A comparison of chemical MSW compositional data between China and Denmark

https://doi.org/10.1016/j.jes.2018.02.010Get rights and content

Abstract

Chemical waste compositions are important for municipal solid waste management, as they determine the pollution potentials from different waste strategies. A representative dataset for chemical characteristics of individual waste fractions is frequently required to assess chemical waste composition, but it is usually reported in developed countries and not in developing countries. In this study, a dataset for Chinese waste was established through careful data screening and assessment, named as CN dataset. Meanwhile, a dataset for Danish waste (DK dataset) was also summarized based on previous studies. In order to quantitatively evaluate the reliabilities of CN and DK datasets, the chemical waste compositions in four Chinese cities were estimated by utilizing both of them, respectively. It is indicated that the usage of CN datasets led to significantly lower discrepancies from the actual values based on laboratory analysis in most cases. Within the datasets, the moisture contents of food waste, paper, textiles, and plastics, the carbon content of food waste, as well as the oxygen content of plastics would induce significant divergences, which should be paid special attention when gathering the information. In addition, the fractional waste compositions in China showed similar features with other developing countries but differ significantly with developed countries. Thus the above-mentioned conclusions could also be true in other developing countries.

Introduction

Due to the rapid growth in the amounts of municipal solid waste (MSW) in developing countries, many large cities are faced with a “garbage siege,” whereby waste dumping sites originally located far outside the conurbations are now surrounding these rapidly expanding cities, resulting in significant human and environmental impacts (Hu et al., 2012, Wu and Xu, 2013). To design a proper waste management system with reduced environmental impacts, knowledge of waste properties is important (Cleary, 2009). Waste properties are often described in terms of fractional waste compositions and chemical waste compositions. Fractional compositions determine the potential for recycling and energy recovery (Tai et al., 2011), while chemical compositions are essential for estimating pollutant potentials from different waste strategies (Manfredi et al., 2011, Yang et al., 2012, Yang et al., 2013). For example, higher plastic content will increase the heating values of MSW and subsequently make it more effective to recover energy by incineration. However, the fossil carbon contained in plastic fractions would induce higher greenhouse gas (GHG) emissions when MSW is incinerated (Yang et al., 2012).

It is general knowledge that fractional waste compositions differ from one place to another and change over time, due to economic development, waste management policies, and energy supplies (Wang and Nie, 2001, Wei et al., 1997). Correspondingly, chemical waste compositions also change owing to the varied contributions of waste fractions. The chemical compositions of mixed waste can be measured by laboratory analysis (He et al., 2010, Huang et al., 2003, Zhang et al., 2009) or be calculated by combining fractional waste compositions in specific scenarios and the general chemical characteristics of individual fractions (Yang et al., 2012, Zhao et al., 2009a, Zhao et al., 2009b, Zhao et al., 2011). Fractional waste compositions can be obtained by on-site sorting and weighing, which is frequently conducted due to low technical requirements (Ministry of Housing and Urban–Rural Development of the People's Republic of China, 2009). Laboratory analyzes of the chemical compositions of mixed waste are rarely reported in developing countries, as the sample preparation and analysis is labor-intensive and requires technical knowhow and analytical facilities. The same situation occurs for the chemical characteristics of individual fractions, which conversely often refer to existing datasets. Generally, the chemical characteristics of individual fractions consist of major parameters, e.g., moisture content, organic element content, heating values, and trace parameters, the latter of which usually refer to heavy metal content (Zhang et al., 2008). Heavy metals are usually contained in just a few specific items, for example over 90% of cadmium and mercury in MSW comes from batteries (Riber et al., 2009). The availability or non-availability of these materials in the waste can significantly induce the differences in heavy metal content. It is thus hard to estimate heavy metal content by employing the aforementioned methods. In existing studies, major parameters are often taken into account, whereas trace parameters are often left out. For this study, the major parameters are termed as “chemical characteristics” due to their data availability.

