Chapter 30 - Microalgae: a promising tool for plastic degradation

Abstract

The use of plastics in the present-day routine is an unavoidable part of human life. It is posing a global environmental threat due to its never-ending accumulation. Complete disposal of plastics is a major problem, and for their complete degradation an effective solution or method has not been discovered yet. However, in order to turn to a biological approach for coping with the ever-increasing fear of plastic aggregation and decay, the development of a methodology would be useful for posterity. To eliminate plastic wastes, two scenarios exist: produce biodegradable plastics from renewable materials or fossil fuels as building blocks, such as hydrobiodegradable/oxo-biodegradable; or find appropriate microalgae and their toxins for the development of a protocol to effectively biodegrade the plastics. Just as biodegradation of plastics is a constructive option, as they are eco-friendly with not much harm done to the environment, the development of biodegradable plastic is also equally effective. Some of the algae that are isolated from the plastic wastes are green-algae, blue-green algae, diatoms, etc. Polyethylene is basically carbon and hydrogen polymer, which is exceptionally resistant to biodegradation (less than 0.5% over 100 years), whose degradation is dependent mainly on moisture, light, and temperature. The most used types of plastics like polyethylene terephthalate and polypropylene are a major threat as they are used in the manufacture of bottles, fibers, packing materials, etc. The degradation or disposal of these plastics is leading to their conversion into microsized particles which is further leading to harm to the environment, mainly when these microplastics interact with microalgae like Spirulina. However, landfill, incineration, and chemical methods are some of the conventional methods for polyethylene disposal that are fatal to the environment as they cause hazardous effects on flora and fauna.