Mechanical Biological Treatment Research Articles

LANDFILL MINING IN THE FRAMEWORK OF INTEGRATED WASTE MANAGEMENT: CASE STUDY OF AN ITALIAN LANDFILL

A remediation project involving landfill mining (LFM) was designed and is ongoing at the 40-year-old Villadose landfill in Rovigo, Italy. The original natural clay lining the bottom of the old landfill is being recovered and used as technical material. Meanwhile newly constructed landfill sectors, designed to contained more than four times more waste than previously are being filled with both excavated waste and fresh municipal solid waste. A laboratory scale experiment was conducted to simulate the expected landfill conditions and analyse the effects of different waste fractions on emissions. The fresh municipal waste although pretreated at a mechanical biological treatment plant shows a significant residual emission potential, in terms of TOC, and NH4. A landfill housing such quality of waste would not be expected to have achieved final storage quality by the end of its aftercare life. The joint disposal of this waste fraction and the substantially degraded excavated waste may contribute to shortening this timeline. This paper reports the landfill mining operation, an assessment of the emissions from the landfill simulation reactors and the implications for the expected landfill behaviour.

Contaminants, biochemical methane potential, and biodegradability of different bio-waste categories: guidance for anaerobic digestion

This study evaluated the anaerobic digestion suitability of bio-waste from different sources by comparing their biochemical methane potential (BMP), biodegradability (BI), and content of contaminants (heavy metals and physical impurities) − an often-overlooked factor but one of particular concern in bio-waste. Predominant heavy metals included Cu and Zn, while recurring physical impurities comprised plastics and organic non-biodegradable matter. Food waste from food processing plants were most suitable, exhibiting low contamination and high biogas conversion (BMP > 549 NmLCH4/gVS and BI > 86 %). Conversely, organic fractions from mechanical biological treatment were highly contaminated, while green waste displayed low biogas conversion (BMP < 368 NmLCH4/gVS and BI < 72 %). Food waste from households and medium/large-sized producers also demonstrated high biogas conversion, but variable contamination levels could compromise their suitability. Assessing contaminants alongside BMP and BI provides a comprehensive approach for selecting suitable bio-waste feedstocks that can be introduced in biogas plants.

Analysis of the Prices of Recycling Byproducts Obtained from Mechanical–Biological Treatment Plants in the Valencian Community (Spain)

Municipal solid waste (MSW) management in Spain, particularly in the Valencian Community, heavily relies on mechanical–biological treatment (MBT) plants followed by landfill disposal. These MBT facilities utilize mechanical processes like shredding, screening, and sorting to segregate recyclables (metals, plastics, paper) from organic material and other nonrecyclables. While public funding supports these plants, private entities manage them through complex, long-term concession contracts. This structure restricts access to crucial data on the sale prices of the byproducts generated during MBT. Publicly available information on relevant company and administration websites is typically absent, hindering transparency surrounding byproduct revenue. This study addresses this gap by analyzing 2012’s available data on revenues obtained from byproduct sales following mechanical treatment at MBT plants within the Valencian Community and comparing them with Spanish national data. This research revealed a significant finding—the statistical distribution of average prices obtained from Ecoembes auctions in the Valencian Community mirrored the corresponding distribution for prices calculated from auctions conducted in other Spanish regions. This suggests a potential uniformity in byproduct pricing across the country. It has also been found that none of the analyzed price distributions exhibited a normal (Gaussian) distribution. The findings also highlight the need for alternative pricing models that move beyond simple averages and account for regional variations and outliers. As actual prices are not available after 2012, this lack of transparency poses a challenge in comprehensively evaluating the economic viability of MBT plants. Furthermore, it raises concerns regarding whether the revenue generated from byproduct sales reflects fair market value. Limited public access to this information can potentially indicate conflicts of interest or inefficiencies within the waste management system.

