Mechanical And Biological Treatment Research Articles

Material flow and environmental performance of the source segregated biowaste composting system.

Life cycle assessment (LCA) is performed to investigate the environmental impacts of two alternative approaches in a biowaste management system. The system inventory is based on actual data and on-site sampling for two consecutive years at the mechanical and biological treatment (MBT) facility at the prefecture of Chania (Greece). The facility pertains as MBT for household waste and material recycling (MR) for the recyclable fractions in two different process lines. The mass balances and environmental performance are assessed from waste generation to end-use. The LCA and ReCiPe 2016 methodology estimate the endpoint environmental impacts on human health, ecosystem quality and resource scarcity. The results show that biowaste source segregation in an integrated waste management system not only significantly benefits its recoverability potential it also improves its environmental performance. Impacts on human health (HH) have reduced by 4.6 times, on freshwater ecosystem quality (EQf) by 6.3 times and resource scarcity (RS) usage by 2.5 times when biowaste is combined with compost production and use, material recovery and reprocessing for fertilizer and raw material substitution.

Is pyrolysis technology an advisable choice for municipal solid waste treatment from a low carbon perspective?

With worldwide concern about climate change, waste-to-fuel technologies have been revived in the argument over whether waste-to-energy is still the best choice. A process-oriented life cycle assessment for municipal solid waste (MSW) was performed on the basis of full-scale operational data to compare the carbon footprints of the pyrolysis technology enhanced by mechanical and biological treatment (MBT) and incineration technology. Material and carbon flow analyses reveal that MBT produces refuse-derived fuels (RDFs) of 330 kg/ton MSW for pyrolysis, in which 67% of the carbon ends up in tar and char. Based on the Chinese energy structure in 2020 and MSW composition with 13% plastics, incineration and MBT–pyrolysis provide similar net carbon savings around 200 kg CO2-eq/ton. As the MSW contains more plastic fraction and the energy system becomes greener, the carbon savings from MBT–pyrolysis are less affected compared with those from incineration. The full-scale MBT–pyrolysis was verily optimised to maximise the RDF production and yield more tar and less syngas by identifying the important parameters, resulting in 30% higher savings in carbon footprint. With the energy structure at year 2050, the carbon footprints from MBT–pyrolysis are completely superior to that from incineration, regardless of the waste composition and heat recovery. From the low carbon perspective, fuel recovery with MBT − pyrolysis deserves priority over electricity recovery with incineration. This potential difference between waste-to-fuel and waste-to-energy technologies is for the first time quantitatively identified, and thus calls for a reconsideration on the long-term waste management and technological improvements.

Effects of the reinforcement content and reinforcement scale on the shear strength characteristics of mechanically biologically treated waste.

Mechanical and biological treatment (MBT), which can be used for waste reduction and for the burning of methane from biological treatments to generate electricity and heating, has become a popular research topic in environmental geotechnical engineering. This study investigated the mechanical behaviour of MBT waste and the effects of different reinforcement contents and reinforcement scales on its shear strength characteristics, and 68 groups of MBT waste samples from the Hangzhou Tianziling landfill were tested in the laboratory with a direct shear test apparatus. The samples exhibited displacement hardening behaviour in their mechanical response. The results show that the content and scale of the reinforced materials in MBT waste play an important role in the strength characteristics of MBT waste, and graphs showing the variation of the MBT waste shear strength and shear strength parameters with different reinforcement contents and reinforcement scales are shown. The range of cohesion c is 6.0-12.0kPa, and the internal friction angle φ is 15.6-26.6°, respectively. The results of this study provide a reference for the assessment of slope stability at MBT landfills.

Assessment of Pretreatments for Highly Concentrated Leachate Waters to Enhance the Performance of Catalytic Wet Peroxide Oxidation with Sustainable Low-Cost Catalysts

