Search

Metal is one of the most widely used materials in the world. It was a crucial driving force in technological development since the industrial age and continues to push us forward to this day. As metal consumption grows, so does the amount of scrap metal generated. Proper utilization of this waste is crucial in mitigating the negative environmental impacts of the metalworking industry. The processing and use of raw materials is often associated with high resource consumption and high emissions. The utilisation of scrap metal instead of raw metal can lead to up to 10 times less electricity consumption and up to 30 times fewer CO2 emissions. However, selecting the most suitable scrap metal processing technology is crucial, particularly in the case of the metal melting furnace which is the backbone of the industry. The efficiency of this process determines the environmental indicators for the entire scrap metal melting process. This paper conducts an analysis of 8 types of metal melting furnaces based on 11 environmental criteria. Furthermore, a SWOT analysis is conducted to evaluate the efficiency of the metal smelting process in Latvian metalworking enterprises and the potential for future expansion.

More production is needed as fish consumption increases. The increasing demand for fish also has implications for fish feed, the efficiency of its production and sustainability. Three protein alternatives – Black Soldier Fly, Yellow Mealworm, and Soybean – are compared to assess the sustainability of raw materials and their environmental impact. Each alternative has advantages and disadvantages. The advantages of Black Soldier fly and Yellow Mealworm are a valuable source of protein, sustainable growth (as the feed can be used in food waste) and no need for arable land. The disadvantages of Black Soldier fly and Yellow Mealworm are cost, unbalanced diets can adversely affect growth, and the nutritional impact on fish varies depending on the species of fly or mealworm. The advantages of soybeans are price, availability, and high protein content, while the disadvantages are the lack of essential amino acids, which affect the quality of the fish, and poor taste. An LCA study has been carried out on the proteins of black soldier fly, yellow mealworm and soybean. The most important impact categories from the PEFCR are climate change, particulate matter, acidification, land use, terrestrial eutrophication, and water use. The total single point value for the Black Soldier fly protein is 1.43E+01 µPt, the Yellow mealworm protein is 3.89E+02 µPt and the Soybean protein is 9.72E+01 µPt. The significant effect is due to the electricity consumption and the ingredients used in the feed. Sensitivity analysis was carried out for Black Soldier fly protein and Yellow Mealworm protein production where feed formulation was varied. In both sensitivity analyses, the lower environmental impact is from the new feed structure, which may be due to the use of food waste and wheat as feed ingredients in the new feed structure.

The marketability of fish depends on the visual appearance of the fish, so the feed ingredient pigment contributes to the nutritional value and visual appearance of the product. The benefits of a natural pigment derived from microalgae are the ecological benefits, as the culture can fix carbon and release oxygen. The economic aspect is a benefit of synthetic pigments. The Life Cycle Assessment (LCA) method was used to determine the environmental impact of natural and synthetic pigments. The results obtained from the LCA are expressed according to the impact categories defined by the Product Environmental Footprint Category Rules (PEFCR). A sensitivity analysis was also carried out comparing the environmental impacts of electricity generated with hydropower or using a field mix from Norway for the natural pigment. The total single score value for natural pigment is 1.17E+01 mPt and the largest impact is from sodium nitrate and electricity. The sensitivity analysis results for electricity from the country mix is 1.82E+01 mPt. The total single score value for synthetic pigment is 8.24E−01 mPt, with the largest impact from methanol. Synthetic pigments have a lower environmental impact than natural pigments, but a sensitivity analysis shows that the environmental impact can be reduced by choosing an alternative to electricity. It should be noted that the comparison presented represents a general comparison of alternatives, as the input data is derived from a literature review.

Among other sectors prioritized in delivering the circular economy targets, such a major sector as health care should also be highlighted. According to World Bank data, current health expenditure is still rising, reaching globally 10.02 % in 2016 compared to 8.56 % in 2000. To ensure protection of public health, the management of health care waste should be based on the waste management hierarchy. Besides the preventive measures (waste minimization, green procurement, sustainable planning, environmental management systems), treatment methods should also be viewed in the context of the waste management hierarchy. To analyse the possibility to apply circular economy principles into health care waste management, evaluation of resource recovery alternatives as well as its multi-dimensional assessment was done. In the article quantitative and qualitative assessment was conducted through multicriteria decision analysis with a goal to do a quantitative and qualitative assessment of healthcare waste and resource potential assessment.

As food consumption increases, so does the number of agricultural by-products. That is why it is necessary to find the best possible uses for them, operating by the principles of the bioeconomy. This work aims to gather information on the possibilities of using grain byproducts to develop new products and evaluate which bran products are the most suitable for commercialisation based on economic, environmental, social, and technical factors. Two methods were used in this work: literature review and multi-criteria decision analysis. As a result, 30 products were identified that could be made by using wheat bran, straw, husk, and dust. The products were divided into six groups – packaging materials, building materials, adsorbents, fuel, thermal insulation materials, and chemicals. In multi-criteria decision analysis, it was looked at seven bran products of which the best alternative for further commercialisation is mycelium-based biocomposite.

Multi-criteria decision analysis (MCDA) is widely used to solve various decision problems through alternative evaluation. MCDA methods can be used in every field that can define a problem, alternatives and criteria. However, finding the appropriate method can influence the results, in this research five MCDA methods have been tested on the renewable energy sector in Latvia to find the best alternative. The main results showed that TOPSIS, VIKOR and PROMETHEE-GAIA have similar priority selection and the highest ranking was selected for hydropower plant, but MULTIMOORA and COPRAS results were beneficial to Solar PV.

Recently introduced European Green Deal has set a target for Europe to become the first climate-neutral continent by 2050. This ambitious commitment will bring a serious challenge for the EU. However, the degree of this challenge will not be the same to all EU member states. In this paper, the multi-criteria decision analysis is applied to rank eight selected EU countries (Denmark, Estonia, Ireland, Latvia, Lithuania, Slovenia, Finland and Sweden) regarding GHG performance, and thus illustrate different starting points of the transition to carbon-neutrality. In parallel to the widely used indicator of GHG emissions per capita, evaluation incorporates various other criteria covering energy consumption, population size, and the use of renewable energy and fossil fuel, as well as investment and tax rates. TOPSIS analysis shows that the best GHG performance is achieved by Sweden, while Latvia ranks the lowest. The presented evaluation method could be a useful tool in planning implementation of policies to reach Green Deal settings on European, as well as on a national level.