A bottom-up approach for greenhouse gas emission estimation at the community level: A case study in Japan

Greenhouse gas (GHG) emission mitigation and climate change adaptation in urban communities are urgent. There is enormous potential to improve the GHG inventory at the community level. This research aims to develop a community-scale GHG emission inventory and improve its accuracy and consistency through a bottom-up approach. This study covers direct and indirect emissions categorized into three scopes and selects the Honjo Waseda community in Japan as a case study community. Energy consumption from different sectors (the residential and commercial, transport, and waste management sectors) is evaluated and calculated through Residential Energy Estimation based on the Daily Activities (REEDA) database, National Census, and first-hand field data. The outcome revealed that the residential and commercial sector emissions rank highest in the total GHG emissions of the community, with a value of 39 %. Translated into the scope concept, the emissions under scopes 2 and 3 account for 39 % and 61 %, respectively. Furthermore, a sensitivity analysis of the implementation of green technologies to reduce GHG emissions is also conducted. Mechanical biological treatment (MBT) implementation could yield the largest emission reduction (18 %–22 %), followed by implementing electric vehicles, ultralightweight vehicles, photovoltaic systems, and ground heat utilization.

Odor control technologies for municipal solid waste mechanical biological treatment plant: a review

Odor control technologies for municipal solid waste mechanical biological treatment plant: a review

Assessment of 150 TPD mechanical biological treatment (MBT) based municipal solid waste treatment and disposal facility

Assessment of 150 TPD mechanical biological treatment (MBT) based municipal solid waste treatment and disposal facility

Efficient biological treatment: Achieving exceptional reductions in pollutants and ensuring environmental compliance

The study assessed the effectiveness of treatment processes in removing organic matter, biogenic compounds and suspended solids at the subsequent treatment stages one of the Polish municipal wastewater treatment plant. In a comprehensive mechanical-biological treatment, for all tested pollution indicators, i.e. biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP) and total suspended solids (TSS), outstanding results, surpassing regulatory standards, were obtained. The achieved average percentage reduction was from 87 % for TN (standard deviation of 2.7 %) to average 99 % for BOD5 (standard deviation of 0.3 %). The observed average BOD5/COD ratio of 0.45 aligned with typical values reported, and the decrease in the ratio to 0.13 after biological treatment underscored the efficacy of these processes in organic compounds decomposition and managing difficult-to-degrade substances. The BOD5/TN values emphasized the effectiveness of the treatment, maintaining well-balanced proportions between organic carbon and nitrogen compounds. Moreover, raw sewage showed notable susceptibility to nitrogen removal, indicated by the highest average BOD5/TN ratio of 6.72, suggesting a high propensity for biodegradation. This study highlighted that the average BOD5/TP value of 56 in raw sewage indicated a significant susceptibility to phosphorus compound removal. The treated sewage consistently adhered to environmental regulations, demonstrating minimal variability in pollution indicators. That underscored the effectiveness of treatment processes in meeting stringent standards and achieving significant reductions in pollutants. Effective sewage treatment is even more significant, because it is possible to reuse treated sewage e.g. for irrigation in agriculture, what contributes to the sustainable water management.

Development of solid recovery fuel for power generation with bacterial bio-drying of municipal solid waste in Lombok Island West Nusa Tenggara

Abstract The growth of waste in big cities in Indonesia increases sharply every year. The Government’s ability to manage solid waste only reaches 40.09% in urban areas and 1.02% in rural areas, so the right policies are needed so that Municipal Solid Waste (MSW) does not save potential problems that will impact the future. The waste problem is no longer just a matter of cleanliness and the environment but has become a social problem that has the potential to cause conflict. The most likely solution to solving the MSW problem is to use it as a source of alternative fuel, which can be done by a mechanical-biological treatment technology into Solid Recovery Fuel (SRF). The proposed SRF processing method is straightforward and requires a little technology; thus, it could be developed at the community level. The MSW is collected and processed by communities and then sold to power plants or factories or used in communities to replace solid fuels such as wood or charcoal. Compared with the standard RDF and SRF specifications, MSW SRF falls under medium-grade Refuse Derived Fuel (RDF) or SRF specifications. Further comparison with coal, water hyacinth SRF, and sorghum shows that MSW SRF has several advantages, such as low fixed carbon, sulfur, and moisture, that could be beneficial for combustion performance, which concludes that MSW has potential and meet the specification as an alternative fuel for thermal power plant or other industry that utilizes thermal energy. This paper proposes a processing methodology for municipal solid waste into alternative energy. The method could guide local people in using biomass resources to improve local economic prosperity.