Matured compost, derived from a mechanical and biological treatment (MBT) plant, was used as a precursor to produce catalysts through hydrothermal and thermal carbonization, HC and PC, respectively. HC and PC displayed suitable properties to act as catalysts in the catalytic wet peroxide oxidation (CWPO) treatment of the highly polluted leachate waters generated in the same MBT plant (TOC0 = 27 g L−1; COD0 = 60 g L−1; BOD5,0 = 23 g L−1). The influence of catalyst loading and pH were studied, considering multiple additions of H2O2. The best experimental conditions found were T = 80 °C, pH0 = 3.0, 7.2 g L−1 of HC catalyst, 85.7 g L−1 of H2O2, added in five batches in one-hour intervals between each addition. Under these experimental conditions, removals of 43%, 52%, 93%, 82%, 35%, 95% and 93% for the COD, TOC, BOD5, aromaticity, chlorides, turbidity and color number (CN) were, respectively, observed. Ion exchange resins and coagulation–flocculation were studied as pretreatment options to reduce the complexity of the leachate waters and enhance the CWPO results. Both strategies resulted in higher mineralization and enhanced the consumption efficiency of H2O2 (ηH2O2). The sequential treatment using coagulation–flocculation and CWPO with PC catalyst showed the best results, achieving abatement of 94%, 70%, 98%, 93%, 31%, 96% and 95% for COD, TOC, BOD5, aromaticity, chlorides, turbidity and CN, respectively.

A procedure to assess the environmental, social and economic benefits wasted in the paper and cardboard fraction of the unsorted residual waste

The main aim of this study was to define a procedure useful to evaluate the potential environmental, social and economic benefits contained in paper and cardboard (or other recyclables), which are wasted in the unsorted fraction of municipal solid waste (MSW). To give a practical example, the procedure was applied to the 550 municipalities of the Campania region, in Southern Italy, but the developed procedure is applicable in any context in an ‘urban mining’ perspective. The procedure consists of five phases and uses two methodologies: one for the estimation of the composition analysis of the unsorted residual waste and another for the calculation of sustainability indicators able to measure the benefits wasted in the unsorted residual MSW. Six indicators were defined: two for the environment (carbon footprint and ecological footprint), two for the society (health footprint and occupational benefits) and two for the economy (economic profit and economic saving). The first methodology was developed by the regional environmental protection agency to update the MSW regional management plan. The second methodology is based on the use of the Life Cycle Assessment (LCA) through which it was possible to calculate the reference parameters useful for the calculation of the impacts (i.e., loss of benefits) for recycling, mechanical and biological treatment (MBT), incineration and landfilling of paper and cardboard contained in the unsorted residual waste. The obtained results confirmed the presence of such an enormous deposit of recyclable materials contained in the unsorted residual waste, which is a potential source, but not exploited, of environmental, social and economic benefits. For instance, the paper and cardboard ‘urban mine’ of Naples was greater than 16 million of euro (economic profit + economic saving), with a potential saving of around 11.4 million of kgCO2eq. (carbon footprint), 207 million of m2 (ecological footprint), 44 Disability Adjusted Life Years (health footprint), with a creation of 30 job positions in the waste management sector (occupational benefits).

Comprehensive analysis of municipal solid waste rejected fractions as a source of Refused Derived Fuel in developing countries (case study of Isfahan- Iran): Environmental Impact and sustainable development

Refused Derived Fuel (RDF) could be considered as an alternative energy source, which not only helps to improve waste management, but also effectively reduce energy consumption and environmental pollution in huge industries. In the present study, the potential of energy valorization of rejected streams of municipal solid waste (MSW) processed in Isfahan mechanical and biological treatment (MBT) plant is investigated through RDF production. Therefore, various physical and chemical analysis of mechanical treatment rejects (MTR) and composting rejects (CR), as two streams being currently landfilled, were carried out. The results show that, RDF produced from both of these two streams could be classified as net calorific value (NCV): 3, Cl: 1 and Hg: 1 according to the European committee for standardization (CEN standard). Considering the amount of produced RDF from these two streams in Isfahan (300 t/d from MTR and 120 t/d from CR) and their NCVs, about 2 million GJ/year would be saved. As a result, in many cities of developing countries with the same condition like Isfahan, MTR and CR can be used as sources of RDF production and alternative fuels in the cement industry.

Metamorphosing waste as a resource: Scaling waste management by ecomodernist means

