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Bioaugmentation uses microorganisms to detoxify or remove concentrated contaminants from any polluted media. The objective of the present study was to evaluate the efficacy of biological treatment of leachate using microbial strains isolated from leachate. Eight strains were chosen for their capacity to oxidise organic matter and their resistance to heavy metals (Cr, Fe, Zn, and Ni). They were inoculated separately at different concentrations (2%, 4%, and 6%). The results obtained show significant reduction of the pollutant load using these bacterial species. [ABSTRACT FROM AUTHOR]

The leachate is originated from the waste decomposition, inside landfills, and is a very complex effluent to treat given the its composition variability. Because of that, landfills require proper management, even after its decommissioning, since they produce leachate throughout their useful life and for many years after its closure. This work evaluated the influence of a wetlands system implementation on the final effluent quality from a closed landfill leachate treatment station. Three points were considered, the untreated leachate (input equalization tank); the effluent before passing through the wetlands (input wetlands system), which represented the final effluent before its implantation; and the output of third wetland pond that represents the final effluent for standards regulations. From 2014 to 2019, BOD5, COD, N-NH3, and heavy metals were analyzed in these three points, using univariate, such as generalized linear regression models and multivariate analyses, such as cluster analysis. The hierarchical cluster grouped the results from the output of the wetland system in the lower values, evidencing the positive influence of the system. The generalized linear regression models showed that most parameters had increased their removal efficiency when compared to the treatment performed prior. The BOD5 removal efficiency evolved from a maximum of 65.8% to a minimum of 66.5%. In the case of COD, the removal efficiency evolved from a maximum of 44.4% to a minimum of 54%. The removal of N-NH3 by wetlands treatment reached values above 98.7%, allowing the leachate to meet the Brazilian regulation limits for this parameter. [ABSTRACT FROM AUTHOR]

Landfilling and incineration are the most widely used methods for the management and treatment of fruit and vegetable waste (FVW) in Mediterranean markets, despite their potential environmental impact. A comparative life cycle assessment was conducted in this study to evaluate the environmental improvements from replacing the current landfill disposal method for FVW management and treatment in the wholesale market of Amman (Jordan) with an integrated anaerobic digestion process followed by composting. The proposed FVW treatment scenario is the best treatment option for all the assessed impact categories under the system expansion approach. Significant reductions in global warming and terrestrial ecotoxicity impacts categories would be achieved, reaching up to 322% and 352%, respectively, when compared to the current treatment scenario. Furthermore, the higher production of electrical energy (413%), as well as the production of co-products that would avoid the production of 100 kg/d of inorganic fertilizers, would contribute to such a low value of avoided impacts. [ABSTRACT FROM AUTHOR]

The global surge in urbanization and population growth has led to a significant increase in municipal solid waste generation, posing a considerable challenge in identifying suitable landfill sites. This study proposes a novel framework that enhances landfill site monitoring and assessment by combining GIS-based hierarchical analytical processes with a fuzzy inference system (FIS). The study employs a systematic approach involving phases such as feature selection, spatial analysis, criteria weighting, FIS building, and a case study conducted in São Paulo State, Brazil. The proposed framework effectively assesses landfill suitability and offers practical recommendations for landfill management and future site selection. This framework provides actionable recommendations for landfill monitoring and assessment, supporting landfill management while minimizing environmental and social impacts. It offers a comprehensive approach to landfill assessment, enhancing the sustainability of waste management practices. Further research can improve the proposed framework by refining feature selection and incorporating real-time data for continuous monitoring. Additionally, exploring the integration of emerging technologies, such as remote sensing and artificial intelligence, can further enhance landfill site monitoring and assessment. [ABSTRACT FROM AUTHOR]

Waste management is a monumental environmental concern globally especially in developing countries. In Eswatini, a number of factors have prevented the implementation of effective waste management systems. Open dumping is a serious problem in Eswatini, even in regions or cities that have functioning landfills such as Mbabane and Matsapha. For Manzini city, which is the largest city in Eswatini, there is no functioning sanitary landfill; but an open dumping facility. This impairs the countrys' ability for sustainability as the environmental pillar, which is one of three sustainability pillars, is weakened. This necessitates the urgent need for a sanitary landfill, which this paper endeavoured to identify a suitable site. The study based the site selection procedure on Geographic Information System (GIS) integrated with Multi-Criteria Decision Analysis / Making (MCDA/MCDM) using the Analytic Hierarchy Process (AHP) methodology. The identified sites were then scored according to criteria weights to identify the most suitable site for a landfill location around Manzini. The study concluded that Manzini needs a landfill, as well as stating policy implications. [ABSTRACT FROM AUTHOR]

BACKGROUND: Landfill leachate has a complex composition requiring experimental support to formulate a sustainable treatment strategy. This study utilized the particle size distribution (PSD) of the chemical oxygen demand (COD) content to assess the profile of biodegradable and inert COD fractions; it also emphasized the functions and benefits of ultrafiltration and nanofiltration modules coupled to an activated sludge process. The evaluation profited from the field data of a landfill site in Istanbul, where the leachate was actually treated in a membrane bioreactor (MBR) plant. RESULTS: COD and total nitrogen levels fluctuated between 10 100–31 200 mg L−1 and 1150–2800 mg L−1, respectively. PSD analysis for COD, conducted at two extremes, displayed similar results, where the majority of the COD was observed to accumulate at the low extremity of the particle size, 70–72% below 2 nm. Therefore, direct membrane filtration of leachate yielded low COD removals that were limited to 9% with ultrafiltration and to 31–35% with nanofiltration. COD fractionation indicated a ratio of 5% for the inert COD in leachate. The permeate COD of ultrafiltration in the existing plant was 2000 mg L−1, much higher than the inert fraction ratio, which was further reduced to 266 mg L−1 by nanofiltration. CONCLUSION: PSD analysis was an integral complement of respirometry for establishing the size‐biodegradation relationships of different COD fractions. It located the majority of soluble COD fractions below 0.55 nm, thus implying the necessity of a biological process. PSD also identified the generation of soluble residual metabolic products, indicating that residual COD escaping treatment would be equally significant to the removal potential of the biodegradable substrate. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) is an important greenhouse gas (GHG) and an ozone-depleting substance that can be emitted from landfills. Understanding the dynamics of N2O and its contribution to total emissions is critical to effective mitigation measures. This study outlines the dynamics of N2O in solid waste landfills and N2O emissions from them. N2O generation in anaerobic landfills is primarily due to denitrification and, to a lesser extent, nitrification, which occurs in the oxygenated cover soil layer and the working face. However, nitrification and denitrification are very limited within landfills. The landfill leachate contains high concentrations of ammonia (NH3). Thus, a significant amount of N2O is generated from aerobic processes during leachate treatment. Bioreactor landfills emit more N2O than traditional anaerobic landfills. The majority of N2O emitted from bioreactor landfills is generated through different pathways, such as hydroxylamine (NH2OH) oxidation, nitrifier denitrification, and heterotrophic denitrification. These processes are affected by several factors, including the carbon-to-nitrogen (C/N) ratio, NH3 oxidation rate NH3 oxidation rate, redox conditions, and temperature. Addressing N2O emissions from landfills will be necessary to achieve an integrated nitrogen management strategy that helps minimize N2O emissions. [ABSTRACT FROM AUTHOR]

