Environmental Engineering

 👉 Domestic demand = 135 lpcd (liter per capita per day)

        Public demand   = 20 lpcd

         Industrial demand = 50 lpcd

         Commercial demand = 20 lpcd

         Fire demand = 15 lpcd

         Loss and waste = 50 lpcd 

          Total demand = 270 lpcd

👉 IS code says Domestic water consumption between 135 to 225 lpcd

      School/colleges : 45 to 135 lpcd

     Offices : 45 lpcd

     Restaurants : 70 lpcd

     Cinema : 15 lpcd

     Hotels : 180 lpcd

     Hospitals : 340 lpcd

👉  Water treatment design period = 15 years

        Pipe connection to the several treatment units = 30 years

       Distribution system = 30 years

👉 As per GOI manuals 

     Characteristics                                        Acceptable                 Cause for Rejection  

    Total Hardness (as CaCO3) (mg/l)                  200                                    600

   Nitrates (mg/l)                                                    45                                       45

    Iron     (mg/l)                                                     0.1                                      1.0

  Fluorides (mg/l)                                                  1.0                                      1.5

👉 The maximum safe-limits in domestic water supply are

      Sulphates   ≤  200 mg/l

     Chloride      ≤  250 mg/l 

    Nitrates        ≤  45 mg/l

    Fluorides     ≤  1.5 mg/l

👉 Carbonate hardness = min of { Total Hardness or Alkalinity

👉 Total dissolved solids (TDS) content of water supply can be obtained by specific conductance measurements i.e., the electrical conductivity of water.

👉 Chloride content of water is computed by Mohr's method

 👉 Chlorine residual can be computed by following tests:

    (a) Orthotolidine test

    (b) Starch iodide test

    (c) DPD test

    (d) Chlorotex test

👉 Temporary Hardness: Carbonates and bicarbonates of Ca and Mg.

       Alkalinity and softness: Carbonate and bicarbonates of sodium (Na)

       Permanent Hardness: Sulphates and chlorides of of Ca and Mg

 👉Pseudo hardness is given by monovalent cations like sodium (Na+)

👉 The Winkler test is used to determine the concentration of dissolved oxygen (DO) in water.

👉 Miscellaneous Topic: 

Miscellaneous Topic EE-I