Solid Recovered Fuel Production Research Articles

Environmental Assessment of Solid Recovered Fuel Production from Screening Waste Using a Life Cycle Assessment Approach

The circular economy, as a new model of waste management through energy self-sufficiency and valorisation, can be applied to wastewater treatment plants (WWTPs). Screening waste from WWTP pretreatment is the only waste that is not energetically recovered and thus constrains the achievement of zero waste. Previous studies demonstrated the technical feasibility of producing solid recovered fuel (SRF) from this waste. Environmental benefits, including waste reduction, resource conservation, or reduced greenhouse gas emissions are analysed in this work. Environmental impact is quantified using the life cycle assessment (LCA) methodology through the SimaPro 9.2. software and the CML-IA baseline v3.08 impact methodology, that propose 11 impact categories. Five scenarios were established to compare current landfill disposal with the production of densified and non-densified SRF using solar and thermal drying. Within the system boundaries studied, from waste generation to SRF production, results show that landfill is the most environmentally damaging option while producing non-densified SRF using solar drying is the most environmentally viable scenario.

Potential of solid recovered fuel production from autoclave treated healthcare waste in Sultanate of Oman

ABSTRACT Economic growth has a potential impact on waste generation worldwide. Growing recognition for resources recovery from waste including production of a clean energy has led to the development of standards for, and the generation of, Solid Recovered Fuel (SRF). SRF, according to BS EN ISO 21640 is a fuel prepared from nonhazardous/treated waste to be utilized for energy recovery in incineration or co-incineration plants which meets the classification and specification. The amount of combustible fractions (i.e., plastic, textile and paper) that are present in Healthcare Waste (HCW) and Municipal Solid Waste (MSW) provides an opportunity for SRF production. HCW is defined as clinical waste generated from healthcare facilities. Limited efforts in utilizing treated HCW in production of SRF were noted, despite the fact that high content of combustible fractions, hence the novelty of this research. This research addresses the opportunities of utilizing autoclaved HCW as an alternate fuel; through a detailed chemical and physical analysis of autoclaved HCW collected from the Sultanate of Oman hospital and healthcare facilities. Furthermore, this study examines the possible uses of such materials instead of landfilling. The utilization of treated HCW as an alternative fuel is not only saving the land space, but also reduces the carbon emissions originating from landfilling. This in fact would also support the government in achieving its aspiring goal of the net zero carbon emissions by 2050 through better utilization of these materials in production of SRF as an alternative to fossil fuel combustion. The study revealed that autoclaved HCW appears to have a high quality SRF and is classified as (NCV 4, Cl 3); which complies with the potential end users’ specifications. It is estimated that the combined energy output from MSW and HCW combustible fractions could cover about 12.75% of the energy requirements for Oman cement factories. Implications: The results confirm the viability of using autoclave (HCW) as an alternative fuel due to its high thermal energy content. Based on mean Net Calorific Value (NCV) of analyzed HCW that is found around 14 (MJ/Kg (ar)), and the mean Cl level (i.e., 0.814 ± 0.213% (d)); the SRF is classified as (NCV4, Cl 3). This grade is found to be well within the end users accepted range. This opens up the opportunity for creating a market demand for HCW that not only it could boost its recovery, but it could also unlock the value that can generates.

When solid recovered fuel (SRF) production and consumption maximize environmental benefits? A life cycle assessment

Solid recovered fuel (SRF) from non-recyclable waste obtained from source separation and mechanical treatments can replace carbon coke in cement plants, contributing to the carbon neutrality. A life cycle assessment (LCA) of the SRF production from non-recyclable and selected waste was conducted in an Italian mechanical treatment plant to estimate the potential environmental impacts per ton of SRF produced. The analysis would contribute to evaluate the benefits that can be obtained due to coke substitution in best- and worst-case scenarios. The avoided impacts achieved were assessed, together with an evaluation of the variables that can affect the environmental benefits: SRF biogenic carbon content (in percentage of paper and cardboard); transportation distances travelled from the treatment plant to the cement kiln; the renewable energy used in the mechanical facility. On average, about 35.6 kgCO2-eq are generated by the SRF transportation and production phase. These impacts are greatly compensated by coke substitution, obtaining a net value of about −1.1 tCO2-eq avoided per ton of SRF. On balance, the global warming potential due to SRF production and consumption ranges from about −542 kgCO2-eq to about −1729 kgCO2-eq. The research recommended the use of SRF to substitute coke in cement kilns also in low densely-populated areas to mitigate environmental impacts and achieve carbon neutrality at a global level.

