Properties of Water Disinfectants


     Disinfectant

Description

Advantages

Limitations

 

Chlorine

 

Used in a gaseous state.

 

Requires strictest safety measures

 

Efficient oxidant and disinfectant

Efficiently eliminates tastes and odors

Produces after effects. 

Capable of controlling the growth of Algae, Biological Slimes and Micro-organisms

Decomposes Organic Contaminants [Phenols].

Iron and Magnesium Oxidant.

Decomposes Hydrogen Sulfide, Cyanides, Ammonium and other Nitrogen compounds

 

Strict requirements for transportation and storage

Potential danger for health in case of a leak.

Forms disinfection by-products such as Chloroform.

 

Chlorine Containing Substances

 

Hypochlorite

 

Used in liquid and granulated forms in a trade concentration of 10-20%.

 

Can be produced

electrochemically

on-site. 

 

 

Effective against most of pathogens and microorganisms

Relatively safe during storage and use

On-site generation does not require transportation and storage of chemicals

 

Ineffective against Cysts (Giardia, Cryptosporidium)

Loses its effectiveness during long term storage

Potential danger of gaseous chlorine emission during storage

Forms trihalomethane.

When on-site generated, requires either immediate use.

In case of storage, special measures are required to purify the initial water from heavy metal ions.

When on-site generated, NaCIO solution with the Active Chlorine concentration less than 450 mg/l does not form Chlorates during storage

 

 

 

 

 

Chlorine Dioxide

 

 

 

 

 

 

On-site generation only.

 

The most effective disinfectant and strongest oxidation agent among all Chlorine-containing ones.

 

 

 

Operates in low doses

Does not form Chloramines

Does not facilitate Trihalomethane formation

Destroys Phenols as the source of unpleasant tastes and odors.

Effective oxidant and disinfectant for all types of micro-organisms, including Giardia and Cryptosporidium Cysts and Viruses

Does not form Bromides from Bromate.

Facilitates removal of Iron and Magnesium from water by means of their quick oxidation and precipitation of oxides

 

 

 

On-site generation only

Requires transportation and storage of chemicals

In reaction with Organic Impurities forms Non-Organic By-Products

Forms Chlorates & Chlorite Ions

Alternative Substances

 

Ozone

 

Has been used for several decades in some of European countries for the  disinfection, elimination of color and for taste and odor control

 

Strong disinfectant and oxidation agent

Very effective against Giardia, Cryptosporidium and any other pathogenic micro flora

Facilitates removal of turbidity from water

Removes foreign tastes and odors

Does not form Chlorine containing Trihalomethanes.

 

Forms by-products, including: Aldehydes, Ketones, Organic Acids, Bromine-containing Trihalomethanes, (Bromoform inclusive), Bromates (in presence of Bromides): Peroxides, Brom-Acetic Acid.

Necessitates the use of biologically active filters to remove by-products

Does not ensure residual disinfection effect

Requires significant initial equipment cost.

Considerable expenses for operator training and installation support

Ozone reaction with Organic Compounds disintegrates them into smaller elements which can become a feeding media for micro-organism growth in water distribution systems

 

 

 

 

 

 

 

 

 

 

 

Ultra-Violet

 

 

 

 

 

 

 

 

 

 

 

 

Exposure of water to UV rays kills various types of micro-organisms

 

 

 

 

 

Does not require storage and transportation of chemicals

Does not form by-products

 

 

 

 

 

No residual effect

Not efficient against Cysts (Giardia, Cryptosporidium)

Requires considerable expenses for the equipment and technical maintenance

Requires considerable electrical power as operational cost.

Disinfection capability depends on the water turbidity, its hardness (sediment scale build-up on the bulb surface), precipitation of organic impurities on the bulb surface & deviations in the power supply, which creates variations in the UV wave-length.

Electro-Chemical Activation

 

Anolyte

 

 

ECA [Electro-Chemical Activation] of brine solution in an Envirolyte membrane electrolyzer.

 

Strong disinfectant and oxidation agent

Very effective against all kinds of Bacteria & Viruses

Highly effective as Sporicidal Agent

Effectively eliminates bad tastes and odors

Removes bio-films

Significantly less formation of Chlorine Compounds, Halogens & TMT.

No toxic by-products: Clorites (ClO2) and Clorates (ClO3)

No acute or chronic toxicity when diluted in water

Low cost

No transport or storage problem

Easy and safe storage and handling

 

Ventilation around the system may be required to remove fumes