Informed by the European Union’s waste hierarchy, UK policy has normatively shifted the ontological status of waste from matter out of place to a resource for which uses must be found in order to achieve environmental goals of decarbonisation and waste reduction. Technologies linking waste-management with renewable energy have been supported within an ecomodernist framework of market incentives for stimulating private-sector investment in new waste treatment technologies. Under pressure of EU targets, the UK’s policy measures have had several aims: to reduce landfill disposal, increase resource recycling or reuse, expand waste-based renewable energy and thus reduce GHG emissions. As techno-market-fixes, new facilities were meant to convert waste for more beneficial uses, bring it up the hierarchy and localise its management. Consequent tensions can be illuminated by linking concepts of technology scaling and socio-material metamorphosis with critical perspectives on ecomodernism.Although the ecomodernist framework stimulated some waste-management improvements, other outcomes contradict the policy objectives of localising and converting waste for more beneficial uses. These contrary outcomes are illustrated by two technologies, anaerobic digestion (AD) and mechanical and biological treatment (MBT), each with multiple possible spatial scalings and techno-configurations. Financial instruments have most incentivised the easiest socio-material metamorphosis for lucrative returns, especially to produce energy (electricity or gas) for grid systems, suiting large operators. For more environmentally beneficial uses of waste, there have been difficulties in overcoming its recalcitrance for producing commercially viable outputs, e.g. digestate replacing chemical fertilisers, compost improving soil and ‘dirty’ plastics replacing virgin plastics. Techno-configurations and material flows have been scaled towards global goods, distant from the feedstock source. Through the ecomodernist framework, the state’s responsibility for such outcomes has been blurred with the private sector and shifted to anonymous markets.

Green initiative in Suranaree University of Technology in Thailand

Suranaree University of Technology (SUT) has participated in the Universitas Indonesia (UI) GreenMetric World University Rankings since 2013. It attempts to pursue campus sustainability programs and policies. The rankings is broadly based on the frameworks of environment, economy, and equity. The measurement criteria are divided into six categories with different point weighting i.e. setting and infrastructure, energy and climate change, waste, water, transportation, and education. These criteria heavily and directly involve the tasks and responsibilities of SUT's the Division of Buildings and Ground. A lot of environmental challenges in civil engineering and infrastructure works need to be achieved. The results of this year self-assessment show that although the university is in the developing stage, it can preserve both natural and planted forests more than 90%. It takes seriously role in green initiative by contributing 30% of total budget on sustainable efforts each year. It receives four national awards in the recognition of energy conservation initiative for green buildings. The university establishes the Integrated Solid Waste Management Plant (ISWM Plant) based on mechanical and biological treatment (MBT) which turns general wastes into valuable and sellable refuse-derived fuel (RDF). Moreover, these sustainable movements are in the continuous improvement process.

Study and assessment of segregated biowaste composting: The case study of Attica municipalities

This work aims to assess the operation of the first large scale segregated biowaste composting scheme in Greece to divert Household Food Waste (HFW) from landfill and produce a material which can be recovered and used as compost. The source separation and collection of HFW was deployed in selected areas in Attica Region serving about 3700 households. Sorted HFW is collected & transported to the Mechanical and Biological Treatment (MBT) plant in Attica Region that has been designed to produce Compost Like Output (CLO) from mixed MSW. The MBT facility has been adjusted in order to receive and treat aerobically HFW mixed with shredded green waste in a dedicated composting tunnel.The composting process was monitored against temperature, moisture and oxygen content indicating that the biological conditions are sufficiently developed. The product quality was examined and assessed against the quality specifications of EU End of Waste Criteria for biowaste subjected to composting aiming to specify whether the HFW that has undergone recovery ceases to be waste and can be classified as compost. More specifically, the heavy metals concentrations (Cr, Cu, Ni, Cd, Pb, Zn and Hg) are within the set limits and much lower compared to the CLO material that currently is being produced at the MBT plant. In regard to the hygienic requirements of the product it has been found that the process conditions result in a pathogen free material (i.e. E. Coli and Salmonella) which does not favor the growth of viable weeds and plant propagules, while it acquires sufficient organic matter content for soil fertilization. Noticeable physical impurities (mainly fractions of glass) have been detected exceeding the quality control threshold limit of 0.5% w/w (plastics, metals and glass). The latter is related to the missorted materials and to the limited pre-treatment configurations prior to composting.The above findings indicate that effective source separation of biowaste is prerequisite for good quality production and marketing of compost and special consideration should be made to minimize glass impurities prior composting (i.e. awareness raising and pretreatment stage). Therefore, it is feasible to gradually replace the production of questionable quality CLO in MBTs with biowaste compost which is in line with the required quality control standards especially when heavy metals concentrations is concerned.