Syngas Purpose Pyrolysis-Gasification of Organic Fractions of MSW over Metal-Loaded Y-Zeolite Catalysts

The increasing environmental consideration and the growth of instability of the energy market call for methods that can process the organic fraction of municipal solid waste (OFMSW) into fuel instead of disposal. Due to the pyrolysis and gasification that are efficient procedures to achieve valuable products, gasification of OFMSW with different particle sizes and compositions was carried out in the presence of Ni and Ni-Ce-loaded Y-zeolite in a multizone tubular kiln reactor. During the experiments, 500°C was applied in the first reactor zone, while the 2nd zone was at an elevated temperature of 600°C or 900°C in the presence of steam. The combined pyrolysis and gasification experiments were also carried out without a catalyst with the same operating conditions. The feedstock was collected from the organic fraction of a Hungarian mechanical-biological treatment (MBT) plant and was separated into four different fractions based on particle size: &lt;1 cm dry biomass and fine particles, 1-2 cm paper-rich, 2-6 cm paper and plastic-rich feedstocks, and &lt;6 cm mixture of these fractions. During the experimental work, product yields; gaseous product composition; the ratio of H2/CO, CO2/CO, and CH4/CO; and lower heating value were determined in the function of feedstock composition, the applied temperature, and catalysts. It was found that the hydrogen content and H2/CO ratio of gaseous products were increased due to catalyst application and temperature elevation in the 2nd reactor zone. The addition of Ce to the Ni/Y-zeolite catalyst was advantageous in the case of hydrogen formation at a lower temperature (600°C). The hydrogen and methane content of products obtained from the catalytic pyrolysis-gasification of paper and plastic-rich OFMSWs on elevated temperatures were higher, which increased the lower heating value of those products. Based on the elemental analysis of the obtained solid residues, it was found that paper/plastic-rich feedstock released hydrogen and carbon with a higher extent. 1-2 cm feedstock-related solid residues had the highest H/C ratio which caused a 12.5-12.8 MJ/kg gross heating value. As a result, combined pyrolysis and gasification appear to be an efficient method to attain valuable outputs from OFMSW not only in gas but also in solid products.

Monitoring of enteropathogenic Gram-negative bacteria in wastewater treatment plants: a multimethod approach

The wastewater treatment processes are associated with the emission of microbial aerosols, including enteropathogenic bacteria. Their presence in this work environment poses a real threat to the health of employees, both through the possibility of direct inhalation of the contaminated air and indirectly through the pollution of all types of surfaces with such bioaerosol particles. This study aimed to investigate the prevalence of enteropathogenic bacteria in the air, on surfaces, and in wastewater samples collected in four wastewater treatment plants (WWTPs). The effectiveness of conventional culture-biochemical, as well as spectrometric and molecular methods for the rapid detection of enteropathogenic bacteria at workstations related to particular stages of wastewater processing, was also evaluated. Bioaerosol, surface swab, and influent and effluent samples were collected from wastewater plants employing mechanical–biological treatment technologies. The air samples were collected using MAS-100 NT impactor placed at a height of 1.5 m above the floor or ground, simulating aspiration from the human breathing zone. Surface samples were collected with sterile swabs from different surfaces (valves, handles, handrails, and coveyor belts) at workplaces. The raw influent and treated effluent wastewater samples were aseptically collected using sterile bottles. The identification of bacterial entheropathogens was simultaneously conducted using a culture-based method supplemented with biochemical (API) tests, mass-spectrometry (MALDI TOF MS), and molecular (multiplex real-time PCR) methods. This study confirmed the common presence of bacterial pathogens (including enteropathogenic and enterotoxigenic Escherichia coli, Salmonella spp., Campylobacter spp., and Yersinia enterocolitica) in all air, surface, and wastewater samples at studied workplaces. Higher concentrations of enteropathogenic bacteria were observed in the air and on surfaces at workplaces where treatment processes were not hermetized. The results of this study underline that identification of enteropathogenic bacteria in WWTPs is of great importance for the correct risk assessment at workplaces. From the analytical point of view, the control of enteropathogenic bacterial air and surface pollution using rapid multiplex-PCR method should be routinely performed as a part of hygienic quality assessment in WWTPs.

