Environmental Engineering Reference
In-Depth Information
entrapped cells could remove the contaminants much better than the UASB alone.
The maximum specific phenol,
p
-cresol, and
o
-cresol treatment activities of the sys-
tem with the entrapped cells were approximately 13, 16, and 8 times higher than
those without the entrapped cells. Additionally, the bioaugmented system reached a
steady state much quicker and provided higher process stability.
Although CA is a popular entrapment material, there have been reports on its
susceptibility to degradation [4, 67]. However, some studies found that the CA
entrapped cells are durable and perform well after several rounds of reutilization.
A good example is a study by Moutaouakkil et al. [30] which reported that the
CA entrapped cells removed toxic azo dye at high concentrations efficiently even
after reutilizing them 7 times. Lately, the modified or amended CA was developed
for improving contaminant removal efficiencies and the matrix stability. Activated
carbon, bentonite, and skim milk are among the amendments [17].
7.3.1.2 Carrageenan Entrapped Cell Bioaugmentation
The utilization of CN entrapped cells is relatively limited among the selected matri-
ces. To date, there has been no CN entrapped cell bioaugmentation application
for wastewater treatment. There are only a few basic studies on the uses of the
CN entrapped cell inoculation as a treatment scheme by itself. For example,
-CN
entrapped cells were applied to remove total organic carbon [20] and glucose [49]
in liquid systems.
The limitation on the CN entrapped cell applications may be attributed to the
weakness of the material. The traditional
κ
-CN entrapped cell preparation requires
warm temperatures (35-55
◦
C) for dissolving the
κ
κ
-CN powder, which could damage
the viability of cells. Additionally, the
-CN entrapped matrix is sensitive to cations,
such as K
+
and NH
4
+
leading to easy gel abrasion. However, the
κ
-CN structure
is appropriate for cell proliferation. Godia et al. [69] reported a large number of
proliferated cells in
κ
-CN
matrices by clay or skim milk amendments were developed for better gel strength
[70]. Through advancements in material science and technology, it is possible that
κ
-CN after 1-day fermentation (Fig. 7.9). The modified
κ
Fig. 7.9
Images of cell distribution in carrageenan matrix: (
a
) After entrapment and (
b
) After
1-day fermentation [69]
