Multi criteria analysis of municipal solid waste management and resource recovery in Poland compared to other EU countries

Statistics show that the inhabitants of Poland are producing increasingly more household waste. This article attempts to determine the current level of development of Poland in the field of waste management concerning other EU countries and partner countries; identify trends in the mass of generated, segregated, and mixed municipal waste; and obtain an idea of the attitude of the Polish population toward sorting waste at the source to bring the country to a higher level of waste management. The empirical base is statistical data published on the website of the EU Data Explorer and the Central Statistical Office. The ranking of countries was determined by the TOPSIS method using a synthetic indicator based on the selected diagnostic features. The significance of the obtained ranks was tested using the non-parametric Friedman test (p < 0.01). We established that Poland has been consistently ranked 16th-17th over the past 5 years. Unfortunately, thus far, no systematic approach has been found to raise citizens' awareness, which may be due to the lack of the necessary amount of data. Researchers recommend investigating the sensitivity of the relationship between the generation of alternative energy from waste and the authorities' action.

www.nature.com/scientificreports/avoided 15 .Following the green track, waste generation trends in Europe are relatively stable, but societies still produce significant amounts of waste.Although the waste rates differ significantly between different EU countries and partner countries, at the same time, the share of waste sent to landfills is decreasing, while the amount of waste for recycling is steadily increasing 16 .According to 2017 statistics, 46% of all household waste in EU countries and partner countries is recycled or composted, but waste management practices vary widely across EU countries and partner countries; several countries still bury large amounts of household waste in landfills 17 .Statistics show that the inhabitants of Poland are producing increasingly more household waste 18 .At the same time, at least 91% of the country's electricity is produced at thermal power plants running on fossil fuels such as coal, hydrocarbons, and brown coal.Consequently, Poland's transition to renewable energy sources, in particular from waste, is urgently needed.So, the decision on which CE-related strategies, policies and technologies to adopt is critical as it can change the dynamic interactions between all economic actors, including city waste management networks 15 .
Since household waste management is a multi-criteria phenomenon, covering various types of activities to reduce the amount of waste, the effectiveness of such management of household waste can be characterized using various simple signs (waste management operations influencing their quantity) and, on this basis, assessed using synthetic indicators (measures).Therefore, it is necessary to carry out a multi-criteria analysis to understand Poland's development level in waste management and the issues of waste management as a potential energy source.
At present, many studies have already been carried out to study the indicators of the mass of waste in Poland 19 , the level of development of individual voivodeships in the field of waste management 20 , the study of the morphological composition of waste in Poland 21 , the study of the state of knowledge, the level of awareness and attitudes of Polish residents to the economy through a survey 22 , and even examining factors that determine consumer participation in the fight against food waste in restaurants in Poland 23 .However, all these studies were carried out for a specific short period; as a rule, they had a geographical limitation and did not provide an opportunity to see the general situation of Poland's development in this matter.That is, no research has been carried out so far that would show the systemic advantages and disadvantages of the current approaches taken in Poland to manage waste as a potential source of energy to follow the EU strategic plans.At the same time, the study's authors found a positive impact on the economy by increasing the efficiency of resource use, which can ultimately can reduce energy dependence and improve the population's quality of life 24 .
