In the landfill environment context, leachate is the liquid materials that drain from stockpiled material or land. Therefore, leachate comprises of high levels of offensive components derived from ...the material it has passed through. Landfill leachates are also produced as secondary products of the solid organic decomposition processes. The most hazardous products of such leachate are four major types of constituents: soluble organic matters, inorganic components, heavy metals, and xenobiotic organic compounds. Leachates of high concentrations from these components in the early acid phase are mainly due to strong decomposition. During methanogenic phase, a more stable leachate, at relatively lower concentrations, low BOD/COD ratio, and low heavy metals concentrations were recorded. On the contrary, ammonia concentration does not reduce, constituting one of the long-term pollutants within landfill leachate. These chemical constituents can cause serious environmental pollution. The behavior of landfills, its impact on the environment, and treatment methods are discussed. Nowadays, many treatment plants throughout the world are operated by expertise producing high effluent quality. Several treatment technologies are discussed presenting highly efficient system including four basic groups: (1) leachate transfer: based on recycling and combined treatment with domestic sewage, (2) Biological treatment: biodegradation: applying aerobic and anaerobic techniques and (3) chemical and physical procedures: air stripping, adsorption, chemical oxidation, chemical precipitation, coagulation / flocculation, sedimentation / flotation, and (4) membrane technologies.
•Thorough review on recycling waste rubber tyres (WRT) and properties of WRT products•Recycling WRT products in concrete, asphalt and geotechnical applications•Concerns about toxicity of WRT ...incorporated products due to leaching of chemicals•Inadequate research data on leachate analysis of WRT products for metals and PAHs
Waste tyres and their accumulation is a global environmental concern; they are not biodegradable, and, globally, an estimated 1.5 billion are generated annually. Waste tyres in landfill and stockpiles are renowned for leaching toxic chemicals into the surrounding environment, acting as breeding grounds for mosquitoes, and fuelling inextinguishable fires. The properties of waste tyre rubber and engineering applications have been previously reported in a range of publications with respect to the environmental, economic, and technical factors. This study compiles and reviews this research with a focus on geotechnical engineering applications, such as earthworks and infrastructure construction. The applications of waste rubber in construction materials includes cementitious concrete, asphalt concrete, and granular materials for earth structures. Crumb rubber, when used as a sand replacement in flowable concrete fill, improved ductility and strength-to-weight ratio. A 40 MPa concrete mix with 0.6% rubber crumb content exhibited optimal strength and air entrainment capabilities, displaying minimal damage after 56 freeze/thaw cycles. Rubber, as a partial replacement for aggregate in road base and sub-base layers, adversely affected the California Bearing Ratio (CBR) of the graded aggregate base course. Rubber-soil mixtures as the interface of foundation and structure yielded a 60–70 % reduction in vertical and horizontal ground accelerations when subjected to earthquake simulation modelling. There is concern regarding the toxicity of waste rubber incorporated products due to leachates of heavy metals and other chemicals common in tyres. Further comprehensive studies in this area are needed. Leachate studies should be conducted under different pH and liquid to solid ratios.
Sanitary landfilling is still considered worldwide as one of the most common methods applied for the management of the municipal solid waste. As a consequence, vast amounts of landfill leachate are ...generated annually, which are characterized by variability in physicochemical composition, owing to the stabilization process that occurs over the years. However, sustainable management of landfill leachate is a challenging issue, due to diverse chemical composition and high concentration in heavy metals and xenobiotics. Despite the fact that several studies have been reported on the biotreatment of landfill leachate, only in recent years has the microbial composition in such systems have been examined. In the present review, the key role of the microbial ecology involved in depurification and detoxification of landfill leachate in activated sludge and anaerobic systems is interpreted and ecological considerations influencing landfill leachate treatment are stated. Apart from the assessment of landfill toxicity on certain model organisms, this work provides an extensive overview on microbial communities performing key biological processes during landfill leachate treatment, including nitrification-denitrification, anammox and anaerobic digestion. Moreover, microbial aspects affecting nutrient removal efficiency in such biosystems are discussed.
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•Landfill leachate from three distinct landfill sites of Delhi, India was treated.•First attempt to treat landfill leachate with garbage enzyme (GE).•Potential of GE for treatment ...assessed by Leachate Pollution Index.•GE applied in four different proportions of 5%, 10%, 15% and 20%.
In the present study, an attempt has been made to extend the application of garbage enzyme (GE) (fermented mixture of jaggery, organic waste, and water in the ratio 1:3:10) from the domestic wastewater to the urban municipal landfill leachate of Ghazipur, Okhla and Bhalswa landfill sites of Delhi (India). The Leachate Pollution Index (LPI) has been found to be 27.6, 25.4 and 29.2, respectively. The competence of GE was assessed by comparing the initial and final LPIs. The GE was added to the leachate for the contact period of 7–28 days under different mix proportions of 5%, 10%, 15%, and 20%. The maximum final LPI reduction of 74.75% was observed in the Okhla landfill leachate for mixing the proportion of 20% GE after 28 days. However, the mixing ratio of 5% GE showed significant reduction of 60.61% and 55.12% in the final LPI of Ghazipur and Bhalswa landfill leachate, respectively.
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•DOM composition in landfill and incineration leachate was systematically compared.•Transformations of the DOM molecular compositions by MBR/NF were investigated.•Phenolic compounds, ...polyphenols and polycyclic aromatics enriched in MBR leachate.•NF lowered the DOM abundances but with more complex DOM in the NF concentrate.•Coagulation in conjunction with an advanced O3/H2O2 process was used to treat NF concentrate.
