2.2. Test II – cultivation of G. sulphuraria in primary effluent
The goal of Test II was to validate the growth of
G. sulphuraria
in
carbon-rich medium (BOD:N:P ratio of 34.0:15.0:1), and compare
its BOD and nutrient removal capabilities with literature reports.
Again, filter-sterilized primary effluent was used instead of deion-
ized water to prepare modified Cyanidium medium excluding
ammonium sulfate and mono-potassium phosphate dosage.
Initial conditions in Test II (after filter-sterilization) are summar-
ized in
Table 1
. Samples of inoculum were centrifuged and filtered
(0.2 micron) supernatants were used to measure ammoniacal
nitrogen, phosphates, and BOD
5
on a daily basis for 6 days.
2.3. Test III – heterotrophic growth of G. sulphuraria
The goal of Test III was to assess the growth capability of
G. sul-
phuraria
in urban wastewaters in comparison to growth in modi-
fied Cyanidium growth medium. In this test, the following three
culture media were compared: Medium 1: modified Cyanidium
medium prepared in deionized water, but with the N and P levels
adjusted to match those in UWW; Medium 2: Cyanidium medium
prepared with filter-sterilized primary effluent excluding ammo-
nium sulfate and mono-potassium phosphate; and Medium 3:
raw filter-sterilized primary-settled wastewater. Initial conditions
in Test III are summarized in
Table 1
. Dissolved concentrations of
ammoniacal-nitrogen and phosphate were analyzed on days 0, 3,
6 and 10, in triplicate.
Dissolved ammoniacal-nitrogen and phosphates were mea-
sured using HACH DR 6000 spectrophotometer with salicylate TNT method 10031 and Phosver 3 method 8048. Dissolved BOD
5
without nitrification inhibition was measured following the dilu-
tion method 8043 (Hach Company, USA, 2012) in transparent
300-mL Wheaton BOD bottles (Wheaton, USA).