Analysing the Sustainability of the Production of Solid Recovered Fuel from Screening Waste

The development in wastewater management has caused a shift towards a circular model that prioritises energy generation and waste reduction. Traditional unitary processes in wastewater treatment, such as screening, only allow for landfill disposal without energy recovery. However, producing solid recovered fuel (SRF) from waste screening may be a possibility. The economic and environmental viability of this alternative, as a fundamental requirement for its implementation at industrial level, was assessed through a multi-scenario analysis using Monte Carlo simulation. The cost and benefit streams were determined based on the financial net present value (NPVf) and the social net present value (NPVs), including monetised CO2 emissions generated. The results showed that waste drying costs were found to be the most significant ones, with thermal drying being more financially advantageous than solar drying. The densification of SRF raises the costs by 7.88 to 8.48%, but its use as fuel would likely be profitable due to the economic benefits it provides. Current landfill disposal practices, which have an NPVs of −1052.60 EUR/t, are not a feasible, particularly when compared to the other SRF production scenarios, with maximum NPVs of −53.91 EUR/t. SRF production without densification using solar drying is the most acceptable scenario with the lowest NPVs (38.39 EUR/t).

Proposal for Implementation of Extraction Mechanism of Raw Materials during Landfill Mining and Its Application in Alternative Fuel Production

New approaches to waste management and the demands of the circular economy have changed the management of landfills. Over time, the decomposition of buried waste primarily determines the amount of recyclable and combustible materials. This pilot study attempted to assess the feasibility of extracting and recovering energy-intensive raw materials from landfills by developing a waste extraction mechanism and creating a solid recovered fuel (SRF) production line for use as a replacement fuel in the cement industry. The proposed mechanism consisted of two stages. The first stage was recommended to be carried out on the landfill territory by screening out the fine fraction and extracting inert materials and bulky waste. The second stage should be on the mechanical biological treatment (MBT) plant’s territory by adding additional technological equipment to the MBT line. The productivity of the SRF production line was calculated and was 4.9 t/h. The mechanism proposed in the work was tested at the operating test site in Lithuania. The composition of Landfill Mined Residues (LMRs) was studied, and the energy potential of the studied part of the landfill was calculated, which was 196,700 GJ. It has been found that the SRF produced complies with the European Union (EU) standard and, according to its classification characteristics, belongs to class III and can be used as a replacement fuel in the clinker firing process. An environmental and economic efficiency assessment was conducted using SRF in the cement kiln. The calculation result showed that using 10% SRF as a replacement fuel for coal used in clinker firing at 2.51 t/h would save 1274 USD/h in coal costs. This use of SRF will emit 3.64 t/h CO2 and achieve a net savings of 1355 USD/h. The mechanism proposed in this work aimed at reducing waste in landfills by converting materials into energy resources will help achieve the circular economy’s goals.

Specification and Classification of Pelletised Dried Sewage Sludge: Identifying Its Key Properties as a Renewable Material for Enabling Environmentally Non-Harmful Energy Utilisation

Renewable active sludge is a smart material for wastewater treatment and the protection of surface water bodies. The generated pellets (dried and pelletised dehydrated anaerobically stabilised excess sludge) are produced in a quantity of 31.4 ± 5.6 g dry matter (DM) per one Population equivalent (PE) calculated to COD (PECOD) in one day. As pellets are combustible material, their energy utilisation must reach the sustainable development goals (SDGs)—a bridge must be created between “treated sewage sludge as the tool to remove pollutants and nutrients from wastewater” and “preparation of the valuable material as a solid recovered fuel (SRF) that meets customer-specific requirements”. Technical Report CEN/TR 15508 and Technical Standard EN ISO 21640 set up methods for specifying and classifying pellets as an SRF. In the last eleven years (2010–2021), pellets’ net calorific value (NCV) is 13.0 ± 0.7 MJ kg−1 as received (ar). In 2021, the 80th percentile of the Hg/NCV ratio was 0.079 mg Hg MJ−1. In 2010–2021, the annual amount of Hg transferred to stakeholders reduced by 64.3% m/m—from 10.1 kg to 3.67 kg. The halogen contents of the pellets do not threaten corrosion to the incineration facility. Stable pellets’ energy potential and perspective ash composition for critical raw materials recovery qualify pellets as a specific waste stream and a renewable material for SRF production.

