Biodegradable-a large amount of wastes that are generated by industries are formed of substances, which cannot be easily broken down by the microorganisms. these substances are called non-biodegradable. the plastic we use to make polythene bags is an example of a non-biodegradable substance. microorganisms do not eat up these plastics and they choke the soil as no water and air is able to reach it. slowly, the soil turns barren and devoid of life. did you know that a polythene bag could take as much as 30 years to disintegrate?