Activated sludge filtration performance is a significant mean to evaluate membrane fouling trend for wastewater treatment. Here the impact of sunlight irradiation on activated sludge filtration performance and microbial communities in sequencing batch reactors (SBRs) when treating raw landfill leachate were studied. The sludge in photic SBR (i.e., SBR exposed to natural sunlight) exhibited better filtration performance compared to dark SBR (i.e., SBR unexposed to sunlight). The removal efficiency of COD and NH4+‐N in the photic SBR were slightly higher than those in the dark SBR. The contents of the extracellular polymeric substances (EPSs) of sludge in both SBRs initially increased and then decreased. However, in the later period, the sludge filtration performance worsened due to the fungal activity in the dark SBR. Natural sunlight irradiation promoted sludge filtration performance by affecting the microorganism structure in the photic SBR. The bacterial genus Thauera was dominant in the photic SBR (39.35%), whereas Planktosalinus and Ottowia were dominant in the dark SBR (16.84% and 12.55%, respectively). Natural sunlight irradiation had a prominent effect on the fungal diversity in the system, and filamentous bulking caused by the fungi genus Trichosporon's proliferation was observed in the dark SBR but not in the photic SBR, which also increased the polysaccharide content. [ABSTRACT FROM AUTHOR]

In this study, a three-dimensional electrochemical oxidation system, with steel slags as particle electrodes, was applied to deal with landfill leachate. The characteristics of particle electrodes were investigated by scanning electron microscope (SEM), X-ray fluorescence spectroscopy (XRF) and X-ray diffraction (XRD) measurements. It was found that the steel slag exhibited rough and irregular surface and mainly consisted of SiO2 (Quartz), which indicated the enhanced absorbed and electroconducted abilities. Subsequently, comparative degradation tests between two-dimensional (2D) and three-dimensional (3D) electrochemical oxidation systems were carried out and results indicated removal efficiencies of COD. Moreover, NH4+-N from landfill leachate in 3D system was greatly improved compared with that of 2D system. Besides, operating conditions were also optimized to interelectrode distance of 1 cm, current density of 20 mA·cm−2, initial pH value of 4.4 and steel slag concentration of 0.30 g·mL−1, all of which were determined to guarantee excellent landfill leachate removal efficiency. In addition, a possible removal mechanism for this system was proposed. The introduction of steel slag particle electrodes in three-dimensional electrochemical oxidation system implied the concept for "using waste to treat waste", providing a workable way in pollutant elimination. [ABSTRACT FROM AUTHOR]

Simple Summary: Food availability plays a significant role in modulating populations, especially in species relying on human-generated food sources like landfills. Sudden changes in food access can negatively impact vital parameters such as survival. For long-lived scavenger species, understanding how different age groups respond to these changes is essential since landfills are condemned to be closed. We studied the response in terms of apparent survival of griffon vultures to a decline in landfill organic matter after a waste treatment center became operational. The proportion of transients increased in all age groups. Survival dropped in juveniles and adult residents but increased in immature residents. These findings suggest that vultures permanently emigrated at higher rates due to intensified competition after the reduction in food. Intriguingly, immature resident vultures showed resilience, indicating the presence of high-quality individuals despite the food scarcity. The reasons behind reduced survival in adult residents during the final four study years remain unclear but are potentially linked to non-natural mortality. This research highlights the challenges facing scavengers as European landfill sites close, thereby stressing the need for food scarcity studies and timely conservation measures. Food availability shapes demographic parameters and population dynamics. Certain species have adapted to predictable anthropogenic food resources like landfills. However, abrupt shifts in food availability can negatively impact such populations. While changes in survival are expected, the age-related effects remain poorly understood, particularly in long-lived scavenger species. We investigated the age-specific demographic response of a Griffon vulture (Gyps fulvus) population to a reduction in organic matter in a landfill and analyzed apparent survival and the probability of transience after initial capture using a Bayesian Cormack-Jolly-Seber model on data from 2012–2022. The proportion of transients among newly captured immatures and adults increased after the reduction in food. Juvenile apparent survival declined, increased in immature residents, and decreased in adult residents. These results suggest that there was a greater likelihood of permanent emigration due to intensified intraspecific competition following the reduction in food. Interestingly, resident immatures showed the opposite trend, suggesting the persistence of high-quality individuals despite the food scarcity. Although the reasons behind the reduced apparent survival of resident adults in the final four years of the study remain unclear, non-natural mortality potentially plays a part. In Europe landfill closure regulations are being implemented and pose a threat to avian scavenger populations, which underlines the need for research on food scarcity scenarios and proper conservation measures. [ABSTRACT FROM AUTHOR]

Plastics, which are versatile and widely used materials, are being improperly disposed of in landfills or water bodies, leading to significant environmental damage. Traditional methods for plastic waste management, such as thermal decomposition and gasification, require high energy input. Recycling plastics back into their original form is a sustainable option, but demands high purity of recycled plastics and complex pre- and post-treatments. Electrochemical upcycling has recently emerged as a new alternative, which utilizes electrochemical reactions to transform plastic waste into valuable chemical compounds. Its advantages include the ability to operate under mild conditions, the use of eco-friendly energy sources, and increased energy efficiency. This review article provides an overview of electrochemical upcycling technologies for various types of waste plastics and explores their potential for generating value-added products. It also highlights the importance of understanding reaction mechanisms, electrochemical reaction systems, and catalyst development. We believe that the integration of electrochemical upcycling and chemical depolymerization has the potential to contribute to a circular economy and mitigate the environmental impact of plastic waste. [ABSTRACT FROM AUTHOR]