Development of technological line for solid recovered fuel production and its utilization in the cement industry: the case study of Lithuania

This experimental research was purposed to investigate the production and energy potential of solid recovered fuel (SRF), obtained by extraction of prohibited materials, shredding and drying, from refuse-derived fuel (RDF) to use as an alternative fuel in the cement industry of Lithuania. The characteristics of the obtained RDF by separating the biological fraction from the mainstream of municipal solid waste (MSW) have been determined and compared with the criteria set by developing countries. According to EN15359, currently available RDF can't be called SRF and used as an alternative fuel in a cement kiln. The SRF production line by adding six additional technological units to the existing MBT line was developed. The calculation of the SRF production line was carried out and made 1.89 t/h. At the end of the production process of SRF from RDF, the moisture content (MC) of the obtained SRF decreased by 90 %. After the drying stage, the volume of SRF decreased by 19 %. The process of preparing SRF allowed increasing the net calorific value (NCV) by 22.1 % to 28.2 MJ/kg by reducing the MC. The obtained SRF had a high NCV, low MC, permissible Cl and Hg contents. Two scenarios of waste generation in the Alytus region until 2030 have been developed. Based on the waste generation scenarios results, the proposed SRF production line will provide 12 % of the additional fuel for clinker firing during the analyzed period. A cost analysis to assess the economic and environmental savings from the use of SRF was performed. The results showed that adding 12 % of SRF as a replacement fuel, equal to 1.86 t/h, to the coal used in the cement kiln would save 860 USD/h in coal costs. At the same time, it will emit 5.96 t/h of CO2 into the atmosphere, and the net savings will amount to 1,131 USD/h.

Real-time monitoring of volume flow, mass flow and shredder power consumption in mixed solid waste processing

Real-time material flow monitoring is not yet implemented in mixed solid waste processing, but it is important for an efficient quality assured production and the development of the smart waste factory. The present paper shows results of practical investigation of the Real-Time Material Flow Monitoring in a large-scale Solid Recovered Fuel (SRF) production plant and a semi large-scale processing line (Technical line 4.0) using mixed solid waste. The investigations aimed to research the fundamentals for generating mass flow data from volume flow data and volume and mass flow data from shredder power consumption. It could be shown that a mass determination from volume flow data with the help of density determinations can be practically realized in a good approximation (deviation < 1%) to the gravimetrically determined mass in an SRF production plant. With R2 = 0.47, the power consumption of a shredder in the SRF plant shows a low to medium correlation to the corresponding volume flow. In the 31 tests with the Technical Line 4.0, both, the mass flow and the volume flow could be measured in real-time. Combining these data results in the temporal density curve and shows strong fluctuations for shredded commercial waste. Comparing the mean bulk densities for each test with those from the density determinations of taken samples shows a robust correlation (R2 = 0.82). Analyzes of the material composition of the shredded mixed solid waste show strong correlations to bulk density for the proportions of the fractions rest (positive correlation) and plastics (negative correlation).

Production of contaminant-depleted solid recovered fuel from mixed commercial waste for co-processing in the cement industry

Solid recovered fuels (SRF) have increasingly substituted primary fuels in the cement industry, even up to 100%. However, contaminants originating from the discarded consumer products are transferred into waste and SRF. With increasing amounts of SRF being utilized, closely monitoring contaminant concentrations – as is already state of the art in several countries and the cement industry – is gaining importance. SRF producers may need to take measures assuring that quality criteria are met, contaminant concentrations are kept at a low level, or to produce contaminant-depleted SRF. This work investigates and discusses the potential measures to reduce contaminant concentrations: removing the fine fractions, polyethylene terephthalate (PET), polyvinyl chloride (PVC), and black&grey materials. Five streams of mixed commercial waste were coarsely comminuted, screened, PET and PVC were removed using an industrial near-infrared sorter, and black&grey materials were manually removed and further sorted by fourier-transform infrared spectroscopy. Concentrations of Ag, Al, As, Ba, Ca, Cd, Cl, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Sb, Si, Sn, Sr, Ti, V, W, and Zn in the fractions are reported, and the effect of single and combined measures is presented. Results show that black&grey materials contain significant shares of the total Sb, Cl, and Co in the waste stream. Furthermore, the concentration of several contaminants is increased when only PET and PVC is removed. Removing the fine fraction together with PVC can lead to a concentration decrease of all investigated analytes, enabling the production of a contaminant-depleted SRF.

