Thermal pyrolysis as a potential method for the management of plastic waste in developing countries

Shuyi Wong; Andrea Galassi; Taufiq-Yap Yun Hin; Azreen Ibrahim; Jurry Foo; Coswald Stephen Sipaut; Jidon Janaun.

Transactions on Science and Technology, 10(1), 28 - 47.

Back to main issue

ABSTRACT
Plastic is a cheap and versatile material. The production and manufacture of plastics has risen tremendously to cater the needs of the growing world population, even more in the effort of fighting the COVID-19 pandemic. Lack of proper technology and human irresponsibility contribute to the mismanagement of plastic waste. Hence, the severity of plastic waste pollution is heightening, and the Earth and all living things are suffering the consequences. This review explores thermal pyrolysis as a more effective method to manage plastic waste in developing countries like Malaysia. Thermal pyrolysis is compared to existing plastic waste management methods. Factors influencing the yield and composition of pyrolysis products are also being discussed. These include feedstock type, reactor type, temperature, residence time, pressure, and fluidizing gas type and flow rate. Several topics such as the manipulation of pyrolysis parameters and the use of Appropriate Technology-based reactors, are raised as possible areas for further research.

KEYWORDS: Pyrolysis; plastic waste; waste management; thermal degradation; plastic upcycling.



Download this PDF file

REFERENCES
  1. Abbas-Abadi, M. S., Haghighi, M. N. & Yeganeh, H. 2013. Evaluation of pyrolysis product of virgin high density polyethylene degradation using different process parameters in a stirred reactor. Fuel Processing Technology, 109, 90-95.
  2. Abbas-Abadi, M. S., Haghighi, M. N., Yeganeh, H. & McDonald, A. G. 2014. Evaluation of pyrolysis process parameters on polypropylene degradation products. Journal of Analytical and Applied Pyrolysis, 109, 272-277.
  3. Abnisa, F., Daud, W. M. A. W. & Sahu, J. N. 2014. Pyrolysis of mixtures of palm shell and polystyrene: An optional method to produce a high-grade of pyrolysis oil. Environmental Progress and Sustainable Energy, 33(3), 1026-1033.
  4. Abnisa, F. & Daud, W. M. A. W. 2014. A review on co-pyrolysis of biomass: An optional technique to obtain a high-grade pyrolysis oil. Energy Conversion and Management, 87, 71-85.
  5. Aboulkas, A., El harfi, K. & El Bouadili, A. 2010. Thermal degradation behaviors of polyethylene and polypropylene. Part I: Pyrolysis kinetics and mechanisms. Energy Conversion and Management, 51(7), 1363-1369.
  6. Adnan, Shah, J. & Jan, M. R. 2014. Thermo-catalytic pyrolysis of polystyrene in the presence of zinc bulk catalysts. Journal of the Taiwan Institute of Chemical Engineers, 45(5), 2494-2500.
  7. Adrados, A., de Marco, I., Caballero, B. M., López, A., Laresgoiti, M. F. & Torres, A. (2012). Pyrolysis of plastic packaging waste: A comparison of plastic residuals from material recovery facilities with simulated plastic waste. Waste Management, 32(5), 826-832.
  8. Agamuthu, P. & Fauziah, S. H. 2011. Challenges and issues in moving towards sustainable landfilling in a transitory country - Malaysia. Waste Management and Research, 29(1), 13-19.
  9. Aguado, J., Serrano, D. P. & Escola, J. M. 2008. Fuels from waste plastics by thermal and catalytic processes: A review. Industrial and Engineering Chemistry Research, 47(21), 7982-7992.
  10. Aguado, R., Prieto, R., José, M. J. S., Alvarez, S., Olazar, M. & Bilbao, J. 2005. Defluidization modelling of pyrolysis of plastics in a conical spouted bed reactor. Chemical Engineering and Processing: Process Intensification, 44(2), 231-235.