Landfill leachates contain harmful substances viz. chemicals, heavy metals, and pathogens, that pose a threat to human health and the environment. Unattended leachate can also cause ground water contamination, soil pollution and air pollution. This study focuses on management of leachate, by recirculating the rich, nutrient-filled fluid back into the landfills, turning it to a bioreactor, thereby maximising the performance parameters of landfills favourable for electricity production by the waste to energy plants. This study demonstrates a sustainable alternative method for utilising the fluid, rather than treating it using an extremely expensive treatment process. Further, it also experimentally investigates the effect of varying levels of five input parameters of the landfill including waste particle size, waste addition, inorganic content in waste, leachate recirculation rate, and landfill age, each at five levels, on the multiple performance of the landfill using Taguchi's L25 standard orthogonal array. Experimental results are analysed using an integrated MCDM approach i.e. MEREC-PIV method and statistical techniques such as analysis of mean (ANOM) and analysis of variance (ANOVA). The results indicate that the optimal setting of the input parameters is waste particle size at 9 ppm, waste addition at 80 Ktoe, inorganic content in waste at 2%, leachate recirculation rate at 250 l/day and landfill age at 3 years. Further, inorganic content waste is found to be the most significant parameter for the multiple performance of the landfill. This study presents a novel approach to produce input parameters for power plants which may enhance their profitability and sustainability. [ABSTRACT FROM AUTHOR]

• Pressure inhibits H 2 S and MM release, and the inhibition increases with pressure. • The peak concentration of H 2 S in pressure-bearing environment is about 10–70 mg·m−3. • Temperature significantly alters the bacterial community of landfill. • Pressure induces the enrichment of specific SRBs. • Sulfate reduction behavior at 25 °C and 50 °C is mediated by specific SRBs. The behavior of sulfate reduction, which was the source of hydrogen sulfide (H 2 S) odor, was investigated under changing pressure and temperature conditions inside landfills. The results showed that the release of H 2 S and methyl mercaptan (MM) was significantly inhibited at 25 °C and 50 °C under pressure, and the highest H 2 S and MM concentrations released were only 0.82 %-1.30 % and 1.87 %-4.32 % of atmospheric pressure, respectively. Analysis of the microbial community structure and identification of sulfate-reducing bacteria (SRB) revealed that temperature significantly altered the microbial community in the landfill environment, while pressure inhibited some bacteria and induced the growth and reproduction of specific bacteria. Key SRB (Desulfosporosinus- ASV212, Desulfitibacter -ASV1744) mediated differentiated sulfate reduction behavior in the pressure-bearing environment at 25 °C, while key SRB (Dethiobacter -ASV177, Desulfitibacter -ASV2355 and ASV316) were involved at 50 °C. This study provides a theoretical basis for the formulation of landfill gas management and control strategies. [ABSTRACT FROM AUTHOR]

• THMBC coupled model can analyze the rules of a complex degradation process and make up for mistakes in experimental operations. • Recharge of mature leachate and heating can relieve the inhibition and accelerate stabilization. • Intraparticle water release induces large settlement in the early degradation period. • Degradation rate cannot be maintained during winter without reliable insulation measures. The complex process of thermal-hydro-mechanical-biochemical (THMBC) coupled degradation in high food waste content (HFWC) municipal solid waste (MSW) is the main cause of intense heat, gas, and leachate generation in the landfills, which could lead to environmental disasters. A large-scale indoor experiment on HFWC MSW has been done with operations of loading, heated mature leachate recharging to study the rules of degradation. A THMBC coupled degradation model is used to analyze the results in the first 400 days drawn from the experiments, to explain how recharge of heated mature leachate accelerated degradation process and how was the portion of settlement led by intraparticle water release. The numerical simulation also calculated the landfill gas that was not collected in the experiment due to operational defects. The results show that recharging the heated mature leachate allows the stabilization process to occur at least six months earlier and settlement due to intraparticle water release accounts for half of the settlement in the first 60 days. The research indicates highly coupled THMBC model can be used to analyze the complex process in MSW degradation, make up for the shortcomings of physical experiments, and provide theoretical support for the design, construction, and management of landfills. [ABSTRACT FROM AUTHOR]

• The collected stored methane is accumulated in an average of 2.5 h. • Shutdown should be done 3.1 h before Hydro-Quebec's consumption peak. • Collected stored methane represents 10.5% of methane flow. Landfills are extensively applied to dispose of municipal solid wastes in developed and developing countries. Landfill gas generation from biodegradable organic wastes can be collected and converted to energy. When the gas collection system is shutdown, some of this gas can accumulate and be stored inside the landfill. Using the gas storage capacity of the landfill gets a better management of the landfill site because the collected stored gas could transform the landfill into a cheap gas storage system to provide short-term energy and use the energy when needed. This novel study analyzes the stored methane using the gas collection data of a landfill in Quebec province, Canada, for modulating energy production from landfill gas. Twenty episodes of the gas collection system's shutdown and restart as well as different gas flow durations were studied. The results showed that the collected stored methane is accumulated in an average of 2.5 h. Additionally, the collected stored methane represents 10.5% of landfill gas flow. Although the results are site-specific, the methodology of this paper can be used on other landfill sites with similar size and collection conditions. Designing new landfills could take into consideration some elements to enhance gas storage capacity. For instance, designing landfill daily covers with more granular materials and higher porosities can be the next step to enhance the landfill as a gas storage system during shutdowns. [ABSTRACT FROM AUTHOR]

[Display omitted] • The first overview of co-authorship network of microplastics in landfill leachate. • Light color Polyethylene, Polypropylene, and Polystyrene are dominant in leachate. • Microplastics abundance is biased with different sampling and analysis techniques. • There are no global standards for microplastic management. Plastic wastes deposited in landfills eventually break down and degrade into microplastics by physical, chemical, and biological forces. Though microplastics in leachate pose significant threats to the environment, the leachate generated from landfills has not received much attention as a possible source of environmental microplastics. A descriptive and systematic investigation of the global distribution of microplastics in landfill leachate does not exist to date. Therefore, this attempt is to provide a concise scientometric review of the studies on the presence of microplastics in landfill leachate. The present review revealed that the global trend in research on microplastics in leachate has increased exponentially after 2018 and China is the leading country. Different geographical regions have reported different microplastic abundances with the highest of 291.0 ± 91.0 items/L from a landfill in Shanghai. The use of novel sampling techniques to detect small microplastics (20–100 µm) has led to the high abundance of microplastics in landfill leachate in Shanghai. Due to its widespread usage, polyethylene is the most typically encountered polymer type in landfill leachate around the world. However, it is quite challenging to compare the results among studies due to the use of different size categories and extraction techniques. The removal of microplastics by the current leachate treatment facilities is still mostly unexplored, thus it is crucial to develop novel technologies to treat the microplastics in landfill leachate. Further investigations on the transport of microplastics in landfill leachate are urgently required to have a better understanding of potential human exposure and health implications. [ABSTRACT FROM AUTHOR]

