Aerobic biodegradation at seawater-sediment interface of a compostable and food waste-based bioplastic

Bioplastics are heterogeneous groups of material with multiple applications in different fields whose future production will increase more and more over the time. Currently their market presence in much lower than those conventional because of production costs. Bioplastics available nowadays are produced using 1st generation feedstock and they could generate ethical end environmental critical issues related to soil consumption not for human food production. Thus, efforts are made to develop these materials starting from waste, to increase their upstream sustainability reducing their production costs. [1] Another concern regard their compostability because they are not always compostable under home composting conditions. This causes the same injuries produced by the environmental dispersion of conventional plastics. Therefore, the present work was focused on the biodegradation in sea water of a bioplastic material produced By SPlastica srl ©, produced by expired milk and already tested for compostability according to EN 13432:2000. The experiment was carried out in aerobic and controlled laboratory conditions according to ISO 19679:2020 and [2] to simulate the biodegradation at sediment-water interface in sublittoral coastal zone. The bioplastic milk based (SP-Milk) biodegradability was tested against positive control (filter paper), negative control (LDPE) and blank (seawater and sediment without any other material (blank). Its biodegradation percentage reaches, measuring the CO2 developed, the 83.5% in just 52 days with respect to the endogenous respiration rate represented by the blank. Only few gelatinous-like residues of samples remained and were analyzed by optical microscope. The biodegradation data were supported by visual disappearance of the sample and by optical microscopy results that reveal an intense microorganism presence at water-SP Milk residues interface. To the best of our knowledge, comparable results were not obtained yet in a so tiny timeframe and represents a promising first result for further studies on ecotoxicological effects on marine biota. [1] https://docs.european bioplastics.org/publications/fs/EuBP_FS_Renewable_resources.pdf [2] Briassoulis, Demetres & Pikasi, A. & Papardaki, N.G. & Mistriotis, Antonis. (2020). Aerobic biodegradation of bio-based plastics in the seawater/sediment interface (sublittoral) marine environment of the coastal zone – Test method under controlled laboratory conditions. Science of The Total Environment. 722. 137748. 10.1016/j.scitotenv.2020.137748.