Surface World April 2019 Surface World April 2019 | Page 58

WATER & EFFLUENT TREATMENT
and reduce the contact time that the
chemical reagents require during
pH neutralisation.
As the treatment tank and the high speed
industrial mixer have been designed and
assembled here at our Stafford factory we
can ensure that all the constituent parts are
working together as efficiently as possible.
The high speed mixer is supported by the
fabricated mixer bridge and the shaft and
propellor have been designed to ensure that
they accommodate the volume of liquid in
the tank and the dimensions of the whole
fabrication. To help matters further, the
location of the mixer bridge ensures that
when not operational, the half access lid can
easily be opened for maintenance, cleaning
and inspection.
The TM2 high speed industrial mixer is ideal
for applications such as the pH neutralisation
of wastewater. By creating a vortex within the
tank the chemical reagents dosed from the
dosing pumps are forced through the waste
water to give good distribution. Combining
good and even mixing along with a pH
controller offering PID control as well as
proportional control dosing pumps - the
customer can be confident in both the
waste-water treatment process and that
chemical reagents aren’t being needlessly
dosed into the system.
Dosing Pump
One key component of the waster water
treatment is for pH neutralisation to occur.
The customer’s processes generate effluent
on either the acidic or alkaline side of the
pH scale, depending upon which
combination of processes are operating
during their production process.
The waste-water treatment system is able to
neutralise the pH of the incoming effluent if
it’s on the acid end of the pH scale or the
alkaline end, thanks to the system being able
to dose from one of the two chemical dosing
pumps.
Working with an incoming signal from the
tank mounted PS90s pH electrode assembly
and the P7687 PID pH controller - the pH
controller sends a signal to either the acid
dosing pump or the caustic dosing pump.
Each of the pumps are our AT4-AM
proportional dosing pump series with wetted
parts suitable for each chemical reagent.
With a maximum output of 60 Litres / Hour
each, the AT4-AM dosing pumps can be
automatically speeded up or slowed down
by the pH controller to ensure that just the
right amount of chemical reagent is dosed
into the process to neutralise the pH.
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APRIL 2019
Suction Lance Assembly
The suction lance assembly fitted to each of
the chemical dosing pumps allows for easy
manual handling of the chemical containers,
and when operational, maintains the prime
of the dosing pumps. The integrated low
level float switch also provides a signal to
the control panel which can prevent the unit
from operating when the chemical reagent
has been used.
To ensure that operator is aware that an
alarm condition has been entered, an
audible alarm sounds; the alarm beacon
is illuminated and the corresponding low
chemical level indicator is illuminated
on the front of the panel. A remote alarm
connection is also included for the customer
for integration into their internal process
system so that they are aware that the
chemical needs to be replenished to ensure
the pH neutralisation system can resume
correct operation.
The pH neutralisation system uses model
AC.LA.25A suction lances specifically
designed for use with 25 litre chemical
containers. The suction lance is placed into
the container aperture with the lid removed.
The suction lances can be located within the
chemical container by using the adjustable
mounting flange, which also creates a seal
over the opening.
Using suction lance assemblies combined
with the chemical containers being placed
in the bunded area of the enclosure, which
in turn is located behind a transparent cover
plate - ensures that chemical handling risks
are minimised where possible.
Changing the chemical container once the
chemical has been used is simple, as the
suction lance assembly can easily be lifted
out from the empty vessel, and placed into
the new vessel once it’s securely positioned
into the bund.
As well as assisting in the handling of the
chemical reagents, each suction lance
assembly includes an integral non-return
valve to help ensure that the pump remains
primed.
Air Operated Diaphragm
Transfer Pump
As the customers’ effluent is collected in
a sump arrangement located underneath
the water treatment system, it has to be
transferred to the dosing tank for pH
correction.
Contained within an enclosure, complete
with a front mounted transparent cover are
two double diaphragm pneumatic pumps
which are ideal for the job. With wetted
parts in polypropylene and PTFE the double
diaphragm pneumatic pumps are resistant
to the chemistry used in the customer’s
processes.
The control panel controls two solenoid
valves which in turn control the air flow
to the pumps, allowing them to be
automatically turned on, based on the
incoming signal from sump mounted float
switches. The double diaphragm pneumatic
pumps are arranged in a duty and assist
formation, with the assist pump being
switched on when the customer’s processes
generate enough waste water to require
the addition of the second transfer pump.
The air operated double diaphragm pumps
used were the AWE models PP50’s with 1/4”
outlets and maximum flow rates of 50 Litres
/ Minute.
There are many advantages that are
available when using an air operated double
diaphragm pump to transfer waste water,
effluent or even chemical reagents. They
offer exceptional flow rates which can be
easily adjusted by using an air regulating
valve. In addition - with relatively simple
construction, the diaphragm can be easily
removed and cleaned for periodic
maintenance, and they are of simple design
and proven construction meaning that there
really is very little to go wrong with them.
pH Neutralisation
System Commissioning
Following the customer briefing and the
approval of the designs, the process of
completing the fabrications, assembly and
control panel build were completed within 6
weeks. As the plant was designed to be skid
mounted, loading on to a flat bed truck for
same day delivery, and then positioning the
pH neutralisation system to it’s site location
was a relatively simple procedure.
From the customers perspective, once
the inlet and discharge pipework were
connected, power brought onto the system -
the pH neutralisation was ready for
commissioning.
The commissioning of the pH neutralisation
system was completed by two of our Service
Engineers within 7 weeks of us receiving
the order from our customer.
Telephone: [phone]
Visit: www.awe-ltd.co.uk
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