Malaysia encounters a consistent rise in the generation of solid waste and leachate on a daily basis. It should also be noted that leachate has a low degree of biodegradability (BOD5/chemical oxygen demand [COD]), as shown by its BOD5/COD ratio. Its high toxicity levels significantly threaten the environment, water bodies, and human well‐being. High concentrations of COD, color, and ammoniacal nitrogen (NH3‐N) in leachate prevent this wastewater from being allowed to be discharged directly into the water body. Therefore, an effective process to remove the pollutant is desired. The aims of this study are to investigate the performance of ozonation with two metallic compounds, ZrCl4 and SnCl4, and optimize their performance using response surface methodology (RSM). In this study, the performance of ozonation with ZrCl4 (O3/ZrCl4) recorded better pollutant removals compared with the ozonation with tin tetrachloride (O3/SnCl4), as seen in the removals of 99.8%, 93.5%, and 46.3% for color, COD, and NH3‐N, respectively. These removals were achieved by following the experimental model (optimum experiment condition) generated by RSM at O3 dosage of 31 g/m3, COD and ZrCl4 dosage ratio (COD, mg/L/ZrCl4, mg/L) of 1:1.35, with the pH solution of 8.78 and reaction time of 89 min. The R2 of each parameter for this model was recorded as 0.999 (COD), 0.999 (color), and 0.998 (NH3‐N), respectively. These data indicated that the model is well fitted as the predicted data by statistical calculation and in good agreement with the actual data. Practitioner Points: The performance of O3/ZrCl4 and O3/SnCl4 was examined for remediate stabilized landfill leachate.The performance of O3/ZrCl4 and O3/SnCl4 was optimized using RSM, and a set of experimental models was generated and tested.O3/ZrCl4 recorded the higher removal of COD, color, and NH3‐N compared with O3/SnCl4.At best condition, both methods recorded removal as 89% to 99.8% of pollutants in leachate and product clear effluent.This finding gives a new approach to treat landfill leachate effectively and efficiently. [ABSTRACT FROM AUTHOR]

The failure of the waste management system and the distribution of uncontrolled dumpsites across Lebanon has turned this small state into a source of major environmental concern in the Eastern Mediterranean. The coastline of Lebanon hosts several landfills, such as the Tripoli Municipal Solid Waste Landfill, which are often poorly studied. The situation is particularly concerning because the drainage of their untreated leachate often seeps into the surrounding water systems including the Mediterranean Sea and nearby ricers. In the case of the Tripoli Municipal Solid Waste Landfill, no previous studies have investigated the composition of this leachate and its effect on the surrounding water systems. The aim of this study is to assess the seasonal variation of leachate characteristics in this landfill's two units and their potential of contamination on the nearby Abou Ali River and Mediterranean Sea. In accord with the Standard Methods for the Examination of Water and Wastewater, 40 leachate quality parameters (19 physicochemical, and 21 metals) were monitored for two years. The results of this study showed the heterogeneous state of the landfill's body. Leachate quantity and quality heavily depended on weather conditions. The annual fluxes of chemical oxygen demand, chloride, biological oxygen demand, total kjeldahl nitrogen, sulphates, and total phosphorus, were 577 tons, 253 tons, 207 tons, 38 tons, 25 tons, and 7 tons, respectively. The annual fluxes of the Σ21metals achieved 217 tons. The leachate pollution index of Tripoli's landfill indicates its high contaminating potential on Abou Ali River and Mediterranean Sea. [ABSTRACT FROM AUTHOR]

Landfill leachate is a complex wastewater with high concentration and toxicity that poses a serious threat to public health and the environment by contaminating groundwater. Although natural attenuation processes occur within the aquifer, the temporal changes in geochemical parameters and microbial community structure within the pollution plume are not well understood. This study features microcosm simulation experiments conducted using a range of dilution ratios intended to simulate different locations within a landfill leachate pollution plume. The study monitored changes in biogeochemical parameters at different positions of the pollution plume during natural attenuation. The results show that the pollution source of landfill leachate leakage contamination is characterized by high electrical conductivity (EC) and low oxidation–reduction potential (ORP). Biogeochemical parameters within the plume changed significantly, with oxygen being rapidly consumed to form an anaerobic environment that entered an initial stage of acid production followed by methane production. The pH decreased during the acid-producing stage, but then increased during the methanogenic stage, with a concurrent decrease in total organic carbon (TOC) content. In addition, 16S rRNA amplicon sequencing revealed that in areas closer to the pollution source, the bacterial diversity index was lower and the relative abundance of Prolixibacteraceae and Trueperaceae as well as microorganisms capable of anaerobic fermentation, degradation, and heavy metal resistance was higher. Spearman correlation analysis of geochemical parameters and microbial functional genes demonstrated that an environment characterized by low dissolved oxygen (DO) and ORP within the plume could enhance the abundance of microbial functional genes associated with transport and catabolism, energy metabolism, nucleotide metabolism, replication and repair, and membrane transport. [ABSTRACT FROM AUTHOR]

The key to upgrade the efficiency of aerobic remediation of landfills is to determine the distribution characteristics of oxygen concentration during aerobic ventilation. This study discusses the distribution law of oxygen concentration with time and radial distance based on a single-well aeration test at an old landfill site. The transient analytical solution of the radial oxygen concentration distribution was deduced using the gas continuity equation and approximation of calculus and logarithmic functions. Oxygen concentration data from the field monitoring were compared with the results predicted by the analytical solution. The results indicated that the oxygen concentration initially increased and then decreased with prolonged aeration time. With an increase in radial distance, the oxygen concentration rapidly declined, followed by a gradual decrease. The influence radius of the aeration well increased slightly when the aeration pressure increased from 2 to 20 kPa. The field test data agreed with the analytical solution prediction results, preliminarily verifying the reliability of the oxygen concentration prediction model. Results from this study provide a basis of guidelines for the design, operation and maintenance management of a landfill aerobic restoration project. [ABSTRACT FROM AUTHOR]

• The main source of PAEs in landfills for domestic waste and construction waste. • Transformation of PAEs in landfills influenced by physicochemical biology. • Distribution of PAEs in soil–water–atmosphere around landfills. • Suggestions for management and research directions for PAE in landfills. Phthalates (PAEs) are added to various products as a plasticizer. As these products age and are disposed of, plastic waste containing PAEs enters the landfill. The landfill environment is complicated and can be regarded as a "black box". Also, PAEs do not bind with the polymer matrix. Therefore, when a series of physical chemistry and biological reactions occur during the stabilization of landfills, PAEs leach from waste and migrate to the surrounding environmental media, thereby contaminating the surrounding soil, water ecosystems, and atmosphere. Although research on PAEs has achieved progress over the years, they are mainly concentrated on a particular aspect of PAEs in the landfill; there are fewer inquiries on the life cycle of PAEs. In this study, we review the presence of PAEs in the landfill in the following aspects: (1) the main source of PAEs in landfills; (2) the impact of the landfill environment on PAE migration and conversion; (3) distribution and transmedia migration of PAEs in aquatic ecosystems, soils, and atmosphere; and (4) PAE management and control in the landfill and future research direction. The purpose is to track the life cycle of PAEs in landfills, provide scientific basis for in-depth understanding of the migration and transformation of PAEs and environmental pollution control in landfills, and new ideas for the sustainable utilization of landfills. [ABSTRACT FROM AUTHOR]

