Recently, I met someone who told me he was glad the Canadian government was finally
implementing the ban on most single-use plastics ( he was especially referring to the t-shirt bag). He concluded by saying that after all, plastic is bad. I am equally excited about it but do not agree with the phrase ‘plastic is bad.’
While it is fair to say that the ban on single- used plastic is necessary to reduce further spread of micro-plastics and nano-plastics in our environment, the primary issue is the misuse of plastics. This has led to an increased generation of plastic waste and plastic littering in water bodies.
Currently, there are four (4) major technologies for plastic disposal (this post only discusses two, the next post will cover the rest)
- Energy recovery
- Biodegradation, and
- Landfilling is the oldest known method for waste disposal. It started with digging up pits to bury waste, and has been developed to include anti-leaching technologies, carbon-capture, Hydrogen sulphide (H2S) removal and methane-capture. Landfilling works on the principle of natural degradation/decomposition of waste by micro-organisms. However, apart from biodegradable plastics, most plastics require a long time to naturally degrade in a landfill . Single-use plastic straws require 200 years, plastic bottles require about 450 to 1000 years.
- Energy recovery: This occurs by the pyrolysis, incineration or gasification of plastics for the generation of energy in the form of heat, bio-oil, syngas, and biodiesel. The difference in the terms; pyrolysis, gasification and incineration; is dependent on the amount of oxygen used in the process. This will result in different products and by-products. Another factor that influences the product and by-product generated in this process is temperature. As temperature increases, the amount of syngas; which can either be converted to biodiesel or used to generate electricity; increases, and by-products such as ash reduces. An advantage of gasification over incineration is that due to limited oxygen in the process, harmful toxins such as dioxins and furans are not produced. The problem with increasing temperature is that it increases production cost and requires the use of heat-resistant materials.
For these reasons, there is an argument about whether plastic waste can be considered as a renewable source of energy. However, this notion encourages the continued misuse and littering of plastics.