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As a crucial hydrolytic enzyme, urease plays a vital role in anaerobic biological treatment. It is well-known that manganese ions are abundant in landfill leachate, but their concentration fluctuates significantly. However, few studies have investigated the effect and mechanism of different concentrations of Mn2+ on urease activity during anaerobic biological treatment of landfill leachate. This paper aimed to investigate the effects and mechanisms of different concentrations of Mn2+ on urease activity. The results showed that an appropriate amount of Mn2+ could significantly enhance urease activity, while a high concentration of Mn2+ could inhibit it. Insight into the mechanisms behind this phenomenon, various methods such as Zeta potential, particle size, ultraviolet spectroscopy, fluorescence spectroscopy, Fourier transform infrared spectroscopy, and statistical analysis were employed in our study. Research suggested that, on one hand, Mn2+ may form hydrogen bonds with the side chain amino or carboxyl groups of urease amino acid residues, affecting the structure of urease through hydrogen bonding. Additionally, Mn2+ also binds to urease through hydrophobic interactions. On the other hand, the C–OH and C-N functional groups in urease have a strong affinity for Mn2+, and changes in these functional groups can greatly enhance the activity of urease. Furthermore, under the action of high concentrations of Mn2+, while the structure of urease becomes more stable, there is also a steric hindrance phenomenon that affects the substrate from entering the catalytic center. Therefore, studying the mechanism of Mn2+ affecting urease activity has significant biological significance and provides a new perspective for exploring the impact of metals on anaerobic bioprocessing of landfill leachate. [ABSTRACT FROM AUTHOR]

Landfill leachate contains antibiotic resistance genes (ARGs) and microplastics (MPs), making it an important reservoir. However, little research has been conducted on how ARGs are enriched on MPs and how the presence of MPs affects pathogens and ARGs in leachates and soil. MPs possess the capacity to establish unique bacterial populations and assimilate contaminants from their immediate surroundings, generating a potential environment conducive to the growth of disease-causing microorganisms and antibiotic resistance genes (ARGs), thereby exerting selection pressure. Through a comprehensive analysis of scientific literature, we have carried out a practical assessment of this topic. The gathering of pollutants and the formation of dense bacterial communities on microplastics create advantageous circumstances for an increased frequency of ARG transfer and evolution. Additional investigations are necessary to acquire a more profound comprehension of how pathogens and ARGs are enriched, transported, and transferred on microplastics. This research is essential for evaluating the health risks associated with human exposure to these pollutants. [ABSTRACT FROM AUTHOR]

Anaerobic co-digestion (ACoD) has been adjudged as an efficient technology to advance the goal of climate change adaptability and carbon neutrality during waste treatment and bioenergy generation. Prior to digestion integration, an evaluation of the compatibility of the waste streams is critical to enhanced bioenergy output. This study examined the methane potential, microbial ecology, and kinetics during the co-digestion of organic fraction of municipal solid waste (OFMSW), sewage scum (SS), and a blended mixture of 1 part of new and 2 parts of mature leachate (LB) through mesophilic biochemical methane potential (BMP) test. Synergistic interaction within the mixtures increased methane yield by up to 92% (486.7 mL/gVS) over the treatment of OFMSW alone (252.3 mL/gVS). Likewise, the methane yield of LB-containing mixtures was enhanced by 16–41.5% over LB treatment alone (344 mL/gVS). Model estimates by modified Gompertz (MG) and logistic function (LF) were conclusive that the mixtures caused the methane production rate to improve by up to 16% from OFMSW alone and by at least 22% from LB alone. Furthermore, microbial analysis of mixtures revealed the proportion of LB in the mixture had a higher influence on the diversity than OFMSW. Even though acetoclastic Methanosaeta was more dominant, methane production was via a dual methanogenic pathway associated with both acetoclastic Methanosaeta and hydrogenotrophic Methanospirillum. Finally, the results obtained provide an insight on ACoD as a sustainable waste management strategy to enhance bioenergy production and reduce emissions through the recirculation of multiple heterogeneous waste streams into economic use. [ABSTRACT FROM AUTHOR]

In this study, the treatment of landfill leachate in supercritical water conditions with and without catalyst use was investigated. A real waste, namely lathe waste, was used as the catalyst. The experiments were made at a constant 25 MPa pressure, at four reaction temperatures in the range of 450-600°C and four reaction times between 60 and 150 s. Through the experiments, the impacts of reaction temperature, reaction time and the use of lathe waste catalyst on landfill leachate treatment were investigated. The efficiency of the treatment was evaluated in terms of liquid reaction products’ total organic carbon (TOC) and total nitrogen (TN) conversions. As a result, it was seen that elevated reaction temperatures and long residence times favored TOC conversions. On the contrary, greater TN reductions were encountered at lower reaction temperatures. The use of lathe waste was observed to promote the treatment efficiency for all experimental runs. The highest TOC conversion was seen at 600°C and 150 s conditions, which was 57.2% for the noncatalytic treatment. The employment of lathe waste improved this value to 66.9%. As for TN, the highest conversion was encountered at 450°C and at a reaction time of 150 s. At the foresaid reaction conditions, using lathe waste as the catalyst provided 41.9% reduction in the TN content of landfill leachate. [ABSTRACT FROM AUTHOR]

Introduction Landfill leachate, a liquid resulting from waste decomposition, contains nutrients like ammoniacal-N, Na, K, and organic matter. Biological treatments effectively remove degradable organics from young landfill leachate, but aged leachate with recalcitrant organics requires combined physical-chemical and biological methods or advanced technologies, leading to higher treatment costs. Even after treatment, leachate may not meet environmental standards for release. In arid and semi-arid regions with water scarcity and low soil organic matter, leachate application to soil presents a potential solution. Soil’s properties enable it to retain and degrade pollutants while utilizing leachate’s nutrients to enhance fertility and crop growth. However, leachate composition and application rates are critical factors due to potential negative impacts from total nitrogen, salinity, and heavy metals. Alkaline pH in aged leachate reduces heavy metal contamination risk. Detailed leachate characterization before soil application is crucial to prevent environmental and functional problems. This review examines existing research on leachate irrigation’s effects on soil properties and plant nutrition, contributing to sustainable leachate management and agricultural practices in water-limited regions. Additionally, the review explores potential risks associated with leachate irrigation, including soil salinization, heavy metal accumulation, and groundwater contamination. By understanding both the benefits and drawbacks, informed decisions can be made regarding the suitability and implementation of leachate irrigation in specific contexts. Materials and Methods To carry out this study, keywords such as "Landfill leachate", "Composition of landfill leachate" and "Landfill leachate irrigation" were searched in the Web of Science, Google Scholar, ScienceDirect, and SID databases. For these keywords, 205 articles were found from 1989 to 2023. After the screening, quality review, and removal of repetitive and unrelated articles, 110 relevant articles were used. The main criterion for selecting articles was the effects of landfill leachate irrigation on the various properties of soil, and the nutrition of different plant species. The quality of the articles was evaluated through the Scimago Journal Rank (SJR) index, the citation, the Impact Factor, and the source normalized impact per paper (SNIP) index. Results and Discussion Landfill leachate presents a complex environmental challenge due to its potential for both soil contamination and enrichment. Leachate's xenobiotic and heavy metal components can induce soil contamination, altering the natural environment. Studies have documented reduced hydraulic conductivity, increased gas production, and altered microbial communities, ultimately impacting soil productivity. Leachate percolation can also modify physicochemical characteristics, including reduced microbial biomass, phosphorus-fixing capacity, and pH shifts, depending on waste composition. Conversely, research highlights the potential benefits of leachate application in arid and semi-arid regions facing water scarcity and low soil organic matter. Leachate can contribute to the increased organic content, improved soil structure, and regulated pH, enhancing soil fertility and crop productivity. The presence of macro and micro-nutrients such as Fe, Mn, N, P, and Zn further supports leachate's potential as a fertilizer. However, concerns remain regarding inhibitory chemicals in leachate and their potential detrimental effects on plant growth and yield. Studies report instances of leaf injury, reduced yield, and poor survival rates in certain plant species. In contrast, research demonstrates the positive effects of diluted or low-strength leachate application, stimulating plant growth and enhancing yield, particularly for Brassica species and tree species like Acacia confusa, Leucaena leptocephali, and Eucalyptus tortellini. These contradictory findings underscore the intricate interplay of factors influencing leachate irrigation outcomes. Soil characteristics, plant species, leachate source and composition, application methods, and their interactions all play significant roles in determining the success or failure of leachate irrigation. Conclusion Landfill leachate, characterized by its elevated nitrogen and nutrient levels, presents a potential alternative water and fertilizer source for agricultural practices, particularly in arid and semi-arid regions facing water scarcity. However, responsible leachate utilization necessitates a comprehensive approach that balances maximizing benefits with minimizing environmental risks. Prior to agricultural application, detailed leachate characterization is crucial to determine its precise composition and suitability for irrigation. This includes quantifying heavy metal concentrations, salinity levels, and the presence of potentially toxic organic compounds. Concurrent plant selection is equally important, prioritizing species with demonstrated tolerance to leachate constituents. Given the potential for salinity and heavy metal accumulation, continuous application of raw leachate, especially for sensitive crops, should be avoided. Implementing alternating irrigation regimes with conventional water sources can mitigate these risks while providing essential nutrients for plant growth. Monitoring soil health indicators, including pH, organic matter content, and microbial activity, is vital to assess long-term impacts and implement necessary soil amendments. Determining optimal leachate application rates requires a multifaceted approach that considers plant-specific nitrogen requirements, leachate toxicity levels, and soil infiltration capacity. This ensures adequate nutrient supply without exceeding the assimilative capacity of plants and soil, preventing environmental contamination. Further research is needed to investigate the long-term impacts of leachate irrigation on soil health, crop quality, and potential groundwater contamination. Developing standardized guidelines for leachate treatment and application, tailored to specific regional contexts and crop types, is crucial for promoting sustainable and responsible leachate utilization in agriculture. [ABSTRACT FROM AUTHOR]