Simulation and optimization model for mechanical biological treatment biodrying process: validation with experimental results

Simulation and optimization model for mechanical biological treatment biodrying process: validation with experimental results

Performance evaluation of trommel screens: A case study of a municipal solid waste treatment plant

The efficient and effective operation of trommel screens is essential for the economic and environmental sustainability of mechanical biological treatment (MBT) based solid waste treatment plants. The present study evaluated the performance of four trommel screens (aperture sizes of 80, 32, 16, and 4 mm) being used at the MBT plant of the Municipal Corporation Karnal, India. The performance of trommel screens was evaluated at a fixed speed of rotation and inclination angle. For optimum performance, trommel screens must be operated at a particular range of feed rates with regular cleaning every four hours of operation. The organic recovery achieved by 80 mm and 32 mm aperture size trommel screen was 26.95 % and 95.82 %. The organic quality improvement achieved by 80 mm and 32 mm trommel screens was 122.50 % and 108.89 %. The trommel screen's heating value improvement and energy recovery ranged from 70.68 % to 135.16 % and 28.27 % to 98.74 %, respectively. The oversized fractions of trommel screens of opening sizes 80 mm and 32 mm meet the fuel specification prescribed by the Indian Solid Waste Management Rules 2016. The trommel screen's Specific Energy Consumption (SEC) ranged from 0.63 kWh/tonne to 5.66 kWh/tonne. The learnings and outcomes of this study are helpful for designers, policymakers, operators of solid waste treatment plants, and researchers.

Recovery of plastic packaging from mixed municipal solid waste. A case study from Austria

Austria must recycle more packaging materials. Especially for plastic packaging waste, significant increases are necessary to reach the EU recycling targets for 2025 and 2030. In addition to improving separate collection and introducing a deposit system for specific fractions, the share of plastic packaging in mixed municipal solid waste (MSW) could be utilized.In Austria, about 1.8milliontonnes of mixed MSW are generated. This includes about 110,000 t/a of plastic packaging waste. Most of the mixed MSW (94 %) is sent directly or via residues from pre-treatment, such as mechanical–biological treatment or waste sorting, to waste incineration. While materials such as glass and metals can also be recovered from the bottom ash, combustible materials such as plastics must be recovered before incineration.This work aims to evaluate the recovery potential of plastic packaging waste in mixed MSW with automated waste sorting. For this purpose, two of the largest Austrian waste sorting plants, with a total annual throughput of about 280,000 t/a, were investigated. The investigation included regular sampling of selected output streams and sorting analysis.The results show that the theoretical recovery potential of plastic packaging from these two plants is 6,500 t/a on average. An extrapolation to Austria results in a potential of about 83,000 t/a. If losses due to further treatment, such as sorting and recycling, are considered, about 30,000 t/a of recyclate could be returned to plastic production. This would correspond to an increase in plastic packaging recycling rate from 25 % to 35 %.

Acidogenic fermentation of biowaste coupled with nitrogen recovery using selective membranes to produce a VFA-rich liquid with a high C/N ratio