Thus, the article attempts to determine Poland's current level of development in manage waste as a sustainable resource for energy production concerning other EU countries and partner countries and the trend in the mass of generated segregated and mixed municipal waste.The first purpose is to conduct a study by quantitative methods using bibliometric analysis to understand the topic relevance and identify relationships using keywords, followed by the second purpose: based on the multi-criteria decision making method (MCDM), to determine Poland's place in the ranking among other European countries and partner countries and to mathematically substantiate the significance of the ranking results.Comparison of the rating results with the Polish policy pursued in the studied time interval will allow us to identify effective approaches to waste management and adjust these approaches for the development of the waste management field.Accordingly, the study aims to answer the following questions: Question 1: Can municipal solid waste be a sustainable source of energy in Poland?Question 2: What is the level of development of Poland in the field of solid waste management in comparison with other European countries and partner countries, since all these countries follow the same green economy strategies and course, and what are the prospects for the future?Question 3: What is the attitude of the Polish population towards waste segregation at source of generation, as it is one of the effective waste management approaches that promote the development of waste-to-energy to take the country to a higher level in this field.
Combination with publications from Web of Science was not carried out in order to avoid unnecessary repetitions, since the coverage of Scopus is greater than that of the Web of Science 25 and in most cases, peer-reviewed scientific journals are registered in both databases.
The choice of keywords and query formula is justified by the fact that we were interested in current issues related to waste management in particular in Poland and the EU as a whole (to understand Poland's place in the ranking of EU countries).
When determining the time interval under study, the authors were guided by the current situation in the world and existing pressing problems in the area under study.The choice of this time interval was influenced by three main factors: (1) in mid-2013, changes occurred in the waste management system in Poland, namely, a waste segregation system was introduced, and responsibility for waste management was transferred to municipalities.Thus, the first full year of reporting in the new waste management system was 2014; (2) since 2014, the problem of obtaining energy from waste is becoming increasingly urgent every year due to the emergence of an energy crisis due to the imposition of sanctions against Russia in connection with the annexation of Crimea.In previous years, Europe was dependent on Russian energy imports and the EU relied on energy imports from the Russian Federation 26 .Due to the imposition of sanctions and restrictions on the export of equipment for oil and gas production, the need to find our own resources has sharply increased in order to significantly reduce and subsequently eliminate this dependence; (3) the end date of the research time interval is justified by the lack of data for 2022 in the Eurostat database.
The search resulted in a list of 430 documents.Based on these obtained results, all categories of documents were evaluated.Among these documents, 417 were published in English, 7 in Chinese, 3 in Polish, 2 in Portuguese and 1 in German.Documents not published in English were also taken into account as they had an abstract and keywords in English.
Not all identified documents were devoted to the problems of solid waste management in Poland or the European Union countries and partner countries.

