Municipal solid waste management in Scandinavia and key factors for improved waste segregation: A review

The generation of solid waste, more specifically municipal solid waste (MSW), has been considered one of the major global environmental problems since urbanization started. Among Scandinavian states, Denmark and Norway have placed in the top positions (1 and 2 respectively) for high MSW production. Sweden has a steady plan for MSW management/treatments by practising material recycle, biological treatment and energy recovery. The aim of this review is to compare municipal waste generation between Sweden and the rest of Scandinavia. A systematic literature review was performed by screening academic and public articles to assess factors for better MSW management based on technological solutions. Key results include the importance of new tariffs and legislations, producer responsibilities for electronic products, municipality involvement, distribution of re-sponsibilities, and infrastructure developments for better MSW management in Sweden. The application of modern technologies have also been considered for MSW management in Sweden. Societal participation (will-ingness, awareness and concern) in Sweden also plays a significant role in MSW management. A better packaging system, application of interactive visualization (gamification) in waste sorting, public awareness, and infrastructure development could significantly improve the waste sorting process and conversion of waste management from a linear economy towards a circular economy.


Introduction
Solid waste generation/production has existed since human civilization started.Numerous anthropogenic activities actively produce various kinds of waste.The production of waste historically was not considered a problem due to the small size of the population compared with the present population and urbanization (Giusti, 2009).Waste production also strongly correlates with the income generation of the population of that particular country.A study has found that low-income countries contributed only 5% of global waste, whereas lower-middle, upper-middle, and high-income countries contributed 29%, 32% and 34%, respectively (Kaza et al. 2018;Maalouf & Mavropoulos, 2022).The global waste production has already reached the billion tonnes mark annually and it is continuously increasing among the regions, the top 3 locations are East Asia and Pacific (468MT), Europe and Central Asia (392 MT), South Asia (334MT) (Kaza et al., 2018;Cayumil et al., 2021).Along with the economic status of the country, rapid urbanization also plays a significant role in increasing waste production even in developing nations, as the studies have found that the citizens living in the urban areas of the Asia continent produce approximately 760×10 3 tons of municipal solid waste (MSW) daily, and this is predicted to increase to 1.8 million tonnes by 2025 (Pokhrel & Viraraghavan, 2005;Chattopadhyay et al., 2009).It has been speculated that the global waste production rate is relatively faster than the growth of urbanization.Both urbanization and the rapid incline of gross domestic product (GDP) play a vital role in patronizing waste production which is also reflected in China, parts of East Asia, and Middle and Eastern Europe (Hoornweg et al., 2013).With regards to waste production situation in the European Union (EU), approximately 500 million inhabitants generate more than 200 million tons of household waste annually (Bassi et al., 2017).
Waste management plays an essential role in maintaining the environment as well as the hygiene of the inhabitants, and that has been considered to be one of the major contemporary concerns for urban management.To provide a legal framework for waste management in the EU, the first directive was introduced in 2008 (Directive 2008/98/ EC), highlighting the importance of proper waste management, nutrient recovery and recycling procedures effects on the environment and humans (EU, 2022).Later, to announce the EU's circular economy concept in waste management, the directive was amended in 2018 (Directive (EU) 2018/851), strengthening the waste prevention process among the member states.This amendment has focused on biowaste, textile waste and hazardous waste material management establishment among the member states.According to the amendment, the biowaste needs to be collected separately and recycled at the source (ensured by 31 December 2023), and the separation of textiles and hazardous waste collection produced from the households needs to be launched (by 1 January 2025) (EU, 2018).Besides these directives, the EU also introduced the European Green Deal in 2019, focusing on the waste challenges and reducing emissions among the member states (European Commission, 2020;Papamichael et al., 2023).The EU introduced the waste framework directive in 2008 and also developed a European Waste Hierarchy (EWH) that included a number of steps such as prevention of waste, preparation of reuse, recycling and recovery and finally, disposal of waste (EU, 2008).Still, commodity production, use and disposal