Landfill Cover Research Articles

A study on utilization of landfill mined soil like fraction for sustainable reduction in swelling and cracking potential for expansive and marine soils

Landfill mined soil like fraction (LMSF) is derived from mining of legacy landfill waste after removal of larger fraction such as construction debris, clothes, plastics and other recyclables, and accounts for significant proportion of the total legacy landfill waste. LMSF has found applications as landfill cover material; however, owing to its large quantity in many cities, there is a need to explore more applications for its utilization. In this context the present study explores the role of LMSF (filler replacement) with/without ultrafine slag, US (primary admixture) and lime, L (activator) in controlling the shrinkage and cracking of marine and expansive soils during drying. The ratio of the area of crack and shrinkage to total area of specimen, defined as crack and shrinkage intensity factor (CSIF), has been utilized for quantification of the cracking and shrinkage characteristics of soils with/without stabilization. Further, the effect of soil stabilization on the swelling potential (viz., free swell index and swelling pressure) has been evaluated for the soils. In the present study, complete crack mitigation for expansive soil has been achieved for the combination: 40%LMSF (<425 μm) + 50% expansive soil + 8%US + 2%L, while for the marine soil it has been achieved for combination: 40% LMSF (<425 μm/<2 mm) + 50% marine soil + 8.5%US + 1.5%L. The study findings are useful in the context of utilizing LMSF with sustainable admixtures for reducing cracking and swelling potential of soils for various infrastructure applications such as natural and stabilized slopes, embankment, canal bed and ponds.

WITHDRAWN: Physical and numerical modelling of a vegetated three-layer landfill cover system using recycled aggregates without a geomembrane

WITHDRAWN: Physical and numerical modelling of a vegetated three-layer landfill cover system using recycled aggregates without a geomembrane

Effects of hydrogen sulfide on grass traits and water-gas transport in grass-planted unsaturated soil

Vegetation has been found to improve the hydrological performance of landfill cover. However, existing studies ignore the effects of hydrogen sulfide (H2S), which forms the toxic odour generated from municipal solid wastes. Hydrogen sulfide is a potential signalling molecule in regulating plant-stomata aperture, but how the plant–hydrogen sulfide interaction affects the water–gas transport in soil remains unknown. This aim of this study was to investigate the effects of hydrogen sulfide on Bermuda grass growth and its influence on water–gas transport in unsaturated soils. Soil columns, with and without vegetation, were prepared and fumigated with different hydrogen sulfide concentrations. These columns were subjected to controlled drought and rainfall sequentially. The results showed that grass leaves almost wilted without hydrogen sulfide fumigation due to the Pythium diseases caused by the antecedent waterlogged conditions. In contrast, hydrogen sulfide fumigation promoted grass growth because of the fungicidal effects of hydrogen sulfide. In drought, hydrogen sulfide fumigation caused stomata closure, which resulted in a lower matric suction in the vegetated soil than that without hydrogen sulfide fumigation. Accordingly, hydrogen sulfide concentration reduced because of oxidation by metal oxides in soil. Upon subsequent rainfall, more infiltration but lower matric suction was observed in vegetated soils than was found in the bare case, whereas hydrogen sulfide concentration decreased continuously due to gas dissolution in the pore water. Direct application of laboratory findings herein to field cases should be used with caution, because the applied continuous lighting and low evapotranspiration rate of the soil column tests may not be representative of field conditions.

Effect of Dry and Wet Cycles on the Strength Characteristics of Biochar–Clay Mixture

Biochar is an economical and environmentally friendly “green material” with potential benefits in greenhouse gas emission reduction, soil performance improvement, and environmental restoration. Mixing biochar with clay and using it as a landfill cover can effectively reduce the escape of greenhouse gases into the air, which is important for environmental protection. It is suggested that biochar should be mixed with clay and used as a landfill covering layer. In this study, the shear strength was obtained by direct shear test, and the shear strength characteristics of biochar–clay mixture under the influence of different dry and wet cycles, biochar contents, and moisture conditions were studied. The results show that the shear strength of the biochar–clay mixture in the saturated state decreases with increasing wet and dry cycles, with shear strength decreases ranging from 6% to 19%. The cohesion and internal friction angles of the clays and mixtures show a decreasing trend under wet and dry cycles, with the cohesion and internal friction angles decreasing in the range of 2% to 16%. The shear stress–shear displacement curve for the biochar–clay mixture in the saturated state shows strain hardening after wet and dry cycles; the curve in the dry state shows strain softening with a distinct peak and a platform at the front end of the curve. The shear strength of clay in a dry state is larger than that of biochar–clay mixture and always larger than that of clay in a saturated state. The shear strength difference of the mixture between dry and saturated states is obviously smaller than that of pure clay. This paper, therefore, provides theoretical guidance for the application of biochar–clay mixtures to landfill covers.

