Refuse Landfill Research Articles

Transport of pollutants in groundwater of domestic waste landfills in karst regions and its engineering control technologies

Domestic waste produces leachate with a high concentration of pollutants in the landfill process due to biochemical degradation stages like compaction and fermentation. A large number of cases show that anti-seepage membranes widely used in refuse landfills tend to rupture under long-term tension and corrosion, causing leachate to enter the groundwater system and pollute the environment. To reveal the phenomenon of groundwater contamination in refuse landfills, typical domestic waste landfills in karst regions were examined, on the basis of a summary of hydrogeological conditions and hydrochemical characteristics, a three-dimensional groundwater flow model and solute transport model were constructed to analyze the pattern of pollutant diffusion, and its controlling factors, under the current conditions and massive rupture of anti-seepage membrane. The results show that with a minor rupture of the anti-seepage membrane, the area of the low pollution region increases first and then decreases while that of the slight pollution region continuously increases; When a massive rupture of the anti-seepage membrane appears, the ranges of heavy pollution region and total pollution regions continue to grow; Pollutant migrates along the same direction as the groundwater flow and diffuse from high concentration region to low concentration regions under the differential concentration effect. Based on the temporal-spatial distribution characteristics of groundwater pollutants, two engineering control schemes, namely, curtain grouting blocking and group well pumping, were established. A comparison of the two control schemes shows that group well pumping stably maintains water quality safety over the long term, pollutants overflow from both sides of the curtain after they have accumulated to a certain point of concentration, causing damage to the groundwater environment in the conservation area.

Exploring the characteristics of microbial community and enzyme activity in the aged refuse landfill environment of Taiyuan, China

Municipal solid waste landfill is the main disposal option for domestic garbage, in which microbial activities play an important role. However, despite the widespread practice of landfilling, the metagenomic microbial profiles of landfill sites remain poorly characterized. In this study, we used a combination of physicochemical analysis, ultraviolet-visible spectrophotometry, and high-throughput Illumina shotgun sequencing to systematically investigate the changes in soil enzyme activities, microbial community structure, and functional attributes in aged refuse collected from the Xingou Municipal Solid Waste Landfill in Taiyuan, China, with ordinary topsoil from an area within 5 km of the landfill as control soil. Except for neutral phosphatase (P = 0.065), the activities of urease, laccase, dehydrogenase, sucrase, neutral protease, and β-glucosidase were all significantly reduced (P < 0.05) in the aged refuse compared with the control soil. Contrastingly, catalase activity was found to be significantly elevated in the aged refuse. Compared with the control soil, aged refuse was characterized by higher richness and diversity of microbial communities, as reflected by the higher values of community richness estimators (Chao 1 and ACE) and diversity indices (Shannon and Simpson). In total, 186 phyla, 4 354 genera, and 34 459 species were identified, with 132 phyla, 1 914 genera, and 7 369 species showing significantly different abundances between the aged refuse and the control soil. Actinobacteria and Acidobacteria were identified as the dominant phyla in the control soil, whereas Proteobacteria, Euryarchaeota (archaea), and Firmicutes were found to predominate in the aged refuse. Notably, Euryarchaeota and Methanoculleus were the major taxa detected in the aged refuse, but were almost completely absent in the control soil. Xenobiotic biodegradation and bacterial chemotaxis were the main functions of the microflora in the aged refuse, whereas the carbohydrate, amino acid, energy, and lipid metabolism pathways were significantly enriched in the control soil. Moreover, the aged refuse contained a high abundance of genes involved in quorum sensing. Our findings in this study revealed close associations between enzyme activities and variations in the microbial community structure and genes that were actively involved in biodegradation activities at landfill sites. It was found that the landfill environment was characterized by a more complex spectrum of microbial activities than expected. Further investigations are needed to gain a more comprehensive understanding of the microbial community structure and functional attributes as well as their potential influencing factors in the landfill environment.

Degradation of refractory organic matter in the effluent from a semi-aerobic aged refuse biofilter-treated landfill leachate by a nano-Fe3O4 enhanced ozonation process.