management utilize the linear economy model.In 2012, the EU member states (28) consumed 5 billion tonnes of materials.Source of materials from virgin and secondary raw material from waste was 80% and 20%, respectively, and this was an example of the linear economic model in the EU (EPRS, 2017).However, it has been predicted that such linear economic model (extraction-production-use-waste) could not persist in the long term because the volume of the resources is limited (Korhonen et al., 2018b).The global waste problem and management were also highlighted in the targets of several sustainable development goals (SDGs) announced by the United Nations (UN), which introduced the 2030 agenda for sustainable development.The waste related targets included in several SDGs such as; goal 11-sustainable cities and communities, 12-responsible consumption and production, and 14-Life below water (United Nations, 2015).
Waste production has been considered one of the major problems in the EU and creates pressure on the environmental sustainability of this region.Approximately 2.5 billion tonnes of waste were produced in EU member states in 2016, where the percentage of municipal solid waste was less than 10% (EP, 2021).Meanwhile, another report shows that 24% of MSW went to landfills where it significantly impacted groundwater contamination, methane production and losses of recyclable materials (Benetti, 2018;European Union, n.d.).The production of a high volume of MSW have also increased the resource mining /extraction processes three times higher than in the past four decades and the pace has not decreased (Schaffartzik et al., 2014;Wiedmann et al., 2015).Therefore, MSW has been considered a potential waste component that needs to go to recycling processes rather than being dumped in landfills.
Currently, the circular economy (CE) model has increasingly gained attention and exposure due to its concept of utilization of resources from waste products, so resources are used as long as possible or returned as nutrients to the biological cycles (Kirchherr et al., 2017).Some core ideas behind CE was first introduced in 1966 by the economist Kenneth Boulding (Boulding, 1966;Rathore and Sarmah, 2020).The definition of CE has been refined by a number of researchers based on their perspectives (reduce the input of virgin material and output of waste or another way to reduce, reuse and recycle materials in production) (Haas et al., 2015;Ma et al., 2015;Blomsma & Brennan, 2017).However, a recent definition of CE was also developed based on the production-consumption concept (Korhonen et al., 2018a).According to the European Parliament, the CE has been defined as the production-consumption model, which includes sharing, leasing, repairing, refurbishing, and recycling present materials and commodities as long as possible (EP, 2022).As such, CE is also a shift from the linear consumer norms in the existing consumer society (Hobson et al., 2021).
Waste management plays a vital role in the circular economy practice in the EU circular economy scheme as it is interconnected with the EWH framework (EC, 2015).The EU has also set a target for the reuse and recycling of municipal waste to ≥55% by 2025 and landfill waste to ≤10% by 2035, whereas Sweden has already reached for recycling and composting of municipal waste by 47% in 2017 and minimized landfill waste to 0% (EP, 2021).On the other hand, in 2018, the MSW produced in the US was 292.4 million US tones, recycled 23.6% (69 million tonnes) from them, and both the recycling and composting process have increased in comparison with the data from the 1960 s (US EPA, 2022).
Several reviews have been published focusing on improving solid waste management in different parts of the world in recent years.Those studies have indicated a number of factors, including design, process development, digitalization, production of value-added products, advancement of biogas plants for energy production, etc., that could play vital roles in efficient urban waste management (Kurniawan et al., 2022, Norouzi andDutta, 2022;Sondh et al., 2022,).However, to the best of our knowledge, no review has been published focusing on municipal solid waste management in the Nordic region and CE perspective.The main aims of this review are (1) Summarize the most updated and recent information and data on municipal waste production and disposal facilities in Scandinavian countries and compare it with Sweden and (2) assess the factors for better household waste management and present a framework for the application of technological solutions in the waste recycling process as part of the transition from a linear economy towards a circular economy.The purpose of this study is to provide an overview and key factors for effective municipal solid waste management, segregation in Scandinavia and their importance to the different actors (i.e., policymakers, municipalities, regional authorities, urban planners, academia, government organizations, etc) in different global regions to use the factors and their functions in their surrounding waste management system.