Landfill leachate raises a huge risk to human health and the environment as it contains a high concentration of organic and inorganic contaminants, heavy metals, ammonia, and refractory substances. Among leachate treatment techniques, the biological methods are more environmentally benign and less expensive than the physical–chemical treatment methods. Over the last few years, fungal-based treatment processes have become popular due to their ability to produce powerful oxidative enzymes like peroxidases and laccases. Fungi have shown better removal efficiency in terms of color, ammonia, and COD. However, their use in the treatment of leachate is relatively recent and still needs to be investigated. This review article assesses the potential of fungi and fungal-derived enzymes in treating landfill leachate. The review also compares different enzymes involved in the fungal catabolism of organic pollutants and the enzyme degradation mechanisms. The effect of parameters like pH, temperature, contact time, dosage variation, heavy metals and ammonia are discussed. The paper also explores the reactor configuration used in the fungal treatment and the techniques used to improve leachate treatment efficacy, like pretreatment and fungi immobilisation. Finally, the review summarises the limitations and the future direction of work required to adapt the fungal application for leachate treatment on a large scale. [ABSTRACT FROM AUTHOR]

Landfill leachate discharged into watercourse without proper treatment can pollute the water source due to its high chemical oxygen demand (COD). The high pollutant load in landfill leachate has become one of the potential substrates in bio-energy generation by using microbial fuel cell (MFC). MFC integrated with adsorption system has been introduced as an approach to overcome the limitation of stand-alone MFC, which is able to treat the landfill leachate more effectively while simultaneously generating bio-energy. Anode size has been reported to have a significant influence on the power generation of MFC via lab-scale experiments, however the simulation studies on MFC are still limited. This study aimed to develop a simulation model to predict the effect of graphite fiber brush anode size on the performance of a single chamber air-cathode hybrid MFC-Adsorption system, in terms of COD removal and bio-energy generation. The highest power density of 1.33 mW/m² was achieved with 20% anode brush removed. The highest current generation of 2.37 mA and voltage of 7.11 mV was obtained with the largest anode surface area of 0.1288 m² and resistance of 2.76 Ω. The highest COD consumption by electrogenic microorganisms was 4.96 x 10-9 Lmol/mg, and predicted to decrease with decreasing anode size. The efficiency of the simulation model could be further improved by incorporating parameters such as charge transfer kinetic at anode and cathode, adsorption effect by activated carbon as well as the substrate and microbial population behaviour. The simulation model developed was significant towards enhancing the bio-energy generation and reducing the cost of MFC for industrial application. [ABSTRACT FROM AUTHOR]

The effectiveness of using calcium peroxide (CP) to purify landfill leachate from organic and inorganic contamination has been studied under laboratory conditions using samples from a landfill as an example. The degree of purification is assessed depending on the size of the reagent added at CP/leachate ratios of 1/100, 1/50, 1/20, and 1/10 and the duration of its contact with the leachate from 1 to 3 days. The data we obtained indicate an improvement in the quality of wastewater as a result of treatment with calcium peroxide: a decrease in the concentration of heavy metals, inorganic anions, COD, etc. The results of the study support the prospects of using CP at the initial stage of cleaning of landfill leachate. [ABSTRACT FROM AUTHOR]

Humic acids (HAs) produced during the landfill on Cr(VI) fate and their combined impact on the anaerobic digestion (AD) process has not yet been fully elucidated. This study systematically evaluated the interactions and mechanism of HAs on the AD of Cr(VI)-contaminated leachate. Results indicated that high concentrations of HAs (i.e., 200, 500, 1000 mg/L) detoxified the Cr(VI) on AD and the maximum methane production of 1011.63 ± 248.01 mL/g COD was obtained at 500 mg/L HAs, representing an 18.4% increase compared to the control group. Mechanistic studies demonstrated that high concentrations of HAs (i.e., C4-C5) detoxified the Cr(VI) on AD via adsorption and reduction, and the enhanced direct interspecies electron transfer (DIET) played an important role in methane production. The adsorption capacity (32.89 mg Cr(VI)/g HAs) was significantly higher than the granular sludge (3.29 mg Cr(VI)/g TS) and adsorbed Cr(VI) was reduced to less toxic Cr(III) due to the presence of functional groups of HAs (e.g., hydroxyl and phenolic groups), achieving detoxification of Cr(VI) on AD. The increase of viable microbial cells proved the detoxification of high HAs concentrations. Moreover, the increase in the abundance of Syntrophomonas and Methanosaeta has led to the higher methane production at high HAs concentration. [ABSTRACT FROM AUTHOR]

Landfilling is the most popular, economical and simple method for disposing a wide range of waste, which on the other hand beyond doubt serves as a reservoir of toxic substances. The leachate that are released from the contaminants affects the surrounding soil, groundwater and human health. Apart from harbouring contaminants from different sources like pharmaceuticals, medical, livestock, domestic wastes, heavy metals etc., landfill leachates (LFLs) facilitate the survival and dissemination of antibiotic resistance genes (ARGs). Due to the increased population which is directly proportional to the amount of waste produced requires more stringent protocol for the control and treatment of waste that is being dumped. The current review illustrates a panoramic view on the ARGs in the LFLs that includes the occurrence, source, treatment technologies and the scientometrics to analyse the research hotspots. The literature survey confirmed that only a limited number of studies have been reported so far for removal of ARGs in LFLs and still search for a cost effective, streamlined and ubiquitous method of treatment has never ceased. This could be due to the increase as well as the detrimental nature of ARGs, hence a few suitable methods already proposed for removal of ARGs from various sources and their challenges have also been discussed, to provide an insight of different methods to be investigated in LFLs. [ABSTRACT FROM AUTHOR]

Disposal of landfill leachate is a critical environmental challenge due to its high pollution content. Effective treatment technologies are essential to mitigate the adverse impacts on groundwater and surrounding ecosystems. This paper employs bibliometric analysis and utilizes CiteSpace software to conduct a visual analysis of the knowledge graph of 959 research articles on "Disposal of Landfill Leachate" from the Web of Science core database for the period 1996-2022. The results indicate that the publication quantity has undergone three stages: the sprouting stage, the stable development stage, and the rapid development stage. In terms of international collaboration, China and the USA play an absolute core role. The journals Waste Management, Journal of Hazardous Materials, and Water Research are ranked among the top 3 publications in the field of landfill leachate treatment. The keyword co-occurrence clustering analysis revealed 7 clusters, including groundwater quality, heavy metals, hydrogeophysics, municipal solid, hydraulic conductivity, geochemical barriers and waste disposal, representing the primary research topics. This paper provides a comprehensive analysis of the research progress and development trends in the field of disposal of landfill leachate. It contributes to a better understanding of the key research areas and offers potential prospects for future investigations to researchers. [ABSTRACT FROM AUTHOR]