In this study, the transformation and degradation mechanisms of refractory organic matter in biologically treated leachate from a semi-aerobic aged refuse biofilter (SAARB) in a nano-Fe3O4 enhanced ozonation process (nFe3O4-O3) were investigated in batch experiments. A continuous experiment then confirmed the effectiveness of the process for SAARB effluent treatment. In a batch experiment, the effects of influencing factors, including nFe3O4 dosage, O3 dosage and initial pH on the treatment performance of nFe3O4-O3 process, were comprehensively investigated. The results showed that when the nFe3O4 dosage = 6 g L-1, O3 dosage = 0.15 L minute-1 and initial pH = 7, the total organic carbon, absorbance at 254 nm and colour number removal efficiencies were 40.58%, 62.55% and 89.80%, respectively. In addition, most of the humic- and fulvic-like substances in the SAARB effluent were removed, and the condensation degree, aromaticity and humification degree of the organics were substantially reduced. The morphology and elemental valence state analysis showed that the nFe3O4 in the process was relatively stable and could form an nFe3O4-organic complex. Therefore, the probability of organics reacting with hydroxyl radical increased and the oxidation efficiency was enhanced. In the continuous experiment, both the O3 dosage and hydraulic retention time (HRT) were the key influencing factors. The treatment efficiency of the nFe3O4-O3 process was enhanced at a higher O3 dosage and longer HRT. The electrical energy consumption of the continuous nFe3O3-O3 process was calculated to be 17.72 kW h m-3 in SAARB effluent treatment. This study proved the feasibility of biologically treated landfill leachate treatment by the nFe3O3-O3 process.

LARGE-SCALE SUBSIDENCE GEOHAZARD MONITORING WITH SENTINEL-1 SAR INTERFEROMETRY IN CENTRAL LISHUI (CHINA)

Abstract. Ground subsidence has become a serious problem along with the rapid urban expansions. Compared with traditional point-based ground survey techniques (GPS, levelling measurement and in-situ sensors), SAR Interferometry are quite appreciated for large-scale subsidence monitoring with long term and high accuracy. In this study, we focused on large-scale subsidence geohazard monitoring of central Lishui (China) and extracted subsidence velocity map of Liandu District. 57 Sentinle-1 SAR images from April 2019 to September 2020 are analysed with SBAS-InSAR technique. The overall subsidence of Liandu is significantly correlated with the distributions of construction engineering sites with displacement velocity of approximately 30–60 mm/yr. Various types of urban ground subsidence could be identified, including the overall settlement of large construction site, the slope deformation of construction excavation, significant settlement of refuse landfill and mountain crossing tunnel, and small deformation of highvoltage towers in mountainous areas. Our results indicated that the rapid urban developments are the dominant impact factors of subsidence in Lishui, China.

Effect of leachate circulation with ex situ nitrification on waste decomposition and nitrogen removal for early stabilization of fresh refuse landfill.

We determined the effects of ex situ biological wastewater treatment on landfill stabilization under continuous circulation of leachate. Specifically, the waste composition and nitrogen in the leachate during leachate circulation (LC) alone was compared with that in a nitrified leachate circulation (NLC) system. An ex situ sequencing batch reactor (SBR) was applied in the NLC system to oxidize the ammonium to nitrite or nitrate, which was then circulated to landfill for denitrification to nitrogen gas. The chemical oxygen demand (COD) concentration in the leachate was low by NLC versus LC, because in the NLC system, ammonium was oxidized to nitrite/nitrate in the ex situ SBR, and aerobic decomposition and denitrification occurred simultaneously in the landfill, suggesting that the NLC system significantly improves the waste decomposition rate and accelerates landfill stabilization. Because denitrification in the landfill was activated in the NLC system and nitrite/nitrate was reduced to nitrogen gas, the proportion of nitrogen in the gas was higher compared with LC. LC, combined with an SBR, might have value in removing the nitrogen that is discharged from the leachate and in accelerating landfill stabilization, because landfill waste was used as the carbon source for denitrification.

Determination and environmental risk assessment of synthetic musks in the water and sediments of the Jiaozhou Bay wetland, China.

Human activity in estuarine areas has resulted in pollution of the aquatic environment, but little is known about the levels of synthetic musks (SMs) in river water and sediments in estuarine areas. This study investigated the concentrations and distribution of SMs in the Jiaozhou Bay wetland, including celestolide, phantolide, traseolide, galaxolide (HHCB), tonalide (AHTN), musk xylene and musk ketone (MK). The SMs HHCB, AHTN and MK were detected at concentrations of 10.7-208, not detected (ND)-59.2 and ND-13.6ng/L, respectively, in surface water samples and 13.1-27.3, 3.06-14.5 and 1.33-18.8ng/g (dry weight; dw), respectively, in sediment samples. Based on the calculated total organic carbon (TOC) concentrations, there was no significant correlation between SMs and TOC in sediment samples (p > 0.05). The hazard quotients were 0.204, 0.386 and 0.059 for AHTN, HHCB and MK, respectively, which indicated no serious environmental impact, because these values are all less than 1. The concentrations of SMs decreased as the distance to the Xiaojianxi refuse landfill increased in both surface water and sediments. Compared with previous studies, the concentration of SMs in the Jiaozhou Bay wetland was relatively high. Therefore, more attention should be paid to SMs because of their persistent impact on human health and the environment.

