Between 1950 and 2017 an estimated 9.2 billion tonnes of plastic has been produced in the world. Approximately 7 billion tonnes of these plastics have become plastic waste still remaining in landfills or discarded elsewhere in the aquatic environment or land.
The plastics used today are predominantly nonbiodegradable plastics that are petrochemical or fossil-based. Polyethylene and polypropylene, for example, are used in 90% of packaging materials and fossil-based non-biodegradable plastics make up around 99% of global plastics production.
Plastic waste is linked to problems such as blockage of waterways resulting in flooding, and ingestion by livestock and fish with detrimental impact on the livelihoods of farmers and those depending on fish for livelihood. Plastic waste has also resulted in soil pollution with an adverse impact on crop yield. Improperly discarded plastic waste also creates a breeding ground for pathogenic organisms.
When non-biodegradable plastics defragment into microplastics, they pose a new wave of problems to the environment and health. At this scale they still carry all the risks of nonbiodegradable plastics but with improved efficiency. They serve as surfaces for bacteria, heavy metals, and toxins to attach and infiltrate the environment. Microplastics have been detected in water, soil, and air. They make it into the food chain when they get ingested by small aquatic organisms which then get ingested by the fish and seafood humans eat.
Bioplastics do away with the drilling and mining processes associated with petrochemical-based plastics and other materials like metals. Oil refineries have been associated with environmental pollution, health hazards,, and catastrophic accidents over the years. These include oil spills, the release of toxins, and explosions at the refinery. For example, an explosion at a refinery in a Texas city in 2005 resulted in 15 deaths and estimated 170 injuries.
Production of biopolymers like PHA and PLA involves relatively safer processes of fermentation and bioreactions which do not require deep-sea drilling or high-risk mining activities.
Production of bio-based biodegradable plastics mostly requires the use of water, organic substrates, and cultured microbes. Extractions can be carried out with eco-friendly solvents. The raw materials are usually cultivated, by-products of agriculture or food processing, or other organic waste.
VEnvirotech for example produces bioplastics from organic waste which are sustainably sourced directly from the point of waste generation.
Plastics by virtue of their chemistry are generally inert. However, the unreacted monomers, plasticizers, additives, and processing aids that are used in the synthesis and processing of plastics cause major problems. These compounds are not chemically attached to the plastics but get released from the plastics throughout their useful life and upon disposal or recycling.
Bisphenol A (BPA) which is widely used as a plasticizer in plastics and a monomer in the production of polycarbonate is an endocrine-disrupting chemical. It has been detected at high levels in rivers and in human urine samples. Adverse impacts include lipid metabolism disorders, abnormal obesity, and increased cholesterol.
Bioplastics do not make use of toxic monomers therefore, even unreacted residues do not pose the same level of health or environmental threat as those of conventional fossil-based plastics. Lactic acid, for example, the monomer of PLA, is a chemical that is also naturally produced by the human body and is integral to biological function. Additives used in polymers like the PHAs produced by VEnvirotech are mainly minerals and fibres obtained from organic waste from food, agriculture, or slaughterhouse.
Most of the bioplastics of commercial relevance are aliphatic polyesters or non-aromatic polyesters. Aliphatic polyesters like polylactic acids are more prone to degradation compared to aromatic polyesters such as polyethylene terephthalate. This is due to the ester groups along their main chain which readily undergo hydrolytic or enzymatic cleavage.
Biodegradation of plastics occurs in 3 stages
A study of the degradation rate of different bioplastics is summarised in Table 1 below. Biodegradable plastics degrade at different rates in different environments. PHB for example can achieve complete biodegradation within 140 days.
Table 1. The degradation rate of PLA, PHB, and PCL
Bioplastic | Degradation rate | Testing method |
| PLA | 86% degradation after 90 days | ASTM D5338-15 |
| PHB | 99 -100% after 112 -140 days | ASTM D5338-98 |
| PCL | 81% after 90 days | ASTM D5338-15 |
Microplastics from biodegradable bioplastics don’t pose the same problems as those from nonbiodegradable plastics. The reduced size of the bioplastics as they defragment into microplastics creates a larger surface area for microbes to colonise and biodegrade the bioplastics. Therefore microplastics from biodegradable plastics “go away” unlike those from nonbiodegradable plastics which persist in the environment.
When microbes attach to biodegradable microplastics, they metabolise and assimilate the bioplastic. However, when microbes attach to nonbiodegradable microplastics, they hang on, breed and use the microplastic as a transport medium to a living host.
The products of degradation are generally nontoxic since the monomers and additives used to produce the plastics are nontoxic. Bioplastics can be converted to fertilisers at the end of their useful life.
Compostable plastics like VEnvirotech’s range of biodegradable and compostable PHAs do not require special industrial composters at the end of life. These can be decomposed in household compost and will biodegrade under normal environmental conditions.
GHG from PHA production has been estimated at 0.49kg CO2 equivalent per Kg of PHA resin produced. That of petrochemical-based plastic like PE and PP range between 2 to 3 Kg CO2 equivalent per kg of plastic resin. Production of PHA also has an 80% reduction in global warming potential.
Methane from landfilling of organic waste can be reduced by processing this organic waste into bioplastics before they begin to decompose. This is why VEnvirotech takes the onsite processing approach to minimise emissions.
Incineration of plastic waste in landfills or even controlled incineration lead to GHG emissions. Replacing nonbiodegradable plastics with biodegradable ones allows for more sustainable ways to convert plastics to energy or raw materials.
VEnvirotech specialises in the production of bioplastics from revalued organic waste. The company has developed proprietary technology for the onsite conversion of organic waste into raw materials for bioplastic production. It also has 7 different optimised bioplastic formulations intended for processing using injection moulding, 3D printing, and thin film technology.
For prospective clients who require unique formulations or waste upcycling tailored to their specific business goals and operations, VEnvirotech has a team of experts dedicated to providing custom upcycling services.
