By Rucha Pramanick, Ishita Parveen and Preeti Rai
“Be a part of the solution and not of the pollution!”
As and when we begin recognising and establishing ourselves beneath the deep roots of this statement, we find that such sustainable and eco-friendly ideas of eliminating the plastic pollution from around us, led to the introduction of Biodegradable Plastics in today’s world surrounded with polymers, especially the harmful ones.
Source: Plastic Ranger
Science describes an object as "biodegradable"; when it has the quality to break itself down
into the natural environment with the help of fungi or bacteria. For an object to be biodegradable:
The volatility rate must be 50% or more.
Be able to fragment at least 10% of its initial weight above a 2mm sieve after 12 weeks after being first composted;
Get at least 90% biodegraded (compared to the maximum disintegration of a reference substance) in no more than 6 months;
Also, according to OCDE 208, when it comes to toxicity, the resulting compost needs to perform at least 90% compared to the corresponding reference compost.
Biodegradable plastics are basically, the plastics that can be decomposed by the actions of living microorganisms. These plastics are commonly produced with renewable raw materials, microorganisms, petrochemicals, or combinations of all three.
Source: Allied Market Research
Biodegradable plastics can be classified into various forms. Some of them are as follows:-
Source: Almost Zero Waste
Bio-Based Plastics:
Biologically synthesised plastics (also called bioplastics or bio based plastics) are plastics
produced from natural origins, such as plants, animals, or micro-organisms. For example,
Polyhydroxyalkanoates (class of biodegradable plastic naturally produced by various microorganisms like Cuprividus necator) and Polylactic acid (a thermoplastic aliphatic polyester synthesised from renewable biomass, typically from fermented plant starch such as from corn, cassava, sugarcane or sugar beet pulp.)
Source: europeanbioplastic.org
Starch Blends:
Starch blends are basically the thermoplastic polymers produced by blending starch with
plasticizers. Since starch polymers on their own are brittle at room temperature, plasticizers are added in a process called starch gelatinization to augment its crystallisation. While all starches are biodegradable, not all plasticizers are. Therefore, the biodegradability of the plasticizer determines the biodegradability of the starch blend.
Source: Green Dot Bioplastics
Cellulose-based Plastics:
Cellulose bioplastics are mainly the cellulose esters, (including cellulose acetate and nitrocellulose) and their derivatives, including celluloid. Cellulose can become thermoplastic when extensively modified. An example of this is cellulose acetate, which is expensive and therefore rarely used for packaging.
Source: Bioplastics Magazine
Lignin-based polymer composites:
Lignin-based polymer composites are bio-renewable natural aromatic polymers with biodegradable properties. Lignin is found as a by-product of polysaccharide extraction from plant material through the production of paper, ethanol, and more.It is being produced at such great quantities and is readily available for use as an emerging environmentally friendly polymer.
Source: Azom
Finding in and knowing more about the various varieties of biodegradable plastics, we also come to rescue the world out of dangers petroleum based plastics could actually provide. Introducing biodegradable plastics will indeed help us in reducing the hazardous effects the plastic pollution would cause.
Talking about the specific applications, we find that they’re commonly used for disposable
items, such as packaging, crockery, cutlery, and food service containers. Yes, biodegradable
plastics can definitely replace many applications for conventional plastics. Several articles of our day-to-day lives are made of polyethylene. The assembling of an extremely humongous number of this chemical produces CO2. Polyethylene is commonly used for making grocery bags. Polyethylene bags are made from crude oil. Due to excess demand for Polyethene, the already depleting reserves of oil are endangered. These durable bags come with other difficulties too. These bags clog drains and take over 500 years to decompose. It deteriorates the quality of the soil. Plastics are toxic to the environment and cause toxic health hazards. Biodegradable plastics are made of the same chemicals as our regular use of polyethylene, but more chemicals are added to them. These added chemicals propel the quick breaking down.
Are they really a solution to the plastic crisis?
Source: Conserve Energy Future
Biodegradable plastics are often claimed to be sustainable and better for the planet but it proves inaccurate and misleading hence ends up creating plastic pollution. Biodegradable plastic can be a good alternative for the plastic crisis but has a negative impact too. BPs are manufactured by using plant substances like sugar, starch etc. Thus recent modern farming needs more herbicides, pesticides and artificial fertiliser which makes crops toxic and creates risk of contamination. As toxicity is concerned, according to Guardian report, high level of cobalt and lead present in one brand of this kind of plastic raises the question of toxicity left after decomposition.
Another major problem associated with biodegradable plastic is that some have additives which make it harder to recycle. Even PLAs are generally mechanically recycled and can be recycled again but they contaminate the waste stream of petroleum based plastic (chemically recycled). PHAs can be considered as good alternatives but the manufacturing cost is very high and creates no possibility in developing or underdeveloped countries.
As we know, for recycling people needs to segregate biodegradable plastic and traditional plastic but unfortunately due to lack of awareness BPs remain mixed with other plastics. If mixing is contaminated, no possibilities can be found for recycling consequently further adding into wastage. This mixing waste goes into landfills. Some biodegradable plastic starts generating methane while decomposing. Methane is known to be 84 times more potent than carbon dioxide in absorbing heat.
Also, the manufacturing of biodegradable plastic is 20-50% more costly than the production of traditional plastic, hence it is difficult to install these expansive machinery at every small industry or in every part of the world. Precisely 10% croplands are required for production of these plastics. In developing or underdeveloped countries where people are dying due to starvation raises the ethical question whether it is right to expand these industries.
Breaking up biodegradable municipal waste is necessary because accumulated waste in landfills produces methane (CH4 gas), which is 150 times more harmful than carbon dioxide. Biodegradable plastic is designed to break up into multiple smaller bits when exposed to sunlight and air, but never really decompose. If discarded into conventional waste streams such as landfill, or find their way into the open environment such as rivers and oceans, potential environmental benefits are not realised and evidence indicates that this can actually worsen, rather than reduce, the problem of plastic pollution.
It is important to install expansive industrial processore and composers for the process of breakdown which requires high industrial scale temperature. In developing or underdeveloped countries, the installation of these machinery and necessary equipment is an issue hence without processing appropriately discardation is not possible. If this plastic is dumped into the ocean it never decomposes due to cold temperature and consequently either floats on the surface or fragments into micro plastic. According to UNEP, the inclusion of pro oxidant such as manganese, in oxo degradable polymers are claimed to promote fragmentation in UV radiation and oxygen, proved not to break rapidly in the marine environment persisting more than 2-5 years causes undesirable impact.
So, keeping all the known information in a nutshell, we can finally conclude that the biodegradable plastics can’t vanish the harm caused by conventional plastics in totality. Biodegradable plastics are somewhat a 'false solution'. Thus, the best way to cope with plastic pollution is by reducing
the consumption of plastic.
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