The burgeoning issue of landfill leachate, exacerbated by urbanization, necessitates evaluating its biological impact, traditionally overshadowed by physical and chemical assessments. This study harnesses Caenorhabditis elegans, a model organism, to elucidate the physiological toxicity of landfill leachate subjected to different treatment processes: nanofiltration reverse osmosis tail water (NFRO), membrane bioreactor (MBR), and raw leachate (RAW). Our investigation focuses on the modulation of sugar metabolism, particularly trehalose—a disaccharide serving dual functions as an energy source and an anti-adversity molecule in invertebrates. Upon exposure, C. elegans showcased a 60–70% reduction in glucose and glycogen levels alongside a significant trehalose increase, highlighting an adaptive response to environmental stress by augmenting trehalose synthesis. Notably, trehalose-related genes in the NFRO group were up-regulated, contrasting with the MBR and RAW groups, where trehalose synthesis genes outpaced decomposition genes by 20–30 times. These findings suggest that C. elegans predominantly counters landfill leachate-induced stress through trehalose accumulation. This research not only provides insights into the differential impact of leachate treatment methods on C. elegans but also proposes a molecular framework for assessing the environmental repercussions of landfill leachate, contributing to the development of novel strategies for pollution mitigation and environmental preservation. [ABSTRACT FROM AUTHOR]

Landfill leachate contains a significant amount of organic matter, making it a valuable source for CH4 production. However, due to its liquid form, the mono-digestion of leachate could result in a reduced CH4 yield per unit reactor volume. This necessitates its utilization in anaerobic digesters alongside solid waste streams. The objective of this study was to evaluate co-digestion performance of landfill leachate with different wastes using biomethane potential test and assess the optimum combination in terms of CH4 productivity. Modified Gompertz model was used for kinetic characterization. Experiments were held under mesophilic conditions and lasted for 30 days. Among mono-digestion of substrates, landfill leachate exhibited the highest CH4 productivity and yield: 83.17 mL/gVS.d and 793 ± 6.85 mL/gVS, respectively. Fish waste was found to have the lowest energy potential with 350 mL/gVS CH4 yield and 18.24 mL/gVS.d CH4 productivity. CH4 productivities for co-digestion cases ranged from 5.48 to 67.85 mL/gVS.d. Mixing landfill leachate and chicken manure with the same amount on wet weight basis yielded the highest CH4 productivity. On the other hand, inclusion of fish waste consistently resulted in decreased CH4 yield and productivity for all incubations, which suggests that fish waste may not be suitable as a co-substrate for landfill leachate in terms of CH4 production. Monitoring of chemical parameters revealed that buffering capacity of the system and free ammonia formation were the main parameters governing CH4 production. [ABSTRACT FROM AUTHOR]

A hybrid electrolytic water system was constructed including the anodic electro-oxidation treatment of the leachate from a waste incineration plant as well as the coupled cathodic electrolysis for hydrogen production. Four types of electrolyzers were designed with different flow channels and investigated the effect of different electrolysis parameters on the coupled reactions. The results indicate that the pin-type electrolyzer is superior to the other three electrolyzers in term of the degradation performance and energy consumption. At high current density of 4000 A/m2 and the flow rate of 100 ml/min, the pin-type electrolyzer shows the lowest potential of 6.09 V, the COD removal rate of 98.17% for the leachate and the energy consumption of 200.14 W h. The mass transfer mechanism was further explored under different flow channels and current densities, illustrating that the excellent performance of the pin-type electrolyzer is due to its largest mass transfer area and the most uniform inside flow field distribution. The apparent COD degradation kinetic behaviors were studied, indicating that the maximum degradation rate was 0.033 min-1 at the electric density of 4000A/m2. Such electrocatalytic oxidation of waste leachate coupled with hydrogen production would provide a promising route to construct new hybrid electrolytic water systems. [Display omitted] • Electrooxidation of leachate is successfully coupled with hydrogen production. • The coupled electrolytic water system operates well at 4000-5000A/m2. • COD removal rate is 98.17% in Pin-type electrolyzer at 4000A/m2 and 2h • Flow patterns in different electrolyzer channels are studied using PIV. • The apparent kinetics of leachate electrooxidation degradation were studied. [ABSTRACT FROM AUTHOR]

Landfill leachate contributes to groundwater pollution. The Permeable Reactive Barrier (PRB) is a sustainable in-situ method to remediate groundwater. Finding cost-effective and efficient reactive materials is a key problem with PRBs. Hence, the present study aimed to assess the applicability of two composite reactive media beds derived from several waste materials (building waste, sludge, sea sand, iron particles, bagasse, saw dust, bio char, fly ash and coconut coir pith) for PRBs to treat groundwater contaminated by landfill leachate. The study comprised two identical laboratory-scale PRB reactors: an experimental reactor and a control reactor. Each reactor included two reactive media beds in series. In the experimental reactor, one of the two beds was filled with a composite reactive media derived from waste materials with high particle densities, while the other was filled with waste materials of low particle densities. In contrast, both the beds of the control reactor were filled with Granular Activated Carbon (GAC). The experimental PRB demonstrated removal rates of 97.08 ± 0.11% (Pb), 65.01 ± 2.14% (Mn), 55.03 ± 1.06% (Fe) and 78.34 ± 1.58% (COD). The control reactor achieved removal rates of 99.26 ± 0.08% (Pb), 94.46 ± 1.13% (Mn), 80.23 ± 0.93%(Mn) and 98.83 ± 0.14% (COD). The shear strength reductions were 19%, 27%, and 11% for the high-density, low-density, and GAC beds, respectively. The associated reductions in hydraulic conductivity were 24%, 12%, and 35%. The waste-derived reactive media possess multiple properties sourced from different materials and can address the removal of multiple contaminants simultaneously, comparable to GAC. [ABSTRACT FROM AUTHOR]

The Anaerobic Baffled Reactor (ABR) is an effective solution for landfill leachate treatment using an anaerobic fermentation process, which helps to reduce operating costs and sludge volume. To better understand the biological, chemical, and physical processes involved, especially when combining the ABR with an aerobic component, the study aimed to investigate the performance of an Anaerobic–Aerobic Hybrid Baffled Reactor (AABR) that includes an Anaerobic Filter (AF) for treating landfill leachate. This research utilized two glass reactors. The first reactor, designated as AABR-AF, consisted of six independent rectangular glass chambers arranged side by side. The third and sixth chamber designed for aerobic treatment and AF, respectively. The second reactor was used as a control reactor and did not include any aerobic chamber. The highest Removal Efficiencies (REs) for turbidity, COD, BOD, TP, TKN, nitrate, TOC, and TSS in the AABR-AF and ABR-AF were found to be (65.4% and 56.3%), (98.3% and 94.1%), (98.1% and 93.2%), (86.4% and 65%), (89.2% and 76.7%), (81.2% and 64.4%), (88.2% and 79.4%), and (72.4% and 68.5%), respectively. These optimal REs were achieved at an HRT of 48 h and an OLR of 10 kg/m3.d. Also, the highest and the lowest REs in Heavy Metals (HMs) were 89.57% for manganese in AABR-AF and 6.59% for nickel in ABR-AF, in an OLR of 10 kg/m3.d, respectively. The effective removal of Organic Matters (OMs) from landfill leachate using the AABR-AF and ABR-AF was found to be strongly influenced by HRT and OLR. The AABR-AF configuration, featuring a single aerobic chamber in the reactor, exhibited a higher efficiency in removing OMs compared to the ABR-AF configuration. [ABSTRACT FROM AUTHOR]

