What is biodegradable plastic, and how can this material reduce littering?

December 19th, 2023 | Biodegradable plastic

Biodegradable plastic has similar properties as conventional plastic, but when left in the environment these new materials dissolve and degrade into harmless minerals, water, and CO2 thanks to microorganisms such as bacteria, fungi, and algae.

In Dsolve we aim to develop plastic materials that can replace synthetic fibres like nylon and polyethylene in fishing gear and aquaculture equipment. Initial studies have shown that biodegradable nets have similar mechanical properties during fishing, but that they can be completely degraded in seawater when left in the marine environment.

Biodegradable plastic can be made both from natural resources such as vegetable oils and starches (bioplastics), and petroleum-based materials. In other words, not all biodegradable plastics are bioplastics.

The degradtaion process

Exposure to UV radiation, oxygen, heat, wind, waves, seawater, and bacteria all influence the degradation of synthetic materials in the environment. The impact of these factors leads to cracks, surface erosion and abrasion of the material, which further leads to its disintegration into macro-, micro-, and nano-sized plastic pieces. Biodegradation, as part of this degradation process, is based on chemical-biological processes induced by the interaction of the surface of the polymer with enzymes secreted by microorganisms, such as bacteria and fungi. This process is cleaving off molecular fragments, which then can be digested by the microorganisms. The rate of biodegradation depends strongly on the environmental conditions, such as temperature and number of suitable microorganisms.

Natural bacterial strains degrade PBS monofilaments (polybutylene succinate, degradable plastics) into H2O (water) and CO2 through an anaerobic digestion process (source: S-ENPOL)

SFI Dsolve is currently conducting tests on biodegradable equipment under various conditions and temperatures, both in Norway and internationally. Studies indicate that these new biodegradable plastic materials dissolve within 3-5 years in marine environments. This implies that, if used in fishing equipment (e.g., fishing nets), ghost fishing can be significantly reduced. The challenge lies in maintaining the mechanical properties for a desired time frame, while, in the event of equipment loss, achieving a rapid degradation rate.

How can biodegradable materials reduce littering?

Biodegradable materials, in themselves, represent no guarantee for reduced plastic littering. However, unlike the non-biodegradable plastics we use today, these new materials dissolve into harmless minerals, water, and CO2 in the marine environment over time. In simpler terms, lost fishing gear won’t stick around in the marine environment for extended periods. Over time this means that less plastic waste will be piling up in the sea. Additionally, these faster-dissolving materials also reduce the harmful effects of ghost fishing caused by lost gear.