  11. Ahamed, A., Veksha, A., Yin, K., Weerachanchai, P., Giannis, A. & Lisak, G. 2020. Environmental impact assessment of converting flexible packaging plastic waste to pyrolysis oil and multi-walled carbon nanotubes. Journal of Hazardous Materials, 390, 121449.
  12. Ahmad, I., Khan, M. I., Ishaq, M., Khan, H., Gul, K. & Ahmad, W. 2013. Catalytic efficiency of some novel nanostructured heterogeneous solid catalysts in pyrolysis of HDPE. Polymer Degradation and Stability, 98(12), 2512-2519.
  13. Ahmad, I., Khan, M. I., Khan, H., Ishaq, M., Tariq, R., Gul, K. & Ahmad, W. 2015. Pyrolysis study of polypropylene and polyethylene into premium oil products. International Journal of Green Energy, 12(7), 663-671.
  14. Al-Salem, S. M., Evangelisti, S. & Lettieri, P. 2014. Life cycle assessment of alternative technologies for municipal solid waste and plastic solid waste management in the Greater London area. Chemical Engineering Journal, 244, 391-402.
  15. Al-Salem, S. M., Lettieri, P. & Baeyens, J. 2009a. Kinetics and product distribution of end of life tyres (ELTs) pyrolysis: A novel approach in polyisoprene and SBR thermal cracking. Journal of Hazardous Materials, 172(2–3), 1690-1694.
  16. Al-Salem, S. M., Lettieri, P. & Baeyens, J. 2009b. Recycling and recovery routes of plastic solid waste (PSW): A review. Waste Management, 29(10), 2625-2643.
  17. Amin, R. M., Sohaimi, E. S., Anuar, S. T. & Bachok, Z. 2020. Microplastic ingestion by zooplankton in Terengganu coastal waters, southern Andel, L., Kusy, J., Vales, J. & Safarova, M. 2009. Pyrolysis process of waste polyethyleneterephtalate. Chemical Product and Process Modeling, 4(1), 2009.
  18. Ansar, M. A., Assawadithalerd, M., Tipmanee, D., Laokiat, L., Khamdahsag, P. & Kittipongvises, S. 2021. Occupational exposure to hazards and volatile organic compounds in small-scale plastic recycling plants in Thailand by integrating risk and life cycle assessment concepts. Journal of Cleaner Production, 329, 129582.
  19. Antelava, A., Damilos, S., Hafeez, S., Manos, G., Al-Salem, S. M., Sharma, B. K., Kohli, K. & Constantinou, A. 2019. Plastic Solid Waste (PSW) in the Context of Life Cycle Assessment (LCA) and Sustainable Management. Environmental Management, 64(2), 230-244.
  20. Arabiourrutia, M., Elordi, G., Lopez, G., Borsella, E., Bilbao, J. & Olazar, M. 2012. Characterization of the waxes obtained by the pyrolysis of polyolefin plastics in a conical spouted bed reactor. Journal of Analytical and Applied Pyrolysis, 94, 230-237.
  21. Badger, P. C. & Fransham, P. 2006. Use of mobile fast pyrolysis plants to densify biomass and reduce biomass handling costs - A preliminary assessment. Biomass and Bioenergy, 30(4), 321325.
  22. Bagri, R. & Williams, P.T. 2002. Catalytic pyrolysis of polyethylene. Journal of Analytical and Applied Pyrolysis, 63(1), 29–41.
  23. Beheshti, S. M., Ghassemi, H. and Shahsavan-Markadeh, R. 2015. Process simulation of biomass gasification in a bubbling fluidized bed reactor. Energy Conversion and Management, 94, 345-352.
  24. Bengali, S. 2020. The COVID-19 pandemic is unleashing a tidal wave of plastic waste (https://www.latimes.com/world-nation/story/2020-06-13/coronavirus-pandemic-plasticwaste-recycling#:~:text=During%20an%20eightweek%20lockdown%20that%20eased%20June%201%2C). Last accessed on 19 October 2022.