Methodology
The investigation was based on systematic literature review model (Fig. 1).Confirmed information was gathered from various sources through a screening of published literature (both academic and organizational sources and the language included English or Swedish) available from different search engines such as Web of Science (WoS), google scholar science direct, Eurostat (Database of European Commission), and websites of waste management organizations from the Scandinavian regions.Other search words were used during the literature search, for example, solid waste management + gamification, solid waste, circular economy, solid waste circular economy, waste manage-ment+Sweden, environmental management+gamification. Gamification was selected as an example of early technological development showing potential for the coming years.The results showed that Solid waste management-related documents are available from the Web of Science (articles 26, 265; review articles 2, 247 and book chapters 19).The solid waste circular economy-related documents are available from the Web of Science (articles 1846; review articles 416 and proceedings paper 44).The search words' circular economy and waste have brought relatively more documents (total 10, 880), including (articles 8776; review articles 1933 and book chapters 4).The search for 'gamification, waste management' yielded 31 documents (including 27 articles and review articles 4) results in the same database.Our search results showed that most of the literature was published during 2000-2022 time frame.

Waste production in Nordic countries
The trend of municipal waste production in Sweden has changed remarkably during the last two decades.According to Eurostat data, the production of waste (kg/capita) was 386 in 1995, and it has increased by 425 within the next five years (Eurostat, 2022a).The MSW generation per capita was (431 kg/capita in 2020), and it has increased (475 kg/capita in 2021) in Sweden (Eurostat, 2022b;Avfall Sverige, n. d.).However, the situation due to COVID-19 has also played an important role in waste generation worldwide.Studies have found that besides increased medical waste generation, the consumption of packed food during the homestay also increased during the pandemic, and both food waste and plastic package waste increased by 43% and 53%, respectively (Sinha et al., 2020;Filho et al., 2021).The Swedish Waste Association (Avfall Sverige-Swedish) includes several methods for waste treatment, such as; material recycling, biological treatment, energy recovery and the landfill system.Among these methods, the landfill approach has been under tax since 2000, and according to the national waste ordinance, combustible and organic waste were prohibited in landfilling in 2001and 2005, respectively (SFS, 2001;;Eriksson, 2003).
Among the Nordic countries, the MSW production (per capita) trend was highest for Denmark and scored above 800 kg /capita for 2011-20, and the second highest was found in Norway in the same duration (Eurostat, 2022b).The MSW production (per capita) in Norway ranged (from 422-485 kg/capita) in 2011-15.Then it sharply rose to 754 kg /capita in 2016, and the most recent data reports 776 kg /capita, whereas the average EU was 502 kg/capita in 2019 (Environment Norway, 2021;Eurostat, 2022a).However, Norway has several plans for both the reduction of waste material (reduce food waste by 50% by 2030) and double production of bioenergy (combined biomass and MSW) from 14 to 28 TW for better management of MSW (Malinauskaite et al., 2017).In 2020, most of the Nordic countries have reduced the annual municipal waste production (kg/capita) growth except Finland (+5.3%) (Fig. 2).According to a report from Avfall Sverige, 4.96 M tonnes of MSW were treated in Sweden in 2021, and this treated waste was divided into material recycling (31%), biological treatment (15%), energy recovery (50%) and landfill (0.9%), and with the exception of material recycling and biological treatment, the remaining two treatment percentages were increased compared with last year (Avfall Sverige, 2022a).Meanwhile, the recycling process of waste material in Norway is also similar to other Nordic countries, with both material recovery (35%) and energy production (40%) and a small proportion go to landfilling (Becidan et al., 2015).Denmark stands as the highest MSW-producing (per capita) country in the Scandinavian region, and it also used to process MSW by landfilling in the mid-80 s (33%) and it decreased to 19% and 4% in 199519% and 4% in and 200819% and 4% in , respectively (Kjaer, 2013)).In comparison to the MSW processing in the Scandinavian region, the trend in the US is far different from Sweden and the rest of the Nordic countries.According to the Environmental Protection Agency in US (US EPA), though most of the MSW was treated by landfilling (approximately 146 M US tons) (US EPA, 2022).