Simulation of the behavior of a refuse landfill on a laboratory scale

The characteristics and properties of waste in a landfill, and its evolution over time, are difficult to estimate because of the heterogeneity of materials, biomass degradation, density, cover material, and infiltration of water. In this work, a lysimeter was used to simulate how refuse from mechanical-biological treatment (MBT) plants evolved in a landfill over a 45-day period. Water was added as a way to imitate the effects produced during rainy seasons. Field capacity and changes in the physical and chemical properties (volatile solids, biomass, and heating value) were analyzed. The results of this research show that the percentage of biomass lowers, and the heating value increases, after bringing about infiltration and percolation of water in the waste mass. Therefore in order to stabilize waste in a landfill, employing irrigation or leachate recirculation could be advisable. As the heating value increases after percolation, it could also be a good idea to recover the fuel material after stabilization.

Laboratory Simulation Study on Testing and Monitoring of Refuse Landfill Through Electrical Method

Leakage of garbage leachate from refuse landfill can cause pollution to surrounding soil, surface water and underground water, and thus can bring serious damage to our environment. Hence, it is very important to develop a real-time leakage survey system for refuse landfill. In traditional electrical survey method used for refuse landfill, the key point of potentiometric method lies in seepage spot detection while that of resistivity method lies in leachate migration monitoring. At present, there are very few garbage leakage survey systems which can combine these two methods together. By conducting laboratory simulation on the leakage monitoring mechanism of refuse landfill through electrical method, this thesis studied the differences between potentiometric method and resistivity method. Through analysis of actual measurement result data, feasibility of refuse landfill leakage survey system that can monitor seepage spots and leakage scale at the same time has been verified.

Determination of heterocyclic brominated flame retardants tris-(2, 3-dibromopropyl) isocyanurate and hexabromocyclododecane in sediment from Jiaozhou Bay wetland

The concentration and distribution of tris-(2,3-dibromopropyl) isocyanurate (TBC) and the three isomers of hexabromocyclododecane (HBCDs) were analyzed in the sediment of Jiaozhou Bay wetland in China. The concentrations of TBC and the three isomers of HBCDs (α-HBCD, β-HBCD, γ-HBCD) were in the ranges of 1.20 to 8.76, 1.03 to 5.69, 1.13 to 5.46, and 1.18 to 15.04ng·g−1 dw (dry weight), respectively. γ-HBCD was the predominant congener with an average proportion of 52.42% of ΣHBCDs, average inventory of HBCDs was about 93.53ng∙cm−2. Depending on the function of wetland, the concentration of HBCDs tended to decrease as the distance to the Xiaojianxi refuse landfill increased. Compared with previous research studies, the concentration of TBC and HBCDs in the Jiaozhou Bay wetland was at a relatively high level. Therefore, more attention should be paid to TBC and HBCDs on account of their persistent impact on human health and the environment.

Estimating Non-Methane Organic Compound Emission Factor for Municipal Solid Waste Landfill

Non-methane volatile organic compounds (NMOCs) are important precursors of the photochemical reactions which produce ozone and secondary organic aerosols. An accurate emission inventory is essential for air-quality simulations and policy making. The NMOC emission from landfill is an important sector in the anthropogenic source. When estimating anthropogenic NMOC inventory the emission factor for refuse disposal originates from the European study or the estimation for this sector is discarded due to no other referenced data. This research is reviewed the NMOC yields from refuse landfill and the emission factor is from 0.0775 to 3.7625 kg/t. Besides, this paper was particularly concerned with correction of the emission factor by estimating the effects of waste characteristics and the various technologies for landfill. Compared NMOC yields under anaerobic and aerobic conditions for each kind of wastes, only the difference for food waste was obvious.