This research focuses on the production of a liquid stream rich in volatile fatty acids (VFAs) and low ammoniacal nitrogen content (<0.1 g N/L) from biowaste. The liquid stream was obtained by combining (i) mixed culture acidogenic fermentation to maximise VFA production and (ii) gas-permeable membrane (GPM) contactor to recover ammoniacal nitrogen. Three batch fermentation tests of biowaste collected in a full-scale mechanical-biological treatment plant provided high and stable VFA concentrations (37–39 g CODVFA/L). VFAs represented 73–81 % of the soluble chemical oxygen demand (sCOD) concentration, with a predominance of acetic, propionic and butyric acids. A highly specialized microbial community was observed in all batch tests, with Bacteroidota and Firmicutes as predominant phyla (>90 % of relative abundance). The GPM contactor recovered more than 99 % of the ammoniacal nitrogen in the fermentation liquid without VFA losses. The suitability of the produced fermentation liquid with a high C/N ratio for downstream applications was evaluated using biomethane potential tests (BMP) at different total ammonium nitrogen (TAN) concentrations (0.76–3.15 g N/L) and circumneutral pH. Despite achieving similar ultimate methane yields (279–314 NmL CH4/g CODfeed), lower TAN concentrations in the biowaste fermentation liquid improved anaerobic biodegradation kinetics, enhancing its potential applicability for methane production.

A 35-year monitoring of an Italian landfill: Effect of recirculation of reverse osmosis concentrate on leachate characteristics

“Fossetto” landfill (Monsummano Terme - Tuscany, Italy) started operation in 1988 as a controlled landfill accepting mixed municipal solid waste collected without any attempt of recycling. Then, progressively, following the evolution of the state-of-the-art, it adopted biogas extraction and valorisation systems and mechanical-biological treatment for incoming waste (both since 2003). Finally, since 2006, in the plant is performed on-site reverse osmosis leachate treatment with the concentrated leachate being recirculated back into the landfill body. Recently a new landfill cell, separate from the others, was put in operation adding a capacity of 200,000 m3 to the already available 1,095,000 m3. This plant can provide long term leachate composition data to study the evolution and impact of changing landfill technology and waste composition on various parameters. The rise in leachate production (+84 % in 2018–2022 respect to the period before recirculation) cannot be totally attributable to recirculation but could be also linked to the increase in the amount of landfilled waste. The concentration of certain parameters (NH4+, Cl− and to a less extent of COD) increased (+60 %, +58 %, +17 % respectively in the last five years with respect to the period before recirculation); however, this increase did not influence the performance of the treatment plant. Nevertheless, the overall leachate management would benefit from an optimized reinjection system.

Composting and Mechanical Biological Treatment for Reducing Greenhouse Gas Emissions in Bizerte, Tunisia

This study seeks to develop effective solutions and strategies for waste management in the Tunisian municipality of Bizerte by addressing the urgent need for sustainable waste management practices in light of the global imperative to mitigate climate change. With a specific focus on reducing greenhouse gas emissions, this investigation aligns with Tunisia’s commitment to international agreements, including the Paris Agreement and the Global Methane Pledge. This study begins with an exploration of background information, followed by data collection and waste characterization to determine the current situation and to detect gaps that exist in terms of waste management in Bizerte municipality. Two scenarios are proposed as potential solutions for the municipality. The first examines a green waste composting facility with a 1000-ton yearly capacity, which has been operational since 2020. This study describes the compost production process and evaluates the quality of compost derived from green waste. This approach demonstrates its potential for delivering significant environmental and economic benefits. The second scenario delves into the implementation of a mechanical biological treatment (MBT) plant for sustainable handling of residual waste while contributing to a reduction in the municipality’s overall environmental footprint. Using the Sweet software, version 4.0.2, July 2022. this study quantifies the potential reduction in greenhouse gas emissions resulting from composting to be 3%, while the MBT achieves a reduction of 28%.

Refuse-derived fuel (RDF) production and analysis in mechanical-biological treatment (MBT) plant from the municipal solid waste

This study reports on the potential of refuse-derived fuels (RDF), which are produced from Sulaimani Municipal solid waste (MSW) using a biodrying process. Plastic, organic wastes, iron materials, and textiles were used in the formulation of RDF samples. A sample of raw MSW material was collected comprising of 40.6% organic, 29.3% plastic, 6.3% Textiles, 5.1% paper, 3.1% wood, 4.6% glass and stone, 5.2% iron containing materials, and 1.3% others. Physical and chemical properties of the RDF were investigated, including its moisture, ash, total chlorine, and heavy metal content with, calorific value. Based on the experimental results, RDF produced from MSW can be classified into net calorific and total chlorine content values NCV 2 and Cl 4 respectively. In accordance with the European Committee for Standardization (CEN standard), the results of this preliminary investigation of RDF samples made from non-biodegradable and non-recyclable MSW fractions, is necessary to analyze a larger pool of samples in order to project appropriate RDF energy-recovery-enhancing composition.