Waste management framework in Sweden
Sweden has a long history of the betterment of the environment and commitment to environmental protection.To maintain a balanced environment and reduce waste material in Sweden, the major environmental protection activities related to the new waste treatment was introduced in 1969 (Eionet, 2016).In the 90 s, several new regulations regarding waste management were introduced in Sweden.An act about producer responsibilities for certain type of products (ex; packaging, tyres, electrical and electronic equipment, vehicles) and the collection and treatment of household waste was introduced during the 90 s (SFS, 1997(SFS, , 1998;;Eriksson, 2003;Eriksson et al., 2005;Corvellec et al., 2012).According to the Swedish Environmental Protection Agency (Swe EPA), the MSW management responsibilities have been divided into several actors such as the households, extended producers' responsibilities (ESPR) and also the municipalities (total number 290) (Swedish EPA, n. d.).The municipalities have played an important role in Swedish Waste management as they are responsible for collecting, transporting, recovering and disposal of the MSW from households (Petersen & Berg, 2004;Andersson & Stage, 2018).Denmark also introduced its first national waste plan in 1992, and later they have also structured and designed four national waste plans to align closely alignment with European Union directives (Directive 2008/98/EC) (Iyamu et al., 2020).

Common current strategies for waste management in Sweden
Since 1930 Sweden has been planned for low-waste technologies and material recycling for maintaining a decreased volume of waste generation in society (Gutberlet et al., 2020).However, the Arab oil blockage crisis during mid-70 s impacted energy production in Sweden, and that incident initiate the building process of incinerators (Bergquist & Söderholm, 2016;Dzebo & Nykvist, 2017;Gutberlet et al., 2020).According to the Swedish Environmental Research Institute (IVL-In Swedish), a total 38 incineration plants have been established in Sweden.In the beginning decades of the millennium, the waste incineration process produced approximately 10-15% of municipal district heating in Sweden (Finnveden et al., 2007).However, in order to promote recycling of materials, a tax was introduced for waste incineration (2006-10), even though it had less impact (slight decline) on the demand for waste incineration (Furtenback, 2009;Werner, 2017).The Swedish district heating system was mainly dependent on fossil fuels especially in the 80 s, but later both waste incineration and biomass energy became larger contributors to heat energy production (Ericsson & Werner, 2016).As a result, the proportion of biomass, waste incineration and fossil fuels for the district heat production was 46%, 24% and 7% respectively in 2015 (Werner, 2017).Responsibility for Swedish waste management continues to depend on several actors such as; respective local authorities, manufacturers of commodities and other waste generators (including non-manufacturing industries and business) and the household waste management is placed under the responsibility of municipalities (Furtenback, 2009).

Infrastructure development
Household waste collection in Sweden has been also divided into several steps especially for those are living in a communal place.The steps begin after household waste generation, where the resident need to segregate different kinds of waste fractions, mainly food waste, newspapers and packaging (plastic, paper, coloured/transparent glass, metal) in their home.An example from a municipality using optical sorting is the segregation of food waste into green bags and mixed waste into red bags, and according to Avfall Sverige (in Swedish), food waste collection is present in 256 municipalities among the total of 290 municipalities in Sweden (Avfall Sverige, 2022b).Here, the mixed waste includes diapers, sanitary napkins, animal excreta, small trees and flowers, plant pots and tobacco, whereas food waste includes leftover foods, foods left to spoil mixed with edible portions and food portions that are discarded (Kretslopp Sydost, n.d.; Nunkoo et al., 2021) (Table 1, Fig. 3).As a general rule, mixed waste consists of waste that is not packaging material, hazardous waste or food waste.A study has reported that in three municipality areas of Denmark, the major parts of sorted/segregated waste from residential household waste are composed of food and miscellaneous waste, whereas the remaining paper, board and plastic percentage range between 5% and 15% (Edjabou et al., 2015).
Most of the household waste management (either community apartments or houses) follows several steps for waste sorting (Fig. 3).In most cases, the environmental houses for waste sorting can often be accessed by a certain number of apartments and their inhabitants in a specific area.One common way is to use a room or an environmental house close to the apartment block where a number of bins are placed for the sorting of the different kinds of waste fractions (Ibrahim, 2020).For those in single occupancy houses, the close proximity solution is to place plastic bins with smaller bins inside of them for the collection of fractions.Another solution is to have recycling stations placed in a public area for the inhabitants of apartments and houses.There are also recycling centres, accessible by all inhabitants in the municipality, that are often placed in the outskirts of the city.According to Swedish Waste Management, more than 600 recycling centres are established in Sweden and these see approximately 20 million visits per year where individuals drop off special type of waste products (Avfall Sverige, 2022c).Besides these, the available waste collection systems are also briefly discussed in Table 1.

