| Abstract [eng] |
The issue of food waste management is relevant due to the energy and nutritional potential of biomass, which could contribute to the linear economy transformation into a circular, based on the principles of sustainability and resource recovery. The legal requirements of the European Union and Lithuania indicate that from 2023 December 31 member states will have to ensure separate collection or recycling of biodegradable waste at the point of generation. In the Kaunas region, the infrastructure for separate collection and processing of food waste has not yet been implemented, so appropriate ways to manage this waste flow are being sought. When handling food waste, priority must be given to the production of biogas and composting of the residual substrate, ensuring sustainable and highquality production of value-added products, without causing additional negative effects on the environment or human health. The final master's project is aimed at analyzing the possibilities of separately collected food and kitchen waste management in the Kaunas region. To achieve the goals and objectives of the project, elements of the methodology of introducing cleaner production at the company level and introducing the principles of industrial symbiosis at the company and regional levels were used: dematerialization through pollution prevention and industrial metabolism, realizing industrial symbiosis. In 2022, in the conducted feasibility study "Preparation for the introduction of separate collection of food and kitchen waste in the municipalities of Kaunas region", it was decided that the most acceptable alternative for the Kaunas region is the preparation of pasteurized food and kitchen waste biomass in the territory of Zabieliškis MAR and the transfer of biomass to other waste management companies. During the final project, this alternative was considered as the existing situation after the implementation of the project, against which the two alternatives were compared. In the case of the first alternative, it is proposed to process the biomass of food and kitchen waste anaerobically, purify and liquefy the obtained biogas into bio–CH4 and bio–CO2, and compost the obtained digestate with green waste according to the principles of industrial symbiosis. The produced liquefied bio–CH4 could be used in the transport sector (in place of fossil fuel use) and in the industrial sectors (in enterprise gas burners). Liquefied bio–CO2 could be used in manufacturing industries, preventing CO2 from entering the ambient air. Biocompost could be used in the agricultural sector instead of using mineral fertilizers. The environmental benefit of this alternative in terms of GHG reduction is equal to 238.43–667.70 t CO2e/year. or 18–49 kg CO2e/t FW, depending on the fossil fuel replaced by bio–CH4 (natural gas or diesel, respectively). The economic benefit is noticeable due to the income from the sales of value-added products – a total of 1.34 million. EUR/year, when 0.6 thousand tons of bio–CH4, 0,9 thousand tons of bio–CO2/year and 4 thousand tons of biocompost are produced per year. Income after evaluating changes in the amount and price of other energy and material flows would amount to 814.73 thousand EUR/year. or 60.9 EUR/t FW. Project investments would amount to 6.12 million. EUR, payback period 7.5 years. In the case of the second alternative, it is proposed to burn the biogas obtained after the anaerobic treatment of food and kitchen waste biomass in a cogeneration plant, producing electricity and heat energy for own needs and for sale, and, as in the case of the 1st alternative, to further process the digestate together with green waste. The environmental benefit of this alternative in terms of GHG reduction is equal to 151.04 t CO2e/year. or 11 kg CO2e/t FW. The economic benefit is noticeable only due to the supply of electricity to the grid (2.5 GWh/year) and the production of added value biocompost – a total of 403.8 thousand EUR/year. Most of the heat energy is not used due to the undeveloped gas pipe networks near the territory and the fact that the city of Kėdainiai is already being heated using the surplus energy of AB "Lifosa" operating nearby. After evaluating the changes in the amount and price of other energy and material flows, the income would reach 364.4 thousand EUR/year. or 26.87 EUR/t FW. Project investments would amount to 6.68 million. EUR, but the payback period is 18.3 years. Based on the results of the conducted research, the company is recommended to implement the 1st alternative, i.e. liquefied bio–CH4 and bio–CO2 and biocompost production capacity, firstly, due to higher environmental performance in terms of climate change mitigation due to GHG (37–77% higher reduction of global warming potential compared to alternative 2), secondly due to better economic indicators: 8% lower investment requirement to treat 1 tonne of FW and 79% lower investment requirement to reduce climate change by treating FW (i.e. reduce 1 tonne CO2e). |
