Page 168 - Materials Chemistry, Second Edition

Fungal Treatment of Pharmaceuticals in Effluents 149

8.4.1 reacTor Design for pHacs reMoval froM
WasTeWaTer via fungal TreaTMenT
Various nutrient media and reactor configurations have been explored for using WRF
as a reliable, efficient, and rapid way of removing PhACs from wastewater effluent.
The choice of the reactor configuration and design parameters depend on several fac-
tors affecting the performance and the activity of the employed organism. Detailed
study of the process is required to determine growth parameters of the fungi, such
as the optimal temperature, operational pH, dissolved oxygen concentration of the
effluent, fixed nitrogen concentration, reaction kinetics, reaction rate and yield, and
construction materials. The control over the process and the process economic fac-
tors are also substantial factors that are important for scaling-up purposes.
To date, most of the practices on removal of PhACs via fungal treatment have
been carried out in in vitro sterilized conditions, employing synthetic liquid media
and controlled conditions of pH and temperature. Often, spiked concentrations of
the compounds (milligrams per liter) have been used, which might not reflect the
conditions in real WWTP influent. A few studies have been performed under non-
sterile conditions where many contaminants and microorganisms are also present,
and consequently, the removal efficiency of fungi may be hindered. Zhang and
−1
Geiben (2012) have reported 80% removal of carbamazepine (spiked at 5 mg L ) in
non-sterile conditions, employing P. chrysosporium immobilized in polyether foam .
Cruz-Morató et al. (2013) reported successful removal of 7 out of 10 PhACs initially
screened in non-sterile conditions. However, the authors reported comparably lower
biomass concentrations in non-sterile conditions and concluded that the practical use
of fungi for real wastewater treatment practices needs a supply of nutrients (glucose
and nitrogen). Control over pH to ensure the optimal biological activities and enzy-
matic production of the fungi is also needed.
In addition, efficient dye removal from textile wastewaters via fungal treatment
has been reported in non-sterile conditions by different authors (Hai et al., 2009;
Anastasi et al., 2010). For fungal treatment of wastewater, three types of reactors can
be identified with regard to the mode of reactant contact: batch reactors, semi-batch
reactors, and flow reactors. Descriptions of their characteristics and operation are
outside the scope of this chapter but may be found in many texts on chemical reac-
tion engineering (Levenspiel and Levenspiel, 1972). The use of different reactor con-
figurations, including continuous and batch stirred reactors (Rodarte-Morales et al.,
2012), fluidized bed, packed bed, and perfusion basket reactors for the removal of
different pharmaceuticals from wastewater via fungal treatment has proved the pos-
sibility of scaling up the process (Cruz-Morató et al., 2012). In fluidized bed modes,
often the fungal biomass is fluidized by the aid of air or oxygen pulses generated by
an electro-valve (Cruz-Morató et al., 2013).
It is believed that the aeration regime also plays a role in the performance of
fungal reactors. Moreira et al. (1996) demonstrated that the pulsation of oxygen con-
trols the shape and the growth of the fungal pellets in the fluidized bed reactor.
Rodarte-Morales et al. (2012) have studied the effect of two aeration regimes, air
and oxygen pulses, on the performance and morphology of P. chrysosporium pel-
lets in a fed-batch reactor. The authors concluded that oxygen pulsation results in