  25. Bhattacharya, P., Steele, P. H., Hassan, E. B. M., Mitchell, B., Ingram, L. & Pittman, C. U. 2009. Wood/plastic copyrolysis in an auger reactor: Chemical and physical analysis of the products. Fuel, 88(7), 1251-1260.
  26. Brivio, E., Petsa, I. & McPhie, T. 2018. Single-use plastics: New EU rules to reduce marine litter (https://ec.europa.eu/commission/presscorner/detail/en/IP_18_3927). Last accessed on 19 October 2022.
  27. Buekens, A. & Yang, J. 2014. Recycling of WEEE plastics: A review. Journal of Material Cycles and Waste Management, 16(3), 415-434.
  28. Cepeliogullar, O. & E. Putun, A. 2000. Utilization of Two Different Types of Plastic Wastes from Daily and Industrial Life. Journal of Selcuk University Natural and Applied Science, 2000.
  29. Chin, B. L. F., Yusup, S., al Shoaibi, A., Kannan, P., Srinivasakannan, C. & Sulaiman, S. A. 2014. Kinetic studies of co-pyrolysis of rubber seed shell with high density polyethylene. Energy Conversion and Management, 87, 746-753.
  30. Cho, Y., Shim, W. J., Jang, M., Han, G. M. & Hong, S.H. 2019. Abundance and characteristics of microplastics in market bivalves from South Korea. Environmental Pollution, 245, 1107-1116.
  31. Conesa, J. A., Marcilla, A. & Font, R. 1994. Kinetic model of the pyrolysis of polyethylene in a fluidized bed reactor. Journal of Analytical and Applied Pyrolysis, 30(1), 101-120.
  32. Demetrious, A. & Crossin, E. 2019. Life cycle assessment of paper and plastic packaging waste in landfill, incineration, and gasification-pyrolysis. Journal of Material Cycles and Waste Management, 21(4), 850-860.
  33. Demirbas, A. 2004. Pyrolysis of municipal plastic wastes for recovery of gasoline-range hydrocarbons. Journal of Analytical and Applied Pyrolysis, 72(1), 97-102.
  34. Elangovan, N. 2020. Singapore Households Generated Additional 1,334 Tonnes of Plastic Waste during Circuit breaker: Study. (https://www.todayonline.com/singapore/singapore-householdsgenerated-additional-1334-tonnes-plastic-waste-during-circuit-breaker). Last accessed on 19 October 2022.
  35. Elordi, G., Olazar, M., Aguado, R., Lopez, G., Arabiourrutia, M. & Bilbao, J. 2007. Catalytic pyrolysis of high density polyethylene in a conical spouted bed reactor. Journal of Analytical and Applied Pyrolysis, 79(1-2), 450-455.
  36. Fakhrhoseini, S. M. & Dastanian, M. 2013. Predicting pyrolysis products of PE, PP, and PET using NRTL activity coefficient model. Journal of Chemistry, 2013, 487676.
  37. Fauziah, S. H., Rizman-Idid, M., Cheah, W., Loh, K. H., Sharma, S., Noor, N. M., Bordt, M., Praphotjanaporn, T., Samah, A. A., Sabaruddin, J. S. bin & George, M. 2021. Marine debris in Malaysia: A review on the pollution intensity and mitigating measures. Marine Pollution Bulletin, 167, 112258.
  38. Fernandez, Y., Arenillas, A. & Angel, J. 2011. Microwave Heating Applied to Pyrolysis. In: Grundas, S. (ed). Advances in Induction and Fogler, H. S. 2016. Elements of Chemical Reaction Engineering (Prentice Hall International Series in the Physical and Chemical Engineering Sciences) (5th Edition). Pearson. ISBN-10: 0133887510.
  39. Gordon, J. 2022. Law of Supply and Demand - Explained (https://thebusinessprofessor.com/en_US/economic-analysis-monetary-policy/law-of-supplyand-demand-definition). Last accessed on 19 October 2022.
