Synergistic functional activity of a landfill microbial consortium in a microplastic-enriched environment.

Plastic pollution of the soil is a global issue of increasing concern, with far-reaching impact on the environment and human health. To fully understand the medium- and long-term impact of plastic dispersal in the environment, it is necessary to define its interaction with the residing microbial communities and the biochemical routes of its degradation and metabolization. However, despite recent attention on this problem, research has largely focussed on microbial functional potential, failing to clearly identify collective adaptation strategies of these communities.

Adaptation of Anaerobic Digestion Microbial Communities to High Ammonium Levels: Insights from Strain-Resolved Metagenomics.

Ammonia release from proteinaceous feedstocks represents the main inhibitor of the anaerobic digestion (AD) process, which can result in a decreased biomethane yield or even complete failure of the process. The present study focused on the adaptation of mesophilic AD communities to a stepwise increase in the concentration of ammonium chloride in synthetic medium with casein used as the carbon source. An adaptation process occurring over more than 20 months allowed batch reactors to reach up to 20 g of NH N/L without collapsing in acidification nor ceasing methane production.

Effects of microplastics on evaporation dynamics in porous media.

Microplastics (MPs) pollution is an emerging threat to soil ecosystems. The present study aims to investigate the impacts of MPs on soil water evaporation dynamics and patterns. Two series of laboratory experiments were conducted using sand particles and clay mixed with different MPs to investigate how evaporation dynamics and patterns are influenced by the presence of MPs.

Activated sludge microbial communities and hydrolytic potential in a full-scale SBR system treating landfill leachate.

Landfill leachate, due to its recalcitrant nature and toxicity, poses a serious environmental threat, which requires the implementation of effective treatment processes. In this work, a full-scale treatment system consisting of two Sequencing Batch Reactors (SBRs) was used for the processing of landfill leachate of intermediate to mature age (BOD/COD ratio of 0.16).

Preliminary investigation of microorganisms potentially involved in microplastics degradation using an integrated metagenomic and biochemical approach.

Plastic pollution is becoming an emerging environmental issue due to inappropriate disposal at the end of the materials life cycle. When plastics are released, they undergo physical and chemical corrosion, leading to the formation of small particles, commonly referred to as microplastics. In this study, a microbial community derived from the leachate of a bioreactor containing a mixture of soil and plastic collected during a landfill mining process underwent an enrichment protocol in order to select the microbial species specifically involved in plastic degradation.

Preparation of artificial MSW leachate for treatment studies: Testing on black soldier fly larvae process.

When approaching the study of new processes for leachate treatment, each influencing variable should be kept under control to better comprehend the treatment process. However, leachate quality is difficult to control as it varies dramatically from one landfill to another, and in line with landfill ageing. To overcome this problem, the present study investigated the option of preparing a reliable artificial leachate in terms of quality consistency and representativeness in simulating the composition of real municipal solid waste (MSW) leachate, in view of further investigate the recent treatment process using black soldier fly (BSF) larvae.

Antibiotic resistance contamination in four Italian municipal solid waste landfills sites spanning 34 years.

Municipal solid waste landfill is now recognized as a significant reservoir of antibiotics and antibiotic resistance genes (ARGs). This study investigates the contamination of antibiotics resistance, in 10 leachate samples collected from four MSW landfills in north Italy spanning 34 years, including ARGs as well as mobile genetic element (MGEs). Antibiotics (0-434740 ng/L) and ARGs (5.

Intermittent aeration of landfill simulation bioreactors: Effects on emissions and microbial community.

Landfill simulation experiments were run at lab-scale to compare the effects of intermittent and continuous aeration on the evolution of leachate composition and biogas production. The experiments were carried out using six reactors; two of them under continuous aeration, two under intermitted aeration and two anaerobic as a control. Different aeration regimes produced different effects on reactors.

Methane oxidation and attenuation of sulphur compounds in landfill top cover systems: Lab-scale tests.