Expert opinion process
Before proceeding with the biblometric analysis of the found documents, in order to reduce the risk of systematic error in this study, an expert review of the documents was carried out to ensure that the topics of these studies corresponded to the questions posed in the current study.Expert assessment, which is based not on opinions, but on information, is useful 27 .Six authors of the current study served as experts.All experts worked independently to review all retrieved documents and reported to the corresponding author of the article.
Based on the results of expert assessments, 81 documents were rejected as inappropriate and 349 documents were accepted for bibliometric analysis.

Bibliometric analysis
Bibliometric analysis has become increasingly popular for research applications in recent years because it can identify new trends in research activity around the world, as well as explore the body of scientific knowledge and the evolutionary nuances of a scientific problem under study by accurately understanding large volumes of unstructured data.Many studies using bibliometric analysis demonstrate that these studies provide a solid basis for the development of a particular field by processing large volumes of scientific data and contribute to the achievement of high research impact 28 .Also, when conducting bibliometric analysis, the risk of bias is significantly reduced, since this analysis is based on quantitative methods.
For bibliometric analysis, the science mapping technique was used.The annual distribution of selected publications (from 2014 to 2021) is presented in Figs. 1 and 2 shows the priority areas of research related to waste management issues.
It is obvious that from 2014, academic interest in the problems of solid waste management increased until 2019, but in subsequent years the number of publications decreased.The peak of publications in the research area is observed in 2019-62 publications and the next year for the largest number of publications is 2020-48 publications.
Of these publications, sharp superiority is ensured in the subject area of Environmental Science-249 publications and the second highest priority subject area is Energy-75 publications, which indicates the relevance of these scientific problems.
Environmental Science is an interdisciplinary academic field that studies the physical, chemical and biological processes that occur on Earth, as well as the social, political and cultural processes that influence the state of the planet, and contributes to the search for solutions to environmental problems.Consequently, this subject area quite logically contains scientific research devoted to environmentally friendly management of household waste, including those related to its use as a resource for energy production.In this regard, a selection of documents was subjected to bibliographic analysis using the VOSviewer program to establish the most frequently occurring keywords and connections between them.The result of the analysis is presented in Fig. 3.Each node in the network represents a keyword, where the size of the node indicates the frequency of its occurrence.Relationships between keywords are shown.Thicker lines indicate stronger connections between keywords that appear most frequently in a pair.Terms within a cluster have stronger relationships with each other than with terms in other clusters.The VosViewer application used identified 80 items (keywords), 5 clusters, 1272 links and a total link strength of 3454 (Fig. 4).Only relevant elements appearing more than 5 times in the selected 349 publications are presented.This analysis demonstrates that the most frequently occurring positions were "municipal solid waste"-190 cases, landfill (land fill, landfill leachate) with a total of 84 cases, followed by "waste management"-67 cases.
In Fig. 3, publications belonging to the yellow cluster can be considered as publications representing a framework dedicated to circular economy, efficiency assessment and the resulting waste collection and treatment methods (Fig. 5).
The blue cluster contains what appears to indicate a model focused on waste treatment methods (including hazardous waste), primarily incineration and composting, as well as associated devices, temperatures and hazards (Fig. 6).
The red cluster is focused on environmental monitoring of the environment and waste management processes.The greatest number of references to municipal solid waste as a resource for energy production is found in the green cluster (Fig. 7).This cluster contains keywords such as anaerobic digestion-10 cases, biomass-11 cases, biogas-8 cases, combustion-9 cases, household waste 5 cases, carpet energy-5 cases, energy resource-5 cases, environmental policy-7 cases, life cycle assessment-5 cases, mechanical-biological treatment-6 cases, methane-6 cases, organic fraction of municipal solid waste (organic waste)-10 cases, revival energy-7 cases, waste to energy-7 cases.
This analysis shows the relevance of scientific research in the field of converting solid household (or municipal) waste into energy.Also, you can see that in this selection of documents there are such research methods as regression analysis (5 cases) in relation to the assessment of waste generation and its treatment; quantitative analysis (6 cases) in relation to the assessment of pollution and environmental impact; and spatial analysis (5 cases) in relation to the assessment of waste accumulation, environmental monitoring and environmental pollution (Fig. 8).www.nature.com/scientificreports/However, there is a gap in research devoted to the critical assessment of approaches to waste management as a resource for energy production using the method of multi-criteria decision making, in other words, a multicriteria assessment of the waste management system in the country.
The current study seeks to fill this gap.

Data
In this study, the empirical basis is the statistical data on municipal waste by waste management operations, published on the EC data browser website 29 by the Central Statistical Office (GUS) 30 .The current study used secondary data due to the difficulty of obtaining global data.This data comes from Eurostat, which reports waste  www.nature.com/scientificreports/management statistics for 38 countries (European Union countries and partner countries) based on 10 waste management operations from 1995 to 2021.However, the research concerned 30 countries belonging to the European Union and partners (hereinafter referred to as EU countries).8 countries were not included in the study due to lack of necessary data (justification is presented in Sect.Research limits).Of the 10 waste management operations published on the EC data browser website, 4 were included in the study as diagnostic features (the rationale is presented in Sect.Ranking of EU countries).The general preliminary analysis of the waste situation in Poland and in EU countries is limited to 2002-2021, and the time interval from 2014 to 2021 is used for comparative and trend analysis (justification is presented in Sect.Data collection procedure).

