Leachate Production Research Articles

Effect of landfill leachates on urban soil: A review

The increasing generation of Municipal Solid Waste (MSW) is a significant global concern, with landfills receiving around 1.4 billion tonnes of MSW yearly. Inadequate landfill management contributes to environmental degradation, with landfill leachate being a substantial outcome of MSW decomposition. Leachate contains inorganic nutrients, volatile and dissolved organic molecules and heavy metals and its properties vary depending on waste composition, moisture content and seasonal elements. Heavy metals found in leachate include Pb, Cu, Cr, Ni, Mn, Hg, Fe, Zn and Cd and Emerging Organic Contaminants (EOCs) such as Persistent Organic Pollutants (POPs), Endocrine Disrupting Chemicals (EDC), pharmaceuticals and Personal Care Products (PCPs) are also prevalent. Microplastics (MPs) have been found in raw leachate samples at concentrations ranging from 49.0 ± 24.3 to 507.6 ± 37.3 items/L. Landfill leachate production ranks among the most aggressive pollutants to the environment, particularly to soil and poses a danger of contaminating both surface and groundwater. This review examines the potential impacts of landfill leachate on soil quality and the broader implications of this phenomenon, summarizing recent scientific studies and presenting the direct and indirect effects of leachate on soil based on the literature. Bibliometric analysis of publications in the Scopus database reveals a growing scholarly interest in this topic, with the number of publications in the Science Citation Index (SCI) database increasing dramatically to over 464 articles between 2009 and 2024.

Coal Ash Triggers an Elevated Temperature Landfill Development: Lessons from the Bristol Virginia Solid Waste Landfill Neighboring Community

Landfills for disposing of solid waste are designed, located, managed, and monitored facilities expected to comply with government regulations to prevent contamination of the surrounding environment. After the average life expectancy of a typical landfill (30 to 50 years), a large investment in the construction, operation, final closure, and 30-year monitoring of a new site is needed. In this case study, we provide a holistic explanation of the unexpected development of elevated temperature landfills (ETLFs), such as that in the city of Bristol (United States) on the border of the states of Virginia and Tennessee, including the initial role played by coal ash. Despite the increasing frequency of ETLF occurrence, there is limited knowledge available about their associated environmental problems. The study uses mixed (qualitative, quantitative, and mapping) methods to analyze (1) the levels of odoriferous reduced sulfur compounds, ammonia, and volatile organic compounds (VOCs) emitted, (2) the ratio of methane to carbon dioxide concentrations in five locations, which dropped from unity (normal landfill) to 0.565, (3) the location of gas well heads with gradients of elevated temperatures, and (4) the correlation of the filling rate (upward of ~12 m y−1) with depth for registered events depositing coal ash waste. The work identifies spatial patterns that support the conclusion that coal ash served as the initiator for an ETLF creation. The case of the city of Bristol constitutes an example of ETLFs with elevated temperatures above the regulatory United States Environmental Protection Agency (EPA) upper threshold (65 °C), having alongside low methane emissions, large production of leachate, land subsidence, and a large production of organic compounds. Such landfills suffer abnormal chemical reactions within the waste mass that reduce the life expectancy of the site. Residents in such communities suffer intolerable odors from fugitive emissions and poor air quality becomes prominent, affecting the well-being and economy of surrounding populations. Conclusive information available indicates that the Bristol landfill has been producing large amounts of leachate and hazardous gases under the high pressures and temperatures developed within the landfill. A lesson learned, which should be used to prevent this problem in the future, is that the early addition of coal ash into the landfill would have catalyzed the process of ETLF creation. The work considers the public health risks and socioeconomic problems of residents exposed to emissions from an ETLF and discusses the efforts needed to prevent further incidents in other locations.

Removal of Ammonia and Colour from Landfill Leachate using Integrated Electrocoagulation-Zeolite Adsorption Processes

