The waste separation behaviour of primary and middle school students and its influencing factors: Evidence from Yingtan City, China

Waste separation at source has been proved to be an effective way to reduce the amount of municipal solid waste (MSW) which has become a major challenge to China’s ecological environment. However, waste source separation requires effort from each individual citizen. As the important drivers of change and potential influencers of the future world, younger Chinese’s waste separation behaviour is crucial to the long-term successful implementation of China’s MSW separation policy. To explore the waste separation behaviour of younger Chinese and identify the factors that may influence their behaviour so as to better encourage younger generation of Chinese to practice waste sorting in their daily lives, a questionnaire survey of 579 primary and middle school (PMS) students aged between 6 and18 years old (y/o) was carried out in Yingtan City, Jiangxi Province, China. Binary logistic regression was adopted to explore the factors that might influence the respondents’ waste separation behaviour. The results indicate that more than half PMS students in Yingtan have participated in waste separation, and junior year students perform better in waste separation practice than their seniors. Students are found to have basic knowledge of MSW classification, but they are more familiar with recyclable waste and hazardous waste than non-recyclable waste. The analysis also highlights positive relationships between PMS students’ attitude to waste separation, their willingness to do it, their environmental education and their waste separation behaviour. The level of convenience of waste sorting facilities and influences from friends and families are also positively related to the students’ waste separation practice, but families have the strongest influence. The perception of a mandatory waste separation policy would demotivate students in terms of waste separation practice, while giving rewards is considered to be the most effective approach to encouraging waste separation. Finally, management strategies for improving PMS students’ waste separation behaviour are discussed and several recommendations for improvement are made.


