Page 170 - Materials Chemistry, Second Edition

Fungal Treatment of Pharmaceuticals in Effluents 151

metal reduction, and only a limited number of organopollutants are considered (i.e.,
halogenated compounds and dioxins), as shown in the EU’s Working Document on
Sludge (Rodríguez-Rodríguez et al., 2012a; Fytili and Zabaniotou, 2008). On the
one hand, it is well known that pharmaceuticals can accumulate in sewage sludge
at high concentrations, and legislation for most groups of emerging pollutants (i.e.,
pharmaceuticals and polybrominated diphenyl ethers [PBDEs]) does not exist
(Rodríguez-Rodríguez et al., 2012a). Therefore, municipal biosolids may contain
large amounts of PhACs, which can be a potential risk to the environment, counter-
acting the expected benefits of the biosolids applied to the land (Kinney et al., 2006;
Rodríguez-Rodríguez et al., 2011).
Rodríguez-Rodríguez et al. (2011, 2012a) analyzed the pharmaceuticals in raw
sewage sludge. The authors reported the presence of 40 out of 43 screened phar-
maceuticals in the sludge. Some laboratory-scale studies have shown the possibil-
ity of employing naturally degrading microorganisms, specifically WRF, for the
removal of spiked pharmaceuticals and organic pollutants from solid lignocellu-
losic wastes and biosolids (García-Galán et al., 2011; Rodríguez-Rodríguez et al.,
2012a). For example, Rodríguez-Rodríguez et al. employed T. versicolor for the
treatment of raw sewage sludge and reported the complete removal of phenazone,
bezafibrate, fenofibrate, cimetidine, clarithromycin, sulfamethazine, and atenolol
and partial removal of other pharmaceuticals (between 42% and 80%). In addition,
the toxicity of the sludge was substantially reduced after the treatment (Rodríguez-
Rodríguez et al., 2011).
Advanced oxidation processes (AOPs), or aqueous phase oxidation methods,
are emerging technologies that work because of the intermediacy of highly reac-
.
tive radicals, such as OH. By nature, radicals are compounds with unpaired elec-
trons that oxidize other substances to acquire electrons. Often, these radicals are
produced via chemical, photochemical, photocatalytical, or electrochemical meth-
ods (Marco-Urrea et al., 2010c). Recently, the ability of several WRFs, including
T. versicolor and Pleurotus eringyi, to produce these radicals through a quinone
redox cycling mechanism, which is called bio-oxidation (Rodríguez-Rodríguez et
al., 2012a), has been shown. In this novel method, the fungi are incubated with a
lignin-derived quinone and chelated ferric ion. Subsequently, the fungi catalyze
the conversion of the quinone into hydroquinone, and oxidize it to produce semi-
quinone radicals by their lignin-modifying enzymes. By autoxidation, which has
3+
2+
been catalyzed by Fe , Fenton’s reagent is produced, which results in Fe and
−
.
−
O radicals. O then reacts, and OH radicals and/or other oxidizing species (fer-
2
2
ryl ion, under certain conditions of pH and concentration of organic and inorganic
ligands [Hug and Leupin, 2003]) are released (Marco-Urrea et al., 2010c; Gómez-
Toribio et al., 2009a,b). Marco-Urrea et al. have reported the successful use of
−1
this method for more than 80% removal of a spiked concentration of 10 mg L
of clofibric acid, carbamazepine, atenolol, and propranolol after 6 h of incubation
(Marco-Urrea et al., 2010c).
A combination of fungal treatment and filtration yields higher PhAC removal
and is feasible by employing fungal treatment with MBRs. These novel MBRs have
a granular activated carbon-packed anaerobic zone beneath their aerobic zone,
which contains the membrane module and the microorganisms (Hai et al., 2011).