Presently, datasets for the chemical characteristics of individual fractions are extremely scarce. A series of chemical characteristics often referred to was from the handbook written by Tchobanoglous et al. (1993), modified from data obtained in 1966 based on waste in the USA (Kaiser, 1966). In 2007, a comprehensive study focusing on the chemical characteristics of household waste was performed in Denmark (Lagerkvist et al., 2011, Riber et al., 2009), the results of which are available through the EASETECH software package (Clavreul et al., 2014), a widely used tool for life cycle assessment of waste management. In the case of developing countries, there are no comprehensive studies published in this research field. Taking China as an example, researchers (Zhao et al., 2009a, Zhao et al., 2009b, Zhao et al., 2011) tend to refer to chemical characteristics reported in Western countries (Tchobanoglous et al., 1993). However, this may lead to mis-estimation of chemical compositions. For example, the moisture content of mixed MSW in Hangzhou, estimated by refering to Tchobanoglous et al. (1993), i.e., 43.2% (Zhao et al., 2009b), was remarkably lower than the actual measured values, i.e., 57.5% (Ni and Hong, 2005) and 56.5% (Zhuang et al., 2008), which could evoke subsequent incorrect findings in relation to heating values and the leachate generation potential of waste.

The primary aim of this study was to compile waste property data reported for Chinese cities, including fractional waste compositions, chemical waste compositions, and chemical characteristics of individual waste fractions. Fractional waste compositions in developing countries were additionally compared with those in developed countries and the causes of these differences were identified. The Chinese dataset was finally compared with a Danish dataset, by applying the data to four Chinese cities and contrasting the differences in results between the two datasets.

Section snippets

Fractional waste compositions

Fractional waste compositions for 18 Chinese cities were compiled (see details in Table 1). Datasets for megacities as well as smaller cities, and with a certain geographical distribution, are included. Datasets published in the last decade were preferred to older data. Since fractional waste compositions are potentially used for designing waste treatment systems, data were obtained for the remaining mixed waste after source-segregating recyclables in residential areas or waste treatment

Regional variance of fractional compositions

Fig. 1 compares fractional waste compositions between China and other developing countries as well as with developed countries. The data are clearly clustered in two groups, representing China and developing countries in one cluster and developed countries in another cluster. Non-degradable fractions (including plastics, non-combustibles, glass, and metal) contributed similarly in developed and developing countries but showed a large variation, ranging between 15% and 50%. The main difference,

Conclusion

The fast degradable fraction consisting of food waste was the dominant waste fraction in Chinese MSW (> 50% of ww), as was also the case for other developing countries. This was different from developed countries, where waste was found mainly to consist of slowly degradable (paper, wood, and textiles) and non-degradable fractions (plastics, non-combustibles, glass, and metal). Moisture content in mixed waste in China was usually higher than the values in developed countries. Also, a higher

Acknowledgment

The work was supported by the National Environmental Protection Standard Project (2015-4), and the Shanghai Technical Standard Projects (Nos. 14DZ0501500, DB31ZB5-15043).

References (45)

  • D.Q. Zhang et al.

    Municipal solid waste management in China: status, problems and challenges

    J. Environ. Manag.

    (2010)
  • W. Zhao et al.

    Life cycle assessment of municipal solid waste management with regard to greenhouse gas emissions: case study of Tianjin, China

    Sci. Total Environ.

    (2009)
  • Y. Zhao et al.

    Environmental impact assessment of solid waste management in Beijing City, China

    Waste Manag.

    (2011)
  • Y. Zhuang et al.

    Source separation of household waste, a case study in China

    Waste Manag.

    (2008)
  • X.M. Chen

    Methan utilization in municipal solid waste landfill

    (2011)
  • J.F. Gou et al.

    Physical composition and moisture characteristics of municipal solid waste of Lanzhou City

    Environ. Eng.

    (2012)
  • S. He et al.

    Characteristics analysis and treatment countermeasures of domestic waste in Suzhou city

    Environ. Sanitation Eng.

    (2008)
  • J.B. He et al.

    Investigation and analysis of domestic waste within the south area of Haihe river in Tianjin Binhai new area

    Environ. Sanitation Eng.

    (2010)
  • X.J. Hu et al.

    Food waste management in China: status,problems and solutions

    Acta Ecol. Sin.

    (2012)
  • M.X. Huang et al.

    Characteristics and compositions of municipal solid waste in Sichuan Province

    Environ. Monit. China

    (2012)
  • B.S. Huang et al.

    Analysis of physicochemical property and discussion of disposal of MSW in the urban zone of Chongqing city

    J. Chongqing Univ.

    (2003)
  • A.M. Ji

    The Analysis of Physical Characteristics and Incinerating Feasibility of Municipal Solid Waste in Lanzhou (in Chinese)

    (2007)
  • Cited by (53)

    View all citing articles on Scopus
    View full text