In this study, a top cover system is investigated as a control for emissions during the aftercare of new landfills and for old landfills where biogas energy production might not be profitable. Different materials were studied as landfill cover system in lab-scale columns: mechanical-biological pretreated municipal solid waste (MBP); mechanical-biological pretreated biowaste (PB); fine (PBS) and coarse (PBS) mechanical-biological pretreated mixtures of biowaste and sewage sludge, and natural soil (NS). The effectiveness of these materials in removing methane and sulphur compounds from a gas stream was tested, even coupled with activated carbon membranes.

Storage potential and residual emissions from fresh and stabilized waste samples from a landfill simulation experiment.

The storage capacity and the potentially residual emissions of a stabilized waste coming from a landfill simulation experiment were evaluated. The evolution in time of the potential emissions and the mobility of some selected elements or compounds were determined, comparing the results of the stabilized waste samples with the values detected in the related fresh waste samples. Analyses were conducted for the total bulk waste and also for each identified category (under-sieve, kitchen residues, green and wooden materials, plastics, cellulosic material and textiles) to highlight the contribution of the different waste fractions in the total emission potential.

Innovative dual-step management of semi-aerobic landfill in a tropical climate.

Despite concerted efforts to innovate the solid waste management (SWM) system, land disposal continues to represent the most widely used technology in the treatment of urban solid waste worldwide. On the other hand, landfilling is an unavoidable step in closing the material cycle, since final residues, although minimized, need to be safely disposed of and confined. In recent years, the implementation of more sustainable landfilling aims to achieve the Final Storage Quality conditions as fast as possible.

Digestate application in landfill bioreactors to remove nitrogen of old landfill leachate.

Anaerobic digestion of organics is one of the most used solution to gain renewable energy from waste and the final product, the digestate, still rich in putrescible components and nutrients, is mainly considered for reutilization (in land use) as a bio-fertilizer or a compost after its treatment. Alternative approaches are recommended in situations where conventional digestate management practices are not suitable. Aim of this study was to develop an alternative option to use digestate to enhance nitrified leachate treatment through a digestate layer in a landfill bioreactor.

The S.An.A.® concept: Semi-aerobic, Anaerobic, Aerated bioreactor landfill.

Hybrid Bioreactor Landfills are designed to enhance and speed up biological processes, aiming at reducing the duration of post operational phase until landfill completion. S.An.

Ecological risk assessment of agricultural soils for the definition of soil screening values: A comparison between substance-based and matrix-based approaches.

The Italian legislation on contaminated soils does not include the Ecological Risk Assessment (ERA) and this deficiency has important consequences for the sustainable management of agricultural soils. The present research compares the results of two ERA procedures applied to agriculture (i) one based on the "substance-based" approach and (ii) a second based on the "matrix-based" approach. In the former the soil screening values (SVs) for individual substances were derived according to institutional foreign guidelines.

Effect of aerobic pre-treatment on hydrogen and methane production in a two-stage anaerobic digestion process using food waste with different compositions.

Aerobic pre-treatment was applied prior to two-stage anaerobic digestion process. Three different food wastes samples, namely carbohydrate rich, protein rich and lipid rich, were prepared as substrates. Effect of aerobic pre-treatment on hydrogen and methane production was studied.

Recirculation of reverse osmosis concentrate in lab-scale anaerobic and aerobic landfill simulation reactors.

Leachate treatment is a major issue in the context of landfill management, particularly in view of the consistent changes manifested over time in the quality and quantity of leachate produced, linked to both waste and landfill characteristics, which renders the procedure technically difficult and expensive. Leachate recirculation may afford a series of potential advantages, including improvement of leachate quality, enhancement of gas production, acceleration of biochemical processes, control of moisture content, as well as nutrients and microbe migration within the landfill. Recirculation of the products of leachate treatment, such as reverse osmosis (RO) concentrate, is a less common practice, with widespread controversy relating to its suitability, potential impacts on landfill management and future gaseous and leachable emissions.

Aeration of the teuftal landfill: Field scale concept and lab scale simulation.

Long lasting post-closure care (PCC) is often the major financial burden for operators of municipal solid waste (MSW) landfills. Beside costs for the installation and maintenance of technical equipment and barriers, in particular long term treatment of leachate and landfill gas has to be paid from capital surplus. Estimations based on laboratory experiments project time periods of many decades until leachate quality allows for direct discharge (i.

