Definition:

Biodegradable plastic is a type of plastic that can be broken down naturally by microorganisms such as bacteria, fungi, and other microbes into simpler substances like water, carbon dioxide or methane , and biomass. Unlike ordinary plastics, which may remain in the environment for hundreds of years, biodegradable plastics are designed to decompose faster under suitable conditions i.e. temperature, moisture, oxygen, and microbial activity.

Aim :

To test the given plastic and check weather it is eligible to get a tag of biodegradable plastic.

Historical Background:

Indian Standard 17088 has given the requirements for compostable plastics. It is used to decide whether a plastic product can truly be called compostable / biodegradable under composting conditions.The standard checks mainly 4 things:

  1. Biodegradation – Can microbes break the plastic down?
  2. Disintegration – Does it physically break apart during composting?
  3. Effect on composting process – Does it disturb compost formation?
  4. Safety of compost – Does the final compost remain safe and not contain harmful substances?

Principle:

Biodegradable plastics work on the principle of microbial degradation, where microorganisms use the plastic as a food source and convert it into natural products

Objectives:

As an fellow student to study and learn the process of degrading biodegradable plastic.

  1. To understand the types pf biodegradable plastics.
  2. To study about the bacteria and fungi which work to degrade the plastic.
  3. To observe the functioning of the bacterias and fungi on plastic.

10 /6/26 to 20/6 26

I had discussions with Dr. Dixit Sir and learnt about the types of Biodegradable plastic, the criteria of IS 17088, which plastic are we choosing for the test, monomers and linkages of that plastic , which enzymes will break the linkages, and the bacteria and fungi that contain these enzymes.

PBAT Plastic

PBAT plastic stands for Polybutylene Adipate Terephthalate. It is a flexible biodegradable plastic that is designed to break down under suitable composting conditions.

IS 17088:2021 rules for PBAT

Test namePass limit for PBATPBAT Problem
Biodegradation≥90% carbon → CO₂ in ≤180 days at 58°C ± 2°C.Benzene ring slows breakdown. Thick films fail.
Disintegration≥90% pieces <2mm after 12 weeks at 58°C.Enzymes cut ester but stop at benzene. Need special fungi.
Ecotoxicitycompost must grow plants normally.If degradation stops, left over PBAT bits= microplastic.
Heavy metalsPb <50 ppm, Cd <0.5 ppm, etc.PBAT itself ok ,but color additives may fail.