Introduction
Mismanaged municipal solid waste (MSW) through unregulated dumping or open burning, has become a breeding ground for disease vectors, causes environmental concerns through greenhouse gas (especially methane) generation, and can even promote urban violence. At least 33% of solid waste worldwide and over 90% in low-income countries has been severely impacted by mismanaged MSW (The World Bank 2018. In recent years, municipal solid waste pollution has posed a great challenge to the ecological environment worldwide. The World Bank (2022) has estimated that 2.24 billion tonnes of MSW were generated in 2020 and without urgent action, this is expected to increase to 3.88 billion tonnes in 2050.
Both developed and developing countries have taken measures to manage the increasingly serious problem of MSW. However, effective waste management is expensive, and can cost up to 50% of municipal budgets (The World Bank 2022). A waste management system in general includes three stages; collecting and transporting (C&T), treating and disposing of solid material that is no longer useful by landfilling, sea dumping, incinerating and composting. Waste source separation is included in the C&T stage (Zhang et al 2022), and this refers to the separation of MSW into different waste categories for separate collection (Chen et al 2016). Waste separation can be achieved using separate bin services or through direct delivery of specific wastes to drop-off facilities. Different regions classify their waste in different ways. For example, Shanghai requires people to separate waste into four categories, i.e. residual waste, wet waste, recyclable waste, and hazardous waste, while Beijing classify their waste as kitchen, recyclable, hazardous, and other waste, and Zhengzhou's waste classification follows that of Beijing. Yingtain City in this paper classifies their waste into three categories; recyclable, non-recyclable and hazardous waste.
The objective of waste separation is to divert waste for treatment, recovering what can be directly reused and what can be reused after treatment (e.g. composting), after which non-recyclable waste is disposed of by incineration or landfill. The role of waste source separation is to try and reduce the waste that goes to landfill, in order to make it cheaper and more environmentally friendly to dispose the waste. In addition, good source separation reduces contamination and improves the quality of recycled products. By practicing the 3R principles (reduce, reuse, and recycle), good MSW source separation has been widely recognized as a means for effective waste management Wen 2014, Wang et al 2020a). For example, the Western Australian Authority adopted a three-bin system for source separation of household waste in South Australia, New South Wales and Victoria, and achieved 50%-60% recycling rates in these regions in 2014, which is significantly higher than other regions (Western Authority 2014). By encouraging source separation of waste in 1976, the recovery rate for recycling in the United States had been steadily increased and reached 35% in 2011 (ibid). Some Hong Kong (HK) households doubled the quantity of recyclables they recovered after implementing a trial programme of source separation of domestic waste, and some of them also earned extra income from selling recyclable materials which can be used to reduce the costs associated with management (Environmental department of HK 2021). Xu et al (2015) found a waste reduction rate of 87.3% after conducting a small-scale incentive-based source separation model in Guiyang, China. After one year's mandatory waste source separation, Shanghai reported a 71.1% increase in recycle rate (Shanghai Gov 2020). Of course, there are other waste management pathways apart from waste source separation, for example, Delhi employed centralized waste-to-energy (WTE) as a solution to its solid waste crisis (Randhawa et al 2020).
Citizen engagement (i.e. encouraging behaviour change and public participation) has been recommended by the World Bank (2022) as critical to good waste separation and hence to the success of a sustainable waste management system, especially for developing countries where financial constrains are more obvious in terms of waste management. Many developing countries, such as Nepal, Philippines and Thailand, have launched strong citizen engagement initiatives to motivate waste source separation, reuse and recycling. In Panaji City of India, a public campaign called 'Bin Free in 2003' was launched which promoted source separation by engaging local school students, celebrities, business leaders and civic bodies, and also via cultural programmes ranging from music festivals to carnivals. A programme called 'Waste Wise' was also launched in local schools to provide incentives for environmentally friendly behaviour of school students (The World Bank 2022).
Along with its rapid industrialization and urbanization, China has become the biggest MSW producer in the world, accounting for over 15% of the global MSW volume in 2018 (Guo et al 2021). The total volume of MSW in China increased from 155.10 million tonnes (Mt) in 2004 to 242.06 Mt in 2019 (NBSC 2019). The World Economic Forum estimates that China will produce double the amount of household waste generated in America by 2030. To respond to this challenge of MSW production and management, China launched a smallscale waste separation programme in eight cities in the early 2000s, but this programme failed due to factors such as the lack of citizens' willingness to separate waste, inadequate infrastructure and technology, poor coordination among the various government institutions and weak enforcement (Zhou et al 2019). In March 2017 a more ambitious national plan 'The Implementation Plan of Waste Separation' was launched, which urged 46 major cities nationwide to carry out mandatory waste separation by 2020 (NDRC and MHURDC 2017). In June 2019, all prefecture-level cities were required to pass local regulations to adopt mandatory waste separation policy by 2025. On 1st July 2019, the first local mandatory regulation on MSW separation in China came into force in Shanghai City (SMPC 2019), which ushered in China's mandatory waste separation era. Following Shanghai, other cities, such as Beijing (BMPC 2019), Zhengzhou (ZCAB 2019), etc have gradually implemented the mandatory waste separation policy. Mandatory waste separation policy seems to have become the main solution to China's MSW problem, at least for the state government (Wang and Jiang 2020).
However, public support of mandatory waste separation and their willingness to participate is only high in the short term, and considering the cost of long-term enforcement of the mandatory policy, exploring the key determinants of people's waste separation action so as to facilitate a longer term behaviour change would be more cost effective and sustainable (Ayob andSheau-Ting 2016, Hou et al 2020), and that is the focus of this paper. Given the importance of the topic, it is not surprising that much empirical work has been done to explore the influencing factors of people's waste separation practice and different approaches have been employed.
Empirical studies designed to explore the factors that affect people's participation in waste separation based on the source of motivation typically divide the factors into two groups, namely internal/intrinsic motivation and external/extrinsic motivation (Xu et al 2018, Chen et al 2019, He et al 2020, Yuan et al 2022. Internal motivations mainly comprise individual psychological factors (e.g. attitude towards waste separation, willingness to separate waste, environmental awareness and ecological values) and their environmental knowledge. Lou et al (2020), Razali et al (2020) and Govindan et al (2022) employed the Theory of Planned Behaviour (TPB) to identify factors that influence waste source separation behaviour. TPB links beliefs to behaviour by including perceived behaviour control into the Theory of Reasoned Action (TRA) which predicts behaviours that are under a person's control. According to TPB, an individual's behaviour is controlled by six factors i.e. attitude, behaviour intention, subjective norms, perceive power and perceived behavioural control (Kan and Fabrigar 2017). Other researchers have used the knowledge, Attitude, Practices (KAP) model to identify factors that affect people's waste separation behaviour (Banga 2011, Laor et al 2018, Almasi et al 2019, Zand et al 2020. KAP is a quantitative method that reveals factors which may affect behaviour change (Monde 2011). However, both TPB and KAP require the survey questions to be designed in a specific format (i.e. 5 point Likert Scale for TPB, and standardized questionnaires for KAP). An alternative approach would be to include closed and open-ended questions in order to capture more detailed information from the respondents. Hence this paper is based on an approach which categorizes the influencing factors into internal and external factors.
As one of the internal factors, attitude has been found to be a very important predictor of waste separation behaviour; the more positive the attitude then the better the behaviour (Hao et al 2018, Árnadóttir et al 2019, Fan et al 2019. However, Dai et al (2017) found that there was no significant connection between waste separation behaviour of college students and urban residents in Zhengzhou, China and their attitude towards waste separation. Ajzen and Fishbein (1977) reported that people's behaviour was largely determined by their willingness to perform that behaviour; the higher the willingness then the better the behaviour. Empirical evidence of this relationship has also been found in several studies in other areas of waste management practice. For example, Zhang et al (2015) found that urban residents' willingness to recycle household waste was a factor positively affecting their waste recycling activities in Guangzhou, China. By analysing sample data of 2226 college students from four countries (United States, Spain, Mexico, and Brazil), Vicente-Molina et al (2013) found that college students' environmental knowledge positively affected their pro-environmental behaviour. Similarly, Arain et al (2020) evaluated consumer behaviour surrounding e-waste recycling at a university in Midwestern U.S. and found that respondents with more knowledge in e-waste were more likely to have proenvironmental practices when dealing with that form of waste. However, the results of such studies were not unanimous. For example, Alp et al (2008) found no significant correlation between environmental knowledge and waste recycling behaviour for primary school students in Turkey.
External motivations (also called contextual factors and situational factors) refer to the external environment that individuals face when making environmental behaviour choices, including the degree of convenience of waste sorting infrastructure, environmental education, mandatory measures on waste separation, peer pressure, etc , Fan et al 2019, Wut et al 2020. It has been confirmed that good situational factors may facilitate people's pro-environmental behaviour. For instance, the survey conducted by Leeabai et al (2019) demonstrated that waste separation efficiency increased when the location of trash bins was placed at convenient sites for students and staff in Fukuoka University, Japan. The state of a MSW source separation system, especially the degree of convenience of the waste sorting facilities and collection infrastructure, could significantly influence people's perceived cost of waste separation (i.e. the time and effort spent on waste sorting), and finally lead to different behaviour (Chu et al 2016. Some studies found that raising public awareness of environmental protection, and making relevant laws and policies was very important for improving people's waste management behaviour Wen 2014, Zhu 2018). Zsóka et al (2013) found that environmental publicity and education were significantly and positively related to proenvironmental behaviour of high school and university students in Hungary. Empirical studies performed by Chen et al (2018) found that mandatory waste separation policy significantly affected people's waste separation behaviour in Nanjing, China, and the waste source-separation rate increased by 49.7% in the presence of the mandatory policy. Similarly, in Zhengzhou, China, Hao et al (2020) found that college students' waste separation behaviour had improved from 10.1% to 17.8% after the mandatory policy took effect. Moreover, a number of studies showed that people's waste separation behaviour was influenced by external social pressure (i.e. pressure from groups or other individuals who they considered important) (Nguyen et al 2015. Zhang et al (2017) argued that in Beijing, college students' waste separation behaviour was very similar to that of their friends and parents. By surveying young people in Hong Kong, Wut et al (2020) pointed out that peoples' pro-environmental behaviour was affected by social pressure from their family, friends and neighbours.
In addition to internal and external motivation, common demographic information (i.e. gender, age, education level and income) are also widely discussed as factors that may affect people's waste separation and recycling behaviour. Some studies found that women (Fan et al 2019), elderly people Wen 2014, Fan et al 2019), highly educated people (Grazhdani 2015) and high-income people (Diamantopoulos et al 2003, Gelissen 2007 were more likely to participate in waste management activities. However, different conclusions have been reached by Baur and Haase (2015) and Ari and Yilmaz (2017) who found that gender had no effect on environmental behaviour for primary school students in Germany and middle school students in Turkey. Additionally, some demographic characteristics specific to students, such as grade, were also discussed. By surveying primary and middle school (PMS) students in different schools in Italy, Rada et al (2016) found that primary school students performed better in waste separation than middle students. However, Lchsan et al (2019) found, after surveying 128 grade seven students and 128 grade eight students in Indonesia, that whether or not a student would participate in waste separation was not statistically related to their grade.
The above literature review indicates that young people's waste separation behaviour has been less studied relative to that of adults. The notable exceptions to this are studies focused on elementary schools in Turkey (Alp et al 2008), classroom intervention of pupils (10-12 y/o) in Germany (Baur and Haase 2015), 6-18 y/o students in Italy (Rada et al 2016), and grade 7 and 8 students in Indonesia (Lchsan et al 2019). This lack of research on the waste separation behaviour of young people is also the case in China. Although Liao and Li (2019) studied Chinese high school student's (16-18 y/o) waste separation intention, they focused only on students' oncampus behaviour. However, young people i.e. PMS students are an important target audience of environmental education (Boeve-de Pauw et al 2011) and they have a vital role to play in addressing environmental and sustainability challenges (Gusmerotti et al 2016). In addition, the primary school period is considered to be a good starting point for producing environmentally literate citizens who have the necessary skills and awareness to address challenges and to take environmentally friendly actions (Alp et al 2008). If children could develop positive attitudes toward the environment during their early years, such attitudes are likely to become deeply entrenched (Stapp 1978). Furthermore, developing the habit of MSW separation is a long-term process and it should start as early as possible (Chapman and Sharma 2001). Most PMS students attend day schools and share the after-school time with their families. Hence, they could share their informed views and skills about environmental protection with other members of the family and motivate behavioural changes in their parents' (Kasapoğlu andTuran 2008, Rada et al 2016).
Moreover, most studies on people's waste separation behaviour have been conducted in large metropolitan areas such as Beijing . Few studies have looked at the waste separation behaviour of people in small and medium-sized Chinese cities i.e., cities with a permanent urban population of 0.5 million to 1 million (CSC 2014). However, the number of small and medium-sized cities in mainland China had reached 2809 by the end of 2020, and their combined administrative area covered 9.34 million square kilometres, accounting for 97.3% of the total land area in China (NBSC 2021). The population of small and medium-sized Chinese cities was 118.1 million in 2020, accounting for 84.7% of the total population in China (ibid). In addition, the Chinese government has been trying to coordinate the development of small, medium and large cities (Zhang 2018), and strengthening the green development of such cities will become an important focus in the next 20 years (RIDS 2010, People's Daily 2016). However, compared with the larger cities, Chinese small and medium-sized cities are facing more severe challenges in MSW management because of their lower economic development level, ineffective enforcement of relevant regulations and people's lack of environmental awareness (Xue et al 2011). The larger cities have more resources available to bring about positive change in waste separation behaviour, but how to achieve this change within the small and medium-sized cities is a question that requires far more consideration than it has to date.
To fill these important gaps in knowledge, the research described in this paper sought to explore the factors that influence waste separation behaviour of PMS students in Yingtan City, a small and medium-sized city in southeast China. A total of 579 PMS students aged between 6 and 18 y/o studying in the city responded to a survey about their daily practices toward waste (recyclable, non-recyclable and hazardous) separation. Following the introduction, methodology employed in this study will be introduced in section 2, including the sampling method, data collection and data analysis. Empirical results and discussion are presented in section 3. Measures for improvement and conclusions are set out in sections 4 and 5 respectively.

