Bioplastics in reducing environmental concerns related to waste management

Bioplastics in reducing environmental concerns related to waste management

SADAF SALEEM¹, IRAM SALEEM²

1. Department of Plant Breeding and Genetics, University of Agriculture Faisalabad.
2. Department of Environmental Sciences and Engineering, GC University Faisalabad.

A Bioplastic is a biodegradable plastic made by renewable biomass sources instead of petroleum. Different countries use different biological materials to synthesize bioplastics. Most commonly used biological substances for this purpose are agricultural byproducts from wheat, corn starch, potatoes, sugar cane, sugar beets, vegetable fats and oils, feedstocks etc.

Bioplastics over Petrochemical plastics

Conventionally used petrochemical plastics made by petroleum are continuously posing pressure on economy as the oil and gas resources are declining. This also causes an increase in oil and gas prices. But the major concern is their degradation and cross contamination. While recycling their monomers/oligomers may enter in edible materials and leads to food toxicity and serious health issues.

The Bio plastics are better for the environment than conventional plastics because require cheaper source materials (agricultural by-products) as well as low energy costs in manufacturing. Bioplastics provide better acceptability to many households. The most important thing is their biodegradability, this makes bio plastics renewable.

Sources of Bio plastics polymers

Biopolymers are produced from natural resources and crude oil. Four categories of biopolymers sources are;

• Natural raw materials extract, such as starch, cellulose, gelatin, casein, silk and marine prokaryotes.
• Chemical synthesis from bio-derived monomers such as poly-lactic acid (PLA).
• Produced by microorganisms or genetically modified bacteria such as poly hydroxyl alkanoates (PHA), poly hydroxyl butyrate (PHB), hydroxyl-valerate (PHV), bacterial cellulose, xanthan.
• Crude oil like aliphatic and aromatic polyesters, polyvinyl alcohol, and modified polyolefin.

Types of Bioplastics

Broadly two types of bio plastics are now produced, known as poly lactic acid (PLA) and poly hydroxyl alkanoate (PHA). Now a days PLA is the most commonly used. PLA was first produced by Carothers in 1932 by heating lactic acid under vacuum while removing the condensed water. At that time it was used in combination with poly glycolic acid (PGA) and sold under the name Vicryl in the U.S.A. in 1974.

Benefits of bioplastics

Greenhouse-gas-neutralizing polymer

One of the important benefits of PLA is; its production emits fewer CO₂ gas as compared to other hydrocarbon-based polymers. How it is carried out? Actually carbon dioxide is absorbed from air when corn or other plants are grown. “Net / residual” emissions are calculated as total emissions from the cradle to the factory gate minus carbon dioxide uptake during plant production. So in case of PLA the negative values of residual shows the total CO₂ consumption from the cradle to factory is more than its emission to the environment.

Require less production energy

The PLA production uses 68% less fossil fuel resources than traditional plastics. It requires less energy to mold into plastic containers and can be shaped easily as bottles, containers, trays, film and other packaging.

A new potential for Agriculture industry

Bioplastics offer new potential for the industry of agriculture. As the raw material (which is renewable) plays a very important role in the production, it provides agriculture a whole new market of food and investment.

Degradation in natural environment

Bioplastic could be idealized over petrochemical plastic for is its versatility as it degrades naturally when exposed to the environment. For example, a PLA bottle left in the ocean would typically degrade in 6 to 24 months in comparison to conventional plastics (which in the same environment can take several hundred to a thousand years to degrade).

Biodegradability

Organic recovery (aerobic treatment)

Organic recycling is the aerobic treatment of packaging waste in which the microbial transformation of carbon containing material into CO₂, H₂O and biomass occur.

Composting of bioplastics (aerobic treatment)

When entering composting plants, bioplastics converted into CO₂, H₂O and biomass (as part of the compost product). The resulting compost can be used as a soil improver and in replace to mineral fertilizers.

Bio gasification (anaerobic treatment)

In bio gasification plants, methane is produced from organic substrates. The process is attractive because it yields both compost as a product and also renewable energy, the methane is captured to produce electricity and heat in power plants.

References

Bogaert, J.-C. and P. Coszach (2000). “Poly(lactic acids): a potential solution to plastic waste dilemma.” Macromolecular Symposia 153(1): 287-303.

Jamshidian, M., et al. (2010). “Poly-Lactic Acid: Production, Applications, Nanocomposites, and Release Studies.” Comprehensive Reviews in Food Science and Food Safety 9(5): 552-571.

Ueno, T., Ozawa, Y., Ishikawa, M. et al. Biotechnology Letters (2003) 25: 573. doi:10.1023/A:1022888832278