Surface World November 2019 Surface World November 2019 | Page 54

WATER & EFFLUENT TREATMENT
pH Neutralisation System from above
When the waste water has been pH
corrected, the customer requested that
this is discharged into a cascading sump
arrangement via an outlet on the tank.
The customer specified that the outlet was
via a 3” flanged connection and the location
of this agreed during the design phase of
the project. To ensure compatibility with the
customer’s process, the system was also
supplied with the counter to the flange for
simple on-site installation.
that the pH neutralisation system can return
the neutralised effluent to drain through a
cascading sump arrangement.
Pallet / Skid Mounted pH
Neutralisation System
Our customer’s core preference was for a
complete solution to their pH neutralisation
which could easily be positioned into place
and simply integrated into their existing
processes, including drawing the waste
water up into a treatment tank from a sump.
From a practical perspective, in the future,
the pH neutralisation system might need to
be relocated, cleaned or inspected. For this
reason, we included a foot mounted drain
valve allowing the customer to empty the
tank when required.
We provided our customer with a single
fabricated solution which could be lifted
using the skids of a fork lift truck for easy
transportation to site, and so that it could
be simply manoeuvred to the desired site
location.
pH Correction Pumps
Control Panel
The fabricated solution was destined to be
located outside. To protect the instruments
from the environment all the fabricated
enclosures containing the control panel,
instruments, air operated double diaphragm
pumps and the chemical dosing pumps were
provided with transparent covers to protect
them from the elements.
All the wired connections and external
electrical items such as the top mounted alarm
beacon and all electrical glands have been
supplied to IP65 specification, which ensures
that they are suitable to be located outside.
The pH correction tank was fabricated in
chemically resistant polypropylene and also
mounted onto our skid mounting area -
allowing the whole unit to be lifted from a
fork lift as well easily manoeuvred for final
positioning. Access to the tank is via a half
removable lid complete with a mixer bridge
to support the high speed mixer.
The enclosure containing the control panel
was fabricated as a separate chamber
isolating it from the lower enclosure,
which contains the duty & assist air
operated double diaphragm transfer pumps.
The chemical containers were located in
another enclosure located at the opposite
end of the skid mounted unit. This skid
mounted enclosure includes 2 separate
bunded areas - each designed to contain
a 25 litre chemical container with a capacity
of ~35 litres - to contain the contents of
each of the chemical containers in the
event of a spill or leak.
Control Panel
The hoses connecting the air operated
transfer pumps and the chemical dosing
pumps have been supplied as double
confined dosing tube to ensure containment
in the event of the tubing becoming
compromised.
The control panel is mounted into the front
enclosure, behind a removable transparent
covering. This pH neutralisation system uses
a number of inputs to fully automate the
treatment of pH correction of the waste water
with very little human involvement required.
The waste water is transferred to the
treatment tanks using the air operated
double diaphragm pumps. As the volume of
waste water generated can vary depending
on the processes occurring in the customer’s
factory, two air operated double diaphragm
pumps have been fitted; one acting as a duty
transfer pump and the second acting as an
assist. The duty and assist pumps mean that
during normal operation, the duty pump has
the flow rate to transfer enough volume of
waste water to the treatment tank to ensure
it can be corrected.
As the processes used by our customer vary,
the amount of waste-water generated can
also vary. To cope with increased volumes,
a second air operated double diaphragm
pump has been fitted as an assist. This
potentially doubles the amount of waste
water that can be transferred to the treatment
tank, preventing the sump from flooding
in times of increased production.
The duty transfer pump and assist transfer
pump are controlled based on the level in the
sump. By using low level float switches located
in the sump, at a high level, the duty pump is
called to transfer the waste water. If the level
continues to rise to the second high level
(high-high-level), then the assist pump is
engaged to reduce the volume of waste water
in the sump and transfer it for treatment.
Each air operated double diaphragm pump
uses an air feed line which passes through
a solenoid valve. The solenoid valve is
controlled from a level controller within the
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NOVEMBER 2019
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