Limited information is available in the literature regarding the energy consumption and the greenhouse gases emitted during landfill leachates treatment. A full-scale landfill leachates treatment system that included primary sedimentation, biological treatment in sequencing batch reactors, reverse osmosis and mechanical vapor recompression evaporation was monitored and evaluated for the removal of major pollutants, energy consumption and greenhouse gas emissions. Samples were taken during a period of two years from different points of the system, while the actual power consumption was calculated considering the available mechanical equipment and the hours of operation. The quantities of greenhouse gases emitted were estimated using appropriate equations and based on the operational characteristics of the system. According to chemical analyses, biological treatment resulted in partial removal of COD and total nitrogen, while the removal of BOD5 and NH4-N was significant, reaching 90 and 98%, respectively. Use of reverse osmosis increased the removal of all pollutants, satisfying the requirements of the legislation on wastewater discharge into the environment. Power consumption was calculated to be 35.3 KWhr per m3 of treated leachate, while mechanical vapor recompression evaporation was responsible for 60.5% of the total energy required. The contribution of other processes to energy consumption was as follows, in decreasing order: sequencing batch reactors > reverse osmosis > primary treatment. The roots blower vacuum pump used for mechanical vapor recompression evaporation, and the blowers providing air to the sequencing batch reactors, were the most energy-intensive pieces of apparatus, contributing 44.2% and 11.3% of the required energy, respectively. The quantity of greenhouse gases emitted was estimated to be 27.7 Kg CO2eq per m3 of treated leachates. Among the different processes used, biological treatment and mechanical vapor recompression evaporation contributed to 45.7% and 44.1% of the total emissions, respectively. The findings of this study reveal that an integrated landfill leachate treatment system that combines biological treatment and reverse osmosis can assure the protection of the aquatic environment by producing high-quality effluent; however, further research should be conducted regarding the sustainable management of reverse osmosis concentrate. Mechanical vapor recompression evaporation contributes significantly to the environmental footprint of the landfill leachates treatment system due to both high energy consumption and elevated emissions of greenhouse gases. [ABSTRACT FROM AUTHOR]

This study evaluated the feasibility of ionizing radiation combined with coagulation–sedimentation and Fenton oxidation as a treatment method for landfill leachate. The experiments revealed a positive correlation between pollutant removal efficiency and increased ionizing radiation intensity. Remarkable pollutant removal efficiencies were achieved under ionizing radiation at 50 kGy, with a maximum of 27% removal of total organic carbon (TOC), 61% removal of total nitrogen, 51% removal of total phosphorus, and an impressive 93% removal of NO3−-N. With the addition of coagulation–sedimentation and Fenton oxidation, the treatment efficiency further increased by 33% nitrogen, 18% SCOD, and 8% phosphate. The most significant observation from the study was that for all the different treatment methods, the results were always better for leachate samples treated with ionizing radiation than for the untreated samples. Subsequently, biological treatment was applied as a post-treatment method to remove residual organic carbon and nitrogen, which found that the best removal efficiencies were only for the low salt concentration (0.5%) and the removal decreased with increasing salt concentration. These experimental results conclusively demonstrated that when treating leachate wastewater, it was more appropriate to employ physicochemical methods rather than a biological treatment, primarily due to the high salt concentration present. [ABSTRACT FROM AUTHOR]

Waste management systems have developed in recent years toward the adoption of sustainable management principles and practices, such as circular economy, zero waste, resource efficiency, waste avoidance, re-use, and recycling. Nevertheless, landfills continue to be used for waste disposal despite their risks related to contamination and effects on urban development. Most research on landfills focuses on their operational and technical aspects, while the performance and cost efficiency in managing landfills is less commonly studied, especially their post-closure management. However, improving efficiency is very relevant in the context of scarce public sector resources. This paper, therefore, analyzes the efficiency of post-closure management of landfills. Drawing on agency and stewardship theories, we focus on the difference in efficiency between public and private management of post-closure landfills. We use a linear mixed regression model to analyze data from 2015 to 2018 relating to 54 landfills (79% of which are privately managed) in the Emilia-Romagna region of Italy. The results show that public management is more efficient than private management. Results contribute to defining drivers of cost and confirming a disparity in the performance of private and public management. Our results cast doubt on the assumption, which is prevalent in new public management theory, that private operators are more efficient than public ones. We conclude by highlighting that to reach efficiency, it is better to increase the effectiveness of regulation in terms of value for money, without pre-determined preferences for the type of management. [ABSTRACT FROM AUTHOR]

Engineered capping systems are efficient tools for the safety concept for landfills and contaminated land, consisting of multilayer barriers installed at the top of the deposited waste, even years after its closure. The efficiency of such systems is closely associated with avoiding rainwater infiltration into the waste body, a process that can be assessed and monitored with geophysical methods, such as Electrical Resistivity Tomography (ERT). A surface geomembrane capping of approximately 900 m2 was installed over an abandoned unlined landfill in southeastern Brazil and ERT surveys were adopted to assay the effectiveness of the intervention measure. It was possible to verify significantly more resistive regions below the geomembrane and an increase in conductivity values only at approximately 6 m, at the groundwater level of the area. Thus, the reduction of rainwater input possibly, even in the short term, reduces the moisture content and prevents the formation of leachate sheets in unlined landfills, leading the deposit to be more isolated from the surroundings. Lateral flow affected distances as far as 2.5 m from the capping borders, showing that about 70% of the capped area was effectively isolated from the rainfall infiltration. Therefore, capping contributed to reducing leachate production and can be considered an effective method for mitigating impacts from old unlined landfills. [ABSTRACT FROM AUTHOR]

Use of sanitary landfill in waste management may involve complex processes but has proven to be sustainable and effective in mitigating environmental degradation when the site is properly located. Despite this innovation, waste mismanagement compounded by alarming population growth, increasing urbanization and industrialization had raised much environmental concern in Edo State, Nigeria. Therefore, the present study integrated ten most common and applicable selection criteria with a view to identifying suitable landfill sites with environmental and socio-economic benefits for proper waste management, rational land use and sustainable development planning in four Local Government Areas in the State. The selection criteria used are surface water bodies, land use, land slope, depth to groundwater, geology, lineament, soil media, built-up area, road network and airport location. The Analytic hierarchy process technique was used to compute pair-wise comparison matrix for determining criteria weights while the weighted linear combination method was employed in combining the criteria weights. ArcMap 10.2 overlaid the ten thematic maps to generate a landfill site suitability map. The results of the study showed significant land use dynamics and drastically increasing built-up areas. This rapid urbanization had overtaken all the existing dumpsites which failed to meet adopted standards in the metropolis thereby rendering their locations inappropriate in today's urban setting. Hence, the dumpsites constituted potential environmental menaces with socio-economic and health implications. This study has identified eight potential sites for sanitary landfill which could guide decision makers in formulating effective policies towards sustainable environment, urban planning and water resources development in the area. [ABSTRACT FROM AUTHOR]