Ranking of EU countries
Multi-criteria decision making (MCDM) method provide an opportunity for a broad and objective view of various complex phenomena through their comprehensive study.MCDM is a structured approach to selecting the most suitable alternative, taking into account the importance of evaluation criteria and the performance of alternatives for each criterion.The different levels of importance of the criteria are described by assigning weights to them.One of these methods is TOPSIS-a method for determining the order of preference by similarity to the ideal solution.
The ranking of EU countries was carried from 2014 to 2021.We constructed a synthetic indicator (measure) Q of the level of development of countries in the field of waste management as a sustainable resource for energy production using the multicriteria TOPSIS method, which Hellwig 31 introduced to assess the phenomenon described by several indicators synthetically 31 .For the assessment, we identified diagnostic features that characterize individual countries in terms of the level of development in the field of waste management, separation of characteristics, normalization of feature values, calculation of the value of the synthetic measure of development, linear ordering of the unit and the definition of types of development.We carried out linear ordering based on interrank comparisons since this method is characterized by simple construction and high applicability in quantitative regional analyses 20 .This method is the basis for the preparation and interpretation of the ranking of EU countries in terms of the level of development in waste management as a sustainable resource for energy production in recent years.
As diagnostic features for ranking, we chose the values x ij (i = 1, …, m ; j = 1,…, n) of the average amount of waste per person (kg/capita) for waste management operations, which are presented in the statistical reports of Eurostat.
Eurostat reports statistics based on 10 waste management operations.Of all the operations, only those that have a complete representation in the database for a particular operation or country were taken into account.However, for some operations had significant data deficiencies.Thus, due to the lack of data in Eurostat on the required operations, 8 countries out of 38 represented by Eurostat were not taken into account when developing the rating.Also, the authors decided to exclude features that do not have a sufficient set of data and features that do not reflect the specifics of waste management (that is, those features that do carry general information without specifying the phenomena).Acceptance of specific diagnostic features was determined first by the amount of missing data for a particular operation or country, then based on the priority of the waste management operation within the current study (Table 2).
Consequently, out of 10 waste management operations presented to Eurostat, only four were accepted as diagnostic features, namely: X 1 -Disposal-landfill, X 2 -Disposal-incineration (thermal conversion), X 3 - Recovery-energy recovery (mainly used as fuel or other means of generating energy), X 4 -Recycling.
One of the criteria for selecting diagnostic features is not including variables with low level of variation (the limit of is normally 0.2 or 20%) 32 .In the current study, the variation coefficients for all selected diagnostic features for the time interval studied were more than 0.2 (Table 3).
We assigned weights to selected diagnostic features based on the EU waste management policy and the EU Circular Economy Action Plan 11 , which aims to prevent waste generation and manage it more effectively.According to the EU's "waste management hierarchy," the most desirable scenarios are waste prevention and reuse, followed by recycling (including composting), another recovery (e.g., burning waste to generate energy is a contentious issue in some countries), and disposal, e.g., by landfill, which is the most harmful option for both the environment and health, although one of the cheapest.Thus, the following weights w X j were adopted: Total amount of generated waste y i per year for each country is equal: where y i -the total amount of generated waste per year for the i-th country; x ij -waste management operations for the i-th country and j-th diagnostic feature; γ i -other waste management operations (not included as diagnos- tic features); m-number of countries, varies from 1 to 30; n-number of diagnostic features, varies from 1 to 4. Due to the fact that at different times each country has certain priority waste management operations, and the size of countries and the amount of waste generated in different countries differ significantly, for diagnostic purposes the values of x ij were converted to relative values a ij , where i = 1, …, m; j = 1, …, n.So relative values is computed as follows: The definition of a synthetic indicator (measure) was carried out in several stages 33,34 .
(1) www.nature.com/scientificreports/ Step 1: The decision matrix a ij mxn is normalized according to the normalization method Step 2: The weighted normalized decision matrix v ij mxn is obtained by multiplying normalized matrix with the weights of the attributes: Step 3: The positive ideal solution (PIS) and the negative ideal solution (NIS) are determined: (3) where i = 1, …, m; j = 1, …, n.
Step 4: The calculation of distances between the PIS ( NIS) and alternatives.The distance values can be measured using the Euclidean distance, which is given as: Step 5: The determination of the index Q i : where Finally, the preferred ranks R i can be obtained according to the similarities to the Q i in descending order to choose the best alternatives.

Rank significance analysis
We tested the hypothesis about the significance of the obtained ranks using the nonparametric test χ 2 r -Friedman at the level of statistical significance p < 0.01 using Microsoft Excel 2021, since this method is more efficient than analysis of variance in the case of small samples (up to 30 objects in the sample) and nonnormal distributions.0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 X 2 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 X 3 0.000 0.000 0.003 0.000 0.000 0.000 0.000 0.000 where R k = m i=1 R ik is the sum of individual ranks for each year, k = 1, …, c; c is the number of years; m is the number of countries.
The following hypotheses were accepted.Hypothesis H0 = {between the values of synthetic indicators obtained by the TOPSIS method, which were measured for each EU country in different years from 2014 to 2021, there are only random differences}; Hypothesis H1 = {there are nonrandom differences between the values of synthetic indicators obtained by the TOPSIS method, which were measured for each EU country in different years from 2014 to 2021}.
Hypothesis H0 is accepted if the observed values of χ 2 r -Friedman's test are less than the corresponding critical value chosen at a certain level of statistical significance.It means that the differences in indicators are random.
Hypothesis H0 is rejected (hypothesis H1 is accepted) when the observed values of χ 2 r -Friedman's test are more significant than the corresponding critical value selected at a certain level of statistical significance.It means that the differences in indicators are nonrandom, which means that we can investigate the existence of a factor that ensures this nonrandomness.

