WC137 JulyAug 2024 - Magazine - Page 22
AGRICULTURE
Ammonia issues
In Lodi, California (population 65,000), the wastewater treatment plant has experienced many issues with quaternary ammonia compounds and complete loss of nitrification. In November
2023, wastewater operations supervisor Matt Rempfer started
trialling a Moleaer generator. “I wanted to try the technology to
reduce plant upsets and aeration demands,” he said. “It’s worked
very well, and I am asking to extend its use.”
In terms of cost savings, there’s been a reduced need for
aeration and also for UV disinfection in the tertiary tanks
(due to increased clarity of the water) since installation, but
as mentioned, cost savings was not Rempfer’s goal. “I look at
the nanobubbles as a cheap insurance policy to ensure proper
regulation of the plant,” he explains. “We had one plant upset
in December, an ammonia spike due a toxic load delivery, and
recovery time was 10 times faster than normal. It was a few days
versus a few weeks.”
Surfactant troubles
Before Crisman joined Moleaer in 2023, he served for many
years as the plant operations manager at Goleta Sanitary District
in Goleta, Calif.. In 2022, he read a magazine article about the
surfactants problem in Fallbook, Calif.. “That was the problem I was dealing with and it was good to see that it was being
recognized,” he said. “Goleta was my baby. It was my plant. I
spent years using models through GPSx, improving our data
collection, I knew the plant inside and out. We were nearing
design limits for biological oxygen demand (BOD) and total
suspended solids (TSS). Due to droughts and extreme water
conservation in the state, influent surfactant and antimicrobial
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WATER C AN ADA • JULY/AUGUS T 2024
With the generator in place, Goleta Sanitary District saw a 15 per cent reduction in plant wide energy consumption, a 43 per cent reduction in aeration energy usage, a 44 per cent total decrease in chlorine demand, and a 10 per cent
increase in TSS removal efficiency. In Lodi the wastewater treatment plant
experienced many issues with quaternary ammonia compounds and complete
loss of nitrification. Since a nanobubble generator was installed, there’s been
a reduced need for aeration and also for UV disinfection in the tertiary tanks.
concentrations were very high. Even though we’d eliminated
contributions from industrial users in 2016 when we became
aware of the impacts of surfactants, the pandemic increased
surfactant loading. We were in need of a real solution.”
After hearing about nanobubbles, Crisman had no doubt
about their ability to mitigate surfactant issues and allow the
plant to produce better-quality effluent. “I called Moleaer and
their team visited,” he said. “We discussed the problem, where
we would install the generator, and how we would monitor
results. We decided to install at post-screening and grit removal
before the primary clarification, and installation was within
about three weeks.”
With the generator in place, Goleta (average flow of 4.2
MGD or 660 m3/hr) saw a 15 per cent reduction in plantwide
energy consumption, a 43 per cent reduction in aeration energy
usage, a 44 per cent total decrease in chlorine demand, and a 10
per cent increase in TSS removal efficiency. There was also reduced odour, improved oxygen transfer rate, and reduced visual
evidence of surfactant foam. “The nanobubbles start the physical
degradation, making them more biodegradable,” said Crisman.
“We also had improved oxygen uptake rate due to more efficient
and less-inhibited biology. BOD went from being greater than
TSS to equal, suggesting all soluble BOD was converted in the
biological process.”
In the primary clarifier, there was improved solids separation
with clear supernatant down to the sludge blanket and more
compact sludge. There was no evidence of denitrification or fermentation, and multiple primary clarifiers could remain online.
Plant chemical costs reduced by about 11 per cent, and the operations and maintenance budget was trimmed by 4.7 per cent.
“In terms of costs, when the generator is installed on an
existing pump flow, it doesn’t add much energy consumption,”
WAT E R C A N A D A . N E T
Moleaer
pre-sediment tank to control algae growth.
“There are many, many water treatment
plants interested in the technology,” said
Moleaer’s wastewater business development manager Jas Pannu, “but there’s
obviously a lot more regulation of water
treatment compared to wastewater, so
there’s a lot more red tape. But we are confident that this application will grow.”
Pannu grew up in Canada, has a
chemical engineering degree from the
University of British Columbia and an
M.Sc. in civil engineering from San Jose State University. He
explains that during most of his career providing chemical solutions in the water and wastewater treatment industry, he’s seen a
huge appetite for green, chemical-free solutions. “The moment I
learned the impact that Moleaer’s nanobubble technology could
have in wastewater treatment I knew I had to be a part of it,”
he said. “The fact that these air nanobubbles act like chemistry
but provide a domino effect of benefits throughout the entire
wastewater treatment process is amazing.”
