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.

As the population grows, demand for food increases. Fish is considered to be one of the most efficient sources of protein. But as demand increases, we need to think about the efficient and sustainable fish feed. There is a need to replace existing feed ingredients such as fishmeal and fish oil with more sustainable sources of protein and oil. In 1990, fish feed consisted mainly of fishmeal and fish oil, but today’s fish feed is dominated by vegetable protein and vegetable oil. Comparing the advantages and disadvantages of the alternatives is concluded that previously used fish feed ingredients such as fishmeal and fish oil are not the most efficient, sustainable, and economically viable resources. The comparison shows why the composition of fish feed has shifted from 1990 to 2020 towards the use of plant resources in fish feed, as plant resources are more efficient, sustainable, and economically viable.

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.

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.

Abandoned, lost or discarded fishing gear harms marine ecosystems by releasing microplastic waste from synthetic materials, reducing biodiversity, spreading invasive species and causing long-term damage to fragile habitats. Therefore, it is essential to evaluate fishing gear waste quantities and establish efficient waste management strategies focused on reuse, recycling and recovery. This research develops a methodology to assess the quantity of discarded fishing nets and scrap waste from Latvia’s fishing gear industries, explores potential waste valorization scenarios and evaluates them based on the country-specific circular economy principles. The study employs environmental life cycle assessment (avoided burden approach) and environmental damage cost methods to evaluate different waste management scenarios for discarded fishing nets in Latvia. Findings show that manufacturing scraps exceed discarded fishing nets, with Latvia averaging 53 tons of fishing net waste annually from 2018 to 2023, and a notable drop in manufacturing during COVID-19. The assessment of valorization scenarios demonstrates that recycling fishing nets for nylon production and asphalt reinforcement significantly reduces both environmental impact and costs. Specifically, recycling for nylon production avoids 7850 kg of CO₂ eq. and reduces environmental damage costs by 2947 Euro per tonne of discarded fishing nets. For asphalt reinforcement, it avoids 636 kg of CO₂ eq. and results in a cost reduction of 407 Euro per tonne of discarded fishing nets. In contrast, the less environmentally feasible options, syngas production and landfilling, show higher environmental footprints. Syngas production generates 156 kg CO₂ eq. per tonne of fishing nets and incurs an additional environmental damage cost of 31 Euro per tonne, but it is still a preferable alternative to landfilling. Landfilling has the most severe impact, generating 12100 kg CO₂ eq. and costing 29609 Euro per tonne, making it the least favorable option and one that should be avoided. Research underscores the necessity for uniform data collection on fishing net waste and enhanced collaboration among stakeholders to facilitate valorization and investment efforts.

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.