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

University of British Columbia

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. In our case, the biodegradability of cellphone cases was determined under laboratory scale anaerobic and composting assays (58°C) as well as under field scale (60-67°C) composting conditions. The anaerobic assays were conducted under mesophilic (38°C) and thermophilic (55°C) conditions. In the laboratory scale composting assays, two trials were conducted. The first trial was conducted for 46 days using cellphone cases with dimensions of 7 × 3.5 × 0.2 and 4.6 × 3.5 × 0.2 cm. The second trial was conducted for 34 days and the cellphone cases were 2 × 2 × 0.2 and 4 × 4 × 0.2 cm. The highest biodegradation (21%) was achieved in trial 1 by the 4.6 × 3.5 × 0.2 cm phone cases. The field scale composting conditions achieved 55% weight loss of cellphone cases in 80 days. During initial anaerobic assay optimization, microcrystalline cellulose was used as a positive control and three different anaerobic seed (inocula) originated from full-scale anaerobic sludge digesters (mesophilic 1, mesophilic 2, and thermophilic) were assessed. A range of food to microorganism ratios (0.5-5 g chemical oxygen demand (COD)/ g volatile solids (VS)) for the microcrystalline cellulose was tested. It was determined that 0.5 g COD/ g VS Inoculum was the optimal food to microorganism ratio to yield the highest methane production. The subsequent anaerobic biodegradation assays contained three different sized cellphone cases conducted under mesophilic conditions (grinded, 2 × 2 × 0.2 and 4 × 4 × 0.2 cm pieces) for 169 days. The size of cellphone cases did not cause a significant difference in biodegradation under anaerobic conditions. The biodegradation of grinded cellphone cases was also tested under thermophilic conditions for up to 105 days. Mesophilic and thermophilic anaerobic digestion conditions had similar levels of cellphone case biodegradation (6-8%), which was significantly lower than that of composting. The results agree with literature stating that aerobic processes are more effective to break down complex substrates than their anaerobic counterparts.  

Text

2021-02-23

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/77368

Civil Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/