Regulating factors for effective waste management
A number of factors play a role in better waste management, such as; physical, legislative, social, and behavioural factors.

Physical and legislative factors
The very first steps of waste management have started with sorting of waste materials.The sorting of waste materials also greatly depends on the convenience, the situation, and distribution of information as well as the culture of the inhabitants (Rousta et al., 2011).The segregation/sorting of waste on the household level in Sweden works to a high degree; however, there is still an issue with packaging not being segregated and thus incinerated with the mixed waste (FTI, n.d.).While most Swedes say that they recycle, this rate can be improved by addressing individual behaviour.
The convenience factor those could also be considered due to influencing physical factors for increasing waste management efficiency for example; the position of the waste deposition point, coloured bags for waste sorting, type of waste bins and also the placement of environmental houses for waste deposition (Rousta & Ekström, 2013;Amanidaz et al., 2019;Sörme et al., 2019).A recent study has found that the introduction of different coloured bags and provide kerb side waste drop-off facilities in Kalmar (a southern city of Sweden) was increased (35%) and residual waste was decreased (15%) (Sörme et al., 2019).Also, the waste sorting rate was increased by the introduction of white coloured (combustible waste) and black coloured plastic bags (food waste) 29 and 68 wt% respectively for municipal solid waste sorting in Borås, Sweden (Rousta & Ekström, 2013).In addition, the change of waste bin has also shown some positive impact especially cost-effectiveness (approx.54%), increased awareness of hygiene aspects and convenience of access (Amanidaz et al., 2019).The placement of the waste drop-point (distance from the house) has considered to be one of the important factors for successful waste management according to a Spanish study.By decreasing the distance between the house and the recycling bin, the number of citizens sorting their waste from their homes also increased (Gonzalez-Torre & Adenso-Diaz, 2005).Meanwhile, Ando & Gosselin. (2005) has also showed that the waste recycling rate could be increased by 66% when a doorstop collection was introduced instead of drop-off system and similar results were found in a questionnaire-based study in Sweden (Hage et al. 2009).
Alongside these physical factors, the governmental legislation and new regulations also played an important role for waste management and also the production of waste and their sorting processes during the drop-off of waste.For example; recently the Swedish EPA has initiated a roadmap for the sustainable use of plastics with focus on the development of the resource-efficiency use of plastic and reduction of the climate impact, leakage of plastic and microplastics in nature and so on (Naturvårdsverket, 2021).Besides this, the Swedish government has decided on a new ordinance (2022:1274) about producers' responsibilities for packaging (where producers need to have a permit from the Swedish EPA to collect packaging waste from the households) collection, and that would be implemented from 1st January 2023 (Naturvårdsverket, n.d.).This will play an important role for waste management, as most of the plastic wastes is currently considered under mixed waste-incineration-produce heat & power and also responsible for the emission of greenhouse gases (Nordin & Westöö, 2019).
The introduction of a weight-based tariff also plays a vital role for waste sorting processes as the lessening mixed waste and higher amount of collected plastic waste could be seen through the weight-based wastetariff introduced by the municipalities (Andersson & Stage, 2018;Hage et al., 2018).According to Swedish Waste Association report, 31 municipalities from Sweden have weight-based waste tariffs and the charge varies between (1.13-4.00SEK) and (0-3.43SEK) for residual waste and food waste respectively in 2021 (Avfall Sverige, 2022a).

