What brings the difference in the filtered water in Paris and Bangalore?
There is a huge difference between the water coming from taps in Paris and in Bangalore. What causes this difference? How different are the filtration systems of Paris and Bangalore?
Safe and portable water is provided to taps by local water providers. Paris tap water is considered safe to drink according to French, EU and international standards (WHO).
The content of calcium in Paris water is around 80–120 mg/l, which near to the range of hardwater and will cause some limescale. It’s close to some natural mineral waters (that have 80 to 100 mg/l of calcium).
Paris mainly uses processes using Ultraviolet (UV) radiations or Reverse Osmosis (RO).
Using UV
An integral sensor monitors the UV light intensity in each treatment chamber. A custom-built control panel provides communication between the UV units and the plant control room. Incorporated in each UV unit is an automatic wiping mechanism that cleans the quartz sleeves surrounding the lamps and keeps them free of waterborne deposits.
UV works by rendering microorganisms to be able to reproduce by irradiating or disrupting their DNA. Microbial DNA generally absorbs UV most effectively at 265 nm, produced in abundance in medium pressure lamps. They emit UV over a very broad range of wavelengths (about 185–400 nm). Research has shown that, with proper pretreatment and a well-maintained UV disinfection system, this broad output causes permanent inactivation of both pathogenic and non-pathogenic microorganisms such as Escherichia coli (E. coli).
Low pressure UV lamps, an alternative to medium pressure lamps, produce just a single peak of UV output at 254 nm. While also having a strong germicidal effect, it has been shown that some microorganisms are able to repair or reactivate themselves after exposure to UV from low pressure lamps, especially if they’re subsequently exposed to sunlight. This is known as photoreactivation.
Permanent damage caused by medium pressure UV can result from the UV at other wavelengths, such as 240 nm and 280 nm, affecting other intracellular molecules such as RNA and enzymes, which are unable to repair themselves.
RO process
Reverse Osmosis removes 90% to 99% of the contaminants. The pore structure is tighter than in UF membranes. The RO membrane removes all particles, bacteria, and organics. It is extremely effective in removing total dissolved solids (TDS), turbidity, asbestos, lead (and other toxic heavy metals) radium, many dissolved organics, chlorinated pesticides and most heavy volatile organic compounds (VOCs). This technology is used by many leading water bottling plants. Reverse osmosis and activated carbon filtration are complementary processes. Combining their results, will be the most effective treatment against various impurities and contaminants.
Bangalore has a different approach to water filtration.
The first 4 stages of the treatment take place in the T.K. Halli water treatment plant. The treatment that follows this is for the purpose of treating almost pure water since most contaminants are removed in the T.K. Halli plant. Fully treated water then enters steel pipes (preventing leakages) to reach the city and finally individual households.
The Process in Bangalore
Physical impurities form majority of the contaminants in water which in turn impact factors like colour, odour, taste, pH, turbidity and total dissolved solids (TDS).
First, oxygen is absorbed by water falling in thin sheets over various steps in the cascade aerators killing bacteria.
Chlorination is the next step. Huge amounts of chlorine are injected via pipes; about 300kg is used in a day to kill harmful organisms in water. Due to huge amounts being handled, major safety precautions need to be taken to prevent chlorination’s impact on humans.
Next, Alum Dosing takes place. Aluminum Sulphate is mixed with the water ensuring right turbidity levels. Hence, if the municipal water supply is from Cauvery and water gets treated at the source before getting piped, chemical contamination stays low.
Next, filtration takes place. First sedimentation is allowed to occur. Chemicals like alum are added to accelerate its speed and also help smaller, finer, particles to settle. The water Is filtered by passing it through beds of sand filters (or other granular materials). The rapid speed helps remove pathogenic bacteria.
Water is then ready to be pumped and distributed throughout Bangalore.
Conclusion
There is a vast difference between the filtration systems and hence quality of water in Bangalore and Paris. Many chemicals are used in Bangalore unlike Paris. Filtered water of Paris is very close the natural water, making it quite healthy too. This difference could be covered up by installation of more updated healthy-water provider mechanisms in Bangalore with minimal chemical use.
