR and high-throughput sequencing, we measured the pollution levels of 14 antibiotics and 10 ARGs in the leachates of the landfill in Taiyuan, China, and analysed changes in the bacterial community and the correlations of bacteria with antibiotics and ARGs. The main results showed high levels of antibiotics (like enrofloxacin, pefloxacin and oxytetracycline) and ARGs (like sulfonamides, tetracycline, macrolides, quinolones and β-lactam-resistance genes) in the landfill leachates, along with higher diversity and richness of the bacteria. Some types of antibiotics had positive correlations with their corresponding ARGs. The dominant bacteria in the landfill leachates were Pseudomonas, Defluviitoga and Sulfurimonas, which correlated with the antibiotics and ARGs and might have potential effects on degrading them. Antibiotics and ARG pollution existed in the landfill leachates, while bacteria were closely associated with them. It will provide helpful information for the potential application of the bacteria in antibiotics and ARGs pollution control and landfill leachate management.

Progress and prospects in mitigation of landfill leachate pollution: Risk, pollution potential, treatment and challenges

The escalating loads of municipal solid waste (MSW) end up in open dumps and landfills, producing continuous flows of landfill leachate. The risk of incorporating highly toxic landfill leachate into environment is important to be evaluated and measured in order to facilitate decision making for landfill leachate management and treatment. Leachate pollution index (LPI) provides quantitative measures of the potential environmental pollution by landfill leachate and information about the environmental quality adjacent to a particular landfill. According to LPI values, most developing countries show high pollution potentials from leachate, mainly due to high organic waste composition and low level of waste management techniques. A special focus on leachate characterization studies with LPI and its integration to treatment, which has not been focused in previous reviews on landfill leachate, is given here. Further, the current review provides a summary related to leachate generation, composition, characterization, risk assessment and treatment together with challenges and perspectives in the sector with its focus to developing nations. Potential commercial and industrial applications of landfill leachate is discussed in the study to provide insights into its sustainable management which is original for the study.

Adsorption of Cadmium onto Sand-Attapulgite Cutoff Wall Backfill Media

The adsorption of Cd by sand-attapulgite cutoff wall backfill media was investigated with batch experiments for different quantities of attapulgite in the mixture (30%, 40%, 60%, and 100%; dry weight). The adsorption capacity of the media for Cd increased with the increase of attapulgite content (Ap). The change of adsorbed amount (qt) with time (t) exhibited two-stage behavior, with more than 80% of the final qt attained in the first 30 min of the experiments. The Elovich equation was the most suitable for describing the adsorption kinetics of Cd by the sand-attapulgite media. The isotherm data were best fit by the Freundlich equation. Analysis of the results indicates that cation exchange was the major adsorption mechanism. The theoretical maximum adsorption capacities (qm) of the sand-attapulgite media for Cd calculated by the Langmuir isotherm model are 6311 mg/kg (Ap = 30%), 6437 mg/kg (Ap = 40%), 6534 mg/kg (Ap = 60%), and 7034 mg/kg (Ap = 100%). The removal percentage (RP) and the distribution coefficient (Kd) of Cd decreased with the increase of the initial Cd concentration (C0) in the solution. An empirical equation for predicting Kd in terms of Ap and C0 was developed: log(Kd) = − 1.22log(C0) + 0.71Ap + 4.17 (r2 = 0.924). This equation can be used to estimate the distribution coefficient of Cd for sand-attapulgite backfill media. This will provide valuable parameters for the study of Cd transport in the sand-attapulgite cutoff wall media, and for the design of such systems for management of landfill leachate.