Social factors
In addition to physical and legislative factors, the social and demographic factors play an important role for waste management.Rousta et al. (2015) has pointed out that knowledge about what to and where to sort out the waste fractions among the people also impact on recycling behaviour and that a lack of knowledge reduces the efficiency of waste management.It has already been revealed that a number of socioeconomic factors play an important role for municipal solid waste production/generation, such as; occupation, education, income scale and family composition (Bandara et al., 2007;Chen, 2018).Besides these personal features/factors, a study has considered that the social demographics also play an influential role along with economic incentives, awareness on knowledge, and system of collection (Sörme et al., 2019).However, the influence of social demographic variables can be doubtful and weakly correlated with waste sorting behaviour, for example if the local population already has a habit of segregating their waste (Hornik et al., 1995).A research investigation in Kiruna (1193 individuals), in the north of Sweden, found no effect of social demographic factors (for example; gender, marital status, number of children, type of house one lives in, house ownership, location (within town or outside town), dimension of house, employment condition and salary) on the influence of waste segregation behaviour (Vencatasawmy et al., 2000).In contrast, another study has found that both economic and moral motives influence inter-household recycling rates in several municipalities in Sweden (Hage et al. 2009).The opposite result was also found in an investigation in the US and showed that social demographic factors like; age, education, income and household size influence the use of drop-off recycling sites (Sidique et al. 2010).Economic status plays an important role in waste production as the economic development increases the food waste content (Wang & Wang, 2013).Ando & Gosselin. (2005) has also suggested that variations in housing types (occupant demographics) also play an important role in recycling rates.Several studies have found that the knowledge of the consumer and the assurance (commitment) to

Table 1
The common solid household waste sorting options in different cities in Sweden.

Structure Short description Illustration
Two bins system These two bin systems are mainly placed in single-family houses and row house systems.
This type includes two similar size bins with different colours; one is used for combustible waste, and another is used for biodegradable waste material (especially food waste).There are examples of bins within the bins for packaging waste as well.

Roadside bins
These bins are mostly placed at bus stops outside different buildings and close to shops.People can drop different kinds of waste, packaging waste and biodegradable waste in these bins.
These bins are placed for mixed municipal solid waste; a few have a separate section for dropping cigarette butts.
Optical sorting Different coloured bags are used for sorting different kinds of waste materials.
Different colour-based sorting system has been recently introduced in different parts of Sweden.Both the waste collection and sorting of recycled material have increased due this kind of collection system (Sörme et al.,2019)

Mixed waste fraction
The difference between optical illustration and mixed waste fraction whereas the waste materials are placed in the same container.The waste materials are placed in the same container but in different coloured bags.
The difference between the optical illustration and the mixed waste fraction is that the final sorting of the waste material would be performed in the main facilities for waste management by a mechanical system.

Sensory bin
These kinds of waste bins are mainly placed in the big shopping mall, and people can use them to deposit food waste and biodegradable products, e.g., paper cups, plates, and wooden cutleries.
The bin opening is activated when a human comes in front of the bin.This kind of bin could effectively reduce the smell of food waste.

Container collection
Placement of containers in recycling stations for public access Different containers have been placed in common places (close to a shopping mall or public area).Each container is marked with paper, plastic, and coloured and non-coloured glass materials.
(continued on next page) A. Sandhi and J. Rosenlund waste recycling are two factors that have been considered as inherent, whereas economic reward and social influence are also considered extrinsic factors (Castagna et al., 2013;Hornik et al., 1995;Rousta et al., 2015).