Characterization of methanotrophic community and activity in landfill cover soils under dimethyl sulfide stress

Landfill cover soil is the environmental interface between landfills and the atmosphere and plays an important role in mitigating CH4 emission from landfills. Here, stable isotope probing microcosms with CH4 or CH4 and dimethyl sulfide (DMS) were carried out to characterize activity and community structure of methanotrophs in landfill cover soils under DMS stress. The CH4 oxidation activity in the landfill cover soils was not obviously influenced at the DMS concentration of 0.05%, while it was inhibited at the DMS concentrations of 0.1% and 0.2%. DMS-S was mainly oxidized to sulfate (SO42-) in the landfill cover soils. In the landfill cover soils, DMS could inhibit the expression of bacteria and decrease the abundances of pmoA and mmoX genes, while it could prompt the expression of pmoA and mmoX genes. γ-Proteobacteria methanotrophs including Methylocaldum, Methylobacter, Crenothrix and unclassified Methylococcaceae and α-Proteobacteria methanotrophs Methylocystis dominated in assimilating CH4 in the landfill cover soils. Of them, Methylobacter and Crenothrix had strong tolerance to DMS or DMS could promote the growth and activity of Methylobacter and Crenothrix, while Methylocaldum had weak tolerance to DMS and showed an inhibitory effect. Metagenomic analyses showed that methanotrophs had the genes of methanethiol oxidation and could metabolize CH4 and methanethiol simultaneously in the landfill cover soils. These findings suggested that methanotrophs might metabolize sulfur compounds in the landfill cover soils, which may provide the potential application in engineering for co-removal of CH4 and sulfur compounds.

Evaluating gas breakthrough pressure and gas permeability in a landfill cover layer for mitigation of hazardous gas emissions

The construction of an engineered cover layer over landfills is a common method applied to reduce the emission of hazardous gases into the atmosphere. Landfill gas pressures can reach 50 kPa or even higher in some cases, thus posing a serious threat to nearby properties and human safety. As such, the evaluation of gas breakthrough pressure and gas permeability in a landfill cover layer is of great necessity. In this study, the loess soil that is often applied as a cover layer in landfills in northwestern China was used to conduct gas breakthrough, gas permeability, and mercury intrusion porosimetry (MIP) tests. Resultantly, the smaller the capillary tube diameter, the higher the capillary force, and the more significant the capillary effect. Gas breakthrough could be attained with no difficulty, provided that the capillary effect was minimal or approached zero. A good fit between the experimental gas breakthrough pressure–intrinsic permeability relationship and a logarithmic equation was found. The mechanical effect blew up the gas flow channel. In the worst-case scenario, the mechanical effect could lead to the overall failure of a loess cover layer in a landfill. A new gas flow channel was formed between the rubber membrane and the loess specimen as a result of the interfacial effect. Although both the mechanical and interfacial effects can elevate the gas emission rate, the latter did not play a role in the improvement of the gas permeability; therefore, misleading interference took place in the evaluation of the gas permeability, and an overall failure of the loess cover layer. To tackle this problem, the point at which the large- and small-effective stress asymptotes cross on the volumetric deformation–Peff diagram may be applied to give early warning signals of the potential overall failure of the loess cover layer in landfills in northwestern China.

Leaching Behaviour of Synthetic Leachate through a Sewage Sludge and Red Gypsum Composite as Intermediate Landfill Cover

This paper examines the environmental impact of the use of compacted sewage sludge:red gypsum (SS:RG) mixture as intermediate landfill cover in terms of yield and quality of leachate as characterised by hydraulic conductivity and leaching behaviour. A series of column tests using the constant head method is carried out by percolating the synthetic leachate through samples that have been compacted at various degrees (60, 70, 75, 80 and 85%). The leachate quality is monitored at pre-determined days for pH, COD, Cu, Fe and Zn. In general, hydraulic conductivity decreases in three stages, in which the first stage is mainly attributed to the particle rearrangement and hydration of calcium silicate hydrate (CSH). The hydration of CSH increases the pH, which causes the heavy metal to precipitate and be entrapped within the matrices of CSH gel, thereby further reducing the porosity and hydraulic conductivity. A minimum of 75% compaction has shown favourable final porosity, hydraulic conductivity, and leachate quality, although a minimum of 80% compaction is recommended in order to achieve a satisfactory compressive strength of greater than 345 kPa for a landfill operation.

