Decomposition Behavior of Biodegradable and Single-Use Tableware Items in the Warnow Estuary (Baltic Sea)

Due to the increasing demand for alternative and supposedly more sustainable single-use tableware compared to conventional fossil-based plastic items, there now exists a broad variety of innovative new bio-based and biodegradable items. The aim of this research is to conduct a monitoring of the biodegradability of selected tableware items: polylactic acid (PLA), crystallized polylactic acid (CPLA), wood, palm leaf, paper/cellulose and sugar cane bagasse, as well as a common fossil-based plastic polystyrene (PS) as a comparative material in a water column, to determine their possible use as a substitute for single-use plastic flatware. In situ experiments were performed over a one-year period to consider changes in water temperature, salinity gradients, pH values and dissolved oxygen (DO). The main findings show that tableware items composed of palm leaf, sugar cane bagasse and paper are less resistant to estuary conditions. However, wood, PLA, CPLA and PS items showed a certain resistance during the experimentation period. Furthermore, items placed in the upper incubators degraded relatively faster than those of the same material but placed in the lower incubators. The results indicate that temperature and exposure to natural light could be an important factor in terms of accelerating the degradation of the materials considered.