City backgrounds
As shown in figure 1, Yingtan is a prefecture-level city of Jiangxi province, southeast China. It covers an area of 3556.7 km 2 with an urban population of 0.733 million at the end of 2019 (YCBS 2020), in 2020, Yingtan City had a GDP of 98.266 billion yuan, an increase of 4.0% compared to 2019 (YCBS 2021). Based on its population, Yingtan is a typical small and medium-sized Chinese city (CSC 2014).
Yingtan City started urban waste separation in 2019 via the 'Implementation Plan of Urban Domestic Waste Classification Project' (thereinafter referred to as the 'Implementation Plan'). According to the Implementation Plan, waste separation pilot areas would be set up in Meiyuan Street, Yuehu District in 2020, and the pilot area would be expanded to the whole of Yuehu District in 2022. By 2025 an urban household waste separation management system would be established for all parts of the city (YCMB 2020). The Implementation Plan also classified the solid waste in Yingtan City into three categories i.e., recyclable waste, non-recyclable waste and hazardous waste. Recyclable waste refers to the waste that can be processed and used again, and includes many kinds of glass, paper, metal, plastic, textiles, electronics goods, etc Non-recyclable waste comprises single-use materials, such as plastic bags, polystyrene cups and disposable nappies, hazardous waste has dangerous or toxic properties that could cause harm to human health or the environment and includes fertilizers, motor oil, paints, detergents, batteries and Mercury thermostats. The Educational Department of Yingtan City was requested by the Implementation Plan to include waste separation related education in the school curriculum so as to increase PMS students' awareness to waste separation. At the same time, the Implementation Plan hoped that the parents would be influenced by their children in their understanding of the importance of waste separation, which would eventually to lead to a higher participation rate of community waste separation.