Behavioural factors
To implement and successfully continue municipal solid waste management (including waste generation and waste reduction), the acceptance and behaviour of the mass population are considered the diving factors (Pietzsch et al., 2017;Minelgait ė & Liobikien ė, 2019).The 3 R (reduce, reuse and recycle) behaviour of an individual towards waste management also need to be understood before establishing a waste management practice (Cecere et al., 2014).In the case of municipal solid waste management, both the lack of knowledge and social norms of the population play a significant barrier (Maycox, 2003).
Generally, the mass behaviour regarding waste management was found to be relatively country-specific in the EU.A recent study has found through analysing the municipal solid waste data (2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016) from the EU that some respondents from some countries (ex: Romania and Malta) were very rarely reduced waste, whereas the highest recycling behaviour was found in the respondents of Austria, Belgium and Germany (Minelgait ė & Liobikien ė, 2019).Age classification play an important role for waste sorting behaviour in human.A study has also revealed that the female college students were more concerned and separated MSW compared to male students in 10 different Chinese universities (Zhang et al., 2017).It could assume that the young generation could play a vital role for waste management from their behavioural point.Hedefalk et al. (2015) has also indicated that as a part of development of critical thinking development regarding the environment among children, the teacher needs to discuss the connection between the society and the environment with regard to role of separation of waste materials.Sweden has been considered one of the top countries in the EU due to creating awareness and a responsible approach among the inhabitants for municipal solid waste management (Nukusheva et al., 2023).Moreover, it has already reported that the adolescents can be more aware and future-oriented especially in the case of waste management (Prestin & Pearce, 2010).
Based on the review of this section, we can draw several outcomes.Initially that households interact with waste management both inside houses and apartments and in the outside environment as well as in The big containers and placed party below the surface soil and it could be accessible and nonaccessible based on their establishment authorities.
Several labelled containers (durable materials such as composite and aluminium) have been placed close to community places.A recently developed container can produce 50% less CO 2 than the surface-based container system ( Hellemaa, 2022) Mobile vacuum waste collection One of the modern technologies where bins are placed partly underground, and with the help of specially equipped vehicles, the stored waste material is collected 1-3 times a week Besides a sustainable and stable system, this system also reduces the bad odour from the waste materials.The access of rodents and insects towards waste materials also restricted due to the closed system (Aerbin, n.d.) Fig. 3. Access to different levels of waste sorting facilities from the complex community houses (green line) and single-family house (red line) residents.
A. Sandhi and J. Rosenlund between these two categories (Fig. 4, Table 1).We call these environments private, public and in between.Households also need to have knowledge about the waste system in both these contexts, correct behaviour as well as access to bins and correct placement of bins.Outside of the household, the distance is a factor, and sometimes it is necessary to transport waste to the recycling centres, for example; A culture of waste segregation can be developed within households, affecting the willingness to sort waste.We have used these categories of interest to develop a framework of challenges during municipal solid waste management (Fig. 4).This framework can be used to focus further studies in this area and the application of different technical solutions to target these challenges.To further identify the factors relevant for waste management and recycling we recommend that future studies examine how different technologies work in the three different contexts presented in Fig. 3.We also observed a lack of studies focusing on the relevance of purely physical properties such as hatches, rooms, and doors to impact willingness of mass population in the waste segregation process.

Technological factors
The gamification technologies have already included in several sectors such as education, health, marketing and environmental management.Application of gamification could also play an important role for household waste material segregation in different age levels.In environmental management-related games, the games play a significant role in encouraging people about ecological action and its consequences (Willoughby & Smith, 2016;Ouariachi et al., 2020;).However, game-based learning and gamification are different based on their perspectives.The game-based learning adds the actual game to provide knowledge and skill to the users (Jääskä et al., 2021).That is using mechanisms from games (such as point, leader boards, missions, achievements) to promote a good environmental behaviour.Shortly it can be defined as applying game design elements/segments in a non-game situation (Deterding et al. 2011;Helmefalk, 2019;Helmefalk & Rosenlund, 2020a).These can be used to connect the physical, behavioural, social and infrastructural levels as well as providing a bridge between the different contexts (Fig. 4).Several activities under the waste management scheme have been integrated with gamified approaches to perform tasks in a sustainable method, and it has been found that gamification could change human behaviour about recycling waste materials (Table 2) (Lidia et al., 2018;Aguiar-Castillo et al., 2019;Helmefalk & Rosenlund, 2020b;Papamichael et al., 2023).For example, learning about waste management at home by doing quizzes and challenges can improve the behaviour in open spaces.This can also reduce the distance between citizens and other stakeholders within the waste management system (Helmefalk et al., 2023).As such we suggest testing gamification solutions in different contexts (Fig. 3) and improving the use of different types of bins (Table 1).

