Biodegradation of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) Plastic under Anaerobic Sludge and Aerobic Seawater Conditions: Gas Evolution and Microbial Diversity

Poly­(3-hydroxybutyrate-co-3-hydroxyhexanoate) (poly­(3HB-co-3HHx)) thermoplastics are a promising biodegradable alternative to traditional plastics for many consumer applications. Biodegradation measured by gaseous carbon loss of several types of poly­(3HB-co-3HHx) plastic was investigated under an...

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Bibliographic Details
Published in:Environmental science & technology 2018-05, Vol.52 (10), p.5700-5709
Main Authors: Wang, Shunli, Lydon, Keri A, White, Evan M, Grubbs, Joe B, Lipp, Erin K, Locklin, Jason, Jambeck, Jenna R
Format: Article
Language:English
Subjects:
Anaerobic conditions
Anaerobic microorganisms
Anaerobic treatment
Biodegradability
Biodegradation
Carbon
Carbon content
Cellulose
Gas evolution
Marine environment
Microbiology
Microorganisms
Plastics
Polymers
Powder
Seawater
Sludge
Temperature
Thermoplastic resins
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Summary:Poly­(3-hydroxybutyrate-co-3-hydroxyhexanoate) (poly­(3HB-co-3HHx)) thermoplastics are a promising biodegradable alternative to traditional plastics for many consumer applications. Biodegradation measured by gaseous carbon loss of several types of poly­(3HB-co-3HHx) plastic was investigated under anaerobic conditions and aerobic seawater environments. Under anaerobic conditions, the biodegradation levels of a manufactured sheet of poly­(3HB-co-3HHx) and cellulose powder were not significantly different from one another over 85 days with 77.1 ± 6.1 and 62.9 ± 19.7% of the carbon converted to gas, respectively. However, the sheet of poly­(3HB-co-3HHx) had significantly higher methane yield (p ≤ 0.05), 483.8 ± 35.2 mL·g–1 volatile solid (VS), compared to cellulose controls, 290.1 ± 92.7 mL·g–1 VS, which is attributed to a greater total carbon content. Under aerobic seawater conditions (148–195 days at room temperature), poly­(3HB-co-3HHx) sheets were statistically similar to cellulose for biodegradation as gaseous carbon loss (up to 83% loss in about 6 months), although the degradation rate was lower than that for cellulose. The microbial diversity was investigated in both experiments to explore the dominant bacteria associated with biodegradation of poly­(3HB-co-3HHx) plastic. For poly­(3HB-co-3HHx) treatments, Cloacamonales and Thermotogales were enriched under anaerobic sludge conditions, while Clostridiales, Gemmatales, Phycisphaerales, and Chlamydiales were the most enriched under aerobic seawater conditions.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.7b06688