CHLORINATION SYSTEMS

Disinfection is accomplished both by filtering out harmful microbes and by adding disinfectant chemicals. Water is disinfected to kill any pathogens which pass through the filters. Possible pathogens include viruses, bacteria, including Escherichia coli, Campylobacter and Shigella, and protozoans, including Giardia lamblia and other cryptosporidia.

Chlorine is universally accepted for combating slime and algae better than any other chemical. The most important aspect of chlorine usage is its economy and effectiveness in killing bio-organisms. Other uses of chlorine include control of H2S and Odor, fly control, sludge bulking and foaming control, ammonia oxidation, BOD reduction, disinfection, bleaching etc.

Chlorination systems normally consist of a tank of chlorine which is added to a water supply by a chemical pump. This addition can occur either at a reservoir or in-line, depending on the details of the water system in question. The chemical pump is usually linked to a flowmeter so that the amount of chlorine that is added depends on the amount of water that is used.

Chlorination

The most common disinfection is by chlorine or its compounds such as chloramines or chlorine dioxide. Chlorine is a strong oxidant that rapidly kills many harmful micro-organisms. Sodium hypochlorite, which is a relatively inexpensive solution that releases free chlorine when dissolved in water. Chlorine solutions can be generated on site by electrolyzing common salt solutions. A solid form, calcium hypochlorite exists that releases chlorine on contact with water. Handling the solid, however, requires greater routine human contact. The generation of liquid sodium hypochlorite is both inexpensive and safer than the use of gas or solid chlorine.

All forms of chlorine are widely used despite their respective drawbacks. One drawback is that chlorine from any source reacts with natural organic compounds in the water to form potentially harmful chemical by-products trihalomethanes (THMs) and haloacetic acids (HAAs), both of which are carcinogenic in large quantities

Chlorine dioxide - is another faster-acting disinfectant. It is, however, relatively rarely used, because in some circumstances it may create excessive amounts of chlorite, Chlorine dioxide is made in water and added/used in water to avoid gas handling problems; chlorine dioxide gas accumulations may spontaneously detonate.

Chloramines - are another chlorine-based disinfectant. Although chloramine is not as strong of an oxidant it does provide a longer-lasting residual than free chlorine, and it won't form THMs or haloacetic acids. It is possible to convert chlorine to chloramine by adding ammonia to the water after addition of chlorine: The chlorine and ammonia react to form chloramine. Water distribution systems disinfected with chloramines may experience nitrification, wherein ammonia is used a nutrient for bacterial growth, with nitrates being generated as a byproduct.

Various Portable and Industrial scale Chlorination systems are available for disinfection in various process industries, water and wastewater treatment plants, Muncipal water treatment plants, in an emergencies or in remote locations. Disinfection is the primary goal, since aesthetic considerations such as taste; odor, appearance, and trace chemical contamination do not affect the short-term safety of drinking water.

Gas Chlorinators

Gas chlorinator is a device to provide a continuous and constant supply of metered chlorine in the safest possible manner. Chlorinators find application in Drinking water treatment, Cooling Water Treatment, Waste Water Treatment, Bleaching, Pharmaceutical formulations and other industrial applications. Depending upon the mode of operation Gas Chlorinators are classified into two types namely Vacuum-Feed Gas Chlorinator and Gravity Feed Gas Chlorinator.

Electro- Chlorination

Electro-chlorination is a simple and proven technology to convert ordinary salt water [or brine or seawater] into Sodium Hypochlorite by means of Electrolysis. It is produced and applied on -site. The device which uses this technology is named as Electro chlorinator or Onsite Hypo Generator.

Basic System Components are: Electrolyser Cell, Rectifier, Storage Tank and Dosing Pump.

Operation

A metered amount of water is mixed with common salt to form brine of required concentration [or Seawater is used]. This is the electrolyte used in the process. Electrolyser Cells are dipped in this measured quantity of Brine Solution, contained in a specially made FRP Tank. These cells are connected to a rectifier, which converts Alternate current to Direct current. When DC Current passes through these Titanium Anodes, Sodium Hypochlorite evolves instantaneously with negligible quantities of hydrogen rising up to the surface, which is vented out. This process is based on the chemistry of Electrolysis of Sodium Chloride. The Sodium Hypochlorite thus generated is collected in a storage Tank and applied directly or pumped to the point of application.