Survey design and data collection
Based on a review of the literature, a pilot study was carried out in April 2020, and following this a semistructured questionnaire comprising a mix of closed and open-ended questions was designed to explore PMS students' waste separation behaviour and the factors that may influence it. The questionnaire comprised five sections. The first section looked at the demographic information of the surveyed students i.e. gender and the grade (in China, grades 1-6 are in primary school for children aged 6-12 y/o, grades 7-9 junior middle school for 13-15 y/o and grades 10-12 senior middle school for 16-18 y/o) they were in. The second section explored students' waste source separation behaviour in general (i.e. in school, at home and outside of the school and home), and the reasons for their behaviour. Based on students' answers to a single-choice question: 'do you participate in waste separation?' their waste separation behaviours were grouped into two: good and poor. Students who always and often separated their waste were considered to have good waste separation behaviour, and students who rarely and never do waste separation were considered to have poor waste separation behaviour. Multiple-choice questions were then asked to the students with good waste separation behaviour regarding the reasons for doing waste separation, and the ones with poor waste separation behaviour regarding their reasons for not doing waste separation. The third section sought to explore the internal factors of the students' waste separation behaviour (i.e. attitude towards waste separation, willingness to do waste separation and their knowledge of a related field). The external factors (i.e. environmental publicity and education, the degree of convenience of waste sorting facilities, waste separation behaviour of the respondents' family members or friends and whether a mandatory regulation being in place) were covered in the fourth section. In this section, students were also asked to rank the effectiveness of measures such as 'punishing the bad waste separation behaviour', 'rewarding the good waste separation behaviour', or 'neither'. Finally, the fifth section was designed to explore the student's levels of general knowledge of waste separation, which is also called abstract knowledge (AK) (Mukherji et al 2016). Six types of waste were provided, and the students were asked to put them in the right categories based on the waste separation standard of Jangxi province (i.e., recyclable waste, hazardous waste and non-recyclable waste). It was assumed that the higher the accuracy of the responses then the better their knowledge of waste separation.
The survey was carried out in May 2020 when Jiangxi Province was classified as a low-risk area based on China's classification of COVID-19 risk levels (JPHC 2020) and all schools in the Province re-opened to their students and teachers although strict entry restrictions applied. A convenience sampling method was adopted. Six class teachers from six schools in Yingtan City (two primary schools, two junior middle schools and two senior middle schools) who had personal connection with the authors were contacted and became key informants. In China, all schools and most universities have class teachers who are in charge of the students in the class and take responsibility not only for the students' study but also their well-being. These class teachers also have a teaching role in their specialist subject.
Through the six key informants, eight other class teachers were contacted. Hence, a total of 14 class teachers (six in primary schools, four in junior middle schools and four in senior middle schools) were recruited to help with administering the questionnaire to the students in their classes. Survey skills training was provided on a one-to-one basis to the 14 class teachers via telephone and/or WeChat (a popular messaging app in China) before the questionnaire survey, and it was made clear that there was no reward for students who completed the questionnaire nor punishment for those who declined to complete it.
A total of 630 PMS students in grades 3-11 from two primary schools (210 students in grades 3-6), two junior middle schools (210 students in grades 7-8) and two senior middle schools (210 students in grade 11, see table 1) were surveyed. After screening out the questionnaires that were not completed, and the ones where the respondents did not follow the instruction after answering the initial 'filter' question (for example, students with poor waste separation behaviour were supposed to answer why they did not want to separate waste, instead, they answered why they did waste separation), 579 (91.9%) responses were considered valid, including 199 from primary school students, 206 from junior middle school students and 174 from senior middle school students.
In-depth phone/WeChat interviews were carried out with key informants (six class teachers and ten of the surveyed students introduced by the class teachers) after the questionnaire survey so as to cover the information gaps identified in the survey data. For example, after the survey results revealed the importance of environmental education in improving the students' waste separation behaviour, class teachers were asked about curriculum design, obstacles in conducting environmental education and possible solutions.
2.3. Estimation model SPSS 24.0 was employed to store and analyse the data from the survey. Crosstab analysis and Chi-square test were employed to explore the correlation between demographic factors of PMS students and their waste separation behaviour. The binary logistic regression model was adopted to explore the internal and external factors that might influence PMS students' waste separation behaviour.
The binary logistic regression model is an effective tool for measuring the relationship between binary categorical dependent variables and one or more independent variables by estimating probabilities using a logistic function (Bai et al 2015). This research considers waste separation behaviour to be the dependent variable. It is a binary variable coded as 0 or 1 to represent 'poor waste separation behaviour' and 'good waste separation behaviour' respectively. The factors that may affect the waste separation behaviour are taken as independent variables X i (i = 1, 2, K 8). They are also binary variables that can be coded as 0 or 1 (the meaning of '0's and '1's are shown in table 2). The binary logistic regression model is established as follows: Where P n is the probability that the nth respondent has good waste separation behaviour; is the odds that the nth respondent is likely to have good waste separation behaviour; X i denotes the sample value of the influencing factor (0 or 1); β 0 is the intercept; β i represents slope parameters.
Odds Ratio (OR) is used to measure the ratio of the odds that the respondent has a good waste separation behaviour to the odds that he/she has poor waste separation behaviour. The OR formula is as follows: In this study, the OR for any possible influencing factor X i indicates that when holding all other variables constant, the respondent is OR times more likely to have good waste separation behaviour when X 1 i = than when X 0. i = Hence when OR > 1, X 1 i = is a positive influencing factor, and when OR < 1, X 1 i = is a negative influencing factor, while when OR = 1, X i is not an influencing factor of waste separation behaviour.

