Ultraviolet Sciences - UV Water Treatment systems for Ozone Destruction and Generation

Ultraviolet Sciences, Inc.
9189 Chesapeake Dr.
San Diego, CA 92123
Ph. 858-571-6590
Fx. 858-571-6596

uvinfo@uvsciences.com

Ozone functions as both an oxidant and disinfectant in the treatment of drinking (potable) water and wastewater.

OZONE DISINFECTION

Our partner, Spartan Environmental Technologies, supplies ozone generators for ozone disinfection applications including drinking water, cooling water, process water, aquaculture, marine parks among many other applications. Below you will find technical information on how ozone disinfects and how it compares to other commonly used disinfectants. If you would like additional information on ozone disinfection or ozone generation equipment call Spartan at 1-800-492-1252 or e-mail info@spartanwatertreatment.com.

"Our new UV-Ozone demo skid is now available for rent. The Uv-Zone is a trial system that provides the user significant amount of variability with these two disinfection controls. This capability allows for trial and error testing on water samples to determine the optimal UV and Ozone dose for the final water remediation needs."

How Ozone Disinfects?

Ozone functions as both an oxidant and disinfectant in the treatment of drinking (potable) water and wastewater. This is similar to chlorine. Chlorine and Ozone, however, operate by different mechanisms when disinfecting water. As a result, ozone and chlorine can act synergistically.

Ozone's germicidal properties are associated with its high oxidation potential. Disinfection by ozone is a direct result of bacterial cell wall disintegration, also known as lysis. This mechanism is different than that by chlorine. Although the exact chemical action of chlorine is not clear, it is believed that the chlorine residual in aqueous solution diffuses through the cell wall of the microorganisms and attacks the enzyme group which results in the destruction of the microorganism.

The graphics below illustrate the process while the photomicrograph show actual bacteria before and after ozonation:

Disinfection Power of Ozone

To demonstrate the disinfection power of ozone and compare it with other oxidizing agents, Morris developed the lethality coefficient:

Lethality Coefficient= 4.6/(Ct99) where:

C = residual concentration in mg/L t99 = time in minutes for 99 percent microorganism destruction (2-log destruction)

Morris, J.C., "Aspects of the Quantitative Assessment of Germicidal Efficiency," in Chap. 1, J.D. Johnson (ED.), Disinfection, Water and Wastewater, Ann Arbor Science, Ann Arbor, MI 1975.

The table below lists parameters for disinfection by ozone for different organisms:

Parameters for Disinfection by Ozone (pH 7; 10-15 degrees C):

Organism
Lethality Coefficient (a)

C 99:10 (b)

Escherichia
500

0.001

Streptococcus faecalis
300

0.0015

Polio virus
50

0.01

Endamoeba histolytica
5

0.1

Bacillus megatherium
15

0.03

Mycobacterium tuberculosam
100

0.005

a - Lethality Coefficient = 4.6/(Ct99)
b - C 99:10 = concentration in mg/liter for 99 percent destruction or inactivation in 10 minutes
(Morris considered these values to be valid within a factor of two)

Comparison of the values in this table with similar values obtained for chlorine is shown in the table below. These values tabulated by Morris illustrate that ozone is a more powerful germicide against all classes of organisms listed by factors of 10 to 100. The table shows values of the lethality coefficient:

Lethality Coefficient at 5 degrees C [(mg/liter)-1(min.)-1]

Agent

Enteric Bacteria

Amoebic cysts

Viruses

Spores

Ozone

500

.5

<5

2

HOCl as Chlorine

20

0.05

>1

0.05

OCl- as Chlorine

0.2

0.0005

<0.02

<0.0005

NH2Cl as Chlorine

0.1

0.02

0.005

0.001