what concentration of Ozone is sometime used as a disinfectant for drinking wate

Question

what concentration of Ozone is sometime used as a disinfectant for drinking water. Ozone is highly reactive it will react benign species found in water, as well as the pathogens it is intended to kill. It found that ozone reaction in water nearly follows first-order kinetics in ozone concentration, such as that its concentration decreases by 50 percent in 12 minutes (t1/2 = 12 min). A water supplier wants to inject ozone into a piper bringing water to the water treatment plant to predisinfect the influent. The 3.0-ft diameter piper is 3,400 feet long with a steady flow rate of 10,000 gal/minozone (in mg/L) should be Injected at the head of the piper so what there will be an ozone concentration of 1.0mg/L at the piper

Explanation / Answer

Ozone is a form of oxygen (O2) with the molecular formula O3. It forms when oxygen in the air is exposed to the discharge of a powerful electric current through air.Ozone is unstable and changes to O2 shortly after its formation. It is a powerful oxidant and one of the most powerful disinfectants available in water treatment. Although ozone is significantly more effective than chlorine at inactivating and / or killing viruses, bacteria and cysts (e.g., Cryptosporidium and Giardia), and has been widely used in Europe for many years to treat municipal drinking water, it has not had similar acceptance in the US. Reasons include its higher cost and the fact it does not remain present long in water. US regulatory authorities have specified less expensive disinfectants such as free chlorine, chlorine dioxide or chloramines to maintain a residual capable of continuing to kill organisms throughout the distribution system. Since ozone quickly converts to oxygen and leaves no toxic residual, it may be more advantageous than chlorine to treat wastewater prior to discharge. Since dissolved ozone reverts to oxygen, the effluent will exert less biological oxygen demand (BOD) on the receiving stream. Ozone’s effectiveness as an oxidant often makes it the method of choice for removing color, organic chemicals and odor-causing contaminants in wastewater. In many cases, depending on the ozone contact time and concentration, it is capable of oxidizing these contaminants to water and carbon dioxide. As examples, toxic herbicides and pesticides may be reduced to more environmentally friendly components; non-biodegradable organic compounds may be reduced to smaller biodegradable parts; proteins and carbohydrates may be lysed at double-bonded carbons to damage and destroy critical components of organisms found in the water. Since the free hydroxyl is so highly reactive, the contact time necessary is minimal, as compared to other disinfectants.

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