  40. Grand View Research. 2015. Malaysia Plastic Compounding Market Size, Share & Trends Analysis Report By Product (PE, PP, TPV, TPO, PVC, PET, PBT, PA, PC, ABS), By End-Use, By Region, And Segment Forecasts, 2018 - 2025 (https://www.grandviewresearch.com/industryanalysis/malaysia-plastic-compounding-market). Last accessed on 19 October 2022.
  41. Hafeez, S., Pallari, E., Manos, G. & Constantinou, A. 2019. Catalytic conversion and chemical recovery. In: Al-Salem, S. M. (ed). Plastics to Energy: Fuel, Chemicals, and Sustainability Implications, 2019, 147-172.
  42. Hamid, F. S., Jia, W. & Zakaria, R. M. 2020. Microplastics abundance and uptake by meretrix lyrata (Hard clam) in mangrove forest. Journal Heikkinen, J. M., Hordijk, J. C., de Jong, W. & Spliethoff, H. 2004. Thermogravimetry as a tool to classify waste components to be used for energy generation. Journal of Analytical and Applied Pyrolysis, 71(2), 883-900.
  43. Hong, S. J., Oh, S. C., Lee, H. P., Kim, H. T. & Yoo, K. O. 1999. A Study on the Pyrolysis Characteristics of Poly ( vinyl chloride ). Journal of the Korean Institute of Chemical Engineers, 37(4), 515-521.
  44. Jahirul, M. I., Rasul, M. G., Schaller, D., Khan, M. M. K., Hasan, M. M. & Hazrat, M. A. 2022. Transport fuel from waste plastics pyrolysis – A review on technologies, challenges and opportunities. Energy Conversion and Management, 258, 115451.
  45. Jung, S. H., Cho, M. H., Kang, B. S. & Kim, J. S. 2010. Pyrolysis of a fraction of waste polypropylene and polyethylene for the recovery of BTX aromatics using a fluidized bed reactor. Fuel Processing Technology, 91(3), 277-284.
  46. Kaminsky, W., Schlesselmann, B. & Simon, C. M. 1996. Thermal degradation of mixed plastic waste to aromatics and gas. Polymer Degradation and Stability, 53(2), 189-197.
  47. Karaduman, A., Şimşek, E. H., Çiçek, B. & Bilgesü, A. Y. 2001. Flash pyrolysis of polystyrene wastes in a free-fall reactor under vacuum. Journal of Analytical and Applied Pyrolysis, 60(2), 179-186.
  48. Kehinde, O., Ramonu, O. J., Babaremu, K. O. & Justin, L. D. 2020. Plastic wastes: environmental hazard and instrument for wealth creation in Nigeria. Heliyon, 6(10), e05131.
  49. Khalik, W. M. A. W. M., Ibrahim, Y. S., Anuar, S. T., Govindasamy, S. & Baharuddin, N. F. 2018. Microplastics analysis in Malaysian marine waters: A field study of Kuala Nerus and Kuantan. Marine Pollution Bulletin, 135, 451-457.
  50. Kreith, F. & Goswami, D. Y. 2004. The CRC Handbook of Mechanical Engineering (Handbook Series for Mechanical Engineering) (2nd ed). CRC Press.
  51. Kumar, S. & Singh, R. K. 2011. Recovery of hydrocarbon liquid from waste high densitypolyethylene by thermal pyrolysis. Brazilian Journal of Chemical Engineering, 28(4), 659-667.
  52. Lam, S. S. & Chase, H. A. 2012. A review on waste to energy processes using microwave pyrolysis. Energies, 5(10), 4209-4232.
  53. Lee, K. H., Noh, N. S., Shin, D. H. & Seo, Y. 2002. Comparison of plastic types for catalytic degradation of waste plastics into liquid product with spent FCC catalyst. Polymer Degradation and Stability, 78(3), 539-544.
  54. Lin, Y. H. & Yang, M. H. 2007. Catalytic pyrolysis of polyolefin waste into valuable hydrocarbons over reused catalyst from refinery FCC units. Applied Catalysis A: General, 328(2), 132-139.
