Mika Horttanainen

The composition, heating value and renewable share of the energy content of mixed municipal solid waste in Finland

For the estimation of greenhouse gas emissions from waste incineration it is essential to know the share of the renewable energy content of the combusted waste. The composition and heating value information is generally available, but the renewable energy share or heating values of different fractions of waste have rarely been determined. In this study, data from Finnish studies concerning the composition and energy content of mixed MSW were collected, new experimental data on the compositions, heating values and renewable share of energy were presented and the results were compared to the estimations concluded from earlier international studies. In the town of Lappeenranta in south-eastern Finland, the share of renewable energy ranged between 25% and 34% in the energy content tests implemented for two sample trucks. The heating values of the waste and fractions of plastic waste were high in the samples compared to the earlier studies in Finland. These high values were caused by good source separation and led to a low share of renewable energy content in the waste. The results showed that in mixed municipal solid waste the renewable share of the energy content can be significantly lower than the general assumptions (50-60%) when the source separation of organic waste, paper and cardboard is carried out successfully. The number of samples was however small for making extensive conclusions on the results concerning the heating values and renewable share of energy and additional research is needed for this purpose.

Potential of phosphorus recovery from sewage sludge and manure ash by thermochemical treatment.

All life forms require phosphorus (P), which has no substitute in food production. The risk of phosphorus loss from soil and limited P rock reserves has led to the development of recycling P from industrial residues. This study investigates the potential of phosphorus recovery from sewage sludge and manure ash by thermochemical treatment (ASH DEC) in Finland. An ASH DEC plant could receive 46-76 kt/a of sewage sludge ash to produce 51-85 kt/a of a P-rich product with a P2O5 content of 13-18%, while 320-750 kt/a of manure ash could be supplied to produce 350-830 kt/a of a P-rich product with a P content of 4-5%. The P2O5 potential in the total P-rich product from the ASH DEC process using sewage sludge and manure ash is estimated to be 25-47 kt/a, which is significantly more than the P fertilizer demand in Finlands agricultural industries. The energy efficiency of integrated incineration and the ASH DEC process is more dependent on the total solid content and the subsequent need for mechanical dewatering and thermal drying than on the energy required by the ASH DEC process. According to the results of this study, the treated sewage sludge and manure ash using the ASH DEC process represent significant potential phosphorus sources for P fertilizer production.

Technical potential of electricity production from municipal solid waste disposed in the biggest cities in Brazil: Landfill gas, biogas and thermal treatment

This article presents an analysis of possibilities for electrical energy production by using municipal solid waste disposed in the biggest Brazilian cities. Currently, the municipal solid waste in Brazil is collected and disposed of at landfills, but there are also other technologies, which in addition to dealing with the garbage can also provide benefits in terms of energy provision. The following scenarios were studied in this work: electricity production from landfill gas (reference scenario); incineration of all municipal solid waste; anaerobic digestion of organic waste and incineration of refuse-derived fuel fractions after being separated in separation plants. According to this study, the biggest cities in Brazil generate about 18.9 million tonnes of municipal solid waste per year (2011), of which 51.5% is biogenic matter. The overall domestic consumption of electricity is 480,120 GWh y−1 in Brazil and the municipal solid waste incineration in the 16 largest cities in the country could replace 1.8% of it using incinerators. The city of São Paulo could produce 637 GWh y−1 with landfill gas, 2368 GWh y−1 with incineration of municipal solid waste and 1177 GWh y−1 with incineration of refuse-derived fuel. The latter two scenarios could replace 27% and 13.5% of the residential electrical energy consumption in the city. This shows that thermal treatment might be a viable option of waste-to-energy in Brazil.

Updating and testing of a Finnish method for mixed municipal solid waste composition studies

More efficient recycling of municipal solid waste (MSW) is an essential precondition for turning Europe into a circular economy. Thus, the recycling of MSW must increase significantly in several member states, including Finland. This has increased the interest in the composition of mixed MSW. Due to increased information needs, a method for mixed MSW composition studies was introduced in Finland in order to improve the national comparability of composition study results. The aim of this study was to further develop the method so that it corresponds to the information needed about the composition of mixed MSW and still works in practice. A survey and two mixed MSW composition studies were carried out in the study. According to the responses of the survey, the intensification of recycling, the landfill ban on organic waste and the producer responsibility for packaging waste have particularly influenced the need for information about the composition of mixed MSW. The share of biowaste in mixed MSW interested the respondents most. Additionally, biowaste proved to be the largest waste fraction in mixed MSW in the composition studies. It constituted over 40% of mixed MSW in both composition studies. For these reasons, the classification system of the method was updated by further defining the classifications of biowaste. The classifications of paper as well as paperboard and cardboard were also updated. The updated classification system provides more information on the share of avoidable food waste and waste materials suitable for recycling in mixed MSW. The updated method and the information gained from the composition studies are important in ensuring that the method will be adopted by municipal waste management companies and thus used widely in Finland.

Potential of energy and nutrient recovery from biodegradable waste by co-treatment in Lithuania

Biodegradable waste quantities in Lithuania and their potential for the co-treatment in renewable energy and organic fertilizer production were investigated. Two scenarios were formulated to study the differences of the amounts of obtainable energy and fertilizers between different ways of utilization. In the first scenario, only digestion was used, and in the second scenario, materials other than straw were digested, and straw and the solid fraction of sewage sludge digestate were combusted. As a result, the amounts of heat and electricity, as well as the fertilizer amounts in the counties were obtained for both scenarios. Based on this study, the share of renewable energy in Lithuania could be doubled by the co-treatment of different biodegradable materials

Understanding biorefining efficiency--the case of agrifood waste.

