Steven Paquette has been appointed president of the U.S. water and environment business unit at WSP | Parsons Brinckerhoff, a global...
This column will discuss well ozone water treatment for residential,
commercial and industrial applications. Well ozone water treatment systems for
the removal of
Iron, sulfur and manganese are the easiest water problems to
eliminate when using an ozone system. This, of course, is made possible by the
oxidation power of ozone. The oxidation process will take place, and
contaminate elimination will occur if the system is sized properly.
The main factors to consider are the big three.
is the water quality?
much flow (gpm)?
much used (gpd)?
You will notice I use the words "ozone systems,"
not just "ozone." The reason is that ozone is merely a gas that
accomplishes the oxidation process. Oxidation is the first step of three that
must be followed in order to be successful.
The ozone process works in three simple steps.
injection/oxidation. Ozone is triatomic oxygen (O3), which has very high
oxidizing power. It is a gas produced from air and high voltage electricity.
The injection of the ozone into the water produces tiny ozone bubbles, which
saturate every drop of water. At this point, oxidation of iron, sulphur and
manganese is immediate.
ozone unit (ozonator) is the device that produces the ozone. Its design should
be simple, waterproof and short circuit protected by resettable breaker field
service and should feature a plastic/non-corrosive housing and stainless steel
ozone generator construction.
must be injected into the water after it is produced. There are two methods
most commonly used.
Pump--A positive displacement injector that pumps the ozone gas into the water
similar to a chemical feed pump for chlorine. There is no restriction of flow
or pressure and it achieves the greatest volume of ozone injection. This is an
important factor when dealing with iron and sulfurs greater than 3 ppm.
device that restricts flow and pressure in order to produce a vacuum. This
vacuum device sucks the ozone gas into the water. Improper sizing will result
in insufficient ozone suction, which will cause insufficient oxidation.
dryers are options that reduce the maintenance of the ozone equipment. Air
dryers remove all of the humidity and moisture from the air prior to the ozonator.
The air is dried to a minimum of –40° F dew point (absolutely dry/no
moisture). Dry air increases ozone production and can extend service life of
the ozone generators and ozone pump.
The elimination (off gassing or venting) of the ozone and other gases/odors,
such as sulfur occurs by an ozone stripping action. As water flows down the off
gas tank, ozonated water rises and strips any gas in the incoming water.
The final step for removing the oxidized material is filtration. The media used
should have low water waste (backwash), high service flow, high removal
capacity and require no chemicals during regeneration. Mechanical filtration is
all that is necessary if proper oxidation has been achieved.
Ozone System vs. Chlorination Systems
The main advantage for the consumer using ozone over
chlorine is the absence of hazardous chlorine byproducts, storage of hazardous
chemicals, absence of chemical odors, and lack of constant replenishment of the
chlorine feeder. Trying to oxidize/kill iron bacteria, sulfur bacteria or
manganese (as well as any microorganisms) with chlorine is difficult and
requires extreme amounts of free chlorine. This leads to dramatically increase
ongoing costs as well as a highly toxic water value.
Ozone Systems vs. Air Injection Systems
Air injection is fraught with difficulties. While it is an
inexpensive treatment method, it cannot be used on high iron and sulfur amounts
and when iron or sulfur bacteria is present.
Iron and sulfur bacteria will grow when in the presence of
air. This leads to pipe, media and equipment clogging. Manganese is more
difficult and resistant to air oxidation.
Safety is another issue. How can you determine that the air
you are injecting into your customers water is safe? You cannot when using a
simple air injector system. Anything in the air (dust, dirt, mold, bacteria,
odors, etc.) around the injector gets sucked or pumped into the water. Ozone is
a sterilizer and it will kill any air borne microbes prior to being injected
into the water.
The main advantage for the dealer when using an ozone system
and immediate oxidation,
and immediate removal of the iron, sulfur and manganese,
or no environmental impact.
To review the overall process: Ozone creates larger
particles of iron, sulfur, and manganese by means of oxidation. The larger
particles become insoluble (separated from the water) and are easily filtered.
The off gassing releases the excess ozone, air and odors. Filtration is the
last step necessary for removing the oxidized particles.
Next month's column will discuss the fine points of selling