JAEA-Review-2010-065.pdf:15.99MB - 日本原子力研究開発機構

2-09
Decomposition of Persistent Pharmaceuticals by
Ionizing Radiation
A. Kimura, M. Taguchi and K. Hirota
Environment and Industrial Materials Research Division, QuBS, JAEA
Introduction
Many kind of water pollutants have been widely spread
in the water environment. These chemicals such as
halogenated organic compounds (dioxin and PCBs),
endocrine disruptors (natural hormones and akylphenols),
and heavy metals were persistent, high toxic and have a low
biodegradability. The risk evaluation of these
pharmaceuticals and personal care products are studied
1)
recently . Some pharmaceuticals would give ill effects on
human and aquatic animals because of its chronic and
reproduction toxicities, and the concentrations of them in the
water environment increased gradually because of
population growth and the diversification of advanced
medical worldwide. However, it is difficult to manage the
environment risk of the pharmaceuticals having great
benefits for human life, and the development of direct
removal methods are considered for them.
The pharmaceuticals have been also detected at the
downstream of water treatment facilities, indicating that
the activated sludge system could not decompose them
completely. Persistent organic pollutants in wastewater
could be effectively decomposed by ionizing radiation,
which produces reactive species, for example, hydroxyl
2)
radicals homogeneously in water . The purpose of this
work is to treat the pharmaceuticals in combination of
ionizing radiation with activated sludge.
Experimental
Oseltamivir, aspirin, ibuprofen, carbamazepine,
mefenamic acid, ketoprofen, chlofibric acid, and dichlofenac
were selected as experimental samples because they were
reported to be consumed a lot worldwide and detected in the
1)
water environment . Each pharmaceutical was dissolved
at 10 mol dm -3 in wastewater at pH value of 7.45 and the
amount of Total Organic Carbon at about 0.05 g dm -3 , which
was collected at an influent of a water treatment facility.
Activated sludge solution was supplied from the wastewater
treatment plant and used for the biodegradation of the
pharmaceuticals. This sludge was acclimated by adding
1 g/dm -3 of glucose and/or granulated sugar of 500 dm -3 /day
for 2 days. The sludge solution of 50 dm -3 was mixed with
the equal amount of the pharmaceutical solution, and stirred
at 100 rpm with aeration at 100 mL/min for 8 hours, which
is the average aeration time of real wastewater treatment
plant with activated sludge system. The -ray irradiation of
the sludge and pharmaceutical solution at 5 mol dm -3 was
carried out at 298 K using 60 Co -ray sources. Each
pharmaceutical solution after biodegradation and -ray
irradiations was analyzed by HPLC (High Perfomemance
liquid chlomatography).
JAEA-Review 2010-065
Results and Discussion
The pharmaceuticals were treated first only by the
activated sludge. Oseltamivir as aliphatic pharmaceutical
was easy to be decomposed and eliminated at 2 hours.
Decomposition yield of aspirin and ibprofen was obtained
more than 90% for 2 and 4 hours, respectively. On the
other hand, carbamazepine, ketoprofen, and mefenamic acid
were not decomposed for 8 hours completely.
Decomposition yield of chlofibric acid and dichlorfenac was
obtained at about 20% after the biodegradation for 8 hours.
Additional water treatment methods, therefore, would be
required to decompose these persistent pharmaceuticals
completely.
Decomposition of carbamazepine, ketoprofen,
mefenamic acid in wastewater was investigated by -ray
irradiation as shown in Fig. 1a. Concentration of
carbamazepine was decreased exponentially as a function of
dose and was almost zero up to 1 kGy, while mefenamic
acid and ketoprofen were decomposed at 2 kGy.
Electron-rich carbamazepine, substituted azepine group,
would be easily decomposed by hydroxyl radicals. The
decomposition yields of ketoprofen and mefenamic acid,
which have carbonyl and carboxy groups as electron
acceptors, were lower than that of carbamazepine.
Concentration of chlofibric acid and dichlofenac decreased
as a function of dose, and were eliminated at 1 kGy as
shown in Fig. 1b. As the phenyl group of dichlofenac is
substituted not only two chlorine groups as a electron
accepter but also amino groups as an electron donor,
decomposition curve of dichlofenac would be almost the
same with that of chlofibric acid. Persistent
pharmaceuticals which were difficult to treat by the
activated sludge system could be decomposed by the
ionizing radiation method.
Concentration / mol dm-3 Concentration / mol dm-3 - 49 -
5
4
3
2
1
Ketoprofen
Mefenamic acid
Carbamazepine
0
0 1
Dose / kGy
2
Concentration / mol dm -3
0
0 0.2 0.4 0.6 0.8 1
Dose / kGy
References
1) K. Fent et al., Aquatic Toxicology 76 (2006) 122-159.
2) A. Kimura et al., Radiat. Phys. Chem. 76 (2007)
699-706.
5
4
3
2
1
Dichlofenac
Clofibric acid
Fig. 1 Decomposition of persistent pharmaceuticals in
wastewater by -ray irradiation. a) diaromatics
(left), b) chlorinated compounds (right).