Description of variables X i
The series of assumed (a priori based on existing literature) influencing factors of PMS students' waste separation behaviour are listed in table 2 and they are coded as '0' or '1'. X 1 -X 3 are possible internal influencing factors of PMS students' waste separation behaviour. X 1 assesses students' attitude towards waste separation. Respondents would be considered as having a positive attitude toward waste separation when they think the measures of waste sorting would help protect the environment, and in this case X 1 equals to '1'. They would be considered as having a negative attitude toward waste separation if they don't think so, and X 1 equals to '0'. X 2 asks whether the students are willing to separate waste; X 2 = 1 if the answer is yes, X 2 = 0 if it is no. X 3 assesses how well students are equipped with the knowledge of waste separation (X 3 = 1 if they have substantial knowledge, X 3 = 0 if they have little knowledge).
X 4 -X 8 are the assumed external influencing factors that may affect PMS students' waste separation behaviour. X 4 is an assessment of environmental education that Yingtan PMS students have received in school; X 4 = 1 when they received sufficient environmental education in school, X 4 = 0 when it is little. X 5 evaluates whether students think waste separation facilities are convenient and easy to use; X 5 = 1 when the answer is yes, X 5 = 0 when it is no. X 6 and X 7 evaluate influences of friends and the family on PMS students' waste separation behaviour would affect PMS students' behaviour. Because PMS students in China go home in the mid-day for lunch and after classes in the afternoon they spend almost as much time (if not more) with their family as they do with their friends. Hence it can be assumed that they are influenced by both family and friends. We consider X 6 = 1 when the families do waste separation, and X 7 = 1 when the friends do waste separation and X 6 and X 7 equals to zero when the families/friends do not do waste separation. Although mandatory regulation on waste separation has not been implemented in Yingtan City at the time of study, given the current trend in China, a mandatory waste separate policy should soon become a reality in the city. To find out the possible influence of a mandatory policy on PMS students, a hypothetical question was asked to the respondents: If mandatory waste To understand the incentives for and deterrents of good waste sorting behaviour, 226 respondents with good waste separation behaviour were asked the reasons they did waste separation, 353 respondents with poor waste separation behaviour were asked why they did not. The results are illustrated in figure 2. Figure 2(a) indicates that the care about the environment and their knowledge of the positive significance of waste separation for the environment was the leading reason that PMS students would maintain good waste separation behaviour (74.3%). The second incentive was having good waste sorting facilities (convenient and easy to use, 50.9%). Other incentives include having good knowledge of waste separation related topics (i.e. having posters around the campus and the community, 46.9%), less trouble (time and energy) involved in waste separation (44.2%), regulations from the school and discipline from the parents (35.8%), and positive influence from other people (30.5%). Figure 2(b) indicates that the number one reason for PMS students not doing waste separation was that people could not find a bin when they had waste to dump, or if they did find one, there were no clear signs on the bins to indicate separation (50.7%). The second popular reason was that waste separation is troublesome, especially the wet waste which is too dirty to separate (45.9%). The third reason was that the surveyed PMS students did not know how to separate waste (44.2%), within which around 22% are in the 7th grade, 17.6% in 7th grade, 7.8% in the 8th grade, 4.7% in the 5th and 6th grades respectively. Other reasons mentioned include the relevant regulation (14.2%), other individuals' waste separation behaviour (11.0%) and environmental awareness (5.9%). In addition, 2.8% had other reasons, for example, some students said they were too busy with their schoolwork to sort garbage.
Clearly, the waste separation behaviour of surveyed PMS students is influenced by their level of knowledge of the subject, the condition (whether it is convenient and easy to use) of the waste sorting facilities, how much trouble is involved in doing waste separation, whether there are regulations/disciplines from schools/parents and social pressure.

Demographic factor and PMS students' waste separation behaviour
To assess whether or not students' gender and their level of study (grade) are related to their waste separation behaviour, Cross-tab analysis and Chi-square tests between respondents' demographic information and their waste separation behaviour were performed and the results are shown in table 4. As shown in table 4, of the total respondents, 49.1% were male and 50.9% were female. Among male students, 42.3% regarded themselves as having good waste separation behaviour while 57.7% had poor waste separation behaviour. Among female students, 35.9% had good waste separation behaviour while 64.1% had poor behaviour. The Chi-square test result in table 4 indicates that whether students saw themselves as having good waste separation behaviour was not statistically related to their gender. This finding is consistent with that of Hao et al (2020) who surveyed 1747 university students in Zhengzhou City, China and found no statistically significant difference between male and female students regarding their waste separation behaviour. This finding echoes the results from Baur and Haase (2015) who found no significant difference between genders for German pupil in their environmental behaviour. The reason for this result, as indicated by Hao et al (2020), might be that parents in a family tend to share household chores in contemporary society and this may influence the waste separation behaviour of both their male and female children. However, this result is different from that of Alp et al (2008) who found girls have better environmental behaviour than boys in Turkish elementary schools. Clearly there is a need for more cross-culture study regarding the relationship between gender and environmental behaviour.
Table 4 also indicates that the respondents were almost equally distributed in primary school (34.4%), junior middle school (35.5%), and senior middle school (30.1%). Among 199 surveyed primary school students, 56.3% regarded themselves as having good waste separation behaviour while 43.7% had poor behaviour. Among 204 junior middle school students, 27.2% behaved better in waste separation practice while 72.8% behaved poorly. Among 174 senior middle school students, 33.3% behaved better in waste separation while 66.7% were poorly behaved. Chi-square test results indicates that students' behaviour in waste separation was significantly related to their level of study (p < 0.05); the higher the level of study the poorer the waste separation behaviour. This finding does not agree with Hao et al (2020) and Dai et al (2017), both of whom found that Chinese college students' waste separation behaviour improved with their years of study. The difference in results may be due to a different focus of education in Chinese universities and schools. While universities focus on the all-round development of students and university students have more opportunity and less academic pressure to develop their interests, schools, especially the senior middle schools, are more exam-oriented and they have to put more weight on high exam scores rather than quality education in areas such as environmental protection (Wang et al 2020b). Another reason for primary school students' better (than middle school ones) waste separation behaviour, as Krettenauer (2017) indicated, might be related to the feelings of connectedness with nature, and older adolescents have a lower preference for natural settings and enjoy nature less than younger students.

Factors influencing PMS students' waste separation behaviour
Results from the binary logistic regression are shown in table 5. The p-value obtained by the Hosmer-Lemeshow goodness of fit test (p = 0.214) is greater than 0.05, indicating that there is no significant difference between the expected frequency obtained by the predicted probability and the one by observed data, i.e., this model fits the data well (Wu 2010). With a predictive accuracy of 77.7%, the binary logistic regression result from this model is considered to be consistent with the survey result. Thus, the model fits the sample data well and the result has statistical significance (Wang and Guo 2001).
Table 5 also indicates that internal influencing factors such as attitude towards waste separation and willingness to do waste separation have a statistically significant effect on the self-reported waste separation behaviour of PMS students (p < 0.05). But having waste separation knowledge is independent from waste separation behaviour (p = 0.142). All external factors i.e., environmental education, level of convenience of waste sorting facilities, family and friends' waste separation behaviour, and whether or not there is a mandatory regulation in place are significantly related to PMS students' waste separation behaviour (p < 0.05).

