Use of Fungal Laccases and Peroxidases for Enzymatic Treatment of Wastewater Containing Synthetic Dyes - Green Chemistry for Dyes Removal from Wastewater - page 218

a considerable effort has been made to develop bioreactors for continu-
ous treatment of dye-containing effluents and also treat real wastewater
from the textile industry. Zhang et al. [85] tested three bioreactors, namely
continuous packed-bed bioreactor, fed batch fluidized-bed bioreactor, and
continuous fluidized-bed bioreactor, for the decolorization of an azo dye
Acid Orange 7 at a rate of 1 g L -1 d -1 using an unidentified wood-rotting
basidiomycota. The working liquid volume of these bioreactors was 1 L.
They found that fungal mycelia immobilized by sodium alginate could be
reused in the fed batch fluidized-bed bioreactor over a two-month period.
Continuous decolorization of Acid Orange 7 (>95%) was achieved in other
bioreactors for a period of two months. Mielgo et al. [86] constructed a
167-mL capacity continuous packed-bed bioreactor with P. chrysosporium
that could remove Acid Orange 7 at a dye loading rate of 0.2 g L -1 d -1 .
Polyurethane foam was used as inert support for fungal biomass immobi-
lization. More than 95% of added dye was decolorized at a hydraulic reten-
tion time (HRT) of 24 h and a temperature of 37°C. The reactor was fed
with 250 mg L -1 h -1 of glucose and 0.6 mg L -1 h -1 of ammonia as carbon and
nitrogen sources, respectively. The decolorization was improved signifi-
cantly with purified oxygen gas as compared with air as an oxygen source,
which was accompanied by an increased production of MnP.
Kim et al. [50] used a microfiltration (MF)-based membrane bioreac-
tor (MBR) with T. versicolor to decolorize three reactive dyes including
Reactive Blue 19 (anthraquinone), Reactive Blue 49 (anthraquinone), and
Reactive Black 5 (diazo). The MF-based MBR was coupled with nanofil-
tration/reverse osmosis membrane filtration to evaluate the impact of the
fungal pretreatment on organics and dye removal. Blánquez et al. [48] con-
ducted a study using a fluidized bioreactor with T. versicolor to decolorize
a mixture of metal complexed dyes called Grey Lanaset G that contains
chromium and cobalt. The bioreactor was fluidized by 0.8 L/min of air
pulses and was operated at 25 C and pH 4.5 with an HRT of 120 h. They
found a good color removal (>90%) using this bioreactor; however, unlike
other dye decolorization, the laccase activity did not seem to be related
to the decolorization of this metal complexed dye. Rodríguez-Couto et al.
[56] compared four different carrier materials for the immobilization of
Trametes hirsuta . They found that stainless steel sponge was the best carrier
to improve laccase production (up to 2,200 U/L) and accelerate decolor-
ization of Lanaset Blau as compared with other materials, including algi-
nate beads, polyurethane foam, and nylon sponge, in two batch bioreactors
with capacities of 180 mL and 1 L.
A number of research papers have been published that explore the pos-
sibility of using white rot fungi to treat real wastewater containing synthetic