Laboratory and field scale biodegradability assessment of biocomposite cellphone cases for end-of-life management

The increase in production of biobased plastics as a replacement for fossil fuel-based plastics has created the need for studies to assess their degradation under various conditions. However, developing reliable laboratory and field-testing protocols for biobased materials and products still requires extensive research. In this study, the biodegradability of a biocomposite consumer product, smart cellphone case, was determined under laboratory scale anaerobic (38 degrees C) and composting assays (58 degrees C) as well as under field scale (60-67 degrees C) composting conditions. The laboratory scale composting assay was conducted for 46 days using cellphone cases with dimensions of 7 x 3.5 x 0.2 and 4.6 x 3.5 x 0.2 cm, which achieved approximately 20% biodegradation. The field scale composting conditions achieved 55% weight loss of cellphone cases in 80 days. The subsequent anaerobic biodegradation assays contained three different sized (grinded, cut into 2 x 2 x 0.2 and 4 x 4 x 0.2 cm pieces) biocomposite cellphone cases conducted under mesophilic conditions for 169 days. Among the conditions tested, the size of cellphone cases did not cause a significant difference in biodegradation under anaerobic conditions. Anaerobic digestion conditions yielded only 6-8% biodegradation, which was significantly lower than that of composting. The results agree with literature on conventional waste streams stating that aerobic microbial processes are more effective to break down complex substrates, similar to biocomposite cellphone cases tested, than their anaerobic counterparts.