Climate Neutral Waste Management Оptions

A methodology for the ecological assessment of technologies for municipal solid waste (MSW) processing and solid recovered fuel (SRF) production is proposed, including calculations of direct, indirect and prevented greenhouse gas emissions at all stages of waste management, taking into account the composition of the waste, the properties of the individual components of the MSW and the characteristics of used equipment. The elemental balance of fossil and biogenic carbon was calculated for MSW management system. It is concluded that MSW processing with recyclables recovery and SRF production can reduce greenhouse gases release from 5.8 to 67.6 % with respect to waste disposal at the MSW landfill.

Influence of input waste feedstock on solid recovered fuel production in a mechanical treatment plant

In solid recovered fuel (SRF) production, type and nature of input waste stream influences the quality of fuel product. This paper presents the influence of input waste stream on SRF production in a mechanical treatment (MT) plant. The SRF was produced at industrial scale from three different types of waste streams: commercial and industrial waste (C&IW), construction and demolition waste (C&DW) and municipal solid waste (MSW). Here, the stream of MSW used for SRF production was energy waste collected from households. In the SRF production from MSW, higher yields of material were recovered in the form of SRF as compared with that of recovered from C&IW and C&DW. Of the input MSW to the MT plant, 72wt% was recovered as SRF, equivalent to 86% energy recovery. The energy consumed to produce unit tonne of SRF from C&IW, C&DW and MSW was 1153MJ, 1246MJ and 1626MJ, respectively. In the SRF production, removal of chlorine (Cl), lead (Pb) and mercury (Hg) from C&IW feedstock was worse than from C&DW and MSW feedstocks. In the SRF production from C&IW, of the input mass of chlorine, lead and mercury to the MT process 60%, 58% and 45%, respectively was found in the SRF. The SRF produced from C&DW contained the lowest mass fraction of the input chlorine, lead and mercury in comparison with the SRF produced from C&IW and MSW, namely 34%, 8% and 30%, respectively. Among the waste components rubber, plastic (hard) and textile (synthetic) were identified as potential sources of polluting and toxic elements, whereas wood, paper & cardboard and plastic (soft) were found to contain the lowest content of polluting and toxic elements. The pollutant and toxic elements investigated in this research work were chlorine, lead, cadmium, mercury and arsenic.

ASSESSMENT OF THE POTENTIAL RISKS OF AIRBONE MICROBIAL CONTAMINATION IN SOLID RECOVERED FUEL PLANTS: A CASE STUDY IN ISTANBUL

In this pilot study, exposure to airborne microorganisms in solid recovered fuel (SRF) plants has been measured. Different steps in SRF production processes such as separation and size reduction can cause generation of airborne microorganisms. Exposure to these biological agents can cause some health problems, so their levels should be measured to assess the potential risks. Therefore, exposure to airborne total bacteria, Gram-negative bacteria, actinomycetes and fungi were measured in the running SRF plant. Sample locations were chosen considering work areas and wind direction in the plant. Airborne microorganisms were collected via AES Sampl air Lite on particular agar plates and incubated for microorganism growth. No thermophilic actinomycetes were obtained from the samples. The measured concentrations of mesophilic heterotrophic bacteria were almost similar at each point throughout the SRF plant (ranged from 920 to 1750 CFU/m ) except the spare waste stock area (427 CFU/m ) and the monitoring room (ranged from 420 to 770 CFU/m3). The highest concentrations were measured near the preshredder (1750 CFU/m ) and in the manual sorting unit (1610 CFU/m ). However, the concentrations of Gram-negative bacteria varied at each point (28 to 700 CFU/m ). Fungi concentrations varied from 280 to 1750 CFU/m and were high near the sorting unit, the ballistic separator, the fine shredder, the end-product stock area and the monitoring room (1750 CFU/m ). The concentrations of mesophilic heterotrophic bacteria, Gram-negative bacteria and fungi did not exceed the recommended limit values.