The leachate generated from a landfill can cause significant harm to the environment and human health, so it must be treated before being discharged. A biochemical method is effective to treat the landfill leachate, but it requires a physicochemical pretreatment to help reduce the organic load and improve the biodegradability of the landfill leachate. In this work, hydrodynamic cavitation was used to pretreat the landfill leachate due to it being cost-effective, without additional chemicals, and environmentally friendly. The pretreatment experiments were conducted under an inlet pressure of 0.4 MPa and a basic pH. The influence of operating parameters such as the orifice opening rate, the arrangement of orifices, and the reaction time on the chemical oxygen demand, ammonium nitrogen, and biochemical oxygen demand removal in landfill leachate was studied, and the energy efficiency was evaluated. The results showed that under the above conditions, the removal rate for the chemical oxygen demand of the orifice plate with an annular orifice arrangement was better than that of the orifice plate with a radiation orifice arrangement, and the orifice plate with an orifice opening rate of 0.0417 had the best effectiveness. The energy efficiency under these two optimization conditions was also the highest. When the optimal operation time was 60 min, the removal rate of the chemical oxygen demand was 22.63%. The biodegradability of the landfill leachate was significantly improved with BOD5/COD increasing by 57.27%. The study provides a theoretical basis and data support for the application of hydrodynamic cavitation as a low-cost and efficient treatment method in the pretreatment of landfill leachate. [ABSTRACT FROM AUTHOR]

Landfill leachate is generated from waste degradation in landfill sites, and its treatment includes biological or combined treatment with physico-chemical methods. A frequently applied technology in the biological stage of landfill leachate treatment plants is based on denitrification and nitrification. Nevertheless, with the availability of a huge number of scientific reports, the management of denitrification and nitrification (D/N) processes in the frame of real wastewater treatment plants (WWTPs) is rather difficult and always remains a critical technological problem. This study aims to perform a comparative assessment between denitrification and nitrification processes during landfill leachate treatment in three different situations in the WWTP of the Municipal Enterprise for Waste Treatment in Sofia City, Bulgaria. The comparative assessment is based on the biotransformation effectiveness of ammonium ions in the course of nitrification and of nitrates in the course of denitrification. Mixed samples (wastewater and activated sludge) were taken from the sequencing batch reactors operating in the mode of denitrification and nitrification. All physico-chemical (pH, dissolved oxygen, organics concentration, BOD5:COD, nitrogen and phosphorous) and biological (sludge volume index, sludge biotic index, quantity of aerobic heterotrophs, denitrifiers and nitrifiers, total dehydrogenase activity) indicators were investigated in the samples from the biobasins in the mode of denitrification and nitrification. The conditions for the implementation of the two processes were compared, along with the state of the activated sludge in the different reactors. The obtained results showed that denitrification was the critical process in the technology on the base of D/N. A major factor that managed the denitrification was the lower concentration of biodegradable organic matter which led to a deformation of the activated sludge structure, a decrease in the count of heterotrophic microorganisms, a decrease in the total activity of the activated sludge and an inhibition of the nitrate reductase activity. The nitrification processes were accomplished with high intensity. The results confirmed that D/N could be optimized and controlled using specific wastewater treatment technology parameters and purposely applied indicators. [ABSTRACT FROM AUTHOR]

Landfill leachate is regarded as a significant point source of pollutants that may pose a hazard to the environment, particularly to surface and ground waters. Leachates are highly variable and heterogeneous. Our study was focused on the characterization of landfill leachates derived from young (YDS) and matured (MDS) dumpsites in terms of the abundance of micropollutants, antimicrobial resistance genes (ARG), and microbial community structure. The concentrations of poly- and perfluoroalkyl substances (PFASs) were found to be higher in MDS compared to YDS, i.e., 13.19 and 7.16 μg/L, respectively. Among pharmaceutical compounds, ibuprofen was detected at the highest concentrations, i.e., 12.54, 12.81, and 13.13 μg/L, in the leachates derived from MDS, YDS, and ponds. The distribution of bacteria, archaea, eukaryotes, and viruses in the three leachate samples was as follows: 85.15 ÷ 88.04%, 9.13 ÷ 12.29%, 2.20 ÷ 2.68%, and 0.12 ÷ 0.15%, respectively. In total, 31 distinct families of ARGs were identified, comprising a total of 80 ARGs. Incubation of P. putida MSCL650 in sterile leachate from the pond resulted in decreasing the minimum inhibitory concentrations for six antibiotics as compared to cells incubated in nutrient broth. Hydrological processes, i.e., runoff and infiltration, can increase the dissemination of ARGs. [ABSTRACT FROM AUTHOR]

Christian Kassar, a process engineer at Black & Veatch in Arizona, recently published an article in AWWA Water Science about the removal of PFAS (per- and polyfluoroalkyl substances) from groundwater using weak-base anion exchange resins. His research focuses on evaluating alternative treatment methods for complete on-site removal and degradation of PFAS from landfill leachate and complex test waters. Kassar is particularly interested in emerging technologies and their potential applications in this field. His work was motivated by the challenges of handling a methanol-based solution contaminated with PFAS, and he hopes that his research represents a small step forward in the larger effort to remove PFAS. Kassar's research has prompted him to explore newer means applicable to treating PFAS-laden regenerant and to develop cost-effective, scalable technologies that can efficiently remove PFAS from water while minimizing the production of harmful residuals. The most exciting aspect of his work is witnessing the advances of water sustainability and the potential for spreading knowledge about innovative technologies to the next generation. [Extracted from the article]

Without proper treatment, leachate can contaminate adjacent groundwater, soils, and streams, resulting in potential risks to public health, the environment, and surrounding biodiversity. This work aims to treat landfill leachate by coagulation-flocculation and optimize the results using the central composite design in combination with the response surface methodology in the Mohammedia-Benslimane landfill in Morocco. The optimization of the process allowed us to find optimal removal efficiencies of color, polyphenols, and nitrates, which reached 68.8%, 77.5%, and 81.0%, respectively. The optimum conditions in this study were pH 7.66, 9.5 g/L of coagulant dose, 9.1 ml/L of flocculant dose, and 10 min of agitation time. The models obtained for the 3 responses are reliable, reproducible, and well-fitted. By optimizing the leachate treatment at the Mohammedia-Benslimane landfill using coagulation-flocculation and the response surface methodology, our study offers an efficient and reliable approach to address the challenges of landfill leachate treatment. The results obtained from this research have significant implications for liquid waste management, particularly in the context of landfill leachate treatment. [Display omitted] • Leachate characterization. • Optimizing treatment of landfill leachate using coagulation-flocculation. • Color removal. • Polyphenols removal. • Nitrate removal. [ABSTRACT FROM AUTHOR]