Test Studies on the Corrosion Features for the Bridge Foundations Durability in a Household Refuse Landfill Environment

Generally, the bridges or buildings cannot be constructed on a refuse landfill, since the special chemical compositions and microorganisms in landfill will impose adverse effects on the concrete foundations. Especially, the impacts on their durability are still unknown. The purpose of this paper is to get the corrosive features of a refuse landfill to give suggestions for the durability design of the structure’s foundation. The present work is based on a bridge construction in Linhai Road, Shanghai, which should pass through a household dump landfill in a rare environment, by means of a low-bridge crossing. With the aims of ensuring the durability in long-term service and providing some reference experiences, we have performed sampling tests on the bridge pile foundations under this corrosive environment, in terms of chlorine ion content, electric flux and strength. With regard to the positions along the radial direction of pile sections, the chloride ion concentrations varies slightly and negligibly with the varying coring depths and increases with the varying coring depths, indicating that the permeability in pile foundations is enhanced gradually with the increasing buried depths. Considering the calculated permeability coefficients, the concretes with the adopted compositions doesn’t meet the expected values. The measured electric flux of concretes under sewage condition is obviously higher than it is under standard curing condition, suggesting that the hazardous substances significantly affects the anti-permeability performance of concretes under on-site geological conditions. The damages of dump environment on the concrete durability of the bridge pile foundations were accessed.

The mixture theory for unsaturated bentonite

Bentonite is a material with low permeability and as such is the preferred material for impervious layer in a refuse landfill. Given the multi-scale structure of the bentonite, contaminant transport in it is a very complex process. In fact, it is coupled with consolidation. The coupling effect affects the contaminant transport by changing the inherent transport feature. In addition, the bentonite clay liner is usually unsaturated. In this article, the mixture theory is used as a framework that describes the transport phenomena and the interactions of the unsaturated bentonite under the multi-field coupling effect. It is also a valuable reference for simulating the contaminant transport in bentonite clay liners.

Test Studies on the Corrosion Features for the Bridge Foundations Durability in a Household Refuse Landfill Environment

Generally, the bridges or buildings cannot be constructed on a refuse landfill, since the special chemical compositions and microorganisms in landfill will impose adverse effects on the concrete foundations. Especially, the impacts on their durability are still unknown. The purpose of this paper is to get the corrosive features of a refuse landfill to give suggestions for the durability design of the structure’s foundation. The present work is based on a bridge construction in Linhai Road, Shanghai, which should pass through a household dump landfill in a rare environment, by means of a low-bridge crossing. With the aims of ensuring the durability in long-term service and providing some reference experiences, we have performed sampling tests on the bridge pile foundations under this corrosive environment, in terms of chlorine ion content, electric flux and strength. With regard to the positions along the radial direction of pile sections, the chloride ion concentrations varies slightly and negligibly with the varying coring depths and increases with the varying coring depths, indicating that the permeability in pile foundations is enhanced gradually with the increasing buried depths. Considering the calculated permeability coefficients, the concretes with the adopted compositions doesn’t meet the expected values. The measured electric flux of concretes under sewage condition is obviously higher than it is under standard curing condition, suggesting that the hazardous substances significantly affects the anti-permeability performance of concretes under on-site geological conditions. The damages of dump environment on the concrete durability of the bridge pile foundations were accessed.

Test Studies on the Corrosion Features for the Bridge Foundations Durability in a Household Refuse Landfill Environment

Generally, the bridges or buildings cannot be constructed on a refuse landfill, since the special chemical compositions and microorganisms in landfill will impose adverse effects on the concrete foundations. Especially, the impacts on their durability are still unknown. The purpose of this paper is to get the corrosive features of a refuse landfill to give suggestions for the durability design of the structure’s foundation. The present work is based on a bridge construction in Linhai Road, Shanghai, which should pass through a household dump landfill in a rare environment, by means of a low-bridge crossing. With the aims of ensuring the durability in long-term service and providing some reference experiences, we have performed sampling tests on the bridge pile foundations under this corrosive environment, in terms of chlorine ion content, electric flux and strength. With regard to the positions along the radial direction of pile sections, the chloride ion concentrations varies slightly and negligibly with the varying coring depths and increases with the varying coring depths, indicating that the permeability in pile foundations is enhanced gradually with the increasing buried depths. Considering the calculated permeability coefficients, the concretes with the adopted compositions doesn’t meet the expected values. The measured electric flux of concretes under sewage condition is obviously higher than it is under standard curing condition, suggesting that the hazardous substances significantly affects the anti-permeability performance of concretes under on-site geological conditions. The damages of dump environment on the concrete durability of the bridge pile foundations were accessed.

