Archive for the ‘Water analysis’ Category

Weight of Water Related to the Weight of Air

The theoretical atmospheric pressure at sea level (14.7 psi) will support a column of water 34 feet high:

weight of air 14.7 psi x 2.31 ft/psi = 33.957 ft, or 34 ft

At an elevation of 1 mile above sea level, where the atmospheric pressure is 12 psi, the column of water would be only 28 feet high: 12 psi x 2.31 ft/psi [....]


Things that can cause toxicity include many of the following:
     Metals: lead, antimony, copper, zinc, chromium, cadmium, nickel, manganese
(permanganate), sliver,
    Oxidizers: chlorine, chloramines, any of the group VII compounds in the
periodic table, permanganates, ozone, fluorine, iodine, peroxides, and
so on.
             All of these compounds are direct toxins, because they directly interfere
with the biological [....]

Calculation of Chemical Oxygen Demand (C.O.D)

Calculation of Chemical Oxygen Demand (C.O.D)


Round bottom flask, water condenser, Burette, Pipette,Heating mantle.


* Mercuric sulphate (< 1gm)

* Sulfuric Acid (1 Kg H2SO4 + 5.5 gm Ag2SO4 ) dissolve for 24 hrs.

* 0.25 N Potassium Dichromate (12.259 gm K2Cr2O7 dried at [....]

Calculation of Total Dissolved Soilds(TDS)

Calculation of Total Dissolved Solids (TDS) of given water sample.


Oven, desiccators, filter paper, pipettes.


* Heat clean dish for 1hour in an oven

* Store in desiccators and weigh immediately before use.

* Stir the sample and pipette a measured volume onto a glass fiber filter.

* Wash with three successive 10ml volumes of reagent [....]

Calculation of Normality

Calculation of Normality

Equivalent weight (EW) = Molecular weight (MW) / Valency (Z)

Normality (N) =Equivalent weight (EW) / Volume of Solution (1000 ml.)

Meq = Actual weight (W) / Equivalent weight (EW)

Example: Molecular wt of K2Cr2O7 is 294.148 gm

Valency = 6 (because of Cr -6)

EW = 294.148/6 = 49.025 [....]

Food-to-Microorganism Ratio(F/M Ratio)

Food-to-Microorganism ratio (F/M ratio)

The food-to-microorganism ratio (F/M ratio) is a process control method/calculation based upon maintaining a specified balance between available food materials (BOD or COD) in the aeration tank influent and the aeration tank mixed liquor volatile suspended solids (MLVSS) concentration The chemical oxygen demand test is sometimes used, because the results are available in a relatively short [....]