Environmental Engineering Reference
In-Depth Information
microbial species biodegrade PE, (Sudhakar et al., 2008): These include
fungal species (
Aspergillus
sp.,
Chaetomium globosum
,
Penicillium
funiculosum
,
Pullularia pullulans
), bacterial species (
Pseudomonas
aeruginosa
,
Bacillus cereus
,
Coryneformes
,
Bacillus
sp.,
Mycobacterium
,
Nocardia
,
Corynebacterium
,
Candida
, and
Pseudomonas
), and
Actinomycetales (
Streptomycetaceae
). PVC was shown to be biodegraded
by
Pseudomonas putida
(Anthony et al., 2004) and white rot fungi (Kirbas
et al., 1999). Species such as
Curvularia senegalensis
,
Fusarium solani
,
Aureobasidium pullulans
Howard (2002), and
Pseudomonas chlororaphis
(Zheng et al., 2005) biodegrade the thermoset polyurethane (PU).
The mechanism of polyolefin biodegradation is not entirely clear but a likely
hypothesis is that it follows paraffin biodegradation by microorganisms
(Albertsson, 1978). In this case, abiotic degradation converts the
polyethylene into low molecular weight fatty acids that are sorbed by the
cells and undergo β oxidation.
However, as already alluded to, lab-culture data do not always translate
into measurable rates in natural or field exposures of PE. Early data on
incubating PE in soil show minimal weight loss even over very long periods
of exposure. Reported experimental results on PEs (
Table 6.5
) are
consistent with very slow biodegradation.