Experimental investigation of sorted municipal solid wastes producer gas composition in an updraft fixed bed gasifier

Three kinds of municipal solid waste (MSW) from mechanical biological treatment plants, i.e., Fraction after Drum Separator (FDS), Solid Recovered Fuel (SRF) and Plastic Packaging Mixture (PPM), were investigated. These samples were gasified in fixed-bed updraft gasifier under allothermal (800 °C) air supply conditions. Two different air equivalence ratios (ER), i.e., 0.15 ± 0.02 and 0.21 ± 0.04 were created to determine the influence on MSW producer gas properties. Derivative thermogravimetry analysis shows the same volatile release temperatures (330 °C, 500 °C) for all tested MSW kinds. Chromatography analysis of MSW producer gas revealed that the reduction of ER from 0.21 to 0.15 increase the heating value of combustible gases. PPM producer gas contains the highest H2 content – 11.39 %. The highest tar content (47.44 g/m3) was measured in SRF producer gas and primarily consisted of benzene, toluene, naphthalene, and acenaphthylene. The results of the sorted MSW gasification experiments show that the allothermal updraft fixed-bed gasifier is suitable for the production of producer gas that can be used in gas engines.

The Treatment of Municipal Solid Waste in Cambodia, Thailand and Vietnam: An Environmental and Technological Analysis of Current and Future Scenarios

The population growth of South-Asian countries is contributing significantly to the escalating volume of municipal solid waste (MSW). Presently, waste management in this region predominantly relies on landfilling, necessitating a shift towards a more sustainable paradigm. To address this imperative, this study explores the feasibility of extending the European-based waste management system for treating MSW in Cambodia, Thailand, and Vietnam. Assuming as current scenario the direct disposal in landfill, the environmental and technical performances of five other proposed scenarios based on the following technologies were assessed: mechanical–biological treatment; incineration; their combination; mechanical recycling; composting and anaerobic digestion. As expected, all alternative technologies showed potential for improving the current scenario. However, from an environmental point of view, incineration of mixed MSW emerged as the sole option that yielded a discernible environmental benefit for all the countries involved in the study (achieving a carbon footprint of about −0.111 t-CO2-Eq./FU). Recycling-based scenarios achieved higher benefits for Thailand and Vietnam (−0.145 and −0.186 t-CO2-Eq./FU, respectively), but not Cambodia (0.072 t-CO2-Eq./FU) due to the lack of valuable materials to recycle. Technical findings showed how separate collection remains the system generating the least amount of waste for disposal (about 0.185 t), having a synergic effect on the combined approach of mechanical–biological treatment and incineration, which boasts the highest specific energy yield (about 0.339 and 1.183 kW/t, for electric and thermal energy, respectively). These results underscore the imperative to extend the analysis to the economic domain, combining diverse criteria to identify the most sustainable solution.

ComLife cycle assessment of municipal solid waste management systems in Ho Chi Minh City

Life cycle assessment (LCA) is a methodology used to evaluate the environmental impacts of municipal solid waste management (MSWM) systems. In this article, the authors apply the LCA method to investigate the best solution for the MSWM system in Ho Chi Minh city, supported by GaBi software. The LCA results from three scenarios of waste-to-energy, composting, and landfilling reveal their effects on global warming potential, acidification potential, eutrophication potential, and photochemical ozone creation potential. Overall, the results indicate that waste-to-energy and composting scenarios are competitive options.Waste-to-energy is environmentally friendly with a total environmental impact of 62%, which is only a quarter of the impact of landfilling. The composting scenario in the mechanical-biological treatment plant shows promising results of 81% reduction in environmental impact, while landfilling is the most polluting scenario with a total environmental impact potential of 257%. In this study, the scenarios are only investigated from an environmental perspective, for the economic and social impacts of waste management, other decision-making tools should be considered.