Effects of Freeze-Thaw Cycles on Permeability Behavior and Desiccation Cracking of Dalian Red Clay in China Considering Saline Intrusion

Red clay with features of high liquid (plastic) limit, low permeability, medium-low compressibility and high strength is widely used in anti-seepage projects including roadbed, earth dam, tailings and landfill cover. This study investigates the hydraulic conductivity and propagation of desiccation cracks of compacted red clay in Dalian, China, considering the effect of freeze-thaw (F-T) cycles and saline intrusion. A series of compacted specimens were subjected to different F-T cycles at various controlled salt concentration of 0.2% and 4%. The surface cracking initiation and propagation process of compacted specimens under wetting-drying (W-D) cycles were monitored by Digital Image Correlation technique. The results indicated that permeability coefficient of compacted specimens increased significantly after the first F-T cycle regardless of specimens with variable dry density and salt concentration. The relationship between the number of F-D cycles and permeability coefficient can be expressed as the exponential function for Dalin red clay. Dry density and Saline inhibits the desiccation cracks of compacted specimens under W-D cycles. However, the F-T cycles have a modest promoting effect on crack propagation on the surface of saturated red clay. This study analyzes the underlying formation mechanisms of desiccation cracking-inducing geohazards and provides some guidance for the long-term performance of infrastructures upon saline intrusion and F-T cycles for red clay.

Analytical solution for coupled water–gas transport in landfill cover

Analytical solution for coupled water–gas transport in landfill cover

Degradation of biogas in a simulated landfill cover soil at laboratory scale: Compositional changes of main components and volatile organic compounds

A laboratory experiment lasting 28 days was run to simulate a typical landfill system and to investigate the compositional changes affecting the main components (CH4, CO2, and H2) and nonmethane volatile organic compounds from biogas generated by anaerobic digestion of food waste and passing through a soil column. Gas samples were periodically collected from both the digester headspace and the soil column at increasing distances from the biogas source. CH4 and H2 were efficiently degraded along the soil column. The isotopic values of δ13C measured in CH4 and CO2 from the soil column were relatively enriched in 13C compared to the biogas. Aromatics and alkanes were the most abundant groups in the biogas samples. Among these compounds, alkylated benzenes and long-chain C3+ alkanes were significantly degraded within the soil column, whereas benzene and short-chain alkanes were recalcitrant. Terpene and O-substituted compounds were relatively stable under oxidising conditions. Cyclic, alkene, S-substituted, and halogenated compounds, which exhibited minor amounts in the digester headspace, were virtually absent in the soil column. These results pointed out how many recalcitrant potentially toxic and polluting compounds tend to be relatively enriched along the soil column, claiming action to minimise diffuse landfill gas (LFG) emissions. The proposed experimental approach represents a reliable tool for investigating the attenuation capacities of landfill cover soils for LFG components and developing optimised covers by adopting proper soil treatments and operating conditions to improve their degradation efficiencies.

Adsorption of the emerging pollutants on Buena Vista landfill cover material and implications on regional aquatic pollution

The occurrence of emerging pollutants in water represents a health risk for humans and the ecosystem. It has been shown that pollutant–soil interactions are determinants in preventing contamination of water sources by leachates from landfills. In this work, batch experiments were conducted to study the soil sorption process of amoxicillin (AMX), acetaminophen (ACP), levonorgestrel (LNG), and chlorothalonil (CTL) in four different soil layers used as cover material in Buena Vista landfill located in the municipality of La Union (Antioquia, Colombia). All soil layers were characterized using FT-IR, XRF and BET experimental techniques. In addition, pH and ionic strength effects on the adsorption process were also evaluated. The % of removal follows the order CTL > LNG > AMX > ACP in all soil layers. ACP y AMX adsorption was best described by pseudo-second-order kinetics, while LNG and CTL adsorption was best fitted by the pseudo-first-order kinetic model. Pollutant adsorptions were found to be favored at pH 6.3. Increasing the solution ionic strength decreases the adsorption of pollutants in all evaluated soil layers. The adsorption process was governed by hydrophilic and hydrophobic interactions. Polar molecules such as AMX and ACP remain in the aqueous phase while nonpolar LNG and CTL interact with clay minerals in the soil surface, presumably through van der Waals forces. Based on our findings, a cover material with both hydrophilic and lipophilic characteristics operating close to neutral, and with low ionic content, is advised for the Buena Vista landfill to improve its role as a barrier in decreasing potential pollutants contaminating groundwater sources.