The amount of waste generated in Malaysia had increased annually due to both economic and population accelerations. This resulted in an increase in leachate production that contains a high amount of ammonia nitrogen (NH3-N) and colour, which is a severe problem for both environments as well as for human health. Therefore, this study aimed to determine the potential of Electrocoagulation (EC) – zeolite adsorption for removing NH3-N and colour from landfill leachate. In the experimental works, two batch studies consist of batch EC using aluminium (Al) cylindrical electrode and batch adsorption study using clinoptilolite zeolites adsorbent were conducted using leachate sample collected from Pulau Burung Sanitary Landfill (PBSL). The batch EC experiment was carried out to determine the optimum removal of NH3-N and colour by the effect of current density (7 - 35 mA/mm2), initial pH (5 - 9), electrolysis time (0 - 90 minutes) and inter-electrode distance (5 - 25 mm). An integrated EC - zeolite adsorption was carried out under the optimum condition of 2.0 g/150 mL adsorbent dosage, contact time of 100 minutes and an initial pH value of 8. Based on the experiment, almost 50% of NH3-N and 95% of colour were removed using a single EC under the optimum current density of 14.0 mA/mm2, pH 5, electrolysis time of 75 minutes and 15 mm of inter-electrode distance. A comparison of colour removal between single EC and EC-Zeolite showed the same degradation performance. The interaction of hydrogen ion (H+) with aluminium hydroxide ion (Al (OH)3) produces during EC stabilises small particles forming larger sludge that reduces colour concentration. The removal of NH3-N increased from 50.0% to 93% when EC was integrated with clinoptilolite zeolite adsorption. In conclusion, the results show that both processes can potentially remove colour while the integrated process effectively removes NH3-N from landfill leachate. The proposed treatment helps optimise process performance while minimising the operational cost of the treatment. Thus, the proposed integrated EC – zeolite adsorption processes can be an alternative to landfill leachate treatment which aligns with the 12thMalaysia Plan to reduce pollution and carbon emissions to become a carbon neutral nation as early as 2050.

Valorisation diagnosis of waste from the decontamination of phosphogypsum leachates through a combined calcium carbonate/hydroxide process

Phosphogypsum is an industrial waste considered as naturally occurring radioactive material. Stack disposal and exposure to the environmental condition involve the production of acid leachates with high potential pollutant loads as heavy metals and radionuclides. In this study, a sequential neutralisation process was applied for cleaning the generated releases, and the two obtained residues were characterised from the physical-chemical and radiological point of view before their valorisation. The cleaning process was made up of two steps: the first one using calcium carbonate until pH = 3.5, and the second one using calcium hydroxide until pH = 12. The residue obtained in the first step was mostly calcium fluoride, while in the second step most phosphates were precipitated, mainly as hydroxyapatite. The final liquid was treated to reduce pH lower than 9, which is the limit included in the current directive for discharges of liquid effluents into coastal waters. The main conclusion was that the solids from the first step could be valorised as an additive in the manufacture of commercial Portland cements and ceramics, while the solids from the second step could be used as raw material for the phosphoric acid manufacture.

Assessment of Leachate Generated by Sargassum spp. in the Mexican Caribe: Part 1 Spatial Variations

In this study, we evaluate the degradation by Sargassum spp. as a consortium in 2020 and 2021, and by species during 2021, collected at different distances from a coastline and in land deposits. The year 2021 had the largest leachate volume and the offshore site with the highest volume (60 mL/day) among five sites of collection. In relation to species’ leachate generation, S. fluitans reached 47.67 mL/day as its peak, which is earlier than S. natans (41.67 mL/day 14 days after S. fluitans). pH shows alkaline behavior and EC reflects the saline condition in the leachate, the consortium and species reaching values of pH 7.5 to 8.3 and 80 to 150 mS/cm of EC; the results do not show significant differences among sites, or between species. Despite a BOD/COD ratio of less than 0.1, the degradation process occurs as evidenced by the presence of leachate. The results confirm the existence of a variability in leachate production and the composition of Sargassum under the influence of factors such as the periodicity, site of collection, and proportions of species. Thus, even though these results emphasize leachate generation, knowing the limitations of leachate generation is crucial information for decision making on Sargassum storage and environmental management.

A review of existing methods for predicting leachate production from municipal solid waste landfills.

Landfilling is one of the predominant methods of municipal solid waste (MSW) disposal worldwide, while the generation of leachate, a kind of toxic wastewater, is among the primary factors behind landfill instability and environmental contamination problems. Precise prediction of leachate production is crucial to landfill safety evaluation and design. This paper presents a comprehensive review of methods for predicting leachate production from MSW landfills. Firstly, compositional characteristics of MSW and leachate generation mechanism are analysed. Factors influencing leachate production are summarised based on the generation mechanism, including the components of MSW, climatic conditions, landfill structure, and environmental factors. Then, we classified the existing methods for predicting leachate production into four categories: water balance formula, water balance model, empirical formula, and artificial intelligence model methods. Advantages, disadvantages, and applicability of different leachate production prediction methods are compared and analysed. Furthermore, limitations in the existing leachate production prediction methods for MSW landfills and scope for future research are discussed.

