COMBINED BIOLOGICAL-PHOTOCATALYTIC TREATMENT FOR THE MINERALIZATION OF A MIXTURE OF CHLOROPHENOLS IN AN ELECTROLYTE-CONTAINING MODEL WATER AND SPONTANEOUS SEDIMENTATION OF TITANIUM DIOXIDE
ABSTRACT: To shorten the
biological treating time and to examine the effect of electrolytes in a model
water on the photocatalytic treatment, the combined biological-photocatalytic
treatment was evaluated for removal of a mixture (total: 100 mg L-1, each: 25
mg L-1) of 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP),
2,4,5-trichlorophenol (2,4,5-TCP), and pentachlorophenol (PCP) in tap water.
The mineralization of the four phenols was performed by aflow (biological
treatment)-circulative flow (photocatalytic treatment) operation under black
light and sunlight irradiations. After a large portion of biodegradable 2-CP
and 2,4-DCP, and around half amount of slightlybiodegradable 2,4,5-TCP were
removed by the biological treatment, the remained three chlorophenols,biorecalcitrant
PCP, and biodegradation products were completely removed by the subsequent
photocatalytic treatment. The combined treatment significantly shortened the
degradation time only the biotreatment. High circulative flow rate (600 mL
min-1) enabled for TiO2 particles to completely suspend in a tubular
photoreactor and resulted in high removals of chlorophenols and TOC. Sunlight
irradiation was successfully used and the saving of the electric energy of
black light was possible. Since TiO2 particles in the tap water spontaneously
sedimented on standing after the photocatalytic treatment, the combined system
can be operated by integrating it with the TiO2 separation.
Author: Dhanus Suryaman,
Kiyoshi Hasegawa, Shigehiro Kagaya, and Toshiaki Yoshimura
Journal Code: jpkimiagg070024