This study analyzed the impact of leachate from a temporary landfill on soil microbial diversity in Tingo María, Huánuco region, Peru. Three treatments were used: untreated soil (S), addition of stream water (T0), leachate (T1), and leachate treated by coagulation and flocculation (T2), with 828.5 ml/week added in three weekly doses. Soil samples were collected from the Reserved Forest of the Universidad Nacional Agraria de la Selva. Twenty-one randomly distributed soil samples were taken and homogenized for analysis. Soil quality parameters measured included sand, clay, silt, texture, pH, organic matter, nitrogen, phosphorus and potassium. As for microorganisms, viable aerobes, lactobacilli, actinomycetes, fungi, nitrogen-fixing bacteria, and Escherichia coli were quantified using specific culture and counting methods for each of them. To evaluate the impact of the leachate on microbial diversity, equity indices (Shannon and inverse Simpson), dominance indices (complementary Simpson and Berger Parker) and the percentage composition of each microorganism per treatment were used. An ANOVA was performed to estimate differences in microbial diversity, with a Tukey test at a significance level of α = 0.05. The study showed that leachates affect soil microbial diversity, reducing equity and increasing the dominance of certain species such as E. coli. They also alter physicochemical parameters, decreasing organic matter and nitrogen but increasing other elements such as phosphorus and potassium. This could have implications for soil health and functionality. [ABSTRACT FROM AUTHOR]

BACKGROUND AND OBJECTIVES: The utilization of stabilization pond system for landfill leachate treatment is hindered by its requirement for expansive land areas and extended retention periods. Although the system effectively removes organic compounds, its ability to eliminate nutrients such as nitrogen and phosphorus is comparatively limited. Consequently, the leachate subjected to treatment often falls short of meeting the mandated standards for effluent quality. In response to this challenge, a research study was undertaken to investigate the potential of utilizing a consortium comprising microalgae and bacteria in the treatment of landfill leachate. METHODS: The microalgae, bacteria, and leachate utilized in this study were sourced from a leachate treatment facility located at the Aceh regional domestic waste management unit in Blang Bintang, Aceh Besar, Indonesia. The two glass photobioreactors were operated batchwise, where the first was provided with a combination of air and carbon dioxide, and the other was solely exposed to air. The pollutant removal efficacy in the leachate effluent was assessed through the measurements of chemical oxygen demand, ammonia, nitrate, nitrite, and phosphate concentrations. Subsequently, macroscopic identification of microalgae and bacteria species was also conducted. FINDINGS: Utilizing a consortium of microalgae and bacteria has demonstrated efficacy in treating leachate, resulting in a notable reduction of contaminants within the effluent. The symbiotic association between microalgae and bacteria in the context of leachate waste treatment is evident. The bacteria's metabolic actions result in carbon dioxide emission, which subsequently serves as a substrate for the photosynthetic activities of the microalgae. The microalgae facilitate the transfer of oxygen, produced through photosynthesis, to the bacteria to support their metabolic processes. Therefore, introducing exogenous carbon dioxide to the consortium yields minimal discernible effects, given that the bacteria adequately fulfill the carbon dioxide requirements of the microalgae. This discovery enhances the efficacy of leachate treatment techniques by leveraging the utilization of pre-existing mixed cultures of microalgae and bacteria found in leachate facilities. CONCLUSION: This study evaluated the microalgae-bacteria consortium's effectiveness in reducing leachate pollutants. The consortium exhibited a significant capability, achieving a 75 percent reduction in chemical oxygen demand and successfully eliminating a range of contaminants. Additionally, it demonstrated effective removal of nitrogen compounds such as ammonia, nitrate, and nitrite, with removal rates reaching 75 percent. Notably, the consortium showed a 99 percent removal rate for phosphate compounds. Even with the introduction of carbon dioxide, the pollutant removal remained consistently high, suggesting that the addition of carbon dioxide did not significantly influence the overall process. [ABSTRACT FROM AUTHOR]

Landfill leachate is a highly corrosive pollutant, and the composition of landfill leachate varies greatly between landfill ages. Landfill leachates of different ages pose a corrosive danger to concrete structures. In this study, four landfill leachates of different ages were selected for concrete immersion corrosion tests to elucidate the corrosion characteristics of concrete. Measurements of concrete mechanical property indices were combined with microscopic analysis methods, such as X-ray diffraction and scanning electron microscopy. The effects of the compositional differences of the landfill leachate of different ages and contact times on the concrete were analyzed and evaluated. The test results showed that the young landfill leachate slowed down the hydration process of concrete and promoted the generation of expansive corrosive crystals such as gypsum and calcium sulfate, which changed the internal microstructure of the concrete and caused irreversible damage. Exposure to leachates caused a decrease of the concrete quality, compressive strength, and dynamic elastic modulus to below their initial values. The participation of intermediate and mature landfill leachate in the hydration process of concrete promoted the hydration reaction in the short term. However, with the prolongation of the test period, this enhancement gradually weakened, and at the same time, the sulfate in the landfill leachate and the hydration products generated ettringite, which produced expansion stress on the internal structure of the concrete, destroying the structure and decreasing its strength. The experimental results of this study provide theoretical support for the treatment of different ages of landfill leachates and the design and protection of landfill concrete structures.

Introduction and purpose: Leachate of the urban waste landfill is one of the most contaminated wastewaters that can pollute surface and groundwater sources, especially the environment. The production trend of urban wastewater is also increasing with a sharp rise in population and the development of urbanization. To address this environmental issue, the present study aimed to consider the simultaneous treatment of mixed landfill leachate and urban wastewater using the electrochemical coagulation process. Methods: The present laboratory study was carried out on the effluent produced from the landfill and urban wastewater produced in Qaemshahr. In this study, effective parameters in the electrochemical coagulation process, including the type of electrodes (iron and aluminum), electrode arrangement (monopolar series-parallel and bipolar series), current intensity (0.5, 1, and 2 amperes), and the initial pH of the wastewater (3.2, 6.1, and 11.4) were investigated for the reduction of chemical oxygen demand (COD) in wastewater containing a mixture of landfill leachate and urban wastewater (in equal proportions). After the appropriate electrode selection under default conditions (current intensity of 1 ampere, wastewater pH, and a duration of 120 min), the impacts of the current intensity and the initial pH of the wastewater on the COD removal rate in various electrode arrangements were assessed. Furthermore, the results were reported after three repetitions for validation purposes. Results: Under optimal conditions, the iron electrode in a monopolar series arrangement with a current intensity of 2 amperes under the wastewater pH and a duration of 120 min resulted in a 57.8% COD removal. Conclusion: Regarding the acceptable performance of the electrochemical coagulation process, it is possible to utilize its potential to treat municipal wastewater and landfill leachate.

The Kalina pond has been well known as a severely degraded area in the Silesia region, Poland. The environmental deterioration results from high contamination of water and bottom sediments with recalcitrant and toxic organic compounds, mainly phenol. The study was aimed at developing a bioremediation-based approach suitable for this type of polluted areas, involving microbiological treatment of water as a key and integral part of other necessary actions: mechanical interventions and the use of physical methods. During the initial biological treatment stage, autochthonous microorganisms were isolated from contaminated samples of water, soil and sediment, then subjected to strong selective pressure by incubation with the pollutants, and finally, cultivated to form a specialised microbial consortium consisting of five extremophilic bacterial strains. Consortium propagation and its biodegradation activity were optimised under variant conditions enabling bacteria to proliferate and to obtain high biomass density at large volumes allowing for the in situ application. After installing aeration systems in the pond, the consortium was surface-sprinkled to launch bioremediation and then both bacterial frequency and the contaminant level was systematically monitored. The complex remediation strategy proved efficient and was implemented on an industrial scale enabling successful remedial of the affected site. Treatment with the specifically targeted and adapted microbial consortium allowed for removal of most organic pollutants within a four-month season of 2022: the chemical oxygen demand (COD) value decreased by 72%, polyaromatic hydrocarbon (PAH) level by 97%, while the content of total phenols and other monoaromatic hydrocarbons (BTEX) dropped below the detection thresholds.