Waste management within the circular economy
CE has a strategy of balancing the system of the natural environment by converting the linear economy model to a circular one and utilize the resources more efficiently.According to Dawson (2019) the circular economy focuses the optimization of the scheme where the maximum values could be achievable from the resources and also decreasing the waste effect towards the environment.In another context, CE practice in waste management mainly focuses on two things; 1) influence the production of sustainable products for long-term use, 2) introduction of new schemes for waste management scheme where producers and consumers also take responsibility for their waste generation (Negrete-Cardoso et al., 2022).The circular economy indicators also provide insights about the sustainability of the products.Regarding key performance indicators (KPI) for circular economy these can for example provide knowledge about product material use and recycling rates but might risk missing out on other aspects of the circular economy.A study has found that the indicators of a circular economy have mostly focused on the assessment based on the preservation of materials instead of the preservation of their functions (Moraga et al., 2019).Still, new digital technologies such as artificial intelligence (AI), internet of things (IoT) and possibly gamification can aid the important monitoring of the circular transition using both internal and external KPI (Papamichael et al., 2023).
Regarding waste management and circular economy strategies in Europe, it could be argued that the waste management strategies in the EU are increasingly moving towards alternative ways of management rather than traditional landfilling techniques.Current regulatory goals target to no more than 10% of MSW will be transferred to the landfill by 2035 (EU, 2018).The calorific value of municipal waste and its transform to the energy become one of the important factors that could help calculate the product value according to CE strategy (Malinauskaite et al., 2017;Negrete-Cardoso et al., 2022).Besides such technological and strategical development for the CE practices in solid waste management, strategy monitoring is also an important task to understand the situation of that particular municipality or region.The EU has initiated an assessment criteria for circular economy practices such as the circular economy monitoring framework (CEMF), and which should assess the progress towards the CE in EU states (EC, 2018).A recent study reported the application of the CEMF in Umeå, Sweden, and assessed the municipality's performance and the improvement needed in certain areas (Henrysson et al., 2022).

Conclusions
This article systematically reviews the current status of municipal solid waste management in the Nordic countries including current A. Sandhi and J. Rosenlund information about their production, management, infrastructure development, framework, influencing factors and circular economy perspectives.The effectiveness of different factors towards successful MSW management and their advantages and disadvantages were also discussed.In general, segregating waste at home has been considered one of the impactful methods for increasing efficiency in the waste management system.But this is not only the most impactful techniques, several other factors could also improve upon the existing waste management system both in Nordic countries and other countries dealing with high volume of MSW production, such as; 1) easy and informative labels of packaging for the right sorting process for the end user, 2) more awareness and motivational information for waste sorting process in the communal places, 3) distance to the sorting facilities as well as; 4) infrastructure development and promoting interactive sorting facilities to increase teenager participants.One of the major limitations for this project that most of the documents (including reports, policy papers) from different authorities are not searchable due to their absence in the internet and also, they are written in different Scandinavian languages.
Overall, the effectiveness and performance for the different factors also need to be investigated according to the socioeconomic condition of their citizens.Research on the infrastructure development and application of AI can be enhanced to be helpful for individual countries for their waste management strategies.Further research opportunities also exist by using gamification as a basis for intervention studies to improve waste sorting behaviour.The context where the research is done must also be considered due to its dependency on where the waste sorting behaviour is performed be it in a private, public or in-between space.
The take-home message from this review that there is no single method or factor that would solve the continuous MSW management issues in a particular region.Therefore, the policymakers need to emphasise both socioeconomic factors and advanced infrastructure developments in respective countries for a better management of MSW and harness it before it turns to be a national economic and environmental burden.

Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.A. Sandhi and J. Rosenlund

Fig. 4 .
Fig. 4. Challenges are classified into private (orange circle) and public (light green circle) for municipal solid waste management.The middle in between section defines the common challenges present in both conditions.

Table 2
Examples of gamification technologies for municipal waste management.