Investigations present that changes in municipal solid waste composition and properties correlate with the size and density of the municipal solid waste type, that mechanical pre-treatment including separation by weight and size can be useful for preparation of refuse derived fuel (RDF) material and solid recovered fuel (SRF) used for energy recovery. The authors determine the parameters of separated components of the coarse fraction (lower heating value, moisture, ash content, carbon, nitrogen, hydrogen, sulphur, chlorine, and metals), and assess their viability for the preparation of alternative fuel.

The mechanical pre-treatment technologies are one of the solutions that are planned to be used in all waste management regions to separate biodegradable municipal waste in Latvia, thus inter alia contributing to implementation of the waste policy of the European Union. In Latvia recent research of the collected household waste composition shows that average bio-waste is 39 %. The article provides the results of experimental work for partly sorted municipal solid waste mechanical pre-treatment in Latvia. The goal is to detect the composition of sorted waste parts after separation by the drum screener for evaluation of the effectiveness of the mechanical pre-treatment. The experimental truckloads of the collected waste (bio-waste and partly sorted) were selected from the apartments in Broceni town during a period of one year (2017/2018). Each truckload was weighed and the mass balance of the materials was established. Mechanical pre-treatment equipment is the bag breaker, drum screener and magnetic separator. Samples were taken from partly sorted municipal solid waste in two fractionscoarse, fine. The composition was determined manually in 11 parts. The moisture of fractions was determined. Results-fine fraction is ~34 %, coarse fraction ~65 % and metal ~1 %; separation of biological waste at source variates from 62 % in the autumn to 17 % in the spring season by mass.

Different kinds of biomass are important renewable energy sources in Latvia. Of course firewood, wood chips and pellets are the main part of biomass, because 54,7 % of the state area is covered by forests. But also other kinds of biomass can play a significant role in the heat and electricity production, especially at municipal heating facilities. Such kinds of biomass are various agricultural and food production residues, livestock breeding buy-products, sewage sludge, organic part of household and industrial wastes, etc. In the present paper, changes of amount and distribution of variety of biomass forms in five year period are analysed. The biomass energy potential for different regions of Latvia for this period is calculated and discussed. The energy potential of agricultural by-products and organic waste are shown on the map of Latvia.

The authors determined the morphological composition of refuse derived fuel (RDF) produced in Latvia and Lithuania by manually sorting. The parameters of RDF (moisture, net calorific value, ash content, carbon, nitrogen, hydrogen, sulphur, chlorine, metals) was determined using the EN standards. Comparing obtained results with data from literature, authors have found that the content of plastic is higher but paper and cardboard is lower than typical values. Results also show that the mean parameters for RDF can be classified with the class codes: Net heating value (3); chlorine (3); mercury (1), and responds to limits stated for 3rd class of solid recovered fuel. It is recommended to separate biological waste at source to lower moisture and ash content and increase heating value for potential fuel production from waste.

In the work, the life-cycle assessment approach is applied to the planning of waste management development in a seaside region (Piejūra) using the Waste Management Planning System (WAMPS) program. In Latvia, the measures to be taken for the climate change mitigation are of utmost importance - especially as related to the WM performance, since a disposal of biodegradable waste presents the primary source of GHG emissions. To reduce the amount of such waste is therefore one of the most significant goals in the State WM plan for 2013-2020, whose adoption is the greatest challenge for municipalities. The authors analyse seven models which involve widely employed biomass processing methods, are based on experimental data and intended for minimising the direct disposal of organic mass at the solid waste landfills. The numerical results obtained evidence that the thermal or biotechnological treatment of organic waste substantially reduces the negative environmental impact of WM practices - by up to 6% as compared with the currently existing.