Refuse recovered biomass fuel from municipal solid waste. A life cycle assessment

Waste disposal is a controversial issue in many European countries: concerns about potential health effects and land value loss as well as the fulfillment of the European Landfill Directive and Waste Framework Directive have significantly changed the way waste should be managed. An appropriate management of municipal solid waste (MSW) may allow a significant enhancement of efficiency in resources use, by recovering both energy and materials from waste, otherwise landfilled, thus replacing fossil fuels and virgin materials with renewable sources. Separation and recovery of the biodegradable fraction of municipal solid waste is encouraged as a mean to produce bioenergy. Therefore, if not source segregated, innovative waste refining technologies may provide potential solutions for separation of organic fraction and improved energy and materials recovery.This paper presents a comprehensive system study of a recently developed technology aimed to improve the MSW management in order to decrease the demand for new landfill space and, at the same time, contribute to the urban energy needs. As part of a wider Life Plus Project entitled MARSS (Material Advanced Recovery Sustainable Systems), funded by European Community in 2012, the environmental assessment of an innovative and enhanced mechanical and biological treatment (MBT) demo plant installed in Mertesdorf (Germany) was performed by means of the SimaPro 8.0.5 LCA software, utilizing ReCiPe (H) Midpoint method for the impact assessment. The plant under study is designed to concentrate the biodegradable part of MSW in the <40mm fraction, through a series of refining and recovery steps, to remove contaminants and obtain a suitable biomass fuel with a final marketable quality fulfilling the requirements for biomass power plants to generate urban decentralized production of heat and power (CHP). This study aims at understanding if and to what extent the MBT-MARSS plant is environmentally sound, by investigating environmental costs and benefits of replacing MSW landfilling and waste-to-energy disposal by means of boosted separation of biomass for energy generation in CHPs and other recoverable fractions (metals, plastic). Steps and/or components that can be further improved are also assessed. Sensitivity of impacts to assumptions regarding the source of replaced electricity was also tested. Results not only emphasize the novelty of a promising new technology, but also the extent of benefits that can be achieved depending on the actual power generation technique that is replaced by means of the energy recovered in the process. The quantitative evaluation of the MARSS technology shows that appropriate design and management of the MBT plant lead to substantial reduction of environmental impacts as well as material and energy resource savings, thus putting forward a technical solution suitable for those cities/countries where other solutions are still lacking or inappropriate or unfeasible.

Comparison of the organic waste management systems in the Danish–German border region using life cycle assessment (LCA)

This study assessed the management of the organic household waste in the Danish–German border region and points out major differences between the systems and their potential effects on the environment using life cycle assessment (LCA). The treatment of organic waste from households in the Danish–German border region is very different on each side of the border; the Danish region only uses incineration for the treatment of organic household waste while the German region includes combined biogas production and composting, mechanical and biological treatment (MBT) and incineration. Data on all parts of the organic waste treatment was collected including waste composition data and data from treatment facilities and their respective energy systems. Based on that the organic waste management systems in the border region were modelled using the EASETECH waste management LCA-model. The main output is a life cycle assessment showing large differences in the environmental performance of the two different regions with the Danish region performing better in 10 out of 14 impact categories. Furthermore, the importance of the substituted district heating systems was investigated showing an impact up to 34% of the entire system for one impact category and showing large difference between each heating system substituted, e.g. in ”Global Warming” the impact was from −16 to −1.1 milli person equivalent/tonne treated waste from substitution of centralised hard coal and decentralised natural gas, respectively.

Recovery of glass from the inert fraction refused by MBT plants in a pilot plant

Selective collection is a common practice in many countries. However, even in some of those countries there are recyclable materials, like packaging glass, erroneously deposited in the Mixed Municipal Solid Waste (MMSW). In the present paper, a solution is proposed to recover glass from the inert reject of Mechanical and Biological Treatment (MBT) plants treating MMSW aiming at its recycling. The inert reject of MBT (MBTr) plants is characterized by its small particle size and high heterogeneity. The study was made with three real samples of diverse characteristics superimposed mainly by the different upstream MBT. One of the samples (VN) had a high content in organics (approximately 50%) and a particle size smaller than 16mm. The other two were coarser and exhibited similar particle size distribution but one (RE) was rich in glass (almost 70%) while the other (SD) contained about 40% in glass. A flowsheet was developed integrating drying, to eliminate moisture related with organic matter contamination; magnetic separation, to separate remaining small ferrous particles; vacuum suction, to eliminate light materials; screening, to eliminate the finer fraction that has a insignificant content in glass, and to classify the >6mm fraction in 6–16mm and >16mm fractions to be processed separately; separation by particle shape, in the RecGlass equipment specifically designed to eliminate stones; and optical sorting, to eliminate opaque materials. A pilot plant was built and the tests were conducted with the three samples separately. With all samples, it was possible to attain approximately 99% content in glass in the glass products, but the recovery of glass was related with the feed particle size. The finer the feed was, the lower the percentage of glass recovered in the glass product. The results show that each one of the separation processes was needed for product enrichment. The organic matter recovered in the glass product was high, ranging from 0.76% to 1.13%, showing that drying was not sufficient in the tests but that it is a key process for the success of the operation.

