Wednesday, 3 November 2010

Water Supply – Demands and Requirements – An Engineering Prospective - Part2


In the Part-1 various drinking water quality requirements have to be mentioned to be considered before the water is to be available home consumers. Just a repetition  of those is below
Now just fill the make a table and fill the appropriate or most suitable water treatment method which can be employed to reduce the each quality concern at the appropriate level so as it would not be harmful to the consumer for drinking. Now if you have made it now just match your result with the table below.

1.       Carbonates -  that is hardness of the water to be removed
2.       Undissolved particles to be removed
3.       Satisfactory Colour, Odour and taste
4.       Removal of Toxic Substances if any.
5.       Pathogens, bacteria, Viruses etc.
6.       Removal of unrequired minerals
7.       Heavy metals
8.       Nitrogen (nitrite, nitrate, ammonium)
9.       Phosphorus
10.   Temperature i.e. setting limit
11.   pH
12.   Organic matter
13.   Fluoride
14.   As (Arsenic)
And specially the ground water contains
15.   Fe2+ and Mn2+
16.   Ca2+ and  Mg2+
...................................................................
..................................................................
S. No.
Quality Concern
Treatment Method which can be employed
1
        Carbonates -  that is hardness of the water to be removed
Chemical precipitation
2
Undissolved particles to be removed
Chemical precipitation
3
Satisfactory Colour, Odour and taste
Activated carbon
4
Removal of Toxic Substances if any.
Activated carbon, Oxidation, Ozone disinfection, Hydrogen peroxide disinfection, Chlorination, ........  Depending upon the type and concentration of toxicity one or more method can be employed
5
Pathogens, bacteria, Viruses etc.
Chemical precipitation, Oxidation, Ozone disinfection, Chlorination. Hydrogen peroxide disinfection
6
Removal of unrequired minerals
Chemical precipitation
7
Heavy metals
Activated carbon
8
Nitrogen (nitrite, nitrate, ammonium)
Aeration, Slow (biological) filtration, Chlorination,
9
Phosphorus
Chemical Precipitation
10
Temperature i.e. setting limit
May be heat exchange
11
pH
We can employ carbonate system to make the pH at required level
12
Organic matter
Oxidation, chemical precipitation
13
Fluoride
Reverse osmosis, Ion exchange....
14
As (Arsenic)
Chemical precipitation
15
Fe2+ and Mn2+
Redox Oxidation
16
Ca2+ and  Mg2+
Carbonate System

So depending upon initial laboratory results, which show that which type of impurities and how much are there is some source, many combinations of above mentioned solutions have been adopted to reach best economical and hazardless solution.

Task: Now your task is that to find out
A)   which agency or authority in your country is responsible for setting standards for drinking water?
B)    Which agency is responsible for drinking water supply at local level?
C)   And how these standards differ (that are they more tight or flexible) from WHO’s prescribed standards for drinking water?
Share your findings in the comments and discuss in the comments so as to give other viewers chance to know more about how it is being done in different parts of the world

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