Evolution processes of trace metal speciation in leachates with different ages from Laogang Refuse Landfill, Shanghai

Trace metals in leachates are forced to be removed with the implement of the latest Chinese standards of landfill pollution control (GB-16889, 2008), and understanding the speciation distribution processes is important for the development of the leachate treatment process. In this work, evolution processes of trace metal speciation were investigated according to the size fractions, hydrophobic/hydrophilic fractions, and geochemical species with the disposal time. The main trace metals, that is, Pb, Ni, Cr Cu, and Zn, were around 0.04–0.52 mg Pb/L, 0.24–1.22 mg Ni/L, 0.12–0.86 mg Cr/L, 0–0.28 mg Cu/L, and 0.58–1.98 mg Zn/L in leachates with the disposal ages of 2–12 years. Pb was found to predominate in suspended solids, with the percentage of 46–100%, and the dominant fraction of Ni and Zn was in dissolved fractions, with the percentage of 28–83 and 34–67%, respectively, while Cr and Cu scattered between suspended solid and dissolved fractions. The predominated geochemical species of Pb, Ni, Zn, and Cu was Me dissolved organic matter and Me CO3, while Cr was dominated as hydroxide complexations. For the hydrophobic distribution in leachates, the main part of Pb, Ni, Cr, and Cu was presented as hydrophobic fractions, with the percentage of >50%, while Zn predominated in the hydrophilic fractions. The evolution processes of trace metals are dependent on both the metals’ nature and the landfill conditions greatly, and the corresponding treatment process should be changed with the landfill ages.

Discussion on MBR Treatment Process of Domestic Landfill Leachate Design Issues in Northeast Area

MBR technology has been widely used in northeast China's leachate treatment projection for its obvious technical advantages. However, the complex nature of the Northeast leachate as well as relatively more calculations design of MBR process, became the key to the success of the project. This article in view of the present our country MBR treatment process of domestic refuse landfill leachate treatment of some design problems and puts forward some personal views and suggestions,, for example the MBR process calculation method of reference.

Indicating landfill stabilization state by using leachate property from Laogang Refuse Landfill

Variation and evolution process of leachate can be applied as a reference for landfill stabilization phase. In this work, leachates with different ages were collected from Laogang Refuse Landfill, and characterized with 14 key parameters. Simultaneously, principal component analysis (PCA) was applied to develop a synthetic parameter-F based on these 14 parameters, and a logarithm equation was simulated for the landfill stabilization process finally. It was predicted that leachates would meet Class I and Class II in standard for pollution control on the landfill site of municipal solid waste (GB 16889-1997) after 32 years and 22 years disposal under the natural attenuation in the humid and warm southern areas of China, respectively. The predication of landfill state would be more accurate and useful according to the synthetic parameter F of leachate from a working landfill.

Treatment of Membrane Concentrated “Young” Landfill Leachate by Coagulation Sedimentation

A self-made coagulant was applied in the treatment of some membrane concentrated reject of the “young” landfill leachate. The optimum operation diameters were determined by orthogonal and single factor experiments. Under the optimum conditions, the values of COD and ammonia nitrogen of water sample after treatment were 88 mg/L and 10.8 mg/L, respectively, which reached the standard in Pollution Control Standard of Domestic Refuse Landfill GB 16889-2008. Therefore, coagulation method can be applied in the treatment of membrane concentrated “young” landfill leachate to achieve standard discharge.

Stability Indices of Refuse Landfill in Tokyo Port

Stability Indices of Refuse Landfill in Tokyo Port

Field assessment of stratified aged-refuse-based reactor for landfill leachate treatment

The aim of this study was to investigate the engineering applicability of the stratified aged-refuse-based process for landfill leachate treatment. In this work, a pilot-scale (10m(3)day(-1)) and a demonstration-scale (200m(3)day(-1)) stratified reactor, containing the aged refuse excavated from an 8-year-old closed landfill cell, were used as a medium by which to treat landfill leachate generated in the Shanghai Refuse Landfill (SRL). The preliminary-treated leachate with initial CODcr, NH(3)-N and total-N concentrations of 2387-8592, 1431-2145 and 1290-2188 mgL(-1), respectively, was intermittently sprayed over the refuse surface eight times a day with 3 h per interval in the pilot study. The results from the pilot operation showed that on average 89.5% of COD, 98.8% of NH(3)-N and 52.6% of total N could be removed from a hydraulic load of 0.267-0.444m(3)m(-3)refuseday(-1). Additionally, similar results were observed for the demonstration system even with the leachate of low BOD(5)/COD ratios (0.17-0.19). The investment and operational costs of this stratified process were about 20000yuan (€2200) and 1-2 yuan (€0.11-0.22) per m(3) leachate treated, respectively. Taken together, the stratified process has some significant advantages including low operation cost, easy maintenance and good adaptability to the leachate of variable quality, which makes this process a viable alternative for the treatment of landfill leachate.