Investigating soil properties and vegetation parameters in different biochar-amended vegetated soil at large suction for application in bioengineered structures

Bioengineered structures, such as landfill cover, vegetated slopes or embankments, green roof and turf are comprised of soil and vegetation where vegetation imparts stability and protection through root reinforcement and hydrologic action. Soil in bioengineered structures often compacted and subjected to prolong drying due to irregular irrigation which necessitates the investigation of soil properties and vegetation growth in biochar-amended soil (BAS) under large suction range and it is scarce in the literature. In the present study, the effect of different biochar types on soil properties, and the vegetation growth in compacted soil and under large suction range was investigated for application in bioengineered structures. The results revealed that the biochar amendment decreased the dry density (5-32%) and increased the water retention capacity (θs by 15-104%, θ1500 by 82-445% and plant available water content (PAWC) by 22-55%), pH (28-77%) and cation exchange capacity (CEC, 16-723%) of the soil. Further, the vegetation growth i.e., vegetation density, dry root mass and shoot mass increased by 8-13%, 33-108% and 4-157% respectively after biochar amendment. The vegetation wilting was started at a higher suction (~ 900kPa) relative to bare soil (800kPa), the permanent wilting point (PWP) increased (by 3-35%) and the complete photosynthetic activity remained unchanged at a higher suction (1600kPa) relative to bare soil (1050kPa) after biochar amendment. Among the biochar types i.e., Sugarcane Bagasse biochar (SBB), Mesquite biochar (MB) and Water Hyacinth biochar (WHB) tested, the MB showed the best performance i.e., the suitable vegetation growth and health status. The improved water retention due to increased porosity, specific surface area (SSA) and presence of hydrophilic functional groups, and the higher pH, CEC and lower dry density in BAS attributed to the higher vegetation growth. The findings of the present study suggest the application of BAS in bioengineered structures.

Impact of leachate on quality of ground water around Chunga Landfill, Lusaka, Zambia and possible health risks

We report the characteristics and possible impact of leachate on quality of groundwater in the Chunga Landfill area of Lusaka, Zambia. Water and leachate samples were collected within and around the landfill for analysis. The pH, biological oxygen demand (BOD), chemical oxygen demand (COD), nitrates, sulphates, chlorides for the leachate and groundwater samples were (6.6 ± 0.1 to 8.7 ± 0.0), (1.7 ± 0.3 to 1,569.6 ± 4.9 mg/L), (4.0 ± 0.0 to 10,378.5 ± 59.2 mg/L), (8.0 ± 0.0 to 37.7 ± 0.4 mg/L), (11.7 ± 0.0 to 273.1 ± 1.7 mg/L), (43.0 ± 1.2 to 974.2 ± 0.8 mg/L) respectively. Heavy metal concentration ranges were cadmium (0.004 ± 0.000 to 1.149 ± 0.021 mg/L, chromium (0.007 ± 0.000 to 2.699 ± 0.039 mg/L), copper (0.013 ± 0.002 to 0.246 ± 0.005 mg/L), lead (0.062 ± 0.005 to 2.591 ± 0.065 mg/L) and zinc (0.008 ± 0.001 to 2.032 ± 0.017 mg/L). The pH of the leachate (8.5 ± 0.0 to 8.7 ± 0.0) meant the landfill was in the methane fermentation phase. An indexing approach was used with the leachate pollution index (LPI) of 30.173, heavy metal pollution index (HPI) of 3,938.92. The heavy metal index (HMI) for copper, lead, chromium, cadmium and zinc were found to be 0.92, 1,124.19, 47.20, 994.17 and 1.48 respectively. Principal component analysis (PCA) showed that anthropogenic activities contributed to pollution with high loading values. Ash from continuous burning of the waste may provide alkalinity which reduces leachate BOD and COD. Results showed that the landfill has outgrown the designed cells capacity as not all leachate was collected by the under-drainage. Results also showed that lack of adequate landfill cover significantly increases rainfall infiltration thereby increasing volumes of leachate produced with a, hence potential for underground water contamination and a human health and environmental problem.