Mobile Platform of SRF Production and Electricity and Heat Generation

The technological frontier is ripe for action on the cycle of municipal waste at local level through the optimization of existing treatment processes, adapting to European Union directives. The study concerns the analysis of the waste cycle in order to rationalize the current paths of the waste by adapting to EU directives, with a view of the entire supply chain - from the delivery to the energy production (WtE, Waste to Energy) – with a intermediate stage of SRF (Solid Recovered Fuel) production. The DIMA has developed an innovative platform for MSW treatment (unsorted and not), based on newly developed technologies that enables its weight and volume reduction and the transformation in SRF high quality, by achieving consistent chemical-physical and particle size parameters through the innovative technology of mechanochemical micronization. This standardized fuel product is therefore suitable for energy recovery within the platform using the most advanced gasification process. The study aims at developing a mobile demonstration plant of 100-200 kWe for energy recovery from waste in cogeneration by conversion of MSW into SRF through a system of characterization, treatment and recycling based on a highly innovative mechanochemical refining system. The SRF is enhanced through more advanced gasification process and it can used for the production of electricity and thermal energy. The production, the gasification and the syngas combustion take place in modular units arranged in appropriate mobile units (containers) appropriately configured, to fully meet the objectives of a sustainable policy management and security of waste. b Unit 1 (waste treater - SRF producer) is developed to operate the transformation of industrial waste in SRF for subsequent gasification inside unit 2 (Boiler Gasifier). It carries out a pre-treatment and mechanochemical micronization waste treatment. The SRF is reduced into pellets to be introduced into the 2 (boiler gasifier) to its gasification (syngas production). The pellet (auxiliary unit 4, pellettizer) is gasified in the unit 2 and enriched in order to obtain synmethan gas for producing electricity in the cogeneration unit 3 (energies production).

Elemental balance of SRF production process: solid recovered fuel produced from municipal solid waste.

In the production of solid recovered fuel (SRF), certain waste components have excessive influence on the quality of product. The proportion of rubber, plastic (hard) and certain textiles was found to be critical as to the elemental quality of SRF. The mass flow of rubber, plastic (hard) and textiles (to certain extent, especially synthetic textile) components from input waste stream into the output streams of SRF production was found to play the decisive role in defining the elemental quality of SRF. This paper presents the mass flow of polluting and potentially toxic elements (PTEs) in SRF production. The SRF was produced from municipal solid waste (MSW) through mechanical treatment (MT). The results showed that of the total input chlorine content to process, 55% was found in the SRF and 30% in reject material. Of the total input arsenic content, 30% was found in the SRF and 45% in fine fraction. In case of cadmium, lead and mercury, of their total input content to the process, 62%, 38% and 30%, respectively, was found in the SRF. Among the components of MSW, rubber material was identified as potential source of chlorine, containing 8.0 wt.% of chlorine. Plastic (hard) and textile components contained 1.6 and 1.1. wt.% of chlorine, respectively. Plastic (hard) contained higher lead and cadmium content compared with other waste components, i.e. 500 mg kg(-1) and 9.0 mg kg(-1), respectively.

Use of MRF residue as alternative fuel in cement production

Single-stream recycling has helped divert millions of metric tons of waste from landfills in the U.S., where recycling rates for municipal solid waste are currently over 30%. However, material recovery facilities (MRFs) that sort the municipal recycled streams do not recover 100% of the incoming material. Consequently, they landfill between 5% and 15% of total processed material as residue. This residue is primarily composed of high-energy-content non-recycled plastics and fiber. One possible end-of-life solution for these energy-dense materials is to process the residue into Solid Recovered Fuel (SRF) that can be used as an alternative energy resource capable of replacing or supplementing fuel resources such as coal, natural gas, petroleum coke, or biomass in many industrial and power production processes. This report addresses the energetic and environmental benefits and trade-offs of converting non-recycled post-consumer plastics and fiber derived from MRF residue streams into SRF for use in a cement kiln.An experimental test burn of 118Mg of SRF in the precalciner portion of the cement kiln was conducted. The SRF was a blend of 60% MRF residue and 40% post-industrial waste products producing an estimated 60% plastic and 40% fibrous material mixture. The SRF was fed into the kiln at 0.9Mg/h for 24h and then 1.8Mg/h for the following 48h. The emissions data recorded in the experimental test burn were used to perform the life-cycle analysis portion of this study.The analysis included the following steps: transportation, landfill, processing and fuel combustion at the cement kiln. The energy use and emissions at each step is tracked for the two cases: (1) The Reference Case, where MRF residue is disposed of in a landfill and the cement kiln uses coal as its fuel source, and (2) The SRF Case, in which MRF residue is processed into SRF and used to offset some portion of coal use at the cement kiln.The experimental test burn and accompanying analysis indicate that using MRF residue to produce SRF for use in cement kilns is likely an advantageous alternative to disposal of the residue in landfills. The use of SRF can offset fossil fuel use, reduce CO2 emissions, and divert energy-dense materials away from landfills. For this test-case, the use of SRF offset between 7700 and 8700Mg of coal use, reduced CO2 emissions by at least 1.4%, and diverted over 7950Mg of energy-dense materials away from landfills. In addition, emissions were reduced by at least 19% for SO2, while NOX emissions increased by between 16% and 24%. Changes in emissions of particulate matter, mercury, hydrogen chloride, and total-hydrocarbons were all less than plus or minus 2.2%, however these emissions were not measured at the cement kiln. Co-location of MRFs, SRF production facilities, and landfills can increase the benefits of SRF use even further by reducing transportation requirements.

