Civil Engineering - Water Supply Engineering - Discussion

There are several disinfection methods which can be applied to high water flows. They can be divided.

Into three main groups:

βUV radiation.
β Ozone.
βChlorine.

The first two groups do not generate significant Disinfection By-Products (DBP\'s) nor interact.

Significantly with the water, they are supposed to disinfect. Despite their efficient disinfecting.

Qualities, they do not guarantee a long-term disinfection, up until the water reaches the consumer Chlorine disinfection, on the other hand, presents the advantages of efficiency and durability.

The concept of Residual Concentration of Disinfectant is associated with disinfection durability. In fact, so as to guarantee the water supply system's disinfection, we need a residual concentration disinfectant to prevent recontamination by pathogenic or indicator micro-organisms, which can Originate in the biofilm formed inside the system, as well as in negative pressure areas (created by Pipe cracks, fissures, etc).

Ozone is 12 times less soluble in water than chlorine, so the maximum disinfectant concentrations you can reach are much lower when you use ozone. Moreover, ozone breaks down very rapidly, and the higher the temperature or the pH, the more rapidly it decays. If the water is rich in organic compounds or suspended solids, a lot of the ozone may be consumed through reactions with these other contaminants, leaving an insufficient amount available to destroy germs. That's why ozone is not an economical option for wastewater with very high amounts of suspended solids or total organic compounds.

Ozone when added in water breaks down into normal oxygen and releases nascent oxygen. Which is a strong oxidising agent that carries out both the removal of organic matter and microorganisms from the water.

But it is highly unstable hence nothing remains in the water till it reaches the distribution system.

Hence it does not safeguard against future recontamination of the water.
(ii) It gives a pleasant taste to water, unlike chlorinated water which becomes bitter.
(iii) It destroyed the cell wall of microorganisms to carry out the disinfection.

Ozone is as good as chlorine, it is more costly than chlorine.

Gives a blue colour in water.

Ozone producers High Tension correct through the air.

It is an oxidising agent.

It is very unstable.

Gives good taste in water.

Less efficient than chlorine.

Answer to this question is option A.

In chlorination residual chlorine of 0.5 mg/l is insured to prevent contamination during distribution, while in Ozone there is no such protection against future contamination.

Ozone O3 is unstable because it quickly releases the nascent oxygen (O) and becomes oxygen (O2) and escapes out of the water. So it is not possible to carry pure treated water up to the customer's outlet tap.

Since ozone is effective in killing it can be used. But only reason is it is costly and should be produced only during the time of use. Because its an unstable compound. The answer might be wrong.

In drinking water, there are two types of bacteria 1 pathogenic 2 non-pathogenic.

Non-pathogenic bacteria is useful for drinking purpose. Ozone kill both the type of bacteria.

A is the correct answer. Ozone is a highly unstable oxidising agent so it does not remain in the water for a long time and it vanishes before the water reaches the consumers.

Ozone treatment isn't widely used for municipal water supplies because it disappears too quickly, making it unreliable for maintaining water safety over long distances.