Investigating the factors affecting the monthly and seasonal production of municipal waste and determining the index factors ( case study: Tehran city)

Introduction: One of the important problems of urbanization is the growing trend of waste production. Knowing the quantity and quality of waste and the factors affecting their production is essential for proper waste management. Considering the importance of this issue, efforts should be made to update and optimize studies related to quantitative and qualitative waste analysis. The lack of information related to waste production and little research in the country has made waste management systems a challenge. To evaluate the urban solid waste management program, identifying the factors that affect the production of urban waste plays a vital role. Knowing the factors affecting the production of urban waste and determining the importance of each factor allows the decision makers to take the necessary measures. The amount and type of waste composition varies in different regions and depends on several factors. The purpose of this research is to investigate the factors affecting waste production, including geographical, social, meteorological, cultural, and economic parameters and to find their relationship with waste production. Also, finding the factors that have the greatest impact on waste production and getting to know them more is one of the goals of this research.
Materials and methods: In this regard, information on urban waste production was collected in the city of Tehran in a period of thirty years, and monthly and seasonal waste time series were prepared. The evaluated parameters in this research include year, month and season of production, average temperature, rainfall, gross domestic product, income, educated population, unemployment rate, student population, population, household size, male and female population. Then, different factors affecting the production of urban waste were identified and the non-linear correlation of each of these factors with production waste was estimated using Python software, and seasonal and monthly heat maps were obtained. Finally, the trend of seasonal and monthly changes of residual was investigated.
Results and discussion: The results showed that the income parameter is the most important economic parameter and has the most impact in the long term among the parameters. The unemployment rate has an effect on waste production in the short term, but it has no effect in the long term. In the long term, the student population has the least effect among the parameters and its correlation coefficient is almost zero, but in the short and medium term, because it is a population parameter, it can have a great effect on the waste generation with a sudden change. The student population parameter has a great effect on waste production and its effect increases from short to long term. The comparison of time, meteorological, social and economic parameters showed that household income, GDP per capita, temperature and demographic factors have a direct relationship on the monthly and seasonal production of urban waste, and according to the correlation coefficient, the greatest effect is per capita GDP, Population and income have a negative impact on production. At the same time, the unemployment rate and the population of educated people in Tehran have an inverse effect with waste production. The study of the population of educated women, as part of the innovation of this research, the importance of which had not been investigated until now, showed that as the number of educated women increases, the amount of waste production decreases. Also, in the monthly production of waste, educated women have the highest correlation coefficient and impact compared to other factors. Due to the climatic conditions of the region, such as the lack of rainfall, the rainfall variable has the lowest correlation with waste production in Tehran. In general, seasonal correlation coefficients were higher than monthly.