Question 4
(4) (a) (i) Define the term hardness of water.
(ii) List three types of filters commonly used in water treatment.
(b) Explain each of the following terms used in water treatment:
(i) sedimentation; (ii) filtration; (iii) chlorination.
Observation
Most of the candidates had difficulty answering this question. They could not give technical definition and explanations of the terms required. The required responses are given below.
4 a (i) Hardness of water is the presence of calcium carbonate/sulphate in water, which
makes obtaining a lather with soap difficult.
(ii) Types of filters used in water treatment are:
- slow sand filter;
- pressure filter;
- bottle filter;
- disk filter and;
- screen filter.
b Sedimentation: This is the process of causing heavier solid particles in suspension, both organic and inorganic to settle by retaining water in a basin.
Filtration: This is the process of removing impurities from water by allowing it to pass through a thick layer of sand or other filtering media.
Chlorination: This is application of chloride or chlorine compound to water to kill bacteria.