Distance to landfill and habitat cover predict colony size in a Western Mediterranean white stork population

Distance to landfill and habitat cover predict colony size in a Western Mediterranean white stork population

Analytical solution for coupled water–gas transport in unsaturated landfill cover system with different root architectures

This study presents an analytical solution for coupled water–gas transport in a landfill cover system considering four different root architectures (i.e., uniform, triangular, exponential and parabolic architectures), which can consider transient diffusive-advective transport of gas under steady-state water distributions in different condition (e.g., rainfall stage and evaporation stage). The proposed solution is verified against an existing analytical solution, validated against an experiment, and compared with a numerical solution. Using the verified analytical solution, simulations were conducted on the coupled water–gas transport. The results show that ignoring water transport can lead to significant error in gas transport results under various conditions (e.g., the methane flux is underestimated by 45% due to ignoring water transport, when the desaturation coefficient α is 0.1 m−1). The parametric study results indicate that triangular and exponential root architectures have greater effect on water–gas transport (e.g., pore-water pressure, gas emission fluxes) compared with the uniform and parabolic root architectures; vegetation has a significant impact on the water–gas transport, especially in dry conditions (e.g., the gas emission flux through vegetated cover is about 26.3% lower than that through the bare cover); the rainfall intensity and volumetric water content at the bottom boundary have significant effect on water–gas transport in the cover. The proposed analytical solution can be used to aid the design of vegetated soil cover system and the verification of other more complex models.

Hydraulic performance assessment of a multi-layered landfill cover system under constant water ponding

Abstract The engineered multi-layered cover system (MLCS) is used to minimize rainwater infiltration into the wastes accommodated in near surface waste disposal facility (NSDF). It is important to assess the hydraulic performance of MLCS before deploying it in the field. For this purpose, an instrumented three-layered soil column representing MLCS was subjected to 1.5 m constant ponding head for 400 days. The variation of volumetric water content and soil water potential was monitored as a function of depth and time. The objective of the study is to understand the long-term hydraulic performance and rate of saturation of different layers of MLCS. Under constant water ponding, the time to saturation for 0.3 m in surface layer, 0.6 m in drainage layer and 1.0 m in hydraulic barrier layer was observed as 24, 223 and 262 days, respectively. The numerical analysis of the MLCS predicted comparable time duration of 25, 234 and 272 days, respectively. It was noted that the numerical simulation performed by using measured wetting hydraulic parameters matched well with the experimental observation. The importance of soil specific calibration of water content sensors to improve the accuracy of observations was demonstrated. Percentage error in the estimation of layer specific soil water storage, clearly indicates that the volumetric water content measurements using profile probe was marginally better than 5TM measurements.

Geostability of Dewatered Sludge as Landfill Cover Material

&lt;p&gt;Dewatered sludge is the main by-product from wastewater treatment and it contains various types of hazardous substances which can cause environmental pollution. The alternative utilization of sludge waste is for covering the landfill or as liner for the landfill. Landfill cover is a critical component to protect the surrounding environment from leachate contamination produced by landfills and it has specific characteristics. This study analyzes the optimum water content, permeability coefficient, and stability of the material consisting of a mixture of dewatered sludge, bentonite, and quicklime. The test results show that the optimum water content in the three composite variables meet the requirements; the highest optimum value was 28%, a mixture with a ratio of 84% sludge, 15% bentonite, and 1% quicklime. The results also show that mixing sewage sludge with bentonite significantly reduces the permeability value with a ratio of 80% sludge, and 20% bentonite produces the lowest permeability coefficient of 1.979 x 10-7 and this has reached the hydraulic conductivity limit of 1 x 10-7. The shear strength and safety factor results test show that V3 had the best results, with a cohesion value of 22.40 kPa, a shear angle of 31.97°, and a safety factor of 5.297. The addition of bentonite tends to reduce the value of the safety factor. This safety factor can reach a high value because of the ratio of the total shear resistance to the working soil shear stress.&lt;/p&gt;&#x0D;

Estimation of unsaturated permeability in a sanitary landfill cover layer in the Brazilian semiarid region