This research presents a novel stand-alone device for the autonomous measurement of gas pressure levels on an active landfill site, which enables the real-time monitoring of gas dynamics and supports the early detection of critical events. The developed device employs advanced sensing technologies and wireless communication capabilities, enabling remote data transmission and access via the Internet. Through extensive field experiments, we demonstrate the high sampling rate of the device and its ability to detect significant events related to gas generation dynamics in landfills, such as flare shutdowns or blockages that could lead to hazardous conditions. The validation of the device's performance against a high-end analytical system provides further evidence of its reliability and accuracy. The developed technology herein offers a cost-effective and scalable solution for environmental landfill gas monitoring and management. We expect that this research will contribute to the advancement of environmental monitoring technologies and facilitate better decision-making processes for sustainable waste management. [ABSTRACT FROM AUTHOR]

We analyzed ground subsidence at the coal ash disposal sites of Stanton Energy Center, a power plant located in Orlando, Florida, USA, by applying 157 Sentinel-1 SAR images obtained between May 2017 and December 2022 in ascending orbit to the PSInSAR technique. A LiDAR DEM with 1 m posting was used for the DInSAR and StaMPS processing for PSInSAR. The results showed significant ground subsidence on the area where solar panels were installed on top of the coal ash landfill. The coal ash landfill was divided into three sites (A, B, and C) according to the landfill sequence. The spatially averaged PSInSAR showed subsidence rates of 7.3 mm/year, 6.2 mm/year, and 8.8 mm/year in sites A, B, and C, respectively. In particular, relatively newly deposited sites A and B showed a decreasing trend in subsidence rate with higher quadratic components in regression function, indicating a stabilization of the subsidence. On the other hand, the oldest site C exhibited the highest (and a relatively constant) subsidence rate, suggesting that the settlement occurred earlier and is now at a constant rate. It is also suspected that new dumping activity near C might have caused a higher subsidence rate than in sites A and B. No subsidence occurred at other solar panel installations on the ground outside the landfill, suggesting that the subsidence was caused by the gravitational compaction of the landfill materials rather than by the instability of the solar facilities. Comparison of PSInSAR results with lower resolution DEMs, such as SRTM and Copernicus DEM, showed range errors of the PS positions proportional to the height deviation from LiDAR DEM, highlighting the importance of accurate DEMs for the time-series analysis of SAR data. [ABSTRACT FROM AUTHOR]

High-strength wastewaters from a variety of sources, including the food industry, domestic septage, and landfill leachate, are often hauled to municipal wastewater treatment plants (WWTPs) for co-treatment. Due to their high organic loadings, these wastewaters can cause process upsets in both a WWTP's liquid and solids treatment trains and consume organic treatment capacity, leaving less capacity available to service customers in the catchment area. A novel pre-treatment method, the Waste Activated Sludge-High Rate (WASHR) process, is proposed to optimize the co-treatment of high-strength wastewaters. The WASHR process combines the contact stabilization and sequencing batch reactor processes. It utilizes waste activated sludge from a municipal WWTP as its biomass source, allowing for a rapid start-up. Bench-scale treatment trials of winery wastewater confirm the WASHR process can reduce loadings on the downstream WWTP's liquid and solids treatment trains. A case study approach is used to confirm the economic viability and environmental sustainability of the WASHR process compared to direct co-treatment, using life-cycle cost analyses and greenhouse gas emissions estimates. [ABSTRACT FROM AUTHOR]

Meeting climate change mitigation targets by 2050, as outlined in international pledges, involves determining optimal strategies for forest management, wood supply, the substitution of greenhouse gas‐intensive materials and energy sources, and wood product disposal. Our study quantified the cumulative mitigation potential by 2050 of the forest sector in the province of Quebec, Canada, using several alternative strategies and assessed under what circumstances the sector could contribute to the targets. We used the Carbon Budget Model of the Canadian Forest Sector to project ecosystems emissions and sequestration of seven alternative and one baseline (business‐as‐usual [BaU]) forest management scenarios over the 2018–2050 period. Three baskets of wood products were used in a Harvested Wood Products model to predict wood product emissions. The mitigation potential was determined by comparing the cumulative CO2e budget of each alternative scenario to the BaU. The proportion of methane emissions from landfills (RCH4%) and the required displacement factor (RDF) to achieve mitigation benefits were assessed both independently and jointly. The fastest and most efficient way to improve mitigation outcomes of the forest sector of Quebec is to reduce end‐of‐life methane emissions from wood products. By reducing methane emissions, the RDF for achieving mitigation benefits through intensification strategies can be reduced from 1.2–2.3 to 0–0.9 tC/tC, thus reaching the current provincial mean DF threshold (0.9). Both a reduction and an increase in the harvested volume have the potential to provide mitigation benefits with adequate RCH4% and RDF. Increased carbon sequestration in ecosystems, innovations in long‐lived wood products, and optimal substitution in markets offer potential avenues for the forest sector to contribute to mitigation benefits but are subject to significant uncertainties. Methane emission reduction at the end of wood product service life is emerging as a valuable approach to enhance mitigation benefits of the forest sector. We determined the Quebec forest sector's carbon mitigation potential using alternative strategies (forest ecosystems/product decay/substitution). We estimated the displacement factors that are required for wood products by 2050. We estimated the landfill CH4 emission reductions that must be achieved by 2050. Conservation alternatives increase carbon sinks by 2050, and intensification alternatives increase carbon sources by 2050. With improved methane management and optimal substitution, both conservation and intensification scenarios could provide mitigation benefits. Quebec's forests sector can contribute to enhanced climate mitigation benefits if sustainable forest management, optimum use of wood, and improved methane management of landfills are achieved. [ABSTRACT FROM AUTHOR]