Attitude towards waste separation
As shown in table 5, PMS students' attitude towards waste separation has a significant positive effect on their waste separation behaviour (B = 0.598, p = 0.030). The odds of PMS students who have a positive attitude towards waste separation also having good waste separation behaviour is 1.819 times that of those who had a negative attitude towards waste separation (OR = 1.819). This result agrees with Liao and Li (2019) who studied 562 high school students around China and found that the students' pro-environmental attitude has a positive influence on their intention to separate waste. It is also in line with the results from Ari and Yilmaz (2017) who investigated the pro-environmental behaviour among middle school students in Turkey and found that the presence of a positive attitude toward the environment led students to display pro-environmental behaviours. The finding in the study echoes that of Gusmerotti et al (2016) regarding Italian junior high school students' pro-environmental behaviour and that of Hao et al (2020) regarding Chinese college students' waste separation behaviour. Table 5 also indicates that there is a significant positive correlation between PMS students' willingness to separate waste and their waste separation behaviour (B = 0.444, p = 0.040); the higher the willingness, the better the pro-environment behaviour. The odds of PMS students who are willing to participate in waste separation practice and having a good waste separation behaviour is 1.559 times that of those who are unwilling to participate (OR = 1.559). This echoes Hao's et al (2020) result that higher willingness to do waste separation is related to better waste separation behaviour for college student in Zhengzhou City, China. A further question was asked to explore which type of waste (hazardous, recyclable and non-recyclable) the Yingtan PMS students were more willing to separate and why. It was found that Yingtan's PMS students were most willing to separate recyclable waste (77.9%, see figure 3) followed by hazardous waste (52.8%), and they are least willing to separate non-recyclable waste (28.8%). As for the reasons of the different level of willingness towards different type of waste, as one of the respondents indicated in a telephone interview, food leftovers (nonrecyclable) were more troublesome to dispose than plastic bottles (recyclable), and people often did not know how to dispose of hazardous waste properly and hazardous waste specific bins were not easy to find. Hence how much trouble is involved in undertaking waste separation and the convenience of the waste sorting facility are key factors determining PMS students' willingness to separate waste. This result was reflected in the reasons that PMS student would/would not do waste separation in figure 2.

Willingness to separate waste
This result also coincides with the finding of Boyes et al (2009). By looking at Australian secondary school students' willingness to take climate change action and their perceived value of such action, Boyes et al (2009) found that willingness to engage in behaviours that involve minimal inconvenience such as switching off unused electrical appliances and the ones that are well embedded in social practice such as recycling often exceeds the perceived benefit/utility of those behaviours. On the other hand, students' willingness to take proenvironmental action that may cause personal inconvenience (e.g. using public transport rather than owning a private car) were found to be less than might be expected (Boyes et al 2009)   different measures to persuade people to adopt pro-environmental practices i.e., to strengthen environmental education in areas concerning minimal personal inconvenience and to adopt other approaches/inducements in areas concerning personal inconvenience.

Knowledge of waste separation
It can also be seen from table 5 that PMS students' knowledge of waste separation (i.e. AK) was not significantly related to their waste separation behaviour (p=0.142). Clearly, for PMS students in Yingtan, those who are more equipped with waste separation knowledge are not necessarily the ones who would have good waste separation behaviour, and vice versa. This echoes the results of Baur and Haase (2015) that knowledge about waste separation has no effect on environmental behaviour for German secondary pupils and of Alp et al (2008) that Turkish elementary school students' behaviour towards the environment is independent from their environmental knowledge, but disagrees with the finding for college students and community residents that more environmental knowledge leads to better waste separation practice To further understand how equipped Chinese PMS students are with waste separation related knowledge (AK), a list of different types of waste was provided and the students were asked to put them in the right categories based on the waste separation standard of Jangxi province (i.e. recyclable waste, hazardous waste and non-recyclable waste). Paint was chosen because PMS students in China, like elsewhere in the world, have art classes such as painting, music, calligraphy, etc Therefore, PMS students might have good access to paint. Medicine was chosen because many parents in China have leftover prescription drugs and expired over-thecounter medication at home that their children might have easy access to.
A summary of students' answers is shown in table 6. The accuracy rate i.e. the percentage of students who gave the correct answer to each type of waste is also provided in table 6. Table 6 indicates that more than 90% of PMS students in Yingtan could make a correct categorization of recyclable waste (i.e. newspapers and plastic bottles), indicating their good knowledge of recyclable waste. But the accuracy rate for hazardous waste (i.e., paint and medicine) was a little lower (84.8% and 84.3%). The lowest accuracy rate (80% and 71.5%) was found for non-recyclable waste (i.e., fruit residues and food leftovers). Food leftovers, as non-recyclable waste, were often mistaken for recyclable waste. As one of the primary school teachers indicate, the majority of students thought food leftovers can be reused. For example, they thought that such waste could be fed to poultry or used as compost. However, these students have ignored the fact that food leftovers do not essentially meet the definition of recyclable wastebecoming a new product after undergoing processing. Similarly, paint and medicine, as hazardous waste, were often mistaken as non-recycle waste because they were, as indicated by an 8th grade student, considered to be toxic and not suitable for recycling. But in fact, paint and medicine are hazardous waste and need to be handled with caution.
It can also be seen from table 6 that senior middle school students have better knowledge than their juniors. This, along with the result outlined in section 3.2 that PMS students' waste separation behaviour was negatively related to their year of study (age), confirms that the level of PMS students' waste separation knowledge has no effect on their waste separation behaviour.

Environmental education
The result in table 5 also indicates that environmental education provided by the PMS students' schools had a significant positive effect on student' waste separation behaviour (B = 0.485, p = 0.037). The odds of PMS students who received environmental education also having good waste separation behaviour was 1.766 times that of those who had not had such exposure (OR = 1.624). This result agrees with Chapman and Sharma's (2001) conclusion that environmental education helped Indian and Filipino PMS students acquire basic understanding of the environment and its associated problems and prompted them to adopt more proenvironmental behaviour. In fact, more than 60% of PMS students who have had environmental education reported that they could realize the importance of waste separation for environmental protection and resource conservation. Hence, it is important for schools to provide environmental education to students as a way of improving their waste separation behaviour. But only 38% of surveyed students reported that their schools had provided environmental education programmes, whether via in-class teaching or out of class activities. Two out of the six key informants (class teachers) indicated that environment related teaching had not yet been included in their curriculum, while the other four said they had included environmental education in the syllabus but there is, as yet, no detailed design of the programme i.e. what should be included in the programme, who should be teaching it and when and how it should be taught. Table 5 shows that the convenience of waste sorting facilities was an important determinant of students' waste separation behaviour, and higher degrees of convenience is associated with better waste separation behaviour (B = 0.694, p = 0.003). The odds of doing waste separation by respondents who considered the waste separation facilities convenient and easy to use was twice as large as those who considered the opposite (OR = 2.001). This result agrees with Hao et al (2020) and Liao and Li's (2019) finding that improving the infrastructure would help to make waste separation easier. An in-depth telephone interview with one of the key informants revealed that in her school sorting bins were placed every 50-80 meters along the road on campus, and there were clear signs on these bins to indicate the types of waste. But there were only one or two bins scattered at the corridors of the teaching building and in the back of the classrooms, and there were no signs on these bins. In fact, more than half of the surveyed PMS students who self-reported to rarely or never separate waste claimed that not having convenient and easy-to-use waste sorting facilities was the main reason for their poor waste separation behaviour (see figure 2). This indicates the urgency of upgrading the current waste separation infrastructure at the PMS campuses of Yingtan City.

