Environmental Engineering Reference
In-Depth Information
Table 6.5 Summary of Estimates of Biodegradation of
Polyethylenes in Natural Environments by Weight Loss Method
Source: Summarized from Restrepo-Flórez et al. (2014).
Environment Plastic Duration
(days)
Weight
loss (%)
References
Different soils
and coal waste
LDPE 225
0.13-0.28 Nowak et al. (2011)
Seawater
365
1.9
Artham et al. (2009)
Soil
800
0.1
Albertsson (1980)
Soil
3650
0.2
Albertsson and Karlsson
(1990)
Rhodococcus
ruber
30-56
2.5-7.5
Hadad et al. (2005);
Santo et al. (2013); Sivan
et al. (2006)
Seawater
HDPE 365
1.6
Artham et al. (2009)
Soil
800
0.4
Albertsson (1980)
6.5.1 Additives that Enhance Degradation in Common Polymers
Oxo-biodegradable additives claim to combine both photo- and
biodegradability enhancement in a single package (Chiellini et al., 2007).
These are the first additives 19 to claim biodegradability in treated PET used
in soda bottles. The system consists of a photoinhibitor to prevent
premature degradation, a metal salt prooxidant (e.g., stearates of iron,
cobalt, and manganese) and a biodegradation promoter that includes
microcellulose powder (Ammala et al., 2011). Adding 1-5% by weight of
additive masterbatch to polyolefin is claimed to render the material
environmentally degradable. There is little doubt that oxo-biodegradables
effectively catalyze photodegradation but only a modest improvement in
biodegradability is usually obtained (Yashchuk et al., 2012). After a year of
natural weathering (abiotic degradation), the oxo-biodegradable films of PE
incubated in compost at 58°C showed 12.4% mineralization over a period
of 3 months; biodegradation at 25°C was only 5.4% (Ojeda et al., 2009).
Chiellini and Corti show a mineralization of up to 50% for pre-degraded
oxo-biodegradable PE in soil (over a period of 550 days) but lower rates
 
 
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