Influence of input material and operational performance on the physical and chemical properties of MSW compost

Certain controversy exists about the use of compost from MSW (municipal solid waste) and, specifically, from the organic fraction of MSW that has not been separated at the source. In this case, the final composition of MSW compost is related to the performance of the separation process in MBT (Mechanical and Biological Treatment) plants as well as the composition of raw materials and the particular features of composting systems. In an effort to investigate the quality of MSW compost, 30 samples of this product obtained from 10 different MBT plants were studied. The main physical and chemical properties were analyzed and were compared with the requirements of current legislation. The composting systems used to produce these compost samples were studied and the input materials were characterized. The results reveal that the heavy metal content in MSW compost was below the legal restrictions in all samples but one; however, in most of them the percentage of Pb was high. The fertilizing potential of MSW compost has been demonstrated by its high nutrient concentrations, particularly N, K, P, Ca and Mg. Nevertheless, here the percentage of inert impurities with a size larger than 2 mm, such as plastic or glass, was seen to be excessively high exceeding in some cases the legal limit. The source of such pollution lies in the composting inputs, OFMSW (organic fraction of MSW), which showed high percentages of improper materials such as plastic (9%) or glass (11%). Accordingly, the performance of the sorting stage for the collection of the raw material must be improved, as must the refining process, since this does not remove the necessary amounts of these impurities from the final compost.

Packaging glass contained in the heavy residual fraction refused by Portuguese Mechanical and Biological Treatment plants

Mechanical and Biological Treatment (MBT) is an important strategy to manage Municipal Solid Waste (MSW) in Europe. The presence of recyclable materials on MSW depends on different factors such as inefficiencies in the Municipal Solid Waste collecting schemes and to the low level of citizenship environmental education. Among other products, MBT plants produce a residual fraction, named here as heavy residual fraction, that contains a significant amount of packaging glass which in Portugal is currently landfilled. This material is not recycled because it is heavily contaminated with other materials, preventing its processing in Material Recovery Facilities (MRF).In this paper the characterization, including particle size and composition, of the residual fraction of six Portuguese MBT plants is presented. The relevant variables that determine the heavy residual fraction characteristics were identified. It was observed that the MBTr particle size distribution is different and depends mainly on the place on the flowsheet where the MBTr exits the process, which is determined by the type of biological process and by the aperture of the last screen where the product passes through. The content in glass varies from 33 to 83%. These values are mainly related with the upstream glass sorting and with the efficiency of the recovery of the organic fraction which is the glass main contaminant. The second main contaminant is “stones”.The quantity of glass contained in this product in all the plants that will be in operation in Portugal in 2014 was estimated. The work shows that if all the 48,000 of glass could be recovered the Portuguese recycling rate would increase by 4.4%.

The effect of different pretreatments on biomethanation kinetics of industrial Organic Fraction of Municipal Solid Wastes (OFMSW)

This paper studies the effect of both thermochemical (under different pressures, temperatures and alkaline agent dosage) and biological (using mature compost, sludge and the fungus Aspergillus awamori) pretreatments on the kinetic of dry-thermophilic (20% Total Solids and 55°C) anaerobic digestion of industrial organic fraction of the municipal solid wastes (OFMSW).Municipal solid waste, which was not collected separately, from an industrial 30mm-trommel placed in a Mechanical and Biological Treatment (MBT) plant was used in this study.The kinetic equations for substrate-utilization and product-generation from Romero's model (1991) have been used to characterize process kinetics and determine the effect of pretreatments on kinetic parameters. The results obtained in this study indicate than the best pretreatment is precomposting, since an increase of the microorganism's maximum specific growth rate (μmax) between 160 and 205%, with respect to non-pretreated OFMSW, can be achieved.