Resumo A camada de cobertura de aterros sanitários tem como função principal minimizar fluxos de gases tóxicos à atmosfera e a infiltração de águas pluviais para o interior do maciço, no entanto a permeabilidade à água em condições saturadas (ksat) não transmite a real situação em que o solo se encontra, sobretudo em aterros sanitários de regiões semiáridas, sendo a permeabilidade na condição não saturada (knsat) essencial para compreender o comportamento dessa camada. Dessa forma, este trabalho teve como objetivo estimar o comportamento de knsat de um solo utilizado na camada de cobertura de um aterro sanitário do semiárido brasileiro. Foi realizada a caracterização geotécnica do solo e, em seguida, verificou-se o comportamento da sucção com variações de umidades volumétricas. Posteriormente, realizou-se o ajuste das curvas de retenção, obtendo-se o modelo que apresenta melhor ajuste. Com base nos dados obtidos para ksat, foi possível inferir os valores de knsat. Os dados experimentais mostram que o modelo de com melhor ajuste obteve valores de knsat entre 10-7 e 10-15 m/s. Desse modo, verificou-se que baixas umidades observadas nos solos dessa região promovem diminuição brusca da permeabilidade à água na condição não saturada, favorecendo o uso desse solo em camadas de cobertura de aterros sanitários. Com o conhecimento do comportamento dessa permeabilidade, é possível ter controle do processo de execução e a consequente redução de riscos de acidentes ambientais, seja pela migração de gases para a atmosfera, seja pela elevação do nível de líquidos da célula sanitária.

Influence of dissolved organic matter and heavy metals on the utilization of soil-like material mined from different types of MSW landfills

Soil-like material (SLM) mined from municipal solid waste (MSW) landfills can be used as nursery cultivation soil, landfill cover, and as a building material. However, SLM utilization is restrained by heavy metal (HM) contents whose speciation and migration are influenced by their dissolved organic matter (DOM) content. Therefore, the properties of aged refuse and the correlation between DOM and HM forms were studied using samples from different types of MSW landfills. The dominant components of aged refuse were SLM (18.80%–83.51%) and plastics (11.17%–65.51%). The moisture, organic matter, and pH ranged from 29.55% to 57.92%, 15.70%–57.68%, and 7.84–8.51, respectively. The Zn content was highest (455.48–1379.27 mg/kg) in the SLM, followed by Cu (96.29–428.90 mg/kg), Cr (49.10–236.21 mg/kg), Pb (53.52–222.71 mg/kg), and Ni (20.92–39.10 mg/kg). The SLM cannot be used for agriculture because the HM contamination exceeds the multiple of 0.07–7.99. Zinc in the acid-soluble state and reducible state had the highest mobility in SLM. However, Cu and Pb, mainly in the oxidizable state, and Cr and Ni, in the oxidizable and residual states, were relatively stable. In the sanitary and simple MSW landfills, the average proportion of protein-like materials decreased from 84.44% to 82.61% and from 65.58% to 55.94%, respectively, as the landfill depth increased. Both the acid-soluble and oxidizable HM states and all forms of Zn in the SLM were significantly positively correlated with tyrosine-like materials (r = 0.58*–0.87**). Protein-like materials may enhance the mobility of HMs.

In-situ removal of odorous NH3 and H2S by loess modified with biologically stabilized leachate

The loess regions distribute widely in Northwestern China, North America and Eastern Europe. For these regions, landfill is a suitable technology for solid waste treatment. However, as a landfill cover material, loess is not very effective in controlling the emission of malodorous gases. The present study modified loess with biologically stabilized leachate, and investigated the capacities and mechanisms of the modified loess to remove odorous NH3 and H2S. The removal rates of NH3 and H2S at different acclimation time, targeted gas concentrations and temperatures were measured. It was found that the NH3 removal rate of the modified loess was up to 0.08 μmol/(g·hr), which was 1.8 times that of the virgin loess. The H2S removal rate of the modified loess was up to 1.74 μmol/(g·hr), which was 1.25 times that of the virgin loess. The half-meter loess layer modified by biologically stabilized leachate achieved nearly 100% removal of H2S. The improvement of NH3 and H2S removal ability was mainly due to the enrichment of relevant microorganisms. This work proposed a novel method for in-situ control of malodorous pollutants in landfills in the loess regions, and proved that the in-situ removal of NH3 and H2S using the loess modified with biologically stabilized leachate is feasible and cost-effective.