The raw liquid and the bio-treatment（MBR） effluent of landfill leachate were irradiated using electron beam（EB） technology. The effect of EB irradiation on the molecular weight，organic composition of pollutants in the landfill leachate，as well as the improvement of biodegradability were investigated. Results showed that EB irradiation coupled with the coagulation process achieved a good COD removal of landfill leachate. Furthermore，the macromolecular organic pollutants（molecular weight >100 ku） in the leachate solution could be destroyed while some small molecular weight organics（molecular weight，0.5-1 ku） would be polymerized during the EB irradiation. Additionally，EB irradiation could effectively remove macromolecular humus in the bio-treatment effluent of the leachate and transform them to small molecular weight organic compounds which would enhance the biodegradability of the landfill leachate.

Nano zero-valent iron (nZVI) is an effective adsorbent for removing various organic and inorganic contaminants. In this study, nZVI particles, synthesized in our previous work, were used for landfill leachate pretreatment. The adsorption performance was tested at various adsorbent concentrations (50–500 mg Fe0/L), pH (3–8), and contact times (15–330 min). Chemical oxygen demand, dissolved organic carbon (DOC), nitrate (NO3-), and ammonium (NH4+) removal efficiency were approximately 75%, 60, 57, and 33%, respectively. The obtained data were fitted well by the Langmuir isotherm and adsorption kinetics of pseudo-second-order equations (R2 > 0.9). The adsorption capacities were found to be 29.62, 21.01, and 3.12 mg/g for DOC, NH4+, and NO3−, respectively, at Fe0 concentration of 50 mg Fe0/L, pH of 8, and contact time of 120 min, which was determined as the effective operational conditions in this work. The obtained removal levels were higher compared to the conventional activated carbon adsorption (72.3%). Results suggest that nZVI has the potential to create effective adsorption relevant to landfill leachate pretreatment, thereby providing more efficient biological treatment by decreasing important pollutants before biological treatment. HIGHLIGHTS Nano zero-valent iron (nZVI) can be used as an effective adsorbent for removing chemical oxygen demand, dissolved organic carbon (DOC), NO3-, and NH4+ from landfill leachate.; The adsorption capacities were found to be 29.62, 21.01, and 3.12 mg/g, for DOC, NH4+, and NO3−, respectively, at an nZVI concentration of 50 mg nZVI/L.; The obtained data were fitted well by the Langmuir isotherm and adsorption kinetics of pseudo-second-order equations.;

Abstract The aim of this study was to systemically evaluate how different pyrolysis temperatures (400, 550, and 700 °C) and particle sizes (1–2 mm and 63–75 µm) were influenced biochar evolution, made from urban pruning waste, during pyrolysis process and to establish their relationships with biochar potential for removal of lead (Pb), cadmium (Cd), and manganese (Mn) from real municipal solid waste landfill leachate. The effects of pH (2–7), contact time (30–300 min) and adsorbent dosage (0.1–5 g L−1) on heavy metals removal were also examined. The results showed that physicochemical properties of biochar were greatly influenced by pyrolysis temperature. Particle size, however, showed little influence on biochar characteristics (p > 0.05). The yield, volatile matter, hydrogen and oxygen contents, and surface functional groups decreased consistently with increasing pyrolysis temperature. An increase in the pH, electrical conductivity, ash, fixed carbon, and specific surface area values was also found. In biochar samples formed at high temperatures (i.e., 550 and 700 °C), Fourier transform infrared spectroscopy-FTIR studies confirmed the increase in aromaticity. Field emission scanning electron microscopy-FESEM images showed differences in the microporous structure and lower size pores at higher temperatures. Biochar pyrolyzed at 700 °C with a particle size of 63–75 µm (i.e., Lv700-63) showed the highest removal efficiency performance. Pb and Cd ions were completely removed (100%) by 0.2 g L−1 Lv700-63 at 7.0 pH and contact times of 120 and 90 min, respectively. The maximum percentage removal of Mn was 86.20% at optimum conditions of 0.2 g L−1 Lv700-63 dosage, 7.0 pH, and 180 min contact time. The findings suggests that the surface complexation, π-electron coordination, and cation exchange were the dominant mechanisms for the Pb, Cd, and Mn removal onto Lv700-63.

BACKGROUND AND OBJECTIVES: The utilization of stabilization pond system for landfill leachate treatment is hindered by its requirement for expansive land areas and extended retention periods. Although the system effectively removes organic compounds, its ability to eliminate nutrients such as nitrogen and phosphorus is comparatively limited. Consequently, the leachate subjected to treatment often falls short of meeting the mandated standards for effluent quality. In response to this challenge, a research study was undertaken to investigate the potential of utilizing a consortium comprising microalgae and bacteria in the treatment of landfill leachate.METHODS: The microalgae, bacteria, and leachate utilized in this study were sourced from a leachate treatment facility located at the Aceh regional domestic waste management unit in Blang Bintang, Aceh Besar, Indonesia. The two glass photobioreactors were operated batch-wise, where the first was provided with a combination of air and carbon dioxide, and the other was solely exposed to air. The pollutant removal efficacy in the leachate effluent was assessed through the measurements of chemical oxygen demand, ammonia, nitrate, nitrite, and phosphate concentrations. Subsequently, macroscopic identification of microalgae and bacteria species was also conducted.FINDING: Utilizing a consortium of microalgae and bacteria has demonstrated efficacy in treating leachate, resulting in a notable reduction of contaminants within the effluent. The symbiotic association between microalgae and bacteria in the context of leachate waste treatment is evident. The bacteria’s metabolic actions result in carbon dioxide emission, which subsequently serves as a substrate for the photosynthetic activities of the microalgae. The microalgae facilitate the transfer of oxygen, produced through photosynthesis, to the bacteria to support their metabolic processes. Therefore, introducing exogenous carbon dioxide to the consortium yields minimal discernible effects, given that the bacteria adequately fulfill the carbon dioxide requirements of the microalgae. This discovery enhances the efficacy of leachate treatment techniques by leveraging the utilization of pre-existing mixed cultures of microalgae and bacteria found in leachate facilities.CONCLUSION: This study evaluated the microalgae-bacteria consortium’s effectiveness in reducing leachate pollutants. The consortium exhibited a significant capability, achieving a 75 percent reduction in chemical oxygen demand and successfully eliminating a range of contaminants. Additionally, it demonstrated effective removal of nitrogen compounds such as ammonia, nitrate, and nitrite, with removal rates reaching 75 percent. Notably, the consortium showed a 99 percent removal rate for phosphate compounds. Even with the introduction of carbon dioxide, the pollutant removal remained consistently high, suggesting that the addition of carbon dioxide did not significantly influence the overall process.

Coagulation sedimentation is a critical pretreatment step in the advanced treatment of landfill leachate. Traditional coagulation processes for treating landfill leachate have drawbacks such as low water recovery，loose flocs，and low pollutant removal efficiency. A delayed stirring pelleting coagulation process of landfill leachate was put forwarded based on the theory of mechanical syneresis. Through long periods of high-intensity mechanical agitation，it could homogenize suspended solids. The results showed that the removal efficiency of SS，turbidity，and COD could reach 92.33%，99.92%，and 35.84% under optimal conditions of pH=12，stirring strength of 1 500 r/min，PAC and PAM dosage of 3 000 mg/L and 60 mg/L. The image particle measurement system revealed that under optimal conditions，the d50 of floc was 3.76 mm and the sedimentation velocity was 20.08 mm/s，which was approximately 60% higher than that of conventional coagulation. According to the floc sedimentation rate，projection area and effective particle size，the three-dimensional fractal dimension was 2.890 9 and the effective density was 0.087 6 g/cm3. It was found that the floc produced by delayed stirring pelleting coagulation had fast sedimentation speed and high density，and the supernatant recovery rate after floc could increase from 45% conventional coagulation to 85%.

