FOOD PRODUCTION NOTES

TOPIC EIGHT

WATER

Definition:

Water is a chemical compound containing two volume of hydrogen to one volume of oxygen.

Water is pure in its nutrition state but is rarely found so because.

1. It dissolves oases and collects particles of dust as it falls through the air.

2. It dissolves some mineral e.g. calcium carbonate, magnesium carbonate, calcium sulphate, iodine etc.

SOURCES OF WATER.

1. Rainfall. Collected in the following ways.

                   -natural lakes.

                   -rivers and springs.

                   -artificial reservoirs.

                   -underground lakes and wells.

Relative fitness of water.        

Water could be

a.wholesome

b.suspicious

c.dangerous.

Wholesome: from springs, deep well, and upland surfaces.

Suspicious water: stored, rainfall water, and surface water from cultivated land.

Dangerous water: rainfall water, to which sewerage has got access and shallow wells.

Classification/types of water

A. soft water.

B.hard water.

 

Soft water:

 Generally water is soft.

-soft water is mildly acidic .a practical test is that it will produce lather easily when soap is dissolved in the water.

 

Hard water:

This is the water containing dissolved salts (sulphate bicarbonate and chlorides) of calcium and magnesium.

There are two types of hardness of water:

              1. Temporarily hardness

              2. Permanent hardness.

Temporarily hardness.

Is caused by calcium bicarbonate or magnesium bicarbonate in solution.

Softening temporarily hardness.

-by boiling

-adding sodium bicarbonate (lime).

-adding sodium carbonate.

 

Permanent hardness.

Is caused by calcium or magnesium salts in solution present a sulphate or chlorides.

Removal is by:

-use soda.

-ammonia solution or borax.

-lime and soda or sodium hexametaphosphate for large scale.

Advantages of soft water.

-soap lathers easily.

-no formation of scum. Which cause colour discoloration

Disadvantages of hard water.

-wasteful during laundry i.e. more soap is required to form lather therefore wastes soap time and energy.

-scale forms on pipes and cause blockage that would lead to burst.

-scale (fur) forms in boilers and it settles and it is expensive to de-scale.

- using too much fuel to heat water as the fur that forms in kettles and boilers reduce the efficiency.

-wastage of time because of fur in boilers.

-forms scum with soap when rinsing and therefore can discolor white garments.

 

WATER CONTAMINATION.

Water may be contaminated by-

-Micro-organism.

-chemical

-soil.

 

Water treatment.

Water treatment is the process which is undertaken to make undesirable water more desirable.

This includes removal of pathogens, suspended matter unpleasant taste and odour certain dissolved minerals and variety of unpleasant or potentially harmful chemical.

Ground water is usually clear requires softening and removal of iron taste and odour following by chlorination to avoid contamination.

Treatment methods of water

·        Aeration

Oxidation will remove reduce heat taste and odours and precipitate iron and magnesium.

·        Softening

Removal of divalent cations of calcium and magnesium, removal of water hardness caused by salts (carbonate sulphate)

·        Sedimentation.

Removal of suspended and colloidal matters.

·        Stabilization:

To prevent collision and deposition in distribution process system.

·        Disinfection:

To kill or remove the pathogens.

The character and degree of treatment will depend upon the nature of water which in term depends upon the source and quality required.

Uses of chlorine:

-killing of microorganisms.

-used as an oxidizing agent/oxidizes iron, manganese and hydrogen sulphide.

-destroy some taste and odours producing substances control of algae and slime organisms.

Reasons for storing water;

1. To emphasize pumping rate over the day

2. To equalize supply and demand over a long period.

3. To store water for emergencies as firefighting or accidental breakdown.