The USA, China and India are the top three producers of municipal solid waste. The composition of solid wastes varies with income: low-to-middle-income population generates mainly organic wastes, ...whereas high-income population produces more waste paper, metals and glasses. Management of municipal solid waste includes recycling, incineration, waste-to-energy conversion, composting or landfilling. Landfilling for solid waste disposal is preferred in many municipalities globally. Landfill sites act as ecological reactors where wastes undergo physical, chemical and biological transformations. Hence, critical factors for sustainable landfilling are landfill liners, the thickness of the soil cover, leachate collection, landfill gas recovery and flaring facilities. Here, we review the impact of landfill conditions such as construction, geometry, weather, temperature, moisture, pH, biodegradable matter and hydrogeological parameters on the generation of landfill gases and leachate. Bioreactor landfills appear as the next-generation sanitary landfills, because they augment solid waste stabilization in a time-efficient manner, as a result of controlled recirculation of leachate and gases. We discuss volume reduction, resource recovery, valorization of dumped wastes, environmental protection and site reclamation toward urban development. We present the classifications and engineered iterations of landfills, operations, mechanisms and mining.
Landfill mining, LFM, is considered to be one of the alternatives to overcome adverse effects of unscientifically created landfills/dumpsites, UCLDs, and engineered landfills, ELFs. However, the ...feasibility of various pathways for the valorization of its yield, designated as the landfill mined residues, LMRs, for sustainable development is still being debated mainly due to not in-place schemes for comprehensive characterization of the landfill-mined-soil-like-fractions, LFMSF, which is a major component of LMRs. Due to this lacuna, proper guidelines, and strategies for utilization of the LFMSF as a manmade resource could also not be developed so far. Another constraint in this context is that the physicochemical characteristics of LFMSF have been attributed to its age, which is difficult to obtain (if not impossible), due to lack of know-how about the method of disposal, turning, and leveling of MSW, and variation in the decomposition pattern between UCLDs and ELFs. With an intention to address these issues, a comprehensive characterization of LFMSF obtained from some of the UCLDs/ELFs in India was conducted by considering their physical, chemical, mineralogical, and thermal characteristics. Based on the experimentally generated data and its statistical analysis, it has been demonstrated that the characteristics of the LFMSF are primarily influenced by its OM. Subsequently, easy to employ relationships between the OM and the characteristics of LFMSF have been developed. It is believed that these relationships will be very much useful for a quick estimation of the LFMSF characteristics that would be very handy for defining its appropriate applications to fulfill sustainable development goals.
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Waste away Reno, Joshua O
2016., 20160209, 2016, 2015-02-09
eBook
Though we are the most wasteful people in the history of the world, very few of us know what becomes of our waste. InWaste Away, Joshua O. Reno reveals how North Americans have been shaped by their ...preferred means of disposal: sanitary landfill. Based on the author's fieldwork as a common laborer at a large, transnational landfill on the outskirts of Detroit, the book argues that waste management helps our possessions and dwellings to last by removing the transient materials they shed and sending them elsewhere. Ethnography conducted with waste workers shows how they conceal and contain other people's wastes, all while negotiating the filth of their occupation, holding on to middle-class aspirations, and occasionally scavenging worthwhile stuff from the trash.Waste Awayalso traces the circumstances that led one community to host two landfills and made Michigan a leading importer of foreign waste. Focusing on local activists opposed to the transnational waste trade with Canada, the book's ethnography analyzes their attempts to politicize the removal of waste out of sight that many take for granted. Documenting these different ways of relating to the management of North American rubbish,Waste Awaydemonstrates how the landfills we create remake us in turn, often behind our backs and beneath our notice.
AbstractGas permeability (ka) and gas diffusion coefficient (Dp) are vital for controlling gas transport through earthen landfill cover overlying municipal solid wastes or acid mine tailings. Soil ...clods generated during the construction of landfill cover can result in various soil microstructures. However, the effects of soil microstructure on Dp and ka are unclear. This study aimed to investigate and compare effects of soil microstructure on measured ka and Dp of compacted manufactured sand tailings (MST)-bentonite mixtures, considering the effects of specimen preparation method, compaction water content (wcomp), and wetting path. The related pore size distributions (PSDs) were measured by mercury intrusion porosimetry. The measurements show that the average ka of as-compacted specimens increased and then decreased as wcomp increased (i.e., a lower soil air content ε—gas-filled volume per unit soil volume), while Dp reduced monotonically. It was because the compacted MST-bentonite mixtures exhibited a multimodal PSD, in which macropores significantly increased the average advective flow velocity of gas. However, the average diffusive flow velocity of gas was independent of pore size, according to the kinetic theory of gas molecules. Conversely, ka and Dp both decreased as ε decreased when the water content of the as-compacted specimen was increased along the wetting path by spraying water, due to the wetting-induced collapse of macropores. These illustrated that Dp was mainly controlled by the ε and tortuosity of gas-filled pores, while ka was dominated by well-connected gas-filled macropores. Moreover, the PSD of specimens was affected by the specimen preparation method, bentonite content, and sieving treatment, thus affecting ka and Dp.