The fate of biobased and biodegradable cellulose-derived plastics in landfills represents an important topic from economic and environmental points of view. Anaerobic digestion is a cost-effective waste-to-energy technology. The behaviour of six polymer types—that is, cellulose (C), cellulose acetate (CA), viscose (V), nanocellulose (NC), acetate textile (AT), and heteropolysaccharide pectin (P)—was studied under anaerobic batch mesophilic conditions in a landfill leachate for 147 days. The cumulative biogas production was as follows: C>V=CA>>AT>>NC=P. Metagenomic analysis revealed notable variations in the proportion of bacterial and archaeal domains with the highest archaeal abundance in the presence of CA (80.2%) and C (78.5%). At the end of digestion, cellulolytic, hydrolytic, and dehydrogenase activities were measured in the intact samples, as well as the liquid and solid fractions, under aerobic and anaerobic conditions. Cellulolytic activity in P was detected only in the pellet, while in NC, activity was mostly in the supernatant under both aerobic and anaerobic conditions. Scanning electron microscopy and confocal scanning laser microscopy showed a defragmentation and degradation of polymeric substrates as well as microbial colonisation. Based on the results, landfill leachate is appropriate for the anaerobic biodegradation of cellulose-derived polymers; however, the process is polymer specific.

Changes in the activated sludge performance in an anaerobic/aerobic biological treatment system for leachate was discussed under the condition of tetracycline (TC) exposure. The results show that a low concentration of TC did not have an obvious effect on the removal of chemical oxygen demand (COD) while a high concentration of TC had a certain promoting effect. Under the stimulation of TC, the particle size distribution of anaerobic/aerobic sludge tended to be more uniform, the particle size of anaerobic sludge decreased while the settleability increased; however, the particle size of aerobic sludge increased due to bulking. With the addition of TC, the concentration of most heavy metal ions in sludge samples increased.TC exposure results in the release of a large amount of extracellular polymeric substances (EPS), thus leading to a smoother surface of anaerobic sludge and a rougher surface of aerobic sludge. The high removal efficiency of COD under the high concentration of TC was also presumed to be due to EPS promoting the microbial absorption of anaerobic substances in the leachate. The results clearly showed that TC had a bacteriostatic effect. After antibiotic exposure, the abundance and diversity index of bacteria in each reactor decreased obviously, the microbial community evolved, and the dominant species at the genus and phylum levels of anaerobic/aerobic reactors changed. This study provides a better understanding the effect of TC on activated sludge and has reference value for the management of antibiotic exposure in leachate treatment facilities. [ABSTRACT FROM AUTHOR]

This study applied ultraviolet/peroxymonosulfate (UV/PMS) and UV/hydrogen peroxide (UV/H2O2) processes to the advanced treatment of membrane bioreactor (MBR) effluent. The degradation efficiency of refractory organic matter and the reaction mechanisms of the two processes were systematically investigated. The results showed that the degradation efficiency of the UV/PMS processes was significantly lower than that of the UV/H2O2 process when the PMS concentration was significantly lower than the H2O2 concentration, e.g. the UV254 removals under optimal conditions were 72.92% and 82.21%, respectively. Additionally, the UV/PMS process could operate over a broader pH range. The degradation efficiency of the UV/PMS process was slightly increased by HCO3– and Cl- due to the activation of PMS, while in the UV/H2O2 process, HCO3- and Cl- depressed the degradation efficiency by competing with organic matter to react with reactive oxygen species (ROS). After the two processes, the aromaticity, humification, condensation degree, and molecular weight of refractory organic matter in the MBR effluent were considerably decreased. Fulvic- (HA) and humic-like substances (FA) were greatly degraded by the two processes. The UV/PMS had a superior degradation efficiency for macromolecular HA in the early stage of the reaction, and the UV/H2O2 could degrade HA to protein-like substances in the latter stage of the reaction. These differences between the two processes could be attributed to the dominance of different ROS, with SO4•- and HO• dominating in the UV/PMS, and HO• dominating in the UV/H2O2. The results of this study provide theoretical support for the application of MBR effluent treatment. Highlights Comparison on the MBR effluent treatment of UV/PMS and UV/H2O2 is studied. UV/PMS process can better destroy humic-like substances in the early reaction stage. Humic-like substances are transformed into protein-like compounds in UV/H2O2 process. UV/PMS and UV/PMS performs differently due to their different dominant ROS. [ABSTRACT FROM AUTHOR]

Landfill leachate is a mixture of highly concentrated organic and inorganic pollutants and needs to be treated properly due to their toxicity and serious adverse effects on the environment. Recently, advanced oxidation processes have been successfully applied for leachate treatment. In this study, the removal of chemical oxygen demand (COD), total organic carbon (TOC) and absorbable organic halogens (AOX) in waste leachate stabilized by the electro-Fenton (EF) process, which is one of the advanced oxidation processes, was investigated. For this purpose, a jacketed reactor in which the electrochemical process takes place was designed and iron electrodes were used for maintenance and cost efficiency in this process. Within the scope of the study, the efficiency of the important process parameters, such as pH, current density, catalyst amount, oxidant dose and electrolysis time, was determined and their values were optimized. Optimum values were found to be as pH 3, current density 150 A/m2, hydrogen peroxide amount 500 mg/L and electrolysis time 10 min. The best removal efficiencies were obtained as 71.7% COD, 97.4% AOX and 90.87% TOC under optimum conditions. In addition, within the scope of this study, the collapsibility and operating costs of the sludge having formed as a result of the EF process were also examined. It has been observed that especially the sludge formed as a result of the EF process has good settling properties. When the results were evaluated, it was confirmed that the EF process can be used efficiently to break down leachate organics in terms of wastewater quality and discharge limits. [ABSTRACT FROM AUTHOR]

[Display omitted] • Estimated amount of ∑ 26 PFAS released from landfills (M ̇ SW) was 36.8 g/ha-yr. • 97% and 3% of M ̇ SW was found in leachate and stormwater, respectively. • Less than 1% of M ̇ SW was found in gas condensate and groundwater. • ∑ 8 PFAA-precursors/∑ 26 PFAS was consistent in the leachate released. • PFAS from landfills will be released for an estimated period of over 40 years. Per- and polyfluoroalkyl substances (PFAS) have been found at high levels within landfill environments. To assess PFAS distributions, this study aimed to evaluate PFAS mass flux leached from disposed solid waste and within landfill reservoirs by mass balance analyses for two full-scale operational Florida landfills. PFAS mass flux in different aqueous components within landfills were estimated based on PFAS concentrations and water flow rates. For PFAS concentration, 26 PFAS, including 18 perfluoroalkyl acids (PFAAs) and 8 PFAA-precursors, were measured in samples collected from the landfills or estimated based on previous studies. Flow rates of aqueous components (rainfall, evapotranspiration, runoff, stormwater, groundwater, leakage, gas condensate, and leachate) were evaluated through the Hydrologic Evaluation of Landfill Performance model, water balance, and Darcy's Law. Results showed that the average PFAS mass flux leached from the solid waste standardized by area was estimated as 36.8 g/ha-yr, which was approximately 1 % to 3 % of the total amount of PFAS within the solid waste. The majority of PFAS leached from the solid waste (95 % to 97 %) is captured by the leachate collection system, with other aqueous components representing much smaller fractions (stormwater system at 3 % to 5 %, and gas condensate and groundwater at < 1 %). Also, based on the results, we estimate that PFAS releases will likely occur at least over 40 years. Overall, these results can help prioritize components for waste management and PFAS treatment during the anticipated landfill release periods. [ABSTRACT FROM AUTHOR]

Banana peels can be a valuable adsorbent for reducing heavy metals in water. This study investigated the effect of chemical activators on Nipah banana peel (Musa acuminata balbisiana) on their ability to reduce Pb and Cd metals in landfill leachate. Before the adsorption test, the banana peels were treated with a different chemical activator, including detergent, NaOH, KOH, and H3PO4. The results showed that H3PO4 adsorbs relatively high amounts of metals (Pb-75.800%, Cd-18.491%) in landfill leachate among these activators. FTIR analysis showed that banana peels treated with H3PO4 produced sharper carbonyl or carboxyl group peaks. These groups are very influential in the metal adsorption process. SEM-EDS analysis of the H3PO4-treated banana peels showed an increase in carbon and oxygen elements in the banana peels and changes in the pore surface that enhanced the adsorption process on Pb and Cd metals. From this study, banana peels activated with H3PO4 showed great potential to be developed into adsorbents to reduce heavy metal concentration. [ABSTRACT FROM AUTHOR]