  55. López, A., de Marco, I., Caballero, B. M., Laresgoiti, M. F. & Adrados, A. 2011. Influence of time and temperature on pyrolysis of plastic wastes in a semi-batch reactor. Chemical Engineering Journal, 173(1), 62-71.
  56. Lopez, G., Amutio, M., Elordi, G., Artetxe, M., Altzibar, H. & Olazar, M. 2010. A Conical Spouted Bed Reactor for the Valorisation of Waste Tires. The 13th International Conference on Fluidization - New Paradigm in Fluidization Engineering. 16-21 May, 2010. Hotel Hyundai, Gyeong-ju, Korea.
  57. Ludlow-Palafox, C. & Chase, H.A. 2001. Microwave-induced pyrolysis of plastic wastes. Industrial and Engineering Chemistry Research, 40(22), 4749-4756.
  58. Luo, G., Suto, T., Yasu, S. & Kato, K. 2000. Catalytic degradation of high density polyethylene and polypropylene into liquid fuel in a powder-particle fluidized bed. Polymer Degradation and Stability, 70(1), 97-102.
  59. Manaf, L.A., Samah, M. A. A. & Zukki, N. I. M. 2009. Municipal solid waste management in Malaysia: Practices and challenges. Waste Management, 29(11), 2902-2906.
  60. Marcilla, A., García-Quesada, J. C., Sánchez, S. & Ruiz, R. 2005. Study of the catalytic pyrolysis behaviour of polyethylene-polypropylene mixtures. Journal of Analytical and Applied Pyrolysis, 74(1-2), 387-392.
  61. Marcilla, A., Beltrán, M. I. & Navarro, R. 2009. Thermal and catalytic pyrolysis of polyethylene over HZSM5 and HUSY zeolites in a batch reactor under dynamic conditions. Applied Catalysis B: Environmental, 86(1–2), 78-86.
  62. Martínez, J. D., Murillo, R., García, T. & Veses, A. 2013. Demonstration of the waste tire pyrolysis process on pilot scale in a continuous Mastellone, M. L., Perugini, F., Ponte, M. & Arena, U. 2002. Fluidized bed pyrolysis of a recycled polyethylene. Polymer Degradation and Stability, 76(3), 479-487.
  63. Mastral, F. J., Esperanza, E., Berrueco, C., Juste, M. & Ceamanos, J. 2003. Fluidized bed thermal degradation products of HDPE in an inert atmosphere and in air-nitrogen mixtures. Journal of Analytical and Applied Pyrolysis, 70(1), 1-17.
  64. Mastral, F. J., Esperanza, E., Garciía, P. & Juste, M. 2002. Pyrolysis of high-density polyethylene in a fluidised bed reactor. Influence of the temperature and residence time. Journal of Analytical and Applied Pyrolysis, 63(1), 1-15.
  65. McCaffrey, W. C., Kamal, M. R. & Cooper, D. G. 1995. Thermolysis of polyethylene. Polymer Degradation and Stability, 47(1), 133-139.
  66. Miranda, R., Yang, J., Roy, C. & Vasile, C. 1999. Vacuum pyrolysis of PVC I. Kinetic study. Polymer Degradation and Stability, 64(1), 127-144.
  67. Miskolczi, N., Borsodi, N., Buyong, F., Angyal, A. & Williams, P. T. 2011. Production of pyrolytic oils by catalytic pyrolysis of Malaysian refuse-derived fuels in continuously stirred batch reactor. Fuel Processing Technology, 92(5), 925-932.
  68. Miskolczi, N., Bartha, L., Deák, G., Jóver, B. & Kalló, D. 2004. Thermal and thermo-catalytic degradation of high-density polyethylene waste. Journal of Analytical and Applied Pyrolysis, 72(2), 235-242.
  69. Murata, K., Sato, K. & Sakata, Y. 2004. Effect of pressure on thermal degradation of polyethylene. Journal of Analytical and Applied Pyrolysis, 71(2), 569-589.
