Bioregeneration of Activated Carbon in Biological Treatment - Activated Carbon for Water and Wastewater Treatment - page 209

measured to determine the amount of adsorbate before bioregeneration. For the
investigation of bioregeneration, this mixture was then inoculated with acclimated
microorganisms and mineral salts solution. It was aerated and the residual adsorbate
concentration was measured at different time intervals. At the end of bioregenera-
tion, the supernatant was decanted, and GAC was rinsed and put into an autoclave
to terminate the activity of the microorganisms. Then, the sterilized GAC was
reloaded and equilibrated with a known concentration of adsorbate. Finally,
the residual adsorbate concentration was measured. Using the Freundlich para-
meters representing adsorption capacity and intensity respectively, K F and 1/n,
previously obtained from adsorption isotherms, the amount of substance adsorbed
before the bioregeneration step was calculated using the following equation:

K F S e 1 = n q ¼ð S 0 S e Þ: V = W ¼ (7.6)

where,
q

amount of a compound adsorbed per unit weight of carbon (M s /M c ),
S 0 ¼

¼

initial concentration (M s /L 3 ),

equilibrium concentration (M s /L 3 ), S e ¼

total volume of sample (L 3 ),

V ¼

W ¼ weight of activated carbon (M c ).

In the units, s and c denote the substrate and carbon, respectively.
After bioregeneration, the amount of adsorbed substrate left on activated carbon
(q 0 ) was determined by Eq. (7.7):

K F S 0 1 = n q 0 ¼ (7.7)

where,
S e 0 adsorbate concentration in the bulk liquid, (M s /L 3 ).

¼

After addition of substrate and equilibration, the additional amount of substrate
adsorbed (

D

q 2 ) was calculated by Eq. (7.8):

D q 2 ¼ð S 2 S 2e Þ : V = W (7.8)

where,

concentration at the beginning of equilibration (M s /L 3 ),
S 2e ¼

S 2 ¼

equilibrium concentration (M s /L 3 ).

Hence, the total adsorbability (q 2 ) was calculated as follows:

K F S 1 = n
2e

q 0 þ D q 2 ¼ q 2 ¼ (7.9)

Then, the quantity of bioregenerated phenol was calculated as follows:

q 0 ¼

Quantity bioregenerated ð M s = M c Þ¼ q 1 q 1 ð q 2 D q 2 Þ (7.10)

q 0 Þ= Percentage of bioregeneration ð % Þ¼ 100 ð q 1 q 1 (7.11)