Attitude of the Polish population toward waste segregation at the source of generation
Separate waste collection refers to activities that contribute to reducing stored waste and can support improving waste management 18 .Therefore, modern open sources of information were analyzed, such as official reports and scientific studies, to understand Poland's population's attitude to waste segregation at the source of their generation.
All 16 voivodeships in Poland have different levels of waste management.According to the ranking of voivodships in 2015 20 , 4 levels were presented: very high, high, medium, and low.Thus, to analyze the dynamics of selective waste collection by the population in the voivodships of Poland, 2 representative voivodeships from each level were selected following the 2015 study 20 .Since we classified only one voivodeship as very high, 7 were studied (Fig. 9).

Research limits
The general preliminary analysis of the waste situation in EU countries is limited to 2002-2021, data published by Eurostat.The Central Statistical Office and Eurostat characterize these data as "estimated, " as they may differ from the actual ones due to different moisture content of the waste, as well as with or without taking into account the mass of waste collected from areas without organized waste collection.The ranking of countries by the level of development in waste management was carried out for the time interval from 2014 to 2021, while we did not consider countries such as the Croatia, United Kingdom, Bosnia and Herzegovina, Montenegro, North Macedonia, Albania, Serbia, Kosovo in the ranking due to the lack of data in this time interval.The analysis is

Ranking of EU countries
An initial analysis of the dynamics of waste accumulation in Poland over the past 20 years (from 2002 to 2021) shows a periodically changing character (Fig. 10).Clear periods of increased municipal waste production can be observed from 2004 to 2008 and 2014-2021.We observed a similar trend in other EU countries (Table 4).
Reports show a significant increase in the production of waste in Poland by 24.7% in 2005 compared to 2004, then this increase is insignificant, and since 2008 a gradual and stable decline in the production of municipal waste is visible until 2015.In 2015, there was an increase in collected household waste by 5.2% compared to the previous 2014, and the increase continues steadily, including 2021 (Table 4).
The decrease in household waste in 2008, 2009, and 2010 is substantiated by the study 19 as a decrease in household coverage.However, this may not be the only factor.Research 19 showed that generated household waste in 2010 accounted for approximately 10% of all generated waste, but not all household waste was collected.The authors also found that in Poland, only a part of the population was covered by household waste collection, which in 2010 was less than 80%.At the same time, we noted that in the same years, the amount of municipal waste per capita in Poland also decreased (Fig. 11), and it is likely that population changes did not significantly affect this trend.
On the other hand, 2008 is known to be the crisis state of the world economy, which also became a financial crisis in the EU countries.According to experts 35 , Poland is the only country in the EU and Central and Eastern Europe (apart from Kosovo and Albania) whose economy was unaffected by this crisis.However, it is possible that the crisis affected some segments of the population and contributed to decreased purchasing power, resulting in a slight reduction in household waste generation.The increase in the waste amount since 2015 can be justified precisely by the fact that for Poland, 2014 was the first full year of the implementation of the amendment to the Law on Maintaining Cleanliness and Order in the Communes, and checks were carried out on the conclusion of contracts with the population for waste collection.That is, the efficiency of the work of bodies in waste management has increased.www.nature.com/scientificreports/EU waste legislation is an essential factor in developing the policies and behavior of the inhabitants of these countries.For example, all interviewed respondents in Austria emphasized the role of regulations in promoting recycling 36 .
At the same time, EU countries have the opportunity to establish their national waste policy, which can be more stringent than EU policy (for example, Austria, Finland, and Sweden, which occupy positions in the top ten countries in waste management) 36 .In addition, the strategic approaches of countries occupying higher positions (Tables 5, 6) are based to a greater extent on the system of segregated waste collection by the population.The fact that waste segregation at the source of their generation is the most effective justifies it 37 .However, as a study 38 showed, based on an analysis of material and energy flow networks in EU countries, none of the country achieved near-maximum robustness of the material and energy flow networks (that is sustainable circular waste management systems) in the period 2010-2018; and none of the EU countries were recognized as energy selfsufficient in the period from 2004 to 2018 due to.This study notes that only Bulgaria and Germany sometimes had higher resilience values, while the Netherlands has an underlying increased fragility to shocks, despite having a more efficient system for handling its material flows and being a leader in CE in terms of material circularity and energy.Although incineration is not the preferred method because it is not environmentally friendly, in the Netherlands the decision to recycle or incinerate "is one of the most important issues in waste management" and has seen the country significantly reduce landfills and provide district heating and electricity in certain areas.On the other hand, new generation plants for the production of energy from waste are effective for processing large volumes of waste, so the demand for incinerated waste is growing 39 .Thus, in the EU countries there is heterogeneity in waste management, since some countries have settled on waste storage, others on incineration, and still others have a high level of waste recycling and energy recovery from it, although the level of waste generated per capita in these countries is very high.
It should be emphasized that concerning the EU countries, Poland's performance looks more attractive in some years, and according to the ranking results, Poland's position in the ranking among other studied EU countries annually improves from 25th place in 2014 and has been consistently ranked 16th-17th for the last 5 years (Tables 5, 6).
We should note that the quality of municipal waste management is significantly differentiated by country.It is evidenced by the ratio of the maximum synthetic value of Q i to the corresponding minimum at the level for each year under study (Table 7).
Thus, we can see that there has been no active development in Poland in recent years in this area, but at the same time, there has been no decrease in this level.

