Potential Of Pyrolysis As a Plastic Waste Energy Source In Urban Areas: A Case Study At Chiwaridzo Phase 2 Location In Bindura Town
- Author
- Primrose Dhunga
- Title
- Potential Of Pyrolysis As a Plastic Waste Energy Source In Urban Areas: A Case Study At Chiwaridzo Phase 2 Location In Bindura Town
- Abstract
- Traditional recycling and re use methods such as open burning of plastics have proven ineffective and environmentally unsustainable. This study is aimed at examining the potential of pyrolysis as an environmentally friendly energy recovery option for plastic waste in urban areas (Chiwaridzo Phase 2). Three samples of the most abundant different plastic types (LDPE, HDPE and PET) were collected from three different dumpsites (Dumpsite 1, 2, and 3) within Chiwaridzo Phase 2 through waste sorting and each sample was divided into six samples resulting in 18 samples. Three dumpsites for sorting were selected using random sampling (true random number generator). Samples for sorting within each dumpsite and samples for pyrolysis were selected using purposive sampling. All pyrolysis experiments were conducted at a temperature range of 4500C-9000C and a heating rate of 0.1-10C/s in a stainless steel reactor using a zeolite catalyst at a catalyst feed rate of 1:10. Emitted pyrolysis gases were analysed thermo-gravimetric software printout. At p>0.05, the statistical package of social science (SPSS) version 20 was utilized to analyse all statistical data. Between the three dumpsites, a One Way Analysis of Variance (ANOVA) was done to see the most abundant plastic type across all dumpsites. The significance of differences in the mean quantities of pyrolysis products (char and oil) recovered from different plastic types, in the mean concentrations of gases emitted during pyrolysis of the three different types of plastic and EMA emission standards were determined using post-hoc analysis. All statistical analyses were performed with a 95% confidence level (p>0.05).The order of abundance of pyrolysis oil was fluctuating depending on plastic type. HDPE plastic had the highest concentration of oil (52%), while PET recorded the least concentration (19%). There was a statistical difference in oil concentration across all plastic types with LDPE recording 29%. LDPE recorded the highest weight in terms of char with an average 42% and there was no statistical difference between weight of char from LDPE and HDPE (p>0.05). All plastic types pyrolysis recorded highest concentrations of CO with LDPE being highest (978.50mg/cm3) followed by LDPE (938.33 mg/cm3) and HDPE recorded the least among the three (932.67 mg/cm3). LDPE also recorded the highest concentration of SO2 (56.167±0.600 mg/cm3) and HDPE had the least with 50.167±1.990. On the other hand, HDPE recorded the highest concentration of NO2 (136 mg/cm3) with LDPE recording the least with 107.83 mg/cm3. The results concluded that pyrolysis is an environmentally friendly method for plastic waste management since escaped gases were within the SI 72 of 2009 standard limits. Trace elements were found to be present in char obtained from different plastic wastes with Zn across plastic types being statistically significant (p=0.002) with no significant difference on the level of lead (Pb) (p=0.084) and in terms of Cr concentration there was a statistical significant (p=0.008). Modified pyrolysis equipment must be used which can separate and harvest non-combustible volatile gases released during pyrolysis so they can be used for other industrial processes. Process parameters, use of plastic waste and mixture of different wastes during disposal and prior to pyrolysis affect product yields across plastic type and the presence of trace elements in products hence need for waste segregation during disposal and close monitoring of process parameters is needed.
- Date
- 2024
- Publisher
- BUSE
- Keywords
- Plastic waste, Pyrolysis, Dumpsite, Case study, ,Chiwaridzo Phase 2, Bindura, Zimbabwe
- Dumpsite
- Supervisor
- Mr P Nhokovedzo
- Item sets
- Department of Environmental Sciences
- Media
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Dhunga - SHEM.pdf