Water & Wastewater Asia March/April 2023

IN THE FIELD
must be handled at a hazardous waste
management facility.
For Wallac, this posed two challenges: Firstly,
wastewaters containing phenolic ethoxylates
had to be transported over long distances;
and secondly, handling the wastewater at a
hazardous waste management facility was
costly.
For those reasons Wallac was keen to try
out an alternative after they found out about
Roxia’s non-thermal plasma technology.
The solution presented by Roxia provided a
possible alternative to the earlier-mentioned
conventional water treatment methods.
FROM LAB TESTING TO FULL SCALE
Shortly after reaching out to Roxia, a lab test
was run with a water sample from Wallac.
The RPO’s purification process worked
as follows: firstly, treated water would run
through a non-thermal plasma field. This
would create strong oxidants from the treated
water and surrounding air, which in turn would
destroy pollutants and disinfect the water with
lasting effects. The product’s design would
create a large plasma-water contact area,
which would make the removal of pollutants
from the water more efficient. The water from
the process could then be reused on-site.
Plasma generated
oxidants effectively
remove colour, odour
and organic residues
while disinfecting
the water
weeks. “Installation of the RPO test equipment
went through without any relevant issues.
Within two weeks we had the process in full
service,” said Ahonen.
In addition to removing the chemicals
efficiently, the RPO’s reactor core could
tolerate “difficult” wastewaters and would
require no air pre-treatment or compressors to
produce and deliver the oxidants to the water.
It was also low maintenance, due to the core
being made of stainless steel and having no
moving parts, as well as the plasma electrodes
being not easily corroded by the process.
During the trial period, Roxia specialists
also regularly collected water samples. They
conducted a detailed analysis and used the
results to optimise the process for maximum
convenience and energy efficiency. According
to Ahonen, the plasma oxidation process
“worked like a charm”.
Wallac also had the ability to monitor the
plasma oxidation process in real-time
through the Roxia Malibu online portal. The
Roxia Malibu portal is a combined Industrial
Internet of Things (IIoT) online process
monitoring, maintenance, and analysis
tool. The data collected is sent to a cloud,
processed there, and finally shown in the
Malibu online portal. It also has a customised
user interface tailor-made for individual
processes, allowing for ease of use and
access for users. The portal thus enabled
preventive maintenance and analysis of the
process.
PLASMA OXIDATION IS HERE TO STAY
With plasma oxidation successfully removing
the harmful substances, Wallac no longer
needed to transport the wastewater over
long distances to hazardous waste treatment
plants. After seeing the results from the RPO
test units, Wallac chose it as their new water
treatment solution.
When asked whether Wallac would choose
the same product again, Ahonen gave an
optimistic response: ”I would recommend
this product to any process where harmful
substances need to be removed from waste
solutions before discharge to sewer. Roxia’s
technology enables us to meet EU emission
limits, even production operations where
Triton X-100 is used.”
Images: Roxia
After treatment with plasma oxidation, there
were no traces of phenolic ethoxylates
detected in the waters. With positive results
from the lab, the testing was taken to the
full-scale, on-site unit for a trial period of a few
Plasma Oxidizer equipment at Wallac; a remote view in Roxia Malibu
WATER & WASTEWATER ASIA | MARCH/APRIL 2023 33