A 35-year monitoring of an Italian landfill: Effect of recirculation of reverse osmosis concentrate on leachate characteristics

“Fossetto” landfill (Monsummano Terme - Tuscany, Italy) started operation in 1988 as a controlled landfill accepting mixed municipal solid waste collected without any attempt of recycling. Then, progressively, following the evolution of the state-of-the-art, it adopted biogas extraction and valorisation systems and mechanical-biological treatment for incoming waste (both since 2003). Finally, since 2006, in the plant is performed on-site reverse osmosis leachate treatment with the concentrated leachate being recirculated back into the landfill body. Recently a new landfill cell, separate from the others, was put in operation adding a capacity of 200,000 m3 to the already available 1,095,000 m3. This plant can provide long term leachate composition data to study the evolution and impact of changing landfill technology and waste composition on various parameters. The rise in leachate production (+84 % in 2018–2022 respect to the period before recirculation) cannot be totally attributable to recirculation but could be also linked to the increase in the amount of landfilled waste. The concentration of certain parameters (NH4+, Cl− and to a less extent of COD) increased (+60 %, +58 %, +17 % respectively in the last five years with respect to the period before recirculation); however, this increase did not influence the performance of the treatment plant. Nevertheless, the overall leachate management would benefit from an optimized reinjection system.

Neurobehavioral deficits, histoarchitectural alterations, parvalbumin neuronal damage and glial activation in the brain of male Wistar rat exposed to Landfill leachate

Concerns about inappropriate disposal of waste into unsanitary municipal solid waste landfills around the world have been on the increase, and this poses a public health challenge due to leachate production. The neurotoxic effect of Gwagwalada landfill leachate (GLL) was investigated in male adult Wistar rats. Rats were exposed to a 10% concentration of GLL for 21 days. The control group received tap water for the same period of the experiment. Our results showed that neurobehavior, absolute body and brain weights and brain histomorphology as well as parvalbumin interneurons were severely altered, with consequent astrogliosis and microgliosis after 21 days of administrating GLL. Specifically, there was severe loss and shrinkage of Purkinje cells, with their nucleus, and severe diffused vacuolations of the white matter tract of GLL-exposed rat brains. There was severe cell loss in the granular layer of the cerebellum resulting in a reduced thickness of the layer. Also, there was severe loss of dendritic arborization of the Purkinje cells in GLL-exposed rat brains, and damage as well as reduced populations of parvalbumin-containing fast-spiking GABAergic interneurons in various regions of the brain. In conclusion, data from the present study demonstrated the detrimental effects of Gwagwalada landfill leachate on the brain which may be implicated in neuropsychological conditions.

Estimation of Leachate Volume and Treatment Cost Avoidance Through Waste Segregation Programme in Malaysia

This study aims to calculate the avoided leachate volume and treatment cost from waste segregation practices compared to the existing waste disposal methods of landfilling. The mathematical equations were used to analyse the waste segregation rate, leachate volume and treatment cost. The study findings reveal that 99.4% of mixed waste was disposed of in landfills, resulting in an annual generation of 565 thousand cubic meters (m3) of leachate with an estimated treatment cost of MYR 19.82 million (USD 4.36 million). The segregated waste, which accounts for only 0.06%, reduces 354 m3 in leachate volume and a cost-saving of MYR 12.42 thousand (USD 2.73 thousand) in the treatment expenses per year. The findings concluded that waste segregation practice could reduce waste management costs by reducing leachate production and treatment costs and environmental impacts.

Study of the Effect of Adding Eco-Enzyme to the Process of Decomposing Organic Waste on the Quality of Compost, Leachate, and Methane Gas Production

Waste generation is increasing along with the increase in population and human living needs. The most dominant waste composition in Indonesia is organic waste, which accounts for 53.97% of the total waste. Eco-enzyme is one of the waste utilization products that has the potential to become an activator for the decomposition process and reduce the environmental effects of waste decomposition. The aim of this research is to analyse the micronutrient content of compost, reduce leachate toxicity, and accelerate the production of methane gas resulting from decomposition using eco-enzymes. The method used was an experimental method (trial) to obtain primary data from laboratory test results during 28 days of research. The research results show that, in general, there is a significant difference in the quality of compost in organic waste that uses eco-enzyme compared to that that does not use eco-enzyme. The results of measuring the quality of the leachate resulting from decomposition show that the quality of the leachate that uses eco-enzyme is better and has lower toxicity than without using eco-enzyme (control). In the production of methane gas, the results show that methane gas production in decomposition using eco-enzymes reaches the methanogenesis process more quickly.