Testing the hypothesis about the significance of the calculated synthetic indicators
To understand the significance of the ranking results of EU countries obtained during the study period, the χ 2 r -Friedman's test was used, which compares three or more matching or paired groups.The results are presented in Table 8.
At the same time, χ 2 r -Friedman's test allows you to establish that the change in the values of indicators from condition to condition is not random, but it does not indicate the direction of changes and their causes.

Analysis of the dynamics of selective waste collection by the population in the voivodeships of Poland
Selective waste collection is the basis for more successful and efficient waste management.First, this helps to reduce the number of landfills for waste storage and the number of areas allocated for landfills.In Poland, there is a Decree of the Minister of the Environment No. 1 of December 29, 2016, on a detailed method for the selective collection of individual waste fractions 40 , which specifies which municipal waste is subject to separate mandatory collection; therefore, selective collection of waste by the population would necessarily be carried out to a greater extent or lesser degree.www.nature.com/scientificreports/According to the Central Statistical Office in Poland (GUS) 30 , which maintains statistics regularly, we can see the following over the past 20 years (2002-2021).The population of Poland (Fig. 11) has had different dynamics since 2002, but after 2010, it has been constantly decreasing, while there has also been a slight decrease in the urban population from 61 to 59% 30 .However, the country's total amount of municipal waste continues to grow (Fig. 12).
According to the ranking of voivodeships in 2015 20 , the highest level of waste management is Mazowieckie voivodeship.Four voivodships have a high level, among which Śląskie and Wielkopolskie have average indicators, Lubuskie and Łódzkie can act as representatives of the average level of waste management, and Lubelskie and Podkarpackie voivodeships have the lowest level of development.MSW generation is growing in all voivodeships, including the 7 above (Fig. 13).
It is interesting that the population density in these 7 voivodships mainly decreases slightly (by 1.9-4.8%),except for the Mazowieckie (+ 3.1%) and Wielkopolskie (+ 0.7%) voivodships (Fig. 14).We can also note that the total amount of waste per 1 km 2 and selectively collected waste per 1 km 2 has increased significantly, with the amount of selectively collected waste per 1 km 2 increasing by 1.7-3.1 times in 2021 compared to 2015, in contrast to 1.2-1.4times for the total amount of waste.This proves the positive attitude of residents towards waste segregation at the source.This indicator is reliable because it shows the actual behavior of residents, and not the declarative attitudes that are often obtained in surveys.
Lubelskie became the leader among the studied voivodships, where the total waste production per 1 km 2 increased by 1.4 times (the decrease in population density is 4.8%), while selective waste per 1 km 2 increased by 3.1 times, which is 50% of the total waste collected in 2021 compared to 22.7% in 2015 (Table 9).However, no one knows how long the selective collection of municipal waste can be effective without additional incentives and motivation.
Table 9 shows that the amount of mixed waste is decreasing but still significantly prevailing since less than half of the total amount of municipal waste collected was selectively collected.www.nature.com/scientificreports/It is essential that among municipal solid waste, a significant part is food or kitchen waste from households, nonhazardous biodegradable waste from gardens or parks, offices, points and catering establishments or retail stores, as well as comparable waste from the food industry and plants (Table 10).

