Scaling up the treatment of the fine fraction from landfill mining: Mass balance and cost structure

Potential health risk assessment of contaminants in soil-like material recovered from landfill mining

Landfill mining is an innovative technique to clear dumpsites and recover valuables from legacy waste. Bio-earth, referred here as soil-like material, constitutes a major portion of the legacy waste fraction. The characterisation of Soil Like Material from Ariyamangalam Dumpyard and estimation of pollution indices by comparing with the background soil helps in the identification of the contamination level. The potential health risk associated with the contaminants in Soil Like Material is highlighted. A statistical correlation was also done for various parameters of Soil Like Material to identify the indicator element through the Spearman rank correlation method. The degree of contamination based on eight heavy metals taken into account shows a value of 48.23, which is in the range of very high contamination. The major pollution is induced by the lead present in the Soil Like Material compared to the background soil, followed by chromium and zinc. Lead shows the maximum contamination factor of 19, pollution index of 23.3, geo-accumulation index of 4.2 and enrichment factor of 19. The hazard index is in the order of Cr > Pb > Cu > Ni > Cd > Zn > Hg > As for the heavy metals. Among all heavy metals, the cumulative cancer risk is more due to nickel (0.06 and 0.006 for children and adults, respectively) which is harmful to human health. Hexavalent chromium was found to be an indicator element by significantly correlating with four other parameters. The results of the health risk assessment (HRA) and pollution indices add value to the application of Soil Like Material fractions both onsite and offsite.

Landfill mining in Europe: Assessing the economic potential of value creation from generated combustibles and fines residue

Previous studies showed that resources recovery through landfill mining (LFM) is generally challenging from an economic perspective and that a large share of project costs is related to the external treatment and disposal of bulk process wastes such as combustibles and fines residue. Building on these analyses, this study aims to explore the potential for improving the economy of LFM in Europe by creating value from these bulk process wastes. Specifically, the combustibles are treated through internal incineration with subsequent energy recovery, while fines residue is utilized as construction aggregates. These explored possibilities are investigated considering other varying factors at the site, project, and system levels that cover possible LFM project settings in Europe. A set-based modelling approach is adapted to generate multiple LFM scenarios (531,441) and investigate the underlying critical factors that drive the economy of LFM through global sensitivity analysis. Results show that an additional 16% of LFM scenarios become net profitable, mainly driven by fines residue utilization. Avoided costs for re-landfilling are higher than the revenues from construction aggregates. By contrast, internal incineration is driven by the revenues from recovered energy rather than the avoided gate fee, which is substituted by the costs for building and operating own plants. Overall, the policy conditions remain critical to further improve the economy of LFM in Europe. Recommendations include an inclusive quality standard that relies on pollutant leachability rather than total concentration for higher-value application of fines residue and incentive rather than taxation for producing renewable energy from the combustibles.

The EU Training Network for Resource Recovery through Enhanced Landfill Mining—A Review

The “European Union Training Network for Resource Recovery Through Enhanced Landfill Mining (NEW-MINE)” was a European research project conducted between 2016 and 2020 to investigate the exploration of and resource recovery from landfills as well as the processing of the excavated waste and the valorization of the obtained waste fractions using thermochemical processes. This project yielded more than 40 publications ranging from geophysics via mechanical process engineering to ceramics, which have not yet been discussed coherently in a review publication. This article summarizes and links the NEW-MINE publications and discusses their practical applicability in waste management systems. Within the NEW-MINE project in a first step concentrates of specific materials (e.g., metals, combustibles, inert materials) were produced which might be used as secondary raw materials. In a second step, recycled products (e.g., inorganic polymers, functional glass-ceramics) were produced from these concentrates at the lab scale. However, even if secondary raw materials or recycled products could be produced at a large scale, it remains unclear if they can compete with primary raw materials or products from primary raw materials. Given the ambitions of transition towards a more circular economy, economic incentives are required to make secondary raw materials or recycled products from enhanced landfill mining (ELFM) competitive in the market.