An integrated novel plasma-microalgae approach for landfill leachate treatment using a high-ammonia tolerant strain of Chlorella vulgaris

Landfilling is the most common method worldwide to deal with the produced municipal solid wastes (MSW). Nonetheless, one major drawback of landfilling is the production of landfill leachate (LL). Various methods for LL treatment exist which can mainly be divided into biological and physical-chemical methods, however integrating both approaches result in more effective treatment. In this study, an indigenous Chlorella vulgaris was isolated from a landfill leachate treatment site, purified, and genetically identified for leachate treatment purposes. One replicate, C.V.M* (CCAP 211/141), of the tested Chlorella vulgaris showed an outstanding growth in 20 % LL (v/v) with a significant ammonia removal (p < 0.05). To confirm these findings, both of the Chlorella vulgaris replicates (C.V.M* and C.V.N) were further tested in 20 % LL (v/v). A dramatic increase in the growth of C.V.M* by 19-fold over its peer C.V.N with a 75 % ammonia removal (starting from concentration 290.73 mg/L) was observed. This percentage is further improved when injecting plasma activated microbubbles as a pre-treatment step. The plasma pre-treatment resulted in LL decolourisation after 3 h and reduced ammonia-N concentration by 1.9-fold. C.V.M* showed the highest growth in 20 % LL pre-treated by plasma compared to the untreated LL with a final biomass yield of 0.38 g/L, increase in the total ammonia-N removal (79 %) and a significant decrease in the pH value (8.6–6.67). Whole genome sequencing for both replicates revealed differences in genotypes between them which might indicate the possibility of a developed mutation or sexual reproduction that might have increased the ability of replicate/strain C.V.M* to tolerate harsher conditions and higher ammonia-N concentrations in 20 % diluted LL. These results might pave the way for a possible powerful candidate in LL treatment using a high-ammonia tolerant algal strain which when coupled with plasma pre-treatment might provide an effective, eco-friendly, and sustainable LL treatment approach.

Technologies for Treatment of Landfill Leachate: A Brief Review

Abstract: Landfill leachate contains organic compounds like amines, ketones, carboxylic acid, alcohols, aldehydes, phenols, phosphates and inorganic pollutants such as ammonia, phosphorous, sulphate, emerging contaminants like per-and polyfluoroalkyl substances (PFAS) and also the toxic heavy metals like Mn, Cd, Pb, Fe, Ni, Zn and As. In young landfill leachate, the concentration of volatile acid and simply degraded organic matter is high while pH is low. However, in mature landfills, there is more leachate production with high pH. The age of landfill and determination of parameters like BOD, COD, COD/BOD ratio are important to know the appropriate treatment methods. Physicochemical, biological and combined methods are the most reported landfill leachate treatment methods. Advanced oxidation process, adsorption, coagulation-flocculation, bioremediation, phytoremediation, bioreactor, membrane process and air striping are some of the common categories of effective treatment of landfill leachate. For better apprehension, it has been reviewed that treatment efficiencies of different kinds of leachate depend on their composition and method adopted. Studies related to the removal of organic matter and heavy metals are predominant which reported excellent removal efficiency ranging from 80-100%. In addition, physical parameters like color and turbidity can also be removed effectively using appropriate treatment methods. The present article deals with a concise review of existing literature on sustainable landfill leachate treatment technologies which include physical, chemical, biological and combined techniques.

Processing of Leachate Water into Liquid Fertilizer (POC) for Increasing the Economy of Chrysanthemum Farmers

The waste problem is a national problem that has derivative impacts, including the accumulation of waste in landfills which also causes pollution of locations around landfills for leachate production. TPST Piyungan which is the largest waste management site in Yogyakarta has a leachate treatment system but it does not work optimally. One of the leachate treatment technology options is a wetland system that can not only stabilize leachate by reducing heavy metal levels but can also produce liquid organic fertilizer (POC). This study aims to determine the performance of the wetland system using water bamboo to process leachate into liquid organic fertilizer and to determine the impact of testing on flower plants. Besides that, respondent analysis and economic analysis were also carried out. The results showed that the performance of the wetland system produced leachate NPK levels that were still below the standard liquid organic fertilizer, but its application to flower plants showed significant results in helping flower growth. The economic analysis also shows positive parameters and shows that this system is feasible for business development and has promising market potential.