Influence of the family and friends
As can be seen in table 5, the family's waste separation behaviour had a significant positive impact on PMS students' waste separation behaviour (B = 2.686, p = 0.000). The odds of PMS students having good waste behaviour and whose family members also practised waste separation was more than 14 times that of those whose family members did not do waste separation (OR = 14.675). With the highest OR value, families seem to have the strongest influence on PMS student' waste separation behaviour. This result agrees with that of Baur and Haase (2015) who studied the environmental behaviour of primary school students in Germany and found that children who had environmental aware parents would be more likely to exhibit environmentally friendly behaviours. Wut et al (2020) also found that parent's supervision of children's waste separation behaviour would drive children to be more involved in waste separation practice. One of the respondents whose parents always practised waste separation noted that he had been asked to sort waste at home and been taught how to do it by his parents, so sorting waste before dumping it had become a habit. Hence it is important for the Yingtan City government to implement their waste separation policy in a larger scale and get more of its citizens voluntarily involved in it. This would no doubt help improve the waste separation behaviour of all of them. However, the influence from friends is clearly lower than that from the families although having friends who would do waste separation more often does increase the likelihood of PMS students having good waste separation behaviour (B = 0.671, p = 0.004, OR = 1.957). This finding is contrary to the conclusion of Zhang et al (2017) that in China college students' waste separation behaviour was more similar to that of their friends than their parents. The differences in the results may be due to the different living environment between Chinese college students and PMS students. Chinese college students live on campus and spend most of their time with friends rather than family while a majority of PMS students live with their family so their lifestyle and personal habits are more prone to the influence of family members.

Mandatory waste separation measures
It can be seen from table 5 that having in place a mandatory regulation on waste separation had significant but negative impact on PMS student' waste separation behaviour (B = -1.250, p = 0.000). Hence, having mandatory waste separation would not help Chinese PMS students improve their waste separation behaviour, and in fact it works the opposite way. This result is somewhat surprising and does not agree with Hao et al (2020) and Chen et al (2018) who noted that having a mandatory waste separation policy did improve waste separation behaviour of college students in Zhengzhou and residents in Nanjing, China. However, in the same study, Hao et al (2020) also found that a small group of Chinese college students see waste separation as the duty of a responsible citizen and consider receiving a reward/penalty discouragement of their good waste separation behaviour. Berglund (2005) and Dahlén and Lagerkvist (2010) agreed with this point. In fact, one of the respondents clearly stated that he hated being forced to do something, especially when he had no clue what it is and how to do it. At the same time, the survey found that 57.7% of the respondents considered that giving a reward is the most effective way to encourage good waste separation behaviour. Obviously, flexible waste separation policies based on encouragement and guidance would be more suitable for PMS students than simple penalty measures, although (the school) providing good environmental education would lay the foundation for future waste separation policies. Clearly there is an element of 'rebelling' here but could it also be possible that with less resource (than the bigger cities) available, Yingtan, as one of the small and medium-sized cities, has less capacity to implement the mandatory waste separation policies ? It might be something worth considering for the Chinese policymakers at both national level and regional (i.e. small and medium-sized cities) level.
4. Measures for improving waste separation behaviour of Chinese PMS students 4.1. Improve environmental education to enhance PMS students' awareness of waste separation The results suggest that Chinese PMS students' attitude to waste separation and willingness to separate waste have a positive influence on their waste separation behaviour. Also, the more environmental education they had received, then the better their waste separation behaviour. Given a positive correlation between school students' environmental education and their environmental awareness (Chapman and Sharma 2001, Xue et al 2011, Liao and Li 2019, the importance of environmental education in improving Chinese PMS student's waste separation behaviour cannot be stressed enough. Although having waste separation related knowledge is not significantly related to PMS students' waste separation behaviour, about 44% of them reported that their reason for not undertaking waste separation was not knowing how to do it, and this is where education has a key role to play. As the primary source of environmental education for PMS students, schools are responsible for improving students' environmental education. Not only should all schools include environmental education in their curriculum design, there should also be detailed implementation plans. Both in-class teaching and on-campus environmental campaigning should be organized by the school. For example, schools could hire teachers who specializes in environmental education for in-class teaching. School teachers play an important role in environmental education because they are the ones who pass the knowledge and experience on to students (Liao and Li 2019). But the in-depth interview with the class teachers revealed that many of them did now know much about waste separation themselves. Hence training should be provided to the teachers regarding general environmental knowledge and waste separation. Schools could also organize field trips for students to visit MSW incineration and landfill sites, local recycling centre or waste collection points of a local community for them to have better understanding as to how much waste has been produced each day and why it is important to sort waste. This is especially important for a small and medium-sized city like Yingtan where people's environmental awareness is lower than that in bigger cities.
Environmental education can be achieved not only in schools but also outside the campus via television, internet and social media platforms. These informal environmental education channels are especially important for the Yingtan City government whose environmental education budget is relatively low compared to large cities because the channels work not only for children but also for the other public to raise their environmental awareness.