Discussion
In the context of recycling and the circular economy, biowaste can be a source of humus and compost, and most importantly, being highly fermentable, biowaste is a source of energy (in the form of biogas that can be injected into a gas or heating network).Researchers in 43 predict that by 2024 the total amount of waste will increase by 2%, and the amount of household waste generated will increase by approximately 10%.The amount of waste generated is influenced by the behavior and customs of the residents, including gender, marital status, education and age, education and employment, as well as actions and rules related to waste management 43,44 .Following these predictions and what was said earlier, municipal solid waste can be considered as a sustainable resource for energy production.Thus, in Sweden, it was stated that biowaste processing is a success in waste management; there is also a demand for biogas in the country, which is another important factor 36 .In Finland, the interviewed waste experts stated that biowaste represents the most potential waste stream regarding increased recycling 36 .Therefore, the preferred direction is the segregation collection of such waste, and following Decree 40 , it must be collected selectively.
While other categories of waste include packaging, paper (cardboard), and wood waste, some types of plastics are also of interest as an energy resource 2 and should be collected selectively.
One of the elements of the selective collection of domestic waste in Poland is a system of points for the collection of oversized, electronic, hazardous, and other municipal waste that does not fall under the categories of "plastic," "metal," "glass," "paper and cardboard," "biowaste".
Household waste selective collection points (HWSCP) operate under the provisions of the Act of September 13, 1996, to maintain cleanliness and order in communities and are designed to receive used items intended for reuse and repair.These facilities, as elements of the waste management system, are funded by the municipal waste management fee of commune's waste management system, although they sometimes charge for replacement items, which may represent additional income to cover operating costs.The HWSCP system in voivodeships is being developed to cover more territories, including rural territories, for the convenience of the population 30 .First, this excludes (prevents) the formation of illegal waste dumps and environmental pollution, and second, it provides a raw material resource ready for processing following its physical and chemical characteristics.• In 2019, 33.3% of Poles surveyed said they did not know how to reduce waste, 27.7% considered reducing the amount of waste they produced was not vital to them, and 48.2% avoided disposable/perishable products and declared the use of reusable packages 22 .
Based on the results, we can say that people's behavior is constantly changing depending on random external factors, and at present, there are no traditions among the population in the field of waste reduction.However, a survey 22 shows that Polish citizens take various actions to minimize the generated waste, and 70.7% provide waste sorting.

Conclusions
1.The study shows that the production of the total amount of waste in Poland and the amount of waste per capita has constantly been increasing since 2014 while maintaining a stable record of waste and analysis of the situation, providing funding for the operation of the waste management system, and carrying out informative, educational and monitoring work to reduce waste.2. The conducted research allowed obtaining a positive answer to question 1 posed in the introduction: municipal waste can be one of the sustainable sources of energy in Poland.This is evidenced directly by the increase in energy recovery from waste (R1-Recovery-energy recovery), as well as indirectly by the increase in the amount of waste segregated at source, which allows for methane fermentation of biodegradable waste (R3-Recovery-biological methods), and also increases the efficiency of recovery R1. 3.According to the ranking of EU countries according to the TOPSIS method, it can be seen that in recent years, there has been no active development of Poland in the field of waste management compared to other EU countries, but at the same time, there has been no decrease in this level.Poland has consistently ranked 16th-17th in the last 5 years.At the same time, at the level of statistical significance p < 0.01, there are significant nonrandom differences between the values of synthetic indicators Qi obtained by the TOPSIS method.4. In each of the 7 surveyed voivodeships in Poland, in the years 2015-2021, there was a significant increase in selective waste collection, and in one of them it was as much as twofold.This proves the positive attitude of residents towards waste segregation at the source of its generation, which indirectly gives a positive answer to question 3, which is one of the research objectives.Raising citizen awareness can visibly affect the selective waste collection, which in turn will make it possible to apply modern recycling methods to them to generate energy, but this needs more research.Although in different years some studies in this area have been carried out, no systematic approach has been found in this direction or systematization of the available data (possibly due to the lack of the required amount of data). 5.It is recommended to carry out studies to determine the sensitivity of the relationship between the actions of the authorities and the generation of alternative energy from waste. https://doi.org/10.1038/s41598-023-48026-3www.nature.com/scientificreports/