Dynamic evolution and response strategy of demand in buffer zone between scattered groundwater sources and hazardous waste landfill

Groundwater contamination by landfill leachate is a major concern. Ignoring the long-term increase in leakage caused by the aging of engineered materials may lead to underestimation of the buffer distance (BFD) demand of landfills. In this study, a long-term BFD prediction model was developed by coupling an engineering material aging and defect evolution module with leachate leakage and migration transformation model, and was applicated and validated. The results showed that under landfill performance degradation, the required BFD was 2400 m, i.e., 6 times higher than under undegraded conditions. With the degradation of the performance, the BFD required to attenuate the heavy metal concentrations of groundwater increases more than the BFD required to attenuate organic pollutants. For example, the BFD required for zinc (Zn) was 5 times higher than that required for undegraded conditions, while for 2,4-dichlorophenol (2,4-D), the BFD was 1 times higher. Considering the uncertainties of the model parameters and structure, the BFD should be greater than 3000 m to ensure long-term safe water use under unfavorable conditions such as large leachate production and leakage, weak degradation and fast diffusion of pollutants. If the actual BFD does not meet the demand due to landfill performance degradation, the landfill owner can reduce the reliance on the BFD by reducing the waste leaching behavior. For example, the landfill in our case study would require a BFD of 2400 m, but by reducing the leaching concentration of zinc in the waste from 120 to 55 mg/L, this requirement could be reduced to 900 m.

Analysis and Characterization of the Solid Waste from Kabagarame Dumping site in Bushenyi District, Uganda.

Poor municipal solid waste management poses a very big threat to the environment as well as human health through the production of leachate and greenhouse gas emissions. This research focused on analyzing and characterizing solid waste at the Kabagarame dumping site in the district of Bushenyi, in Uganda. Specifically, wet solid waste samples were characterized and analyzed. The results revealed organics (45.25 %), food waste (24.17 %), inorganics (12.54 %), this was followed by plastics (11.38 %), mixed paper (2.88 %), glass of all kinds (2.36 %) and wood of all kinds (1.42 %). The findings also suggest that understanding the composition of municipal solid waste is essential for creating the best disposal strategy for recovering resources trapped in waste. Keywords: Characterization, solid waste, Kabagarame, and dumping site

Analysis and Characterization of the Solid Waste from Kabagarame Dumping site in Bushenyi District, Uganda.

Poor municipal solid waste management poses a very big threat to the environment as well as human health through the production of leachate and greenhouse gas emissions. This research focused on analyzing and characterizing solid waste at the Kabagarame dumping site in the district of Bushenyi, in Uganda. Specifically, wet solid waste samples were characterized and analyzed. The results revealed organics (45.25 %), food waste (24.17 %), inorganics (12.54 %), this was followed by plastics (11.38 %), mixed paper (2.88 %), glass of all kinds (2.36 %) and wood of all kinds (1.42 %). The findings also suggest that understanding the composition of municipal solid waste is essential for creating the best disposal strategy for recovering resources trapped in waste. Keywords: Characterization, solid waste, Kabagarame, and dumping site.

Characterization of in-barn heat processed swine mortalities.

In-barn heat processing of mass swine mortalities to inactivate pathogens could facilitate more carcass disposal options and reduce the risk of pathogen spread in the event of a foreign animal disease (FAD) outbreak. A 12.2 × 12.2 × 2.4 m (W × L × H) heat processing room was created using a temporary wall inside a de-commissioned commercial gestation barn in northwest Iowa. Eighteen swine carcasses (six per group) divided into three weight groups (mean ± SD initial carcass weights: 31.8 ± 3.3, 102.7 ± 8.1, and 226.3 ± 27.6 kg) were randomly assigned a location inside the room. Three carcasses per weight group were placed directly on concrete slats and on a raised platform. One carcass per weight group and placement (n=6) was instrumented with five temperature sensors, inserted into the brain, pleura, peritoneal, ham, and bone marrow of the femur, and a sensor was attached directly to the skin surface. Environmental conditions (ambient and room) and carcass temperatures were collected at 15-min intervals. Carcasses were subjected to an average room temperature of 57.3 ± 1.2°C for 14 days. The average (±SD) reduction from initial weight for the carcasses on slats was 45.0 ± 4.70% (feeder), 33.0 ± 8.30% (market), and 34.0 ± 15.80% (sow), and for the carcasses on a raised platform, it was 39.0 ± 6.80% (feeder), 49.0 ± 11.30% (market), and 45.0 ± 6.70% (sow). There was a significant interaction between carcass placement (slats and raised) and carcass weight loss for the market weight group. When average carcass surface temperature was at 40.6, 43.3, and 46.1°C (data grouped for analysis), the average internal carcass temperature for most measurement locations was significantly different across carcass weight groups and between the carcasses on a raised platform and those on slats. This preliminary analysis of carcass weight loss, leachate production, and temperature variation in carcasses of different sizes can be used for planning and evaluating mass swine mortality management strategies.