AbstractMunicipal solid waste (MSW) landfills are regarded as one of the major sources of greenhouse gas (GHG) emissions across the world. An innovative and sustainable biogeochemical cover system ...that consists of soil, biochar, and basic oxygen furnace (BOF) slag is being developed to mitigate fugitive landfill emissions such as methane (CH4), carbon dioxide (CO2), and hydrogen sulfide (H2S). Biochar-amended soil can mitigate CH4 emissions by oxidizing CH4 with the help of methanotrophs (CH4-consuming microorganisms), whereas BOF slag can mitigate CO2 and H2S emissions by adsorption and various mineralogical reactions. However, BOF slag is highly alkaline in nature, with pH values usually above 12, and the effect of such high pH on the overall performance of biogeochemical cover system is not known. This study aims at investigating the effect of pH on CH4 oxidation and methanotrophic community structure in landfill cover soil and cultivated consortia through laboratory incubation experiments. In this regard, soil suspension and enrichment cultures were incubated at pH values ranging from 2 to 12, CH4 oxidation rates were measured, and the microbial community structure was analyzed using 16S rRNA gene amplicon sequencing. The optimal pH for CH4 consumption was found to be 7 in enrichment culture and 7.6 in soil suspensions. Very low or no CH4 consumption was observed at extreme pH values of 2 (enrichment culture) and 12 (enrichment culture and soil suspension). A shift in microbial community structure was observed in enrichment cultures initiated at different pH values. Type II methanotrophs were enriched under acidic pH conditions and Type I methanotrophs were enriched in incubations from pH 4 to 10. Soil suspensions were more stable, but also showed slight shifts in the microbial community dominated by Type I methanotrophs and methylotrophs at pH 7.6–10.0. These results demonstrate that at an extreme alkaline pH (∼12), CH4 oxidation is inhibited as growth of methane-oxidizing bacteria (MOB) is arrested in the landfill cover soil.
Gasification of excavated landfill waste is one of the promising options to improve the added-value chain during remediation of problematic old landfill sites. Steam gasification is considered as a ...favorable route to convert landfill waste into H2-rich syngas. Co-gasification of such a poor quality landfill waste with biochar or biomass would be beneficial to enhance the H2 concentration in the syngas, as well as to improve the gasification performance. In this work, steam co-gasification of landfill waste with biochar or biomass was carried out in a lab-scale reactor. The effect of the fuel blending ratio was investigated by varying the auxiliary fuel content in the range of 15–35 wt%. Moreover, co-gasification tests were carried out at temperatures between 800 and 1000 °C. The results indicate that adding either biomass or biochar enhances the H2 yield, where the latter accounts for the syngas with the highest H2 concentration. At 800 °C, the addition of 35 wt% biochar can enhance the H2 concentration from 38 to 54 vol%, and lowering the tar yield from 0.050 to 0.014 g/g-fuel-daf. No apparent synergetic effect was observed in the case of biomass co-gasification, which might cause by the high Si content of landfill waste. In contrast, the H2 production increases non-linearly with the biochar share in the fuel, which indicates that a significant synergetic effect occurs during co-gasification due to the reforming of tar over biochar. Increasing the temperature of biochar co-gasification from 800 to 1000 °C elevates the H2 concentration, but decreases the H2/CO ratio and increases the tar yield. Furthermore, the addition of biochar also enhances the gasification efficiency, as indicated by increased values of the energy yield ratio.
•Steam co-gasification of landfill waste with biochar or biomass was carried out.•No clear synergetic effect was observed in the case of biomass co-gasification.•The addition of biochar promotes synergetic effects on the H2 yield production.•Addition of biochar produces higher H2 yield than that of biomass.
