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.