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the environment despite global regulatory action to restrict their use in industrial processes and products. The objective of this reconnaissance sampling was to understand current industrial use and ongoing sources of PFAS in Ontario. Fourteen PFAS were analyzed in effluents from four sectors: electroplaters, laundry and carpet cleaners, landfills, and circuit board manufacturers that discharge to sewersheds connected to wastewater treatment plants. Maximum concentrations were detected in carpet cleaning wastewater: 79,000 ng/L for perfluorohexane sulfonate (PFHxS), 26,000 ng/L perfluorooctane sulfate (PFOS), and 9400 ng/L perfluorooctanoic acid (PFOA). Total summed PFAS (∑PFAS14) concentrations were highest in laundry and carpet cleaners > electroplaters > landfill leachate > circuit boarders. These results indicate that PFAS continue to be used in select manufacturing and processing facilities and that the elevated levels are associated with past and current uses in commercial products. [ABSTRACT FROM AUTHOR]

[Display omitted] • PFAS concentrations in aqueous samples were measured at two landfills. • PFAS in municipal solid waste leachate was more variable than MSW ash leachate. • PFAS concentrations were stable within landfills (coefficient of variation < 50 %) • Leachate in uncovered trenches had the highest fluctuations. • PFAS fluctuations associated with alkalinity, total organic carbon, and ammonia. Studies of per- and polyfluoroalkyl substances (PFAS) fluctuations at landfills have focused on municipal solid waste (MSW) leachate. Few studies exist that evaluate fluctuations (defined by the coefficient of variation, CV) in MSW incinerator ash (MSWA) landfill leachate and that evaluate PFAS fluctuations in stormwater, groundwater, and treated liquids on-site. In this study, aqueous landfill samples (leachate, treated leachate, stormwater, gas condensate, ambient groundwater, and effluent from a groundwater remediation system) were collected from a MSW and an MSWA landfill geographically located within close proximity (less than 40 km). The objective of this study was to compare the leachate compositions between these two landfill types and to evaluate temporal variations. Results indicated that the CV of total detected PFAS concentrations in leachate was higher for the MSW landfill (CV = 43 %) compared to the MSWA landfill (CV = 16 %). The total detected PFAS concentration in MSW leachate samples (mean: 9641 ng/L) was higher than in MSWA leachate samples (mean: 2621 ng/L) (p < 0.05). Within a landfill, PFAS concentrations were correlated (r s > 0.6, p < 0.05) with alkalinity, total organic carbon (TOC), and ammonia. Results from the on-site leachate treatment system at the MSW landfill indicated reductions in COD, TOC, and ammonia; however, the ∑ 26 PFAS concentration increased 3 % after the treatment. Overall, results demonstrated that differences between landfill types and fluctuations in PFAS within landfills should be considered when designing landfill leachate collection and treatment systems to remove PFAS. The comparative analysis in this study can provide insights into optimizing leachate management for MSW and MSWA landfills. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three PFAS leached from biochar derived from construction/demolition (CDD) wood. • 5:3 FTCA was reduced by CDD wood biochar in landfill leachate batch leaching. • Low biochar surface area and high matrix organic matter hinder PFAS sorption. • CDD wood biochar not recommended for in-situ landfill leachate PFAS reduction. With regulations for per-and polyfluoroalkyl substances (PFAS) impending, the abundance of these chemicals of emerging concern in municipal solid waste (MSW) landfill leachate increasingly challenges landfill operators to seek on-site leachate pre-treatment options. This two-staged study explores the potential reuse of biochar derived from construction and demolition debris (CDD) wood as an in-situ PFAS sorbent for application within MSW landfill leachate collection systems. Batch leaching tests were first used to examine the feasibility of capturing PFAS from landfill leachate using two sources of CDD-wood-derived biochar. Then, columns were used to test the in-situ sorption capabilities of the same biochars under simulated landfill conditions. All leachates were characterized for pH, chemical oxygen demand, ammonia-nitrogen, and 92 PFAS. Seventeen PFAS were detected in the batch leaching experiment, and nine PFAS were detected in column leachates. In the batch leaching scenario, Biochar 1 achieved a maximum of 29% PFAS reduction compared to controls. Columns containing Biochar 1 generated leachates with PFAS concentrations 50% to 80% higher than those in control columns for the duration of the experiment. Columns containing Biochar 2 generated leachates with PFAS concentrations 44% less than controls in week 1 and similar concentrations in weeks 2, 3, and 4. In this study, PFAS removal from landfill leachate using biochar derived from CDD wood was not significant. Further research on biochar derived from CDD wood is needed before it can be recommended as an in-situ landfill leachate pre-treatment method. [ABSTRACT FROM AUTHOR]

This study investigates landfill leachate treatment using aluminum (Al-Al) and iron (Fe-Fe) electrodes in electrocoagulation (EC). Aluminum experiments revealed COD removal percentages of 22% (pH 7.4) and 20% (pH 6.0), while iron demonstrated higher efficiency at 32% (pH 7.4) and 30% (pH 6.0). Both processes excelled at neutral pH, with Fe-Fe EC displaying superior removal efficiency. To address electrode passivation, external aeration improved COD removal (31% to 61%) under specific conditions (3 V, pH 7.4, 60 min). The EC process established a neutralization mechanism, eliminating the need for further treatment before discharge. External aeration and polarity changes at intervals mitigated passivation, enhancing COD removal (61% to 69%). Voltage testing (1 V, 3 V, 5 V, 7 V) revealed a direct correlation, peaking at 91% efficiency with 5 V. Specific energy consumption was 2.34 kWh g−1, and sludge generation varied with voltage. The combined use of external aeration and polarity shifts resulted in 270 ml of sludge, demonstrating improved efficiency in the EC process. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Water Treatment is the property of CNOOC Tianjin Chemical Research & Design Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Refractory substances (humus) and salts (chloride (Cl−) and sulphate (SO42−) ions) remain in the biotreated landfill leachate treatment, and it is necessary to carry out further treatments by a suitable method before discharge. In this study, the effect and operational mechanism of a combination of the coagulation Fe0/H2O2 and ultra-high lime aluminium (UHLA) processes for the treatment of refractory organic substances and salts in the leachate effluent of a semi-aerobic aged refuse biofilter (SAARB) were investigated. The results showed that polyferric sulphate is a relatively efficient coagulant comparing to FeCl3, Al2(SO)4, and polyaluminium chloride. The Fe0/H2O2 process further removed refractory organics from wastewater, achieving 49.8% of total organic carbon removed. Further treatment by the UHLA process was carried. The results demonstrated that the amount of precipitant, reaction duration, and temperature had a significant impact on the Cl− and SO42− removals. After three treatments, the cumulative SO42− and Cl− removal efficiencies were 98% and 80%, respectively. The SO42− and Cl− were removed in the form of precipitates such as UHLA, specific components of which included calcium alumina, Fremy's salt of calcium, aluminium chloride, and calcium hydroxide. Overall, the UV254, CN, Cl−, and SO42− removal efficiencies from the SAARB effluent were 94.08%, 98.73%, 79.96%, and 98.44%, respectively, for the combined coagulation Fe0/H2O2 and UHLA processes. Therefore, the combined processes could effectively remove residual pollutants in the biologically-treated landfill leachate, and the study provides a useful reference for the removal of refractory organic matter and salts in landfill leachate. Highlights Coagulation-Fe0/H2O2-UHLA process is effective to SAARB effluent treatment. Refractory organics are substantially degraded by the coagulation-Fenton-like stage. Both Cl− and SO42− in SAARB effluent are greatly removed by UHLA process. [ABSTRACT FROM AUTHOR]

Arsenic contamination of groundwater has affected human health and environmental safety worldwide. Hundreds of millions of people in more than 100 countries around the world are directly or indirectly troubled by arsenic-contaminated groundwater. In addition, arsenic contamination of groundwater caused by leakage of leachate from municipal solid waste landfills has occurred in some countries and regions, which has attracted widespread attention. Understanding how domestic waste landfill leachate affects the arsenic's migration and transformation in shallow groundwater is crucial for accurate assessment of the distribution and ecological hazards of arsenic in groundwater. Based on literature review, this study systematically summarized and discussed the basic characteristics of landfill leachate, the mechanism of arsenic pollution in groundwater, and the effect of landfill leachate on the migration and transformation of arsenic in groundwater. Combined with relevant research findings and practical experience, countermeasures and suggestions to limit the impact of landfill leachate on the migration and transformation of arsenic in groundwater are put forward. [ABSTRACT FROM AUTHOR]