Figure 1 .
Figure 1.Distribution of scientific research on solid waste management issues published from 2014 to 2021, by year of publication (349 documents).

Figure 2 .
Figure 2. Distribution of scientific research on municipal solid waste management, published from 2014 to 2021, by subject area (349 documents).

Figure 3 .
Figure 3. Analysis of matches by keywords of the created selection of documents (349 documents) for 2014-2021 related to solid waste management issues in Poland and EU countries.

Figure 4 .Figure 5 .
Figure 4. Identified keywords and connections between them that are most often repeated in the studied selection of publications.

Figure 6 .
Figure 6.Blue cluster of bibliometric analysis by keywords of a selection of documents (349 documents) from 2014 to 2021.

Figure 7 .
Figure 7. Green cluster of bibliometric analysis by keywords of a selection of documents (349 documents) from 2014 to 2021.

Figure 8 .
Figure 8. Methods of analysis identified using bibliometric analysis using keywords of a selection of documents (349 documents) from 2014 to 2021.

χ 2 r
-Friedman's test was applied to compare the synthetic indicators Q i of each country under study from 2014 to 2021 (c = 8 > 3) in the same sample of m = 30 EU countries.(7)

Figure 9 .
Figure 9.The range of tests (the figure was created by the authors in ArcGIS, background data source: Topographic Objects Database).

Figure 10 .
Figure 10.Statistical data on the generation of municipal waste in Poland concerning the total amount in the EU countries for 2002-2021 (data source Eurostat 29 , edited by the authors).

Figure 11 .
Figure 11.The amount of municipal waste generated per capita for the study period.

χ 2 r
(em) (c = 8, m = 30) = 65.49.χ 2 r (cr) (p < 0,01) = 18.48.χ 2 r (em) > χ 2r (cr).χ 2 r -Friedman's test showed that we should reject the H0 hypothesis about the randomness of synthetic indicators since the calculated value of the test statistics exceeded the critical value at the chosen level of statistical significance p = 0.01, i.e., the error of the first kind is less than 1%.Therefore, Poland's level of development in waste management, which it occupies among other EU countries over the studied 8 years, is not accidental and is the result of the influence of certain factors (p < 0.01, m = 30).

Figure 12 .
Figure 12.The population of Poland and the total amount of municipal waste for 2002-2021.

Figure 13 .
Figure 13.Dynamics of municipal waste in seven voivodships of Poland.

Table 2 .
Rationale for the selection of diagnostic features for the current study.
when Cj is a benefit attribute max i v ij , when Cj is a cost attribute

Table 4 .
Dynamics of changes in municipal waste generation.*Δ is the increase in the amount of waste compared to the previous year.

Table 5 .
The values of the synthetic indicator Q i (i = 1, …, m) for the countries studied (according to the multi-criteria TOPSIS method).

Table 6 .
Summary table of ranks R i according to similarity to Q i in descending order to select the best alternatives (i = 1, …, m) (according to the multi-criteria TOPSIS method).

Table 7 .
The ratio of the maximum synthetic value to the corresponding minimum.

Table 8 .
The individual ranks of Poland and the sum of the ranks of EU countries as a whole for the period under study according to χ 2 r -Friedman's test.

Table 10 .
The content of biowaste in the total mass of MSW in different countries of the world.