  70. Musale, H. K., Bhattacharyulu, Y. C. & Bhoyar, R. K. 2013. Design Consideration Of Pyrolysis Reactor For Production Of Bio-Oil. International Journal of Engineering Trends and Technology, 5(2), 83-85.
  71. Onu, P., Vasile, C., Ciocîlteu, S., Iojoiu, E. & Darie, H. 1999. Thermal and catalytic decomposition of polyethylene and polypropylene. Journal of Analytical and Applied Pyrolysis, 49(1), 145-153.
  72. Onwudili, J. A., Insura, N. & Williams, P. T. 2009. Composition of products from the pyrolysis of polyethylene and polystyrene in a closed batch reactor: Effects of temperature and residence time. Journal of Analytical and Applied Pyrolysis, 86(2), 293-303.
  73. Othman, N., Basri, N. E. A. & Yunus, M. N. M. 2008. Determination of Physical and Chemical Characteristics of Electronic Plastic Waste (Ep-Waste) Resin Using Proximate and Ultimate Analysis Method. ICCBT, 2008 - D - (16) - pp169-180.
  74. Panahi, A., Wei, Z., Song, G. & Levendis, Y. A. 2019. Influence of Stainless-Steel Catalyst Substrate Type and Pretreatment on Growing Carbon Nanotubes from Waste Postconsumer Plastics. Industrial and Engineering Chemistry Research, 58(8), 3009-3023.
  75. Pariatamby, A., Hamid, F. S., Bhatti, M. S., Anuar, Norkhairah & Anuar, Norkhairiyah. 2020. Status of microplastic pollution in aquatic ecosystem with a case study on cherating river, Malaysia. Journal of Engineering and Technological Sciences, 52(2).
  76. Park, S. S., Seo, D. K., Lee, S. H., Yu, T. U. & Hwang, J. 2012. Study on pyrolysis characteristics of refuse plastic fuel using lab-scale tube furnace and thermogravimetric analysis reactor. Journal of Analytical and Applied Pyrolysis, 97, 29-38.
  77. Qureshi, M. S., Oasmaa, A., Pihkola, H., Deviatkin, I., Tenhunen, A., Mannila, J., Minkkinen, H., Pohjakallio, M. & Laine-Ylijoki, J. 2020. Pyrolysis of plastic waste: Opportunities and challenges. Journal of Analytical and Applied Pyrolysis, 152, 104804.
  78. Rigamonti, L., Grosso, M., Møller, J., Martinez Sanchez, V., Magnani, S. & Christensen, T. H. 2014. Environmental evaluation of plastic waste management scenarios. Resources, Conservation and Recycling, 85, 42-53.
  79. Rochman, C. M., Hoh, E., Kurobe, T. & Teh, S. J. 2013. Ingested plastic transfers hazardous chemicals to fish and induces hepatic stress. Scientific Reports, 3, 3263.
  80. Saad M. M. 2016. The Risk of using Plastic Packaging’s in Food Industry Referring to Phthalate Hazards. Nutrition and Food Technology: Open Access, 2(2), doi http://dx.doi.org/10.16966/2470-6086.119.
  81. Sakata, Y., Uddin, M. A. & Muto, A. 1999. Degradation of polyethylene and polypropylene into fuel oil by using solid acid and non-acid catalysts. Journal of Analytical and Applied Pyrolysis, 51(1), 135-155.
  82. Sakthipriya, N. 2022. Plastic waste management: A road map to achieve circular economy and recent innovations in pyrolysis. Science of the Sarijan, S., Azman, S., Said, M. I. M., Andu, Y. & Zon, N. F. 2018. Microplastics in sediment from Skudai and Tebrau river, Malaysia: A Sharuddin, S. D. A., Abnisa, F., Daud, W. M. A. W. & Aroua, M.K. 2016. A review on pyrolysis of plastic wastes. Energy Conversion and Management, 115, 308-326.