Nanofiltration concentrated leachate (NFCL) is a high-concentration organic wastewater produced from landfill leachate during the process of membrane advanced treatment, which is more difficult to treat than landfill leachate. In this study, the effect and cost of treating NFCL by flocculation combined with a multistage ozone/bioreactor process based on a field scale are discussed. The results show that the process has a good effect on the removal of organic matter and nitrogen pollutants in NFCL, with removal efficiencies of chemical oxygen demand, ammonia nitrogen, nitrate, and total nitrogen being 96.6%, 90.1%, 38.2%, and 75.8%, respectively. The effluent can meet the discharge standard of China's standard with a direct operating cost of approximately USD 18.48–20.82/m3. This study proved the effectiveness, structural rationality, and economic benefit of the process in a practical engineering application, and provided a certain theoretical basis and engineering reference for the wide application of the process in the treatment of leachate membrane concentrate. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Water Treatment is the property of CNOOC Tianjin Chemical Research & Design Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

During adaptation to waters that are rich in xenobiotics, biological systems pass through multiple stages. The first one is related to the restructuring of communities, pronounced destruction of the structure, and multiplication of active biodegradants. The purpose of the present research was to describe the microbiome restructuring that occurs during the adaptation stage in landfill leachate treatment. In a model SBR (sequencing batch reactor), a 21-day purification process of landfill leachate was simulated. Wastewater was fed in increasing concentrations. When undiluted leachate entered, the activated sludge structure disintegrated (Sludge Volume Index—4.6 mL/g). The Chemical Oxygen Demand and ammonium nitrogen concentration remained at high values in the influent (2321.11 mgO2/L and 573.20 mg/L, respectively). A significant amount of free-swimming cells was found, and the number of aerobic heterotrophs and bacteria of the genera Pseudomonas and Acinetobacter increased by up to 125 times. The Azoarcus-Thauera cluster (27%) and Pseudomonas spp. (16%) were registered as the main bacterial groups in the activated sludge. In the changed structure of the microbial community, Gammaproteobacteria, family Rhizobiaceae, class Saccharimonadia were predominantly represented. Among the suspended bacteria, Microbactericeae and Burkholderiaceae, which are known for their ability to degrade xenobiotics, were present in larger quantities. The enzymological analysis demonstrated that the ortho-pathway of cleavage of aromatic structures was active in the community. The described changes in the leachate-purifying microbial community appear to be destructive at the technological level. At the microbiological level, however, trends of initial adaptation were clearly outlined, which, if continued, could provide a highly efficient biodegradation community. [ABSTRACT FROM AUTHOR]

The Kalina pond has been well known as a severely degraded area in the Silesia region, Poland. The environmental deterioration results from high contamination of water and bottom sediments with recalcitrant and toxic organic compounds, mainly phenol. The study was aimed at developing a bioremediation-based approach suitable for this type of polluted areas, involving microbiological treatment of water as a key and integral part of other necessary actions: mechanical interventions and the use of physical methods. During the initial biological treatment stage, autochthonous microorganisms were isolated from contaminated samples of water, soil and sediment, then subjected to strong selective pressure by incubation with the pollutants, and finally, cultivated to form a specialised microbial consortium consisting of five extremophilic bacterial strains. Consortium propagation and its biodegradation activity were optimised under variant conditions enabling bacteria to proliferate and to obtain high biomass density at large volumes allowing for the in situ application. After installing aeration systems in the pond, the consortium was surface-sprinkled to launch bioremediation and then both bacterial frequency and the contaminant level was systematically monitored. The complex remediation strategy proved efficient and was implemented on an industrial scale enabling successful remedial of the affected site. Treatment with the specifically targeted and adapted microbial consortium allowed for removal of most organic pollutants within a four-month season of 2022: the chemical oxygen demand (COD) value decreased by 72%, polyaromatic hydrocarbon (PAH) level by 97%, while the content of total phenols and other monoaromatic hydrocarbons (BTEX) dropped below the detection thresholds. [ABSTRACT FROM AUTHOR]

A significant portion of the hazardous wastes generated by rapid industrialisation and urbanisation end up in landfills. The wastes disposed of in hazardous waste landfills are less biodegradable; thus, the leachate generated due to the physical and chemical changes in the landfill renders high toxicity. If not monitored and handled appropriately, this leachate could lead to contamination affecting human and livestock health and adversely affect the soil and agriculture in the vicinity of the landfill site. A tool to quantify the contamination caused by improper handling of hazardous waste landfill leachate is essential to understand which landfill site would need immediate attention. In the present study, the leachate pollution index is developed based on the predominantly available pollutants in hazardous waste landfill leachate and their toxicity limits. Fuzzy Delphi-Analytic Hierarchy Process has been used to develop the index. These techniques have been used for screening and assigning weights to the pollutants. Further, sub-index curves have been developed considering the available concentration, the toxicity, and the standard concentration limits for each pollutant. The weighted linear sum function has been used to aggregate the weights and sub-index scores. The hazardous waste landfill leachate pollution index developed in this study can serve as a potential tool for quantifying the leachate contamination potential. Furthermore, it can be used as a comparison tool for ranking landfill sites based on the contamination potential. [ABSTRACT FROM AUTHOR]

The burgeoning issue of landfill leachate, exacerbated by urbanization, necessitates evaluating its biological impact, traditionally overshadowed by physical and chemical assessments. This study harnesses Caenorhabditis elegans, a model organism, to elucidate the physiological toxicity of landfill leachate subjected to different treatment processes: nanofiltration reverse osmosis tail water (NFRO), membrane bioreactor (MBR), and raw leachate (RAW). Our investigation focuses on the modulation of sugar metabolism, particularly trehalose—a disaccharide serving dual functions as an energy source and an anti-adversity molecule in invertebrates. Upon exposure, C. elegans showcased a 60–70% reduction in glucose and glycogen levels alongside a significant trehalose increase, highlighting an adaptive response to environmental stress by augmenting trehalose synthesis. Notably, trehalose-related genes in the NFRO group were up-regulated, contrasting with the MBR and RAW groups, where trehalose synthesis genes outpaced decomposition genes by 20–30 times. These findings suggest that C. elegans predominantly counters landfill leachate-induced stress through trehalose accumulation. This research not only provides insights into the differential impact of leachate treatment methods on C. elegans but also proposes a molecular framework for assessing the environmental repercussions of landfill leachate, contributing to the development of novel strategies for pollution mitigation and environmental preservation.

The ability of a composite adsorbent composed primarily of various waste materials to adsorb heavy metals, NH3-N, and chemical oxygen demand (COD) from landfill leachate was investigated through batch sorption experiments. The study determined the optimal contact time and adsorbent dosage for the removal of Pb, Zn, Cu, Fe, NH3-N, and COD to be 15, 90, 30, 180, 30, and 30 min, respectively. The corresponding optimum adsorbent dosages were determined to be 5, 30, 5, 15, 5, and 30 g, respectively. The composite adsorbent exhibited high removal efficiencies, achieving the following maximum values: 96.4% for Pb, 92.7% for Zn, 60.3% for Cu, 87.1% for Fe, 75.0% for NH3-N, and 67.5% for COD. Pb and Fe showed the best fit with a Langmuir isotherm model, with corresponding adsorption capacities of 0.0165 and 1.14 mg/g, respectively. For Zn, Cu, NH3-N, and COD, the equilibrium data demonstrated the best fit with an Elovich isotherm model, with adsorption capacities of 0.004, 0.005, 0.016, and 4.29 mg/g, respectively. The kinetic data followed the pseudo-second-order kinetic model. It presented a potential solution for the disposal of the waste from which it was derived. HIGHLIGHTS This investigates the applicability of a composite adsorbent made of low-cost/waste materials, in landfill leachate treatment.; The composite adsorbent has considerable treatment potential.; This can be an initial study leading to further studies.; The use of waste materials makes treatment economically and practically feasible.; This is also a sustainable reuse application for the waste to be dumped.;