Drinking Water Treatment Process

CHAPTER 2
2. LITