Info

"] Bacteria Effectiveness against ■■ Virus j Spores

Some

No

No

No

Yes No No

Advantages

Inexpensive and well-developed technology, which provides lasting protective residual.

Rapid method of removing color, taste and odor while destroying viruses and spores; generated on site; oxidation products are non-toxic.

Fast method which requires no chemicals.

Requires no special equipment.

Similar to chlorine except less irritating to the eye.

Has long-lasting bactericidal effect.

Disadvantages

Not effective against some spores and viruses; can, in high concentrations, produce products that are toxic to marine life and can cause undesirable taste and odor.

More expensive and less developed than chlorine and it does not leave a protective residue.

Leaves no protective residue, expensive, not applicable on large scale and requires pretreatment for turbidity removal.

Slow and expensive.

Slower and more expensive than chlorine.

Slow and expensive. Amines and other pollutants interfere with its effectiveness.

Other Remarks

Most frequently utilized method in the United States.

Frequently used in Europe; combined with chlorina-tion, it can produce high-quality drinking water.

Mostly used on special laboratory and small industrial applications

Excellent household emergency method.

Sometimes used as swimming pool disinfectant.

Note: A = requirements for drinking water disinfection.

B = requirements for the disinfection of secondary (activated) wastewaters treatment effluent.

Note: A = requirements for drinking water disinfection.

B = requirements for the disinfection of secondary (activated) wastewaters treatment effluent.

Disinfection should kill or inactivate all disease-producing (pathogenic) organisms, bacteria, and viruses of intestinal origin (enteric).

Pathogenic organisms include (1) bacteria of the col-iform group, both fecal and nonfecal, such as Escherichia coli, Aerobacter aerogenes, and Escherichia freundii; (2) bacteria of the fecal streptococcus group; (3) other microorganisms such as Salmonella, Shigella, and the cyst Endamoeba histolytica; and (4) enteric viruses such as the etiologic agents of polio and infectious hepatitis. Test procedures, developed for their identification, are usually involved and time consuming. Therefore, the identifications (Metcalf, Wallis and Melmick 1972) of one group of bacteria (coliform) is usually taken as an indication of water quality and a measure of effectiveness of bacteria disinfection. It is assumed that the absence of coliform bacteria indicates the absence of all pathogenic bacteria.

Enteric viruses in the drinking water are reported to be responsible for hepatitis, poliomyelitis, and other epidemic diseases. Viruses are substantially more resistant to chlorine than bacteria, and the absence of coliform bacteria does not necessarily indicate the absence of viruses. Virology is not developed to the point that routine identification and assay tests are possible. The development of a portable virus concentrator, making routine identification and assay of viruses in water and wastewater more practical, has been reported. The concentrator first removes suspended solids through filtration and absorbs viruses on a cellulose adsorption column. The viruses are then eluted from the adsorption column and subjected to standard laboratory assay. (1972).

The probability of disease (D) when a pathogenic organism is brought into contact with a human water consumer (host) is proportional to the number of organisms (N) and their virulence (V) and inversely proportional to the resistance (R) of the host. The purpose of disinfection is to minimize N and V in equation 8.2(4).

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