Chemical Engineering September 2020 - 44

1,000
900
800
700
600
500
400
300
200
100
Flow
-100
4/30/2019
5/7/2019
5/14/2019
5/21/2019
5/28/2019
6/4/2019
- - Train A flow - - Train B flow
FIGURE 4. The MBR permeate flows (gal/min) for Train A (orange) and Train B (yellow) are shown
TMP
3
2
1
-1
-2
-3
-4
-5
-6
-7
-8
4/30/2019
5/7/2019
5/14/2019
5/21/2019
5/28/2019
6/11/2019
6/18/2019
- - Train A TMP - - Train B TMP
6/4/2019
6/11/2019
6/18/2019
FIGURE 5. The trans-membrane pressure (TMP, in psi) for MBR Train A (blue) and Train B (gray) were
relatively stable
ated via the was pump to maintain
the desired sludge age. once
stability had been achieved, train
a was placed into automatic mode
at 10-min cycles with back pulse.
once the waste cod loading was
sufficient, the ethanol feed system
was deactivated.
Operational data
once the influent wastewater was
relatively stable, the treatment plant
began operating on a continuous
basis, with an average flow of 398
gal/min for train a and 365 gal/min
for train B for the first 45 days of operation.
these results are shown in
Figure 4.
the trans-membrane pressure for
train a had an average of -1.35 psi
with some peaks in the week of may
14, 2019 due to higher mlss, as
shown in Figure 5.
ammonia discharge
levels in the
first 45 days of operation
showed a permeate
discharge average
of 0.41 parts per
million (ppm). after a
slight peak of 2 ppm
on may 6, the discharge
levels quickly
returned to average
values, as shown in
Figure 6.
average
2.5
2
1.5
1
.05
- - Ammonia
cod
44
levels in the mBr permeate were
slightly above 30 ppm and stable
during the first 45 days of operation,
except for June 18 when cod levels
spiked to almost 200 ppm correlating
with the startup of the ethylene
oxide-ethylene glycol plant. when
the startup occurred, 300,000 gal
of ethylene glycol waste from the
purification beds with 120,000 ppm
of cod surged into the bioreactor,
overwhelming the bacteria and significantly
decreasing biodegradation.
But once normalized, cod returned
to normal values.
wastewater cod values entering
the dnF units have an average
of 1,275 ppm. at the end of the entire
treatment train process, mBr
permeate had a cod average of
190 ppm, representing more than
86% removal.
these data demonstrate that, at
Ammonia
the core of the lake charles complex
wastewater treatment solution, mBr
technology utilizing uF hollow-fiber
membranes provides high levels of
cod and Bod removal, combining
secondary and tertiary treatment in a
compact footprint. in addition to the
design parameters listed previously,
facility owners evaluating mBr for
wastewater treatment should bear in
mind the following considerations:
* mBr systems are designed at
lower F/m ratios than conventional
activated-sludge systems to avoid
high membrane fouling rates and
low oxygen transfer efficiencies [1]
* mBr technology should be
considered where stringent effluent
discharge levels are required, with
regards to Bod and tss, as well as
total nitrogen (tn) and total phosphorus
(tp)
* uF membrane separation performance
is independent of the quality
or condition of the biological process
fluid, and the entire treatment
process is simplified
* mBr is an adequate biological
wastewater treatment technology
for gtl plants, as proven with pilot
testing and proof of concept at
sasol
* at sasol, cod removal of 86%
with an average below 30 ppm
has been achieved during the first
months of operation
■
Edited by Mary Page Bailey
Reference
1. Yoon, S.H., " Membrane Bioreactor Processes - Principles and
Applications, " CRC Press, Boca Raton, Fla., 2016.
Author
Brian Arntsen (brian.arntsen@
suez.com) is the global domain
sales leader with SUEZ Water
Technologies & Solutions. Previous
to his work at SUEZ, Arntsen was
CEO of Lockwood & Co. from 1996
to 2000 and also held roles at
Zenon Environmental Inc. and GE.
Arntsen is active in many industry
groups in the water-treatment
FIGURE 6. The MBR ammonia permeate readings, in ppm, are shown
here. Note that a reading of 0 ppm corresponds to a value < 0.015 and
a reading of 2 ppm corresponds to values > 2.0
sector, including the Water Environmental Federation
(WEF) and the Food & Beverage Environmental Conference
(FBEC). In 2017, he was appointed Food & Beverage
subcommittee chair of the Industrial Wastewater
Committee at WEF. He holds an agricultural engineering
degree from the Catholic University in Buenos Aires, Argentina,
and a postgraduate degree in business
management from the I.A.E Business School
in Buenos Aires.
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