Improve the waste sorting facilities
The results indicate that poor waste separation facilities contribute to waste separation inconvenience for Yingtan's PMS students, which has led to lower levels of willingness of PMS student to do waste separation. Hence more effort should be made by the local authority and the school to improve the waste separation infrastructure. There should be enough bins on campus and the bins should be placed in places that are easy to access for the students and school staff. There should be clear signs on all the bins so people know which bin their waste should go to. In fact, more intuitive signs have been suggested by Rada et al (2016) to be used on bins for younger kids, based on their experience with Italian school students. For example, pictures of bottles, paper, fruits etc could be printed on the bins on primary school campus in Yingtan. In addition, smart waste separation facilities could be introduced for elder school children, and indeed the local community. These smart facilities could, on the one hand, help optimize the separation process and increase classification rate by using intelligent sorting techniques, such as image processing technology, on the other hand, make doing waste separation a more interesting, modern and fashionable task for teenage students. This could to some extent improve senior middle school students' waste separation behaviour. Although updating the waste separation infrastructure would induce extra costs for a small and medium-sized city like Yingtan whose economic development level is already lower than big cities, the economic benefit of having a basic waste management system is far more significant.

Call on the parents to improve their waste separation behaviour
The results also indicate that parents' influence on the children's waste separation behaviour is the most significant among all other factors. Hence it is crucial to educate the parents about waste separation and it's benefits for society and the environment, and more importantly, encourage the parents to practice waste separation at home to set a good example for their children to follow. In addition, the Parents' Committee, which have been established in most schools in China as a means of encouraging parents to become more involved in their children's education, could also be used as a platform to increase the awareness of waste separation among parents.
Nonetheless, it is important for the schools to develop social norms of waste separation on campus which may help to improve waste separation behaviours of students since the influence of friends plays a positive role in their waste separation behaviour. In fact, instilling the right waste separation behaviour in school children has been found by others to be beneficial in improving their family members' waste separation behaviour (Kasapoğlu andTuran 2008, Rada et al 2016) and there needs more investigation to see if the same is true in China.

Carrots work better than sticks
The results indicate that having mandatory waste separation regulation i.e. penalizing the ones who do not separate waste, has a negative effect in terms of improving waste separation behaviour for Yingtan's PMS students. Given the fact that reward is considered by more than half of the responding students to be the most effective motivation of waste separation behaviour change, it would seem that incentives may work better than penalties for Yingtan's PMS students when it comes to waste separation. This result is contrary to those of previous studies regarding the effect of mandatory waste separation policy in China , Hao et al 2020 and may be linked to school-aged children being less amenable to being told what to do. It is suggested that the Yingtan government and its schools tailor their waste separation policy based on this result. For example, instead of punishing students who do not want to separate waste, reward points could be given to students who have done a good job in waste separation, and the points could be redeemed for different types of rewards for students in different study levels i.e. symbolic rewards (a star next to their names) for primary school students, books/stationeries for junior middle school students, and bonus points in the national college entrance exams for senior middle school students.

Conclusions, limitations, and future research suggestions
This paper employed a semi-structured questionnaire survey of 579 PMS students from six schools in Yingtan City, China to gather first-hand information on PMS students' MSW source separation behaviour and the influencing factors of it. The research was designed to address two important gaps in knowledge about waste separation behaviour in the context of China; waste separation behaviour amongst school children and in the context of a small and medium-sized city (Yingtan). To date most of the work in China has focussed on thirdlevel students (universities) and larger cities which may be assumed to have greater access to resources to promote waste separation behaviour. It is hoped that this research would help motivate the change of waste separation behaviour in children of small and medium-sized cities in China and other developing countries and contribute to China's successful management of MSW. It is also hoped that the result of this research is applicable to small and medium-sized cities in other developing countries in terms of effective MSW management.
The results indicate that more than half of surveyed students always and often do waste separation and their waste separation behaviour is not different between boys and girls but more related to their grade (age). Indeed, primary school (younger) students perform better in terms of waste separation than middle school (elder) students. This result is contrary to what was found for college students and community residents that the elder the respondents, the better the waste separation behaviour (Zhang and Wen 2014, Dai et al 2017, Fan et al 2019, Hao et al 2020 and indicates the importance of taking into account PMS school students' unique characteristic when guiding their waste separation behaviour.
Internal factors such as attitude to waste separation and level of willingness to do waste separation are positively related to PMS students' waste separation behaviour. However, an unexpected result is that waste separation related knowledge does not appear to have an influence on PMS students' waste separation behaviour. External factors such as environmental education the PMS students received in school, influence from friends and especially from the family, condition of waste sorting facilities are all positively related to waste separation behaviour of the PMS students. Indeed, among all the influencing factors, families have the greatest influence on PMS students regarding their waste separation behaviour and this is a result which differs markedly from research conducted with third-level students. School children spend a lot of time with their parents so it is easy to appreciate how their influence would be so much greater than that of other students, but once they go to university this reverses and student peers become more important.
Another intriguing finding is that the implementation of a mandatory waste separation policy would worsen PMS students' waste separation behaviour and giving rewards to good behaviour is considered by more than half of the students to be the most effective motivation. This result is especially important for the Yingtan City government as they are about to implement a mandatory waste separation policy. Indeed, with limited resources as a small and medium-sized city and strong opposition from PMS students in the City, it might be wiser to implement a lighter-touch waste separation policy in schools.
To improve PMS students waste separation behaviour, it is suggested that schools in Yingtain improve their environmental education for their students and teachers, update the waste sorting infrastructure, make good use of social norms, especially families' influence, and use rewards instead of punishment to guide PMS student to perform better in waste separation. This is also very important for Yingtan City since it has less resources than big cities (i.e. Shanghai, Beijing, etc) to implement mandatory waste separation policies.
The study has some limitations. First, as with many such studies the research reported here is based on selfreported behaviour and its influencing factors, and claimed behaviour of individuals is not always closely associated with practice. Second, PMS students' waste separation behaviour is a complex human behaviour that could potentially be affected by many factors and those included in this study are not all of them. More influencing factors such as family income, parents' educational level and occupation etc should be considered. In addition, the effect of mandatory regulation is hypothetical because Yingtan has not implemented mandatory waste separation policy due to its relatively smaller size and less significance in China's economy. But as it is scheduled by the state government and stated in Yingtan's Implementation Plan, Yingtan will have to implement mandatory policy by 2025. It is hoped that this study would provide some useful insight for Yingtan City government regarding its (future) implementation of mandatory waste separation policy. Further research should consider PMS students' actual waste separation behaviour, and include PMS students' family income, parents' educational level and their occupation etc. It would also be interesting to investigate whether children's change of waste separation behaviour has an impact on the parents' waste separation behaviour. Further research on PMS students' waste separation behaviour and its influencing factors after Yingtan starts to implement mandatory waste separation is also recommended.