The aim of this study was to determine biorefining efficiency according to the choices made in the entire value chain. The importance of the share of biomass volume biorefined or products substituted was investigated. Agrifood-waste-based biorefining represented the case. Anticipatory scenarios were designed for contrasting targets and compared with the current situation in two Finnish regions. Biorefining increases nutrient and energy efficiency in comparison with current use of waste. System boundaries decisively influence the relative efficiency of biorefining designs. For nutrient efficiency, full exploitation of biomass potential and anaerobic digestion increase nutrient efficiency, but the main determinant is efficient substitution for mineral fertilisers. For energy efficiency, combustion and location of biorefining close to heat demand are crucial. Regional differences in agricultural structure, the extent of the food industry and population density have a major impact on biorefining. High degrees of exploitation of feedstock potential and substitution efficiency are the keys.

System analysis of waste oil management in Finland

Waste oil management systems include processes such as generation, collection, recycling, and disposal and result in various environmental, economic, social, and regulatory impacts which complicate waste management analysis. In this paper, the waste oil management system in Finland is analysed using the systems thinking approach to identify the main system components and to describe the interactions between them. The results of analysing the Finnish system increase the understanding of the main factors affecting the performance of waste oil management. The outcome of this analysis can be adapted for the examination of similar systems. The waste oil management system analysis shows an increase in the performance: the waste oil collection rate within the official collection system has increased more than 30% during the last 6 years. The environmental performance of the treatment and recovery system have increased, taking into account the increase of the material recovery rate, more than 70% during the last 6 years.

Areas on which to focus when seeking to reduce the greenhouse gas emissions of commercial waste management. A case study of a hypermarket, Finland

This study focuses on commercial waste, which has received less attention than household waste in regards to greenhouse gas emission research. First, the global warming potential (GWP) of commercial waste management was calculated. Second, the impacts of different waste fractions and the processes of waste management were recognised. Third, the key areas on which to focus when aiming to reduce the greenhouse gas emissions of commercial waste management were determined. This study was conducted on the waste generated by a real hypermarket in South-East Finland and included eight different waste fractions. The waste treatment plants were selected based on the actual situation. Three different scenarios were employed to evaluate the environmental impact of managing mixed waste: landfilling, combustion and more accurate source separation. The GaBi software and impact assessment methodology CML 2001 were used to perform a life cycle assessment of the environmental impacts associated with the waste management. The results indicated that the total GWP of commercial waste management could be reduced by 93% by directing the mixed waste to combustion instead of landfill. A further 5% GWP reduction could be achieved by more accurate source separation of the mixed waste. Utilisation of energy waste had the most significant influence (41-52%) on the total GWP (-880 to -860 kgCO2-eq./t), followed by landfilling of mixed waste (influence 15-23% on the total GWP, 430 kgCO2-eq./t), recycling polyethylene (PE) plastic (influence 18-21% on the total GWP, -1800 kgCO2-eq./t) and recycling cardboard (influence 11-13% on the total GWP, 51 kgCO2-eq./t). A key focus should be placed on treatment processes and substitutions, especially in terms of substitutions of energy waste and PE plastic. This study also clarified the importance of sorting PE plastic, even though the share of this waste fraction was not substantial. The results of this paper were compared to those of previous studies. The output of this analysis indicated that the total GWP can be significantly reduced by identifying an alternative recycling or incineration location for cardboard where it is used to substitute virgin material or replace fossil fuels respectively. In conclusion, it is essential to note that waste management companies have a notable influence on the emissions of commercial waste management because they choose the places at which the waste fractions are treated and utilised.

The MEFLO method's application for the feasibility assessment of energy recovery from municipal solid waste in a small integrated municipal service system

The paper presents the MEFLO ranking method and the Simple Integrated System Management (SISMan) concept for assessing the feasibility of integrated energy and Waste Management System (WMS) alternatives. The MEFLO method is based on dividing the decision-making process into five modules, including mass, energy and financial flows, legislative criteria (e.g., environmental restrictions and target values) and other decision support criteria, such as the local political guidelines. The utilisation of the MEFLO method is presented by comparing five system alternatives, including energy recovery from household waste. The calculations needed in the MEFLO assessment were performed with the SISMan spreadsheet calculation model developed at the Lappeenranta University of Technology. The MEFLO method and the SISMan concept contribute to the design and assessment of different integrated management systems. Any of the appropriate available tools can be used in the model forming and assessment processes, according to the proposed methods.

Modeling and comparative assessment of bubbling fluidized bed gasification system for syngas production- A gateway for a cleaner future in Pakistan

ABSTRACT The present study explores the potential of MSW gasification for exergy analysis and has been recently given a premier attention in a region like Pakistan where the urbanization is rapidly growing and resources are few. The plant capacity was set at 50 MW based on reference data available and the total exergetic efficiency was recorded to be 31.5 MW. The largest irreversibility distribution appears in the gasifier followed by methanation unit and CO2 capture. The effect of process temperature, equivalence ratio and MSW moisture content was explored for inspecting the variations in syngas composition, lower heating value, carbon conversion efficiency and cold gas efficiency. Special attention of the paper is paid to the comparative assessment of MSW gasification products in four regions, namely Pakistan, USA, UAE and Thailand. This extended study gave an insight into the spectrum of socioeconomic conditions with varying MSW compositions in order to explain the effect of MSW composition variance on the gasification products. GRAPHICAL ABSTRACT