Transformations of the molecular compositions of dissolved organic matter (DOM) in incineration leachate (IL) were investigated. Results revealed that DOM in IL had a lower oxidation degree than that in mature MSW landfill leachate (LL). Moreover, aliphatic compounds (2.0 ≥ H/C ≥ 1.5) having the highest bioavailability were the most abundant type of DOM in IL, making IL significantly more biodegradable than LL. Under microbial actions, etc., DOM composed of phenolic compounds (aromaticity index (AI) ≤ 0.50 and H/C < 1.5), polyphenols (0.66 ≥ AI > 0.50) and polycyclic aromatics (AI > 0.66) in MBR-treated effluents were enriched and more diverse than in the untreated leachates. Nanofiltration (NF) dramatically lowered the relative abundances of phenolic compounds, polyphenols and polycyclic aromatics in effluent generated by treatment of IL in a MBR. Although the concentration of DOM in NF effluent was comparatively low, the DOM compositions in the resulting NF concentrate were nearly identical to those in MBR effluent, but were more complex than those in an international standard DOM due to a higher content of CHOS and CHONS heteroatomic compounds. Particularly, coagulation in conjunction with ozone/hydrogen peroxide oxidation process were dramatically reduced most polyphenols and polycyclic aromatics from the NF concentrate.
The present study was performed to determine the effects of vermicompost leachate on growth, quality, and nutrients of
Sedum album
seedlings under salt stress. The study was carried out in Research ...and Practice Greenhouse of Cankırı Karatekin University in Central Anatolia of Turkey. One-month-old seedlings are treated with or without vermicompost leachate at five various NaCl applications (0, 50, 100, 150, and 200 mM). Shoot height, shoot fresh and dry weights, aesthetic appearance score, and crown widths of 10-week-old
S. album
seedlings and plant nutrients were evaluated. Salt stress x vermicompost leachate interaction had a significant effect on all studied traits (
P
< 0.05). The study revealed that vermicompost leachate–supplemented salt concentrations improved the harmful effects of salinity stress on growth and quality traits and macro- and micronutrients of
S. album
. The present study highlights the consideration of the regular application of vermicompost leachate, rich in nutrient content and microbial activity, to improve the detrimental aspects of salinity in salinized soils of arid and semi-arid areas and to improve the quality of soil and plant.
Landfill leachate is a highly contaminated and complex organic wastewater. It can be categorized into young (YL) and mature leachate (ML) based on the landfill age, with significant differences in ...the composition of organic matter, resulting from the significant differences in humification degree. To compare the organic composition of YL and ML, ESI FT-ICR MS was applied to systematically investigate their molecular composition, chemical properties, and structural characteristics. The molecular weight of YL organics was lower than that of ML organics. In addition, O/C and H/C distributions of YL and ML organics were significantly different. YL mainly consisted of CHO compounds and aliphatic compounds. ML mainly consisted of CHON compounds and high oxygen highly unsaturated and phenolic compounds. The unsaturation degree of YL organics was expressed by carbon double bond equivalents ((DBE-C)/C = −0.0336) and was not significantly different from that of ML (−0.0241), but nominal oxidation state of carbon (NOSC = −0.8010) and aromaticity (AImod = 0.1254) of YL were significantly lower than of ML (NOSC = −0.0692; AImod = 0.2464). In addition, YL and ML organics were rich in functional groups, but the YL organics contained more straight-chain structures. The ML organics contained fewer straight-chain structures, a larger number of benzene-ring structures, and more oxygen-containing functional groups. The more complex structural properties of ML organics may be the result of the transformation of YL organics after a long series of reactions, including electrocyclization, decarboxylation, and hydrogen abstraction reactions, which eventually increased the humification degree of leachate organic matter.
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•Molecular composition of young and mature leachates is compared by FT-ICR MS.•Young and mature leachates have significant difference in NOSC and AImod.•DOMs in mature leachate have more complex structure properties.•The DOM transformation from young to mature leachate is proposed.
The leachate produced in landfills represents one of the main environmental risks. Among the main emerging techniques of leachate treatment is evaporation. The present study aimed to implement and ...monitor the performance of natural and forced evaporation technology in open and closed systems. The open pilot experiment system consisted of storage tanks, sprinklers and an evaporative panel, obtaining an average evaporation rate in the system of over 100 L.day−1. For the closed pilot system, different temperatures were combined with different air speeds, simulated by a fan. The results obtained during this operation ranged from 7.7 to 127.2 L.day−1 for the various climatic conditions simulated. In both experiments, wind speed proved to be the most significant climatic characteristic, followed by temperature. With regard to the dispersion of microorganisms in the air, both pilots showed a downward trend in colony-forming units (CFUs) as the distance increased. The volatile organic compound (VOCs) most likely to be present in the atmosphere surrounding the experiments were Dimethyl-Diazene, Tetramethyl-Silane, 2-Nitro-Propane, and 3-Methyl-Butanenitrile. The performance of leachate evaporation, which can be applied in various climatic conditions, leads to the conclusion that these techniques are a viable alternative to conventional landfill leachate treatment methods.
•In the open pilot, the daily evaporation volume was approximately 26 L.m−2.•The best evaporation efficiency of the closed pilot was 353.3 L.m−2.day−1.•The most significant climatic characteristic for the evaporation was wind speed.•The number of microorganisms is inversely proportional to the pilot's distance.•Dimethyldiazene, 2-Nitropropane and 3-Methylbutanenitrile were VOCs detected in air.
