Incineration as a potential solution to Africa’s plastic waste challenges? A narrative review
- Authors: Mazhandu, Z. S. M. , Muzenda, E. , Belaid, M. , Mamvura, T. A. , Nhubu, T.
- Date: 2020
- Subjects: Incineration , Life Cycle Assessment , Plastic waste
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/458865 , uj:40776 , Citation: Mazhandu, Z.S.M. et al. 2020. Incineration as a potential solution to Africa’s plastic waste challenges? A narrative review.
- Description: Abstract: Africa is considered the second most polluted continent and it will contribute the highest amount of waste into the world’s oceans by 2035. A paltry 4% of the total municipal solid waste (MSW) generated in Africa is recycled and yet 70-80% of the MSW is recyclable. In addition, 90% of the waste that is generated is dumped at uncontrolled landfills while 10% is illegally burnt. Africa has accumulated over 130 million tonnes of plastic waste on its landfills. The poor recycling statistics of the continent means that Africa is missing out on the benefits that plastic waste can yield such as job creation and energy generation; both which are lacking in Africa. The objectives of this review are therefore to assess whether incineration can be considered in the management of plastic waste in Africa based on past life cycle assessment studies; to determine the risks associated with incineration as well as evaluate threats to its success. Data was sourced using keywords and phrases in academic databases and grey literature. The results show that opportunities exist for Africa to manage its plastic waste sustainably and therefore, landfilling of plastic wastes is not the solution due to the risk of spontaneous fires that release harmful toxins. In conclusion, as the continent navigates the path to “zero waste to landfills” in line with circular economy principles; it is time for waste to energy technologies such as incineration to be considered in waste management systems. Life cycle assessments (LCAs) within the African context need to be carried out as they are lacking, in order to determine how incineration or other treatment methods such as pyrolysis and use of plastic wastes in cement kilns and blast furnaces can be successfully implemented without increasing eco-toxicological and human toxicological impacts.
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Plastic waste use in the blast furnace as a reducing agent
- Authors: Mazhandu, Z. S. M. , Muzenda, E. , Belaid, M. , Mamvura, T. A. , Nhubu, T.
- Date: 2020
- Subjects: Blast Furnace , Coke , Landfill
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/458868 , uj:40778 , Citation: Mazhandu, Z.S.M. et al. 2020. Plastic waste use in the blast furnace as a reducing agent.
- Description: Abstract: Steel is among the most essential materials in construction, making its manufacture equally important. Steel is manufactured either via an integrated iron and steel making route characterised by the Blast Furnace (BF) and a Basic Oxygen Furnace (BOF), smelting followed by a BOF or in an electric arc furnace. The objective of this paper explores the possibility of using plastic waste in Africa as an alternative reducing agent to coke in the Blast Furnace; a recycling practice that is commonly done in Japan and Europe. There are many benefits that can be accrued environmentally, operationally and economically when using waste plastics in the BF. The hydrogen content in waste plastics is almost three times more than that in pulverised coal making it a better reducing agent environmentally and economically. Plastic waste has a higher calorific value and less impurities, which results in energy savings and less dioxins and furans in the process. In addition, bearing in mind that over 130 million of tonnes of plastic waste are currently in Africa’s landfills, utilising waste plastics in the BF will result in savings in landfills airspace, prevent financial losses incurred through dumping valuable recyclables, protect the environment and the public because if spontaneous fires start in landfills then toxic fumes such as furans and dioxins, cannot be generated if the landfills are plastic free. With such evidence on hand, plastic waste use in the BF presents an untapped beneficial opportunity not only for the continent of Africa but other continents such as North America where landfilling is rife.
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Char production through the co-pyrolysis of coal and biomass in a fixed FED reactor
- Authors: Motlhatlhedi, T. J. , Muzenda, E. , Mamvura, T. A.
- Date: 2020
- Subjects: Cow dung , Char , Coal
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/461807 , uj:41146 , Citation: Motlhatlhedi, T.J., Muzenda, E. & Mamvura, T.A. 2020. Char production through the co-pyrolysis of coal and biomass in a fixed FED reactor.
- Description: Abstract: Coal contributes to 40% of the world’s energy production and the process of energy production from coal contributes to 40% of the world’s carbon dioxide emissions which have led to global warming and climate change. Thermochemical processes like pyrolysis, gasification and carbonification are used to utilize coal and this coal can be mixed with other sources of energy such as biomass for environmental protection, a higher energy densification and char yield. In this study Morupule coal was co-pyrolyzed with cow dung in a fixed bed reactor with the aim of producing char whilst reducing the net carbon dioxide emissions. Co-pyrolysis of coal with biomass yields char, gas and liquid fuel. Char is used in various sectors such as agriculture to improve soil quality hence increasing crop yields and as an adsorbent for wastewater treatment. The co-pyrolysis process was performed at 500oC and atmospheric pressure under an inert atmosphere which contained argon. Pyrolysis using a fixed bed reactor was performed on coal and cow dung at blend ratios of coal to cow dung of 0:100, 50:50, 60:40, 70:30, 80:20, 90:10, and 100:0. Proximate analysis results indicated that char had a higher fixed carbon compared to those from the individual substrates. Calorific value (CV) tests of the chars indicated that reducing to 90:10 ratio the cow dung concentration resulted in CV increases. This study shows that there is a synergic effect between the sub-bituminous Morupule coal and cow dung.
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