The material composition of municipal solid waste (MSW) is studied in order to determine the resource value and develop a rational system for their disposal. For many centuries, organic components predominated in urban waste. This was not a big problem for waste disposal, the main thing was to remove the waste outside the city. Organic waste was subjected to natural decomposition in nature and did not emit any toxic substances.
The development of civilization gradually changed the composition of household waste. More and more non-degradable components appeared: glass, ceramics, metals, rubber, plastics. In the middle of the 20th century, due to the development of chemical industries and the emergence of a large number of artificial materials, the amount of waste began to increase like an avalanche, and the change in the composition of waste required new approaches to their disposal. In addition, hazardous substances began to appear in the waste: mercury, batteries, expired medicines, etc., even small quantities of which can cause serious pollution.
Today, the study of the composition of waste, its origin and the quality of sorting is a necessary step in the development of an effective strategy for the use of waste as secondary material resources and reducing their negative impact on the environment.
The results of the second stage of the study of the morphological composition of municipal waste in the Republic of Belarus, which is carried out in 2020 with the financial support of the Coca-Cola Beverages Belarus within the framework of the project “Civic Engagement in Environmental Monitoring and Improving Environmental Management at the Local Level”, funded by the European Union and implemented by the UN Development Program in partnership with the Ministry of Natural Resources and Environmental Protection of the Republic of Belarus are summed up. The work was carried out in July-August 2020 in Minsk (at 8 control sites) and 12 cities of the republic.
The purpose of the study is to assess the volume of waste generation and losses in the environment before they are involved in the collection system. For this, a specially developed experimental technique is used.
For the first time in Belarus, municipal waste is studied with a detailed breakdown by type and with reference to the type of settlement. A gradation of cities by population was adopted to obtain an objective picture. Among them, small, medium and large cities, including regional centers, were distinguished. The method of two-factor identification is used, when not only the material of the packaging is determined, but also its capacity, as well as the purpose — for the packaging of which goods it was used.
According to the results of the study, in summer, as in winter, the composition of municipal solid waste (MSW) in containers for mixed waste in all types of settlements is formed mainly due to the fraction of organic waste, which is 39% by weight of the entire contents of the container (in winter it was 30 %). The percentage of organic matter is significantly lower in separately collected secondary material resources (SMR), but reaches 8.3%, which is also higher than in winter (6%). The minimum organic content is observed in containers for small towns’ SMR.
Polymer wastes also make up a significant part of both mixed MSW and SMR — 8.2% and 18.9%, respectively. Which is much lower than in winter.
In the composition of the polymer fraction, the determining subfractions are transparent and colored PET bottles, which make up 68% of the total mass of polymers in MSW and 84% in SMR. The most common are transparent and colored bottles with a nominal volume of 1.0-1.5 liters.
Waste glass is present in MSW (9.25%), where it is represented by a sub-fraction of colorless glass container with a nominal volume of 0.5 to 1.0 liters. There is less glass in SMR — 6.7%. It is noteworthy that, compared to winter, the percentage of the fraction increased in MSW and decreased in SMR. This fact may be associated with unauthorized selection of glass from containers and its overflow into the system of procurement points.
The distribution of metal waste between containers for collecting MSW and SMR is due to the lack of specialized containers for aluminum and tin cans and the lesser use of such material for packaging products (compared to plastic). The content of metal containers was fixed at 1.78% in MSW and 0.89% in SMR.
The cities under study
Mixed waste is represented by 39.61% of organic fraction, followed by waste of paper and cardboard (11.43%), polymers (7.55%). The leaders in SMR are the fractions of paper, cardboard and corrugated board (16.94%) and polymers (15.91%). The content of the organic fraction and potentially hazardous waste in the SMR is 11.62% and 11.46%, respectively (3rd and 4th places of the summer study). More than 1/3 of the mass of the polymer fraction in both types of containers is made up of PET containers, represented mainly by color and colorless PET bottles with a volume of 1.0-1.5 liters.
Large cities (regional centers)
In the summer period, significant fluctuations in the morphological composition of waste were noted, depending on the studied settlement. The generalized data show that the leading role in MSW and SMR is played by the polymer fraction — 22% and 28%, respectively. Content of other fractions, incl. organic, is lower — 7.34% in MSW and 16.84% in SMR. In the regional centers, a significant role in the composition of MSW is played by the fraction of paper, cardboard and corrugated board (14%), as well as glass — 17%. The content of these fractions in SMR is significantly lower — 8.8% and 9.6%, respectively.
In medium-sized cities, the composition of MSW is formed by the fraction of organic waste — 52%. In SMR, the percentage of organic matter is significantly lower — 1%. The composition of the SMR is formed mainly due to the fraction of waste paper, cardboard, corrugated board (32%), polymers (22.35%), and also textile waste (16%). For these types of settlements, the minimum content of the organic fraction in the SMR was recorded — less than 1%.
For cities with a population of up to 20 thousand people, the highest content of glass waste in separately collected waste was revealed among all settlements. More than half of the mixed MSW is organic waste. The content of polymers in small towns is 7% in MSW and 21% in SMR.
Thus, in the summer period, an increase in the organic fraction in the waste is noted, which is largely due to the work on cleaning the grass and other vegetation from the courtyard areas, as well as the widespread use of fresh vegetables and fruits in food. Due to the small weight of the plastic packaging, with the clearly noticeable presence of this fraction in the MSW and SMR, its mass fraction, in comparison with the winter study, decreased. At the same time, the most massive component — PET — is actively sorted by the population into appropriate containers.
The data obtained will help in the preparation of proposals for improving the functioning of municipal waste collection systems in the Republic of Belarus within the framework of the National Strategy for Sustainable Socio-Economic Development of the Republic of Belarus, which provides for the maximum involvement of waste in civil circulation for the production of products and energy.