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Paper waste is a raw material for a lot of products with different added value. The engineering, economic and environmental aspects of paper waste recycling are analysed for production of composite material, cellulose nanofibers and nanocrystals, bricks with paper components, porous carbon, film of biopolymer, enzymatic sugar and bioenergy: bioethanol, hydrogen and biofuel. Through multicriteria analysis, it was possible to determine the most feasible paper waste recycling product in case of four product groups: egg packaging boxes, cardboard, reused paper, cellulose nanomaterials (nanofibers and nanocrystals). The production of cellulose nanofibres and cellulose nanocrystals has an advantage over egg packaging and cardboard production as well as reusable paper.

Waste management system is a complex system involving numerous waste streams, collection schemes, treatment processes and various actors. Bus as well as many other systems, waste management is recently experiencing new and more sustainable development trends including the promotion of circular economy and increased material recycling. Hence there is a need for the implementation of an improved waste management system that requires a significant and thorough planning stage, the results of which will significantly depend on the availability of detailed information of the possible waste flows and waste composition. The aim of this paper is to experimentally determine and analyse the composition of unsorted municipal waste to provide assessment for incorporating waste composition analysis into further planning and modelling of a next generation waste management system in Latvia. The experimental results indicate that the unsorted municipal waste stream comprises of up to 32.9 % of recyclable materials and 29.2 % of biodegradable wastes. Thus almost 60 % of the waste currently being subjected to unsorted waste management system in Latvia could potentially be source separated ensuring higher quality of the recovered materials and promoting circular value chains. The results indicate a slight difference between waste composition in different waste management regions, thus noting that, in addition to the number of inhabitants and their habits, the local system in each waste management region may influence the composition of the collected wastes.

The aim of the circular economy is to maximize the value of a product during its use, using secondary raw materials to create new products. This research focus on the possibilities of using waste as an energy resource - both the aspects of waste recovery, from the point of view of reducing the amount of landfilled waste, and the extraction and further efficient use of landfill gas. In this case the TOPSIS analysis method was used, five alternatives were selected - waste as an energy resource, which was evaluated based on four criteria: technological, economic, social, as well as environmental and climate aspects. The results of ranking energy recovery methods from waste using the TOPSIS method clearly show that the most optimal of the selected alternatives is the use of biodegradable (organic) waste for biogas production. This opens up opportunities for biofuels to be applied in road transport.

According to the Latvian policy planning documents, the main macro indicators for monitoring progress of national development are: GDP per capita, income inequity index S80/S20 and national population growth. Policy planning documents propose different sectoral targets that are not linked with each other, sometimes providing conflicting goals. There are international and European Union (EU) targets (especially in the environmental and climate sector) that sometimes contradict with national goals and occasionally are not set as national priorities in Latvia and for which the necessary resources are not appropriated. The authors propose an improved methodological approach interlinking national policy indicators and sectoral models to generate more efficient decision making mechanisms.