Elemental balance of SRF production process: Solid recovered fuel produced from construction and demolition waste

Quality of solid recovered fuel (SRF) demands that the waste components containing pollutant and potentially toxic elements (PTEs) and inert components are sorted out into separate small streams and to concentrate the suitable components into a prepared depolluted combustible fraction stream of SRF. In the SRF production, mass flow of waste components’ type into the output streams determine the quality of SRF. This paper presents the mass flow of pollutant and potentially toxic elements in full-scale SRF production. The SRF was produced from construction and demolition waste (C&DW) through mechanical treatment (MT). The input and output streams of SRF production were chemically characterised for the concentration of inorganic elements in details. The results showed that of the total input chlorine content to the process, 34% was found in SRF and 48% in reject material. Mercury (Hg) and arsenic (As) were found concentrated in fine fraction i.e. of the total input content of mercury and arsenic, 64% and 42% respectively was found in fine fraction. Most of the lead (Pb) was found in reject material and fine fraction i.e. of the total input lead content, 45% and 44% was found in reject material and fine fraction respectively. In case of cadmium (Cd), of the total input content of cadmium, 68% was found in SRF. Among the components of C&D waste, rubber and plastic (hard) were measured to contain higher chlorine (Cl) content i.e. 7.6wt.%, d. and 7.0wt.%, d. respectively. Plastic (hard) was measured to contain 880mg/kg, d. of lead (Pb) which was higher than measured in other components. Textile was measured to contain 12mg/kg, d. of arsenic (As) which was higher than measured in other components.

Elemental balance of SRF production process: Solid recovered fuel produced from commercial and industrial waste

In order to study the mass flow of pollutant and potentially toxic elements (PTEs) in the output streams of solid recovered fuel (SRF) production process, the various streams produced in commercial scale SRF production process are characterized chemically and, the elemental balance of SRF production process is presented. The SRF is produced from commercial and industrial waste (C&IW) through mechanical treatment (MT). The elements investigated for their mass balance in SRF production process are chlorine (Cl), arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg). The results showed that of the total input chlorine 60% was found in the SRF stream and 35% in the reject material stream and rest of 5% was in fine fraction and heavy fraction streams. Of the total input arsenic content 42% was found in the reject material and 32% in the SRF stream and rest (i.e. 26%) was found in the fine fraction stream. In case of cadmium, lead and mercury of their total input content to the process 46%, 58% and 45% respectively was found in the SRF stream. Among the waste components of C&IW, rubber and plastic (hard) were measured to contain the highest content of chlorine i.e. 8.0wt.% (dry basis) and 3.0wt.% (dry basis) respectively. Rubber was also found to contain higher content of cadmium as compared to other waste components. Plastic (hard) was measured to contain higher content of lead (i.e. 400mg/kg, dry basis) than other components of input waste stream. The distribution of waste components (mainly plastic (hard), rubber and to some extent textile) was found significantly more important than other components of input waste stream in defining the concentration of pollutant and potentially toxic elements in output streams of SRF production process.