Experimental investigation and optimal combustion control of untreated landfill gas via fuzzy logic rule knowledge based approach

Optimal combustion control of untreated landfill gas is proposed for an effective usage and a low-cost solution in waste to energy technologies. Variations of methane concentration in untreated landfill gas over time cause undesired performance of combustors in thermal efficiency and gas emission. In this work, the experimental investigation on variables of combustion process is systematically presented to determine an inherent performance index of a combustor, reflecting actual thermal efficiency and gas emission for optimal control. Those quantitative findings can be implemented via fuzzy logic rule knowledge based approach to combustion control. From the experimental results of a can-type combustor, it is confirmed that the optimal combustion control of untreated landfill gas yields the desired exhaust gas temperature with maximum thermal efficiency and minimum gas emission under varying methane concentrations or changes of operating conditions. The proposed methodology can be generalized to optimal combustion control of untreated landfill gas via the fuzzy logic rule knowledge based approach, which is the most suitable to characteristics of each combustor. For industrial applications, the experimental results at a laboratory scale can be extended by increasing the capacity of the studied combustor to obtain the large scale combustion in practical production where the optimal combustion control of the untreated landfill gas is effectively accomplished without cost of gas treatment for usage in conventional processes.

Characterization of Excavated Waste of Different Ages in View of Multiple Resource Recovery in Landfill Mining

With the aim of examining the forcing factors in postmanagement landfills, in this study, excavation waste from nonhazardous municipal waste landfill in Tuscany was characterized for the first time. The specific objective was to estimate the feasibility of sampling and analyzing the excavated waste in order to define its properties and provide information about possible landfill mining projects. Based on the biochemical methane potential assays, it was shown that the excavated waste had not yet been stabilized (i.e., with a production of 52.2 ± 28.7 NlCH4/kgTS) in the landfill, probably due to the low excavated waste moisture content (36% ± 6% w/w). Furthermore, excavated waste has a high calorific value, i.e., 15.2 ± 4.1 MJ/kg; the quantity of combustibles in the industrial shredder waste (16 MJ/kg) was rather modest compared to that of municipal solid waste (20.8 MJ/Kg). In conclusion, during large scale excavation of the landfill, it was possible to evaluate how a dedicated treatment plant could be designed to treat and select waste which might appear in a different category. For excavated industrial waste, detailed mechanical sorting may be convenient for end-of-waste recovery to improve calorific value.

Landfill Impacts on the Environment— Review

Waste management (WM) is a demanding undertaking in all countries, with important implications for human health, environmental preservation, sustainability and circular economy. The method of sanitary landfilling for final disposal of waste remains a generally accepted and used method but the available scientific evidence on the waste-related environmental and health effects is not conclusive. Comparative studies of various WM methods (landfilling, incineration, composting etc.) show that among the municipal solid waste (MSW) treatment and disposal technological options, sanitary landfilling or open dumping is popular in most countries because of the relative low cost and low-technical requirement. The European Union (EU) Directive on waste landfills has introduced specific goals for reducing the volume of disposed waste and very strict requirements for landfilling and landfill sites. Evaluation of the impact of landfills on the environment is a crucial topic in the literature and has received increased attention recently, given growing environmental concerns. The main goal of this survey was to conduct a comprehensive assessment of possible impacts of MSW landfills on the environment. The main conclusion of the overall assessment of the literature is that the disposal of MSW in landfills entails a number of environmental risks but with respect to the current situation and rich style of living adopted in industrially developed countries, the idea of WM systems functioning without landfilling—at least in the foreseeable future within one generation—seems to be somewhat unreal. The results also provided important information of landfills as a source of environmental risk. Results of this research may have an important impact on landfill management and the disposal of waste. From the literature review, it is evident that even if high levels of waste avoidance, reuse and recycling are achieved, some waste materials will always need to be forwarded for disposal.