Use of digestate from a decentralized on-farm biogas plant as fertilizer in soils: An ecotoxicological study for future indicators in risk and life cycle assessment.

Over the last decade, the number of decentralized farm biogas plants has increased significantly in the EU. This development leads not only to an increasing amount of biogas produced, but also to a higher amount of digestate obtained. One of the most attractive options to manage the digestate is to apply it as biofertiliser to the soil, because this gives the opportunity of recovering the nutrients, primarily nitrogen and phosphorus, and of attenuating the loss of organic matter suffered by soils under agricultural exploitation.

Biogas production enhancement using semi-aerobic pre-aeration in a hybrid bioreactor landfill.

Landfilling continues to be one of the main methods used in managing Municipal Solid Waste (MSW) worldwide, particularly in developing countries. Although in many countries national legislation aims to reduce this practice as much as possible, landfill is a necessary and unavoidable step in closing the material cycle. The need for innovative waste management techniques to improve landfill management and minimize the adverse environmental impact produced has resulted in an increasing interest in innovative systems capable of accelerating waste stabilization.

Landfill aeration for emission control before and during landfill mining.

The landfill of Modena, in northern Italy, is now crossed by the new high velocity railway line connecting Milan and Bologna. Waste was completely removed from a part of the landfill and a trench for the train line was built. With the aim of facilitating excavation and further disposal of the material extracted, suitable measures were defined.

Use of the Contingent Valuation Method in the assessment of a landfill mining project.

A comprehensive approach for the evaluation of the economic feasibility of landfill mining (LFM) should take into account not only the direct costs and revenues for the private investor, but also the social benefits or costs (generally called externalities), in such a way that projects generating major social benefits (and no significant private revenues) are not overlooked. With a view to contributing to the development of a common framework for the evaluation of LFM projects, this paper presents the results of a case study where the issue of the assessment of social benefits from a LFM project is addressed. In particular, the Contingent Valuation Method is applied for the monetary assessment of the community-perceived benefits from the remediation of an old uncontrolled waste deposit by means of LFM and the conversion of the area into a park.

Landfill aeration in the framework of a reclamation project in Northern Italy.

In situ aeration by means of the Airflow technology was proposed for landfill conditioning before landfill mining in the framework of a reclamation project in Northern Italy. A 1-year aeration project was carried out on part of the landfill with the objective of evaluating the effectiveness of the Airflow technology for landfill aerobization, the evolution of waste biological stability during aeration and the effects on leachate and biogas quality and emissions. The main outcomes of the 1-year aeration project are presented in the paper.

Bioreactor tests preliminary to landfill in situ aeration: a case study.

Lab scale tests in bioreactor were carried out in the framework of the characterization studies of a landfill where in situ aeration (possibly followed by landfill mining) had been proposed as part of the novel waste management strategy in a region in northern Italy. The tests were run to monitor the effects produced by aerobic conditions at different temperatures on waste sampled at different depths in the landfill, with focus on the carbon and nitrogen conversion during aeration. Temperatures ranging from 35 to 45°C were chosen, in order to evaluate possible inhibition of biodegradation processes (namely nitrification) at 45°C in the landfill.

Test methods for assessing the biological stability of biodegradable waste.

This paper presents some results of investigations for the characterization of waste excavated from closed landfills and of waste sampled during mechanical-biological pretreatment before disposal in landfill. The results reported are those obtained with the tests carried out for the assessment of the biological stability of the waste. Some of the considered tests, such as the ones for the determination of the respiration activity and the biogas production, are well known and have been applied for years; other tests, such as the ones for the determination of BOD5 and COD in leaching test eluate and of the black index, are among the tests considered by the international research community for possible utilization for the evaluation of waste biological stability.

The PAF model: an integrated approach for landfill sustainability.

Lab-scale tests were set up to investigate different options for achieving sustainability by reducing long-term landfill emissions. The options which have been studied and compared with the traditional anaerobic landfill for unprocessed refuse were: mechanical-biological pretreatment, landfill aeration with forced and with natural advective air flow (semi-aerobic), flushing. Combination of different options have been experimented.