Critical review for the quantification of leachate production: Evaluation example for the “Oum Azza” public landfill in Rabat city, Morocco

AbstractThe estimation of leachate quantities produced in landfills is necessary to dimension the treatment plants allowing to reduce the polluting load of these effluents and consequently avoid their negative impacts on the environment. Different leachate quantification methods were used in this study to assess the leachate volume produced at the Oum Azza landfill. The water balance method give comparable estimations of leachate production to the Ouled Berjal landfill ratio. The first method showed average values between 487 and 495 m3/day for 2015, 2018, and 2019, and at the same time, the second method gave values between 470 and 477 m3/day for the same years. In contrast, the World Bank ratio showed high values that vary between 2260 and 2295 m3/day for 2015, 2018, and 2019. The on‐site data and the statistical analysis showed us that the World Bank ratio is not adapted for the estimation of the leachates produced in Oum Azza landfill, while the water balance and the ratio of Ouled Berjal landfill allowed to give comparable results to reality.

Utilization of Kenaf Core Fiber – Marine Clay Mixture as a Landfill Liner Material

Nowadays, leachate production is a big concern and causes a serious hazard to the soil and groundwater which causes the subsurface soil to be polluted as a result of the loss of soil quality and environmental pollution. This study aims to study the potential of using kenaf core fiber and marine clay mixtures as improved landfill liner material. Relevant laboratory tests such as atterberg limit test, specific gravity test, and particle size distribution were performed to examine basic geotechnical properties of marine clay soil collected from Batu Kawan, Penang. Besides that, compaction test and hydraulic conductivity test were carried out for soil mixed with kenaf core fiber to determine the strength and permeability characteristics. The results found that the marine clay has significantly adequate physical properties to be used as a landfill liner. The permeability test for marine clay soil inclusion of kenaf core fibre indicated that the hydraulic conductivity of the samples admixture for 0%, 4%, 8%, and 12% ranged between 6.68 × 10-9 and 1.57 × 10-8 m/s. Compaction of marine clay mix kenaf core fibre samples resulted in maximum dry density, ρdmax that ranged between 0.936 and 1.595 g/cm3 and optimum moisture content, wopt that ranged between 19.8% and 24%. Hence the inclusion of kenaf core fiber in marine clay soil improves the maximum dry density value, decrease permeability of marine clay and could be potentially used for landfill liner material.

Selection, Identification and Functional Performance of Ammonia-Degrading Microbial Communities from an Activated Sludge for Landfill Leachate Treatment.

The increasing amounts of municipal solid waste and their management in landfills caused an increase in the production of leachate, a liquid formed by the percolation of rainwater through the waste. Leachate creates serious problems to municipal wastewater treatment plants; indeed, its high levels of ammonia are toxic for bacterial cells and drastically reduce the biological removal of nitrogen by activated sludge. In the present work, we studied, using a metagenomic approach based on next-generation sequencing (NGS), the microbial composition of sludge in the municipal wastewater treatment plant of Porto Sant'Elpidio (Italy). Through activated sludge enrichment experiments based on the Repetitive Re-Inoculum Assay, we were able to select and identify a minimal bacterial community capable of degrading high concentrations of ammonium (NH4+-N ≅ 350 mg/L) present in a leachate-based medium. The analysis of NGS data suggests that seven families of bacteria (Alcaligenaceae, Nitrosomonadaceae, Caulobacteraceae, Xanthomonadaceae, Rhodanobacteraceae, Comamonadaceae and Chitinophagaceae) are mainly responsible for ammonia oxidation. Furthermore, we isolated from the enriched sludge three genera (Klebsiella sp., Castellaniella sp. and Acinetobacter sp.) capable of heterotrophic nitrification coupled with aerobic denitrification. These bacteria released a trace amount of both nitrite and nitrate possibly transforming ammonia into gaseous nitrogen. Our findings represent the starting point to produce an optimized microorganisms's mixture for the biological removal of ammonia contained in leachate.