A worldwide increase in waste production and energy demand as the world's population grows and consumes more resources: therefore, sustainable waste management strategies are important. The goal of this work is to research the guidelines for the appropriate RDF production and landfill waste management of the Nonthaburi province, Thailand. Refuse Derived Fuel (RDF) produced from landfilled Waste (LW) in Nonthaburi was investigated the physicochemical. The following procedure has implemented for the production of LW to RDF of 25 tons/hr of LW; (i) the LW was placed in a pre-shredder, which was followed by a primary crusher; (ii) metals were removed from the waste stream using a magnetic separator; (iii) the LW was transferred using a conveyor belt to a dynamic disc screen, where recyclable waste was separated into smaller sizes less than 80 mm.; (iv) the waste passed through an air separator to reject high-density materials (soil and glass); (v) the undesired material were separated manually, and (vi) the desired material were baled. RDF composition consisted of 78.16-67.93% plastics, 2.29 -4.34% rubber, 1.27% wood, 1.53-2.19 % textile, and other (soil-like material) 12.19-26.72%. The proximate and elemental analysis of RDF was determined according to the ASTM method. The moisture content was reduced, and the heating value increased to 18.08-29.41 MJ/kg. The results suggested high carbon and low nitrogen content suitable for energy conversion. The separation can effectively convert LW to RDF, which can be applied as an alternative fuel. Therefore, RDF can contribute to a more sustainable and circular economy. [ABSTRACT FROM AUTHOR]

Properly managed urban household waste landfills play a crucial role in achieving sustainable development and ecological civilization. This paper proposes an innovative design method that aims to overcome the limitations and extensive challenges of traditional urban domestic waste landfill design by combining aerial image segmentation with ecological restoration theory. We suggest an enhanced SEVnet, a combination of the basic vnet network and the sequence-and-excitation module, for precise and efficient garbage dump identification. Through this module, the network can independently analyze the significance of each feature channel and provide weights, leading to enhanced image detail recovery and more precise segmentation. We implemented the proposed SEVnet model based on an aerial photography database of urban garbage dumps. Following precise urban garbage disposal site division, we adopt ecological restoration theory to achieve sustainable design. This article presents the Saihanba area in China as a case study, collects pertinent data, and conducts image segmentation and GIS-assisted analysis. This paper examines the landscape application and design of the landfill site based on an analysis and planning of land use in its vicinity. The intervention of landscape ecology imbues the landfill site with new functions. We propose comprehensive planning and landscape restoration design measures from four perspectives, encompassing disadvantages, threats, opportunities, and strengths, using SWOT analysis to better integrate the Hebei Saihanba landfill site with the surrounding environment. This paper introduces a groundbreaking design scheme for a landfill that aligns with the principles of current green and sustainable development. [ABSTRACT FROM AUTHOR]

It is well documented that per- and polyfluoroalkyl substances (PFAS) are routinely detected in leachate from municipal solid waste (MSW) landfills. PFAS-containing products are ubiquitous in society and in end-of-life discarded materials. While considerable data have been generated in recent years for PFAS concentrations in landfill leachate, little published information exists concerning longer-term trends in leachate concentrations. In this study, we examine a ten-year dataset for three MSW landfills located in the upper Midwestern United States where leachate PFAS testing has been performed on a quarterly basis. The significance of these data are considered in light of phase-out initiatives implemented in the US manufacturing companies for longer-chain PFAS including perfluorooctanoic acid (PFOA), perfluorooctane sulphonate (PFOS) and perfluorononanoic acid (PFNA). Findings from this study indicate that the average concentration of longer-chain PFOA in the three landfills decreased from 2400 to 1900 ng/L and the average PFOS concentrations decreased from 1000 to 370 ng/L. This may be indicative of reduced domestic production and use of these compounds. The phase-out of long-chain PFAS has also led to the introduction of shorter-chain replacement compounds such as perfluorobutanoic acid, perfluorobutane sulphonate and perfluorohexanoic acid, and this paper also examines long-term trends in leachate concentrations of these compounds. [ABSTRACT FROM AUTHOR]

This study aimed to develop a multistage treatment system for highly toxic wastewater named reverse osmosis concentrates of landfill leachate. Therefore, a combination of the ammonia stripping process (ASP), catalytic ozone oxidation process (COP), and heterotrophic nitrification–aerobic denitrification process (HNADP) was proposed and the quality of effluent was evaluated for the concentration of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), and total nitrogen (TN). ASP had moderate removal efficiency of NH4+-N, and TN in the effluent. COP was catalyzed by cerium-supported-activated carbon achieved good performance in disposal of COD. The effluent of HNADP had the most significant removal efficiency of COD, NH4+-N, and TN. As a result, the effluent of combined process successfully met the discharge standards for NH4+-N and TN according to Table 1 of GB 16889-2008 in China. To investigate the microbial mechanism of pollutant removal in HNADP, 16S rRNA high-throughput sequencing was performed and the results suggested that the relative abundance and diversity of microorganisms fluctuated with the changes of COD/TN ratio in HNADP. Truepera and Halomonas were identified as the key genera involved in the simultaneous degradation of COD and nitrogen-containing pollutants, the functional genes (hao, amoA, nirS, and nirK) were predicted in nitrification and denitrification process. Overall, this study demonstrates a feasible multistage system for treatment of concentrates and propose that further explorations of combined techniques may lead to even more satisfactory removal efficiencies. [ABSTRACT FROM AUTHOR]

Leachate from landfills can be a significant challenge to manage and treat due to conventional contaminants. The addition of emerging contaminants such as per- and polyfluorinatedalkyl substances (PFASs) makes treatment even more complex. PFASs enter landfills through consumer waste and have been detected in landfill leachates at varying concentrations. The design and decision-making on leachate treatment require essential information since it depends on local factors, e.g. climate, proximity to wastewater treatment plants, and waste type. This study conducted a survey on actively operated public municipal solid waste (MSW) landfills in the Eastern and Northwestern regions of the US to understand the current leachate treatment practices and views from public MSW landfill managers on PFAS treatment. The survey aims to explore the possible adaptations from the industry to the pending regulatory guidelines for the potential PFASs treatment. Results show the majority of the landfills are currently using off-site disposal (72% of the responses), followed by complete onsite treatment (18% of the responses) and pre-treatment onsite and off-site disposal methods (10% of the responses). The factors that guided the selection of treatment methods included climate, economics, and future regulations. Evaporation and recirculation were the most prevalent onsite treatment technologies for public landfills, which reduced the leachate quantity for treatment. The public landfills expressed awareness of the potential impact of PFASs on the changes in leachate treatment. The current state-level regulation, potential federal PFAS regulation, and treatment costs are raising awareness of the onsite treatment for PFASs. The results of this study will benefit the improvement of PFAS awareness and provide critical information that will directly affect the leachate treatment process for PFASs. Implications: This study presents a survey on the current leachate treatment process in the public municipal solid waste landfills in the eastern and northwestern U.S. and their potential process improvement on the impact of PFASs. This study is relevant to the topic of the JA&WMA because the research falls directly within the scope of this journal, and it documents the leachate treatment of landfills, and the results of this study will immediately contribute to our understanding of the waste treatment, benefiting the improvement of PFASs awareness, and providing critical information that will directly affect the leachate treatment process. [ABSTRACT FROM AUTHOR]