Improving material and energy recovery from the sewage sludge and biomass residues

Sewage sludge management is a big problem all over the world because of its large quantities and harmful impact on the environment. Energy conversion through fermentation, compost production from treated sludge for agriculture, especially for growing energetic plants, and treated sludge use for soil remediation are widely used alternatives of sewage sludge management. Recently, in many EU countries the popularity of these methods has decreased due to the sewage sludge content (heavy metals, organic pollutions and other hazards materials). This paper presents research results where the possibility of solid recovered fuel (SRF) production from the separate fraction (10–40mm) of pre-composted materials – sewage sludge from municipal waste water treatment plant and biomass residues has been evaluated. The remaining fractions of pre-composted materials can be successfully used for compost or fertiliser production, as the concentration of heavy metals in the analysed composition is reduced in comparison with sewage sludge. During the experiment presented in this paper the volume of analysed biodegradable waste was reduced by 96%: about 20% of input biodegradable waste was recovered to SRF in the form of pellets with 14.25MJkg−1 of the net calorific value, about 23% were composted, the rest – evaporated and discharged in a wastewater. The methods of material-energy balances and comparison analysis of experiment data have been chosen for the environmental impact assessment of this biodegradable waste management alternative. Results of the efficiency of energy recovery from sewage sludge by SRF production and burning, comparison analysis with widely used bio-fuel–sawdust and conclusions made are presented.

Mass, energy and material balances of SRF production process. Part 2: SRF produced from construction and demolition waste

In this work, the fraction of construction and demolition waste (C&D waste) complicated and economically not feasible to sort out for recycling purposes is used to produce solid recovered fuel (SRF) through mechanical treatment (MT). The paper presents the mass, energy and material balances of this SRF production process. All the process streams (input and output) produced in MT waste sorting plant to produce SRF from C&D waste are sampled and treated according to CEN standard methods for SRF. Proximate and ultimate analysis of these streams is performed and their composition is determined. Based on this analysis and composition of process streams their mass, energy and material balances are established for SRF production process. By mass balance means the overall mass flow of input waste material stream in the various output streams and material balances mean the mass flow of components of input waste material stream (such as paper and cardboard, wood, plastic (soft), plastic (hard), textile and rubber) in the various output streams of SRF production process. The results from mass balance of SRF production process showed that of the total input C&D waste material to MT waste sorting plant, 44% was recovered in the form of SRF, 5% as ferrous metal, 1% as non-ferrous metal, and 28% was sorted out as fine fraction, 18% as reject material and 4% as heavy fraction. The energy balance of this SRF production process showed that of the total input energy content of C&D waste material to MT waste sorting plant, 74% was recovered in the form of SRF, 16% belonged to the reject material and rest 10% belonged to the streams of fine fraction and heavy fraction. From the material balances of this process, mass fractions of plastic (soft), paper and cardboard, wood and plastic (hard) recovered in the SRF stream were 84%, 82%, 72% and 68% respectively of their input masses to MT plant. A high mass fraction of plastic (PVC) and rubber material was found in the reject material stream. Streams of heavy fraction and fine fraction mainly contained non-combustible material (such as stone/rock, sand particles and gypsum material).

Mass, energy and material balances of SRF production process. Part 1: SRF produced from commercial and industrial waste

This paper presents the mass, energy and material balances of a solid recovered fuel (SRF) production process. The SRF is produced from commercial and industrial waste (C&IW) through mechanical treatment (MT). In this work various streams of material produced in SRF production process are analyzed for their proximate and ultimate analysis. Based on this analysis and composition of process streams their mass, energy and material balances are established for SRF production process. Here mass balance describes the overall mass flow of input waste material in the various output streams, whereas material balance describes the mass flow of components of input waste stream (such as paper and cardboard, wood, plastic (soft), plastic (hard), textile and rubber) in the various output streams of SRF production process. A commercial scale experimental campaign was conducted on an MT waste sorting plant to produce SRF from C&IW. All the process streams (input and output) produced in this MT plant were sampled and treated according to the CEN standard methods for SRF: EN 15442 and EN 15443. The results from the mass balance of SRF production process showed that of the total input C&IW material to MT waste sorting plant, 62% was recovered in the form of SRF, 4% as ferrous metal, 1% as non-ferrous metal and 21% was sorted out as reject material, 11.6% as fine fraction, and 0.4% as heavy fraction. The energy flow balance in various process streams of this SRF production process showed that of the total input energy content of C&IW to MT plant, 75% energy was recovered in the form of SRF, 20% belonged to the reject material stream and rest 5% belonged with the streams of fine fraction and heavy fraction. In the material balances, mass fractions of plastic (soft), plastic (hard), paper and cardboard and wood recovered in the SRF stream were 88%, 70%, 72% and 60% respectively of their input masses to MT plant. A high mass fraction of plastic (PVC), rubber material and non-combustibles (such as stone/rock and glass particles), was found in the reject material stream.