The disposal of municipal solid waste (MSW) directly at landfills or open dump areas, without segregation and treatment, is a significant concern due to its hazardous contents of antibiotic-resistant ...bacteria (ARB), antibiotic resistance genes (ARGs), and metal resistance genes (MGEs). The released leachate from landfills greatly effects the soil physicochemical, biological, and groundwater properties associated with agricultural activity and human health. The abundance of ARB, ARGs, and MGEs have been reported worldwide, including MSW landfill sites, animal husbandry, wastewater, groundwater, soil, and aerosol. This review elucidates the occurrence and abundance of ARB, ARGs, and MRGs, which are regarded as emerging contaminants (ECs). Recently, ECs have received global attention because of their prevalence in leachate as a substantial threat to environmental and public health, including an economic burden for developing nations. The present review exclusively discusses the demands to develop a novel eco-friendly management strategy to combat these global issues. This review also gives an intrinsic discussion about the insights of different aspects of environmental and public health concerns caused due to massive leachate generation, the abundance of antibiotics resistance (AR), and the effects of released leachate on the various environmental reservoirs and human health. Furthermore, the current review throws light on the source and fate of different ECs of landfill leachate and their possible impact on the nearby environments (groundwater, surface water, and soil) affecting human health. The present review strongly suggests the demand for future research focuses on the advancement of the removal efficiency of contaminants with the improvement of relevant landfill management to reduce the potential effects of disposable waste. We propose the necessity of the identification and monitoring of potential environmental and human health risks associated with landfill leachate contaminants.
Pharmaceutical and personal care products (PPCPs) have been the focus of increasing concern in recent decades due to their ubiquity in the environment and potential risks. Out-of-date PPCPs are ...usually discharged into municipal solid wastes (MSWs), enter the leachates in MSW landfills, and have serious adverse effects on the surrounding water environment. However, the occurrence and removal of PPCPs from landfill leachates have rarely been examined to date. This lack of knowledge makes the landfill an underestimated source of PPCPs in the environment. In this review, we collected the relevant publications of PPCPs in landfill leachates, systematically summarized the occurrence of PPCPs in landfill leachates globally, evaluated the removal performances for various PPCPs by different types of on-site full-scale leachate treatment processes, and assessed the impacts of landfill leachates on PPCPs in the adjacent groundwater. In particular, influencing factors for PPCPs in landfill leachates, including the physicochemical properties of PPCPs, climate conditions, and characteristics of landfill sites (i.e., landfill ages) as well as sociological factors (i.e., economic development), were extensively discussed to understand their occurrence patterns. Future perspectives were also proposed in light of the identified knowledge gaps. To the best of our knowledge, this is the first review regarding the occurrence and removal of PPCPs from landfill leachates worldwide.
The effect of texturing (co-extrusion using blowing agent) on the longevity of a geomembrane (GMB) when immersed in synthetic municipal solid waste leachate is investigated over a ∼3 year period. ...Based on data at four temperatures (40, 55, 75, and 85 °C), the time to antioxidant depletion of the textured portion of a 1.5 mm core thickness high-density polyethylene (HDPE) GMB is 40% (standard oxidative induction time) and 9% (high-pressure oxidative induction time) faster compared to the 1.5 mm smooth edge of the GMB. However, despite this, stress crack resistance results show that texturing may have no significant effect on the time to nominal failure for this GMB. It is also shown that HDPE GMBs made from nominally the same resin but from different production lots have different rates of stress crack resistance degradation and hence time to nominal failure; this should be considered both in landfill design and landfill construction quality assurance.
A critical examination of the US Environmental Protection Agency's (US EPA's) Greenhouse Gas Reporting Program (GHGRP) database provided an opportunity for the largest evaluation to date of ...landfilled waste decomposition kinetics with respect to different US climate regimes. In this paper, 5-8 years of annual methane collection data from 114 closed landfills located in 29 states were used to estimate site-specific waste decay rates (k) and methane collection potentials (Lc). These sites account for approximately 9% of all landfills required to report GHG emissions to the US EPA annually. The mean methane collection potential (Lc) for the sites located in regions with less than 635 mm (25 in) annual rainfall was significantly (p<0.002) lower than the mean methane collection potential of the sites located in regions with more than 635 mm (25 in) annual precipitation (49 and 73 m3 methane Mg-1 waste, respectively). This finding suggests that a fraction of the in-place biodegradable waste may not be decomposing, potentially due to a lack of adequate moisture content of landfills located in arid regions. The results of this evaluation offer insight that challenges assumptions of the traditional landfill methane estimation approach, especially in arid climates, that all methane corresponding to the total methane generation potential of the buried solid waste will be produced. Decay rates showed a significant correlation with annual precipitation, with an average k of 0.043 year-1 for arid regions (< 508 mm (20 in) year-1), 0.074 year-1 for regions with 508-1,016 mm (20-40 in) annual precipitation, and 0.09 year-1 in wet regions (> 1,016 mm (40 in) year-1). The data suggest that waste is decaying faster than the model default values, which in turn suggests that a larger fraction of methane is produced during a landfill's operating life (relative to post-closure).
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