Reliability-based life cycle assessment for future solid waste management alternatives in Portugal

This paper presents a study related to the application of the reliability-based life cycle assessment (LCA) to assess different alternatives for solid waste management in the Setubal peninsula, Portugal. The current system includes waste collection, transport, sorting, recycling, and mechanical and biological treatment (MBT) by means of aerobic treatment and landfill. In addition, some future expansion plans are discussed. The proposed 18 alternatives were examined with respect to six impact categories based on a customized life cycle inventory (LCI). All the alternatives are designed to comply with the targets prescribed in the Packaging and Packaging Waste Directive and the Landfill Directive. These 18 alternatives were eventually assessed by using the reliability-based LCA methodology with respect to some uncertain parameters and scenarios. The results show that solutions based on anaerobic digestion at the MBT followed by energy recovery are the most advantageous options. Overall, recycling may help to avoid most environmental impacts. Alternatives which treat massively biodegradable municipal waste are also competitive. In addition to the recycling options, electricity production is also an influential determinant which affects the results. The uncertainty analysis focused on testing different energy-from-waste options (like landfill and MBT biogas electricity production) and different recycling substitution ratios. Such a quantitative analysis is proved effective to confirm the reliability of the LCI in the study. In order to improve the sustainability of the solid waste management (SWM) system, final suggestions may concentrate on the closure of aerobic MBT, the enhancement of anaerobic digestion MBT treatment, and the maximization of energy recovery from high calorific fractions of the waste streams. However, the option of stabilized residue applications cannot be encouraged at this stage, especially due to the absence of Portuguese regulations to control the quality of organic products issuing from biological treatment units.

Thermal waste treatment for sustainable energy

Waste disposal, energy production and pollution minimisation are key problems that must be addressed for sustainable cities of the future. In a world with finite resources witnessing a population explosion, much effort is being made to change the way in which developed societies consume energy and materials and dispose of waste. This paper reviews the current UK practices of segregation and treatment of municipal solid waste (MSW) with focus on advanced thermal treatment technologies. MSW is segregated either at source or at dedicated facilities across the country. The residues of waste segregation can be thermally treated for energy recovery. Direct incineration of unsorted waste is currently the main route practiced by the energy from waste (EfW) industry. Typical MSW incinerators can burn wastes with a wide range of calorific values without any waste pre-processing. However, these incineration systems have low energy efficiency and suffer from unfavourable public opinion. Consequently, gas clean-up technologies associated with waste incinerators have been developed further, especially for dioxin removal and fly ash treatment. The two main alternatives to incineration are gasification of pre-processed waste and production of solid recovered fuel (SRF) from mechanical and biological treatment (MBT). Both processes have potentially higher energy efficiencies than incineration and more flexibility in the use of primary products. Further technology developments with regulatory drivers are required to compete with incineration. Another route available for EfW is pyrolysis, producing cheap and storable fuel products. Pyrolysis is suitable only for specific types of waste material. Pyrolysis of waste wood can produce a good-quality char that can be readily burned in coal-fired power plants or other higher energy efficiency thermal systems.

Aerobic digestion of municipal solid waste in Durham, UK

An in-vessel aerobic digestion plant has been in operation at the Thornley waste transfer station in County Durham, UK, since January 2002. Until recently the plant consisted of two aerobic digestion towers with a total capacity in excess of 30 000 t per annum; it processes unsegregated municipal solid waste (MSW) resulting in a diversion rate of over 70% of its input weight from landfill. This type of process is commonly referred to as mechanical and biological treatment (MBT) and is attracting significant interest from local authorities as an alternative to mass burn incineration and landfill disposal. In contrast to some other MBT systems, this system is configured to optimise conditions for maximum degradation of the biodegradable components of MSW commonly referred to as biodegradable municipal waste (BMW). While the current plant has been in operation for 4·5 years, assistance was sought from the UK Department for Environment, Food and Rural Affairs under the New Technologies Demonstrator Programme to support additional research and development with the aim of enhancing the process.

Odour emission factors for the prediction of odour emissions from plants for the mechanical and biological treatment of MSW

In this study, the results of odour concentration measurements sampled from the principal odour sources of 40 dimensionally different and representative Italian waste mechanical and biological treatment (MBT) plants are presented. Experimental data are then used to estimate the odour emission factors (OEFs) relevant to single-process steps. An OEF is a representative value that relates the quantity of odour released to the atmosphere to a specific activity index, which may be for example the waste treatment capacity, the gross weight production, the site surface or a time unit. In this study, the OEFs were calculated as a function of the plant capacity, and expressed in ou E t −1, because of the existence of a proportionality between plant capacity and odour emissions. The results show that the major odour source of a waste MBT plant is represented by the aerobic biological treatment (with an OEF equal to 1.40×10 8 ou E t −1). In general, the OEFs calculated according to this approach represent a model for a rough prediction of odour emissions independently from the specific characteristics of the different plants.