  83. Sati, P. C., Khaliq, F., Vaney, N., Ahmed, T., Tripathi, A. K. & Banerjee, B. D. 2011. Pulmonary function and oxidative stress in workers exposed to styrene in plastic factory: Occupational hazards in Styrene-exposed plastic factory workers. Human and Experimental Toxicology, 30(11), 1743-1750.
  84. Scott, D. S., Czernik, S. R., Piskorz, J. & Radlein, D. S. A. G. 1990. Fast Pyrolysis of Plastic Wastes. Energy and Fuels, 4(4), 407-411.
  85. Singh, R. K. & Ruj, B. 2016. Time and temperature depended fuel gas generation from pyrolysis of real world municipal plastic waste. Fuel, 174, 164-171.
  86. UNEP. 2018. Single-use plastics: A roadmap for sustainability. (https://www.unep.org/resources/report/single-use-plastics-roadmap-sustainability). Last accessed on 19 October 2022.
  87. Sultana, S. & QuaziShahreenHaq. 2020. Press Release: COVID-19 Pandemic Outbreak 14,500 Tons of Hazardous Plastic Waste in a Month (https://esdo.org/press-release-covid-19-pandemic-outbreak-14500-tons-of-hazardous-plastic-waste-in-a-month/). Last accessed on 19 October 2022.
  88. Uddin, M. A., Koizumi, K., Murata, K. & Sakata, Y. 1997. Thermal and catalytic degradation of structurally different types of polyethylene into fuel oil. Polymer Degradation and Stability, 56(1), 37-44.
  89. Undri, A., Rosi, L., Frediani, M. & Frediani, P. 2014. Efficient disposal of waste polyolefins through microwave assisted pyrolysis. Fuel, 116, 662-671.
  90. Vasile, C., Pakdel, H., Mihai, B., Onu, P., Darie, H. & Ciocâlteu, S. 2001. Thermal and catalytic decomposition of mixed plastics. Journal of Analytical and Applied Pyrolysis, 57(2), 287-303.
  91. Westerhout, R. W. J., Kuipers, J. A. M. & van Swaaij, W.P.M. 1998. Experimental Determination of the Yield of Pyrolysis Products of Polyethene and Polypropene. Influence of Reaction Conditions. Industrial and Engineering Chemistry Research, 37(3), 841-847.
  92. Williams, P. T. & Williams, E. A. 1999. Fluidised bed pyrolysis of low density polyethylene to produce petrochemical feedstock. Journal of Analytical and Applied Pyrolysis, 51(1), 107-126.
  93. Worstell, J. 2015. Chapter 4: Semi-batch reactors. In: Worstell, J. (ed). Batch and semi-batch reactors. Butterworth-Heinemann, pp.51–84.
  94. Yin, S. E., Dong, P. & Bie, R. S. 2007. Basic study on plastic pyrolysis in fluidized bed with continuous-feeding. In: Cen, K., Chi, Y., Wang, F. (eds). Challenges of Power Engineering and Environment. Springer: Berlin, Heidelberg.
  95. Zannikos, F., Kalligeros, S., Anastopoulos, G. & Lois, E. 2013. Converting Biomass and Waste Plastic to Solid Fuel Briquettes. Journal of Renewable Energy, 2013, Article ID 360368.
  96. Zhao, D., Wang, X., Miller, J. B. & Huber, G. W. 2020. The Chemistry and Kinetics of Polyethylene Pyrolysis: A Process to Produce Fuels and Chemicals. ChemSusChem, 13(7), 17641774.
  97. Zhou, N., Dai, L., Lyu, Y., Li, H., Deng, W., Guo, F., Chen, P., Lei, H. & Ruan, R. 2021. Catalytic pyrolysis of plastic wastes in a continuous microwave assisted pyrolysis system for fuel production. Chemical Engineering Journal, 418, 129412.
  98. Zuo, M. 2020. Coronavirus leaves China with mountains of medical waste. (https://www.scmp.com/news/china/society/article/3074722/coronavirus-leaves-chinamountains-medical-waste). Last accessed on 19 October 2022.