Birmingham Water Works Board (BWWB) of Birmingham, Ala., has consistently achieved the rating of the number-five water system in the United States...
The installation of ozone equipment on well applications
utilizes the same principles and techniques as chlorinators, air injection and
softener systems. There are only minor variations in sequence, parts and
Ozone Injection Location
To determine this you must first determine what is going to
activate the ozonator. Will it be a pressure switch or a flow switch? To answer
this you must first determine if you are treating all the water from the well
or separating the house use from another use such as irrigation, water to air
heat pumps, livestock and/or multiple homes.
Switch--This method uses the well pumps
pressure switch to activate the ozonator, which means that all the water is
treated, and the ozonator will operate the entire time the well pump operates.
This is a preferred method unless the well pumps cycle will cause undue
"wear-n-tear" (such as with irrigation systems).
Switch--This method uses a flow-activated
switch to turn on the ozonator, which means that not all the water is treated,
and the ozonator will operate only when water is used in the home. This method
is preferable to the immense wear-n-tear that could occur with irrigation or
similar operation/cycles. It also is optimum when there is other usage that is
not to be ozonated.
Ozone Injection Location
The ozone must be injected into the water after the well
pump and prior to the pressure tank when using the pressure switch actuation.
Ozone Injection Devices
You have the choice of injecting the ozone via an ozone pump
or a venturi.
An ozone pump (OP) compresses and injects the ozone without
any restriction of flow or pressure. The OP can inject in any pipeline in any
location. It is a specially designed compressor that is not compromised by
ozone gas. However, there are moving parts that may need service depending on
length of running time and environmental conditions. This service easily is
accomplished with a minimum of parts called a rebuild kit. The OP eliminates
the guesswork and restrictions associated with venturis and can inject 2.5 to 4
times more gas by volume.
A venturi is a device that restricts flow and pressure in
order to create a pressure differential that induces a vacuum. They practically
are service-free but are subject to problems with the restriction of flow and
pressure. They must be installed prior to the pressure tank and as close to the
well pump as possible. Booster pumps are needed quite often depending on the
hydraulics of the system. Venturis must be sized exactly to the gpm and psi
recovery rate. The amount of vacuum must be tested to ascertain that the proper
volume of ozone is being injected.
Ozone Injection Location (FS)
The ozone is injected on the line that is to be treated,
which usually is after the pressure tank and all other branches. The ozone pump
injector is the only device applicable to the flow switch activation method.
Clean/Dry Air Intake
As discussed before in a previous column, the air dryer is
an option to reduce possible service on the ozone pump by reducing the amount
of moisture that enters the ozonator.
Off Gas/Contact Tank (OGT)
The OGT is composed of an empty tank, an inlet/outlet head,
vent device and flow separator. The ozonated water enters the top of the tank
and circulates down to approximately half way. Then the ozone bubbles try to
rise. The rising bubbles mix with gas that is trying to go down (toward the
outlet) during usage. All the bubbles rise and are released at the top through
The vent can be either a float type, which can be used with
the venturi, or an electric/self-cleaning type, which is common with the ozone
pump injection method. Care must be taken to ensure that the vent can release
the amount of gas injected. Float-type vents tend to release a much lower
volume, which can lead to air-locking conditions.
The filtration should be merely
mechanical and not require further oxidative-type media, meaning that if the
ozone equipment has been sized and installed properly, all the water should be
treated and all of the iron, sulfur and manganese should be oxidized. This means
that iron, sulfur and manganese have formed a larger particle that easily can
be filtered. Media such as Birm, Greensand, Pyrelox and KDF that further
oxidation should not be required.
The media of choice should be
non-porous, inert, easily backwashed at a minimal flow rate and approximately 5
micron. There are only two media that fit this description: SP10 and ceramic
media. Both media yield high service flow rates while requiring low backwash
As with any mechanical
filtration and for most applications, backwash with water only is all that is
It is paramount to size the
filter according to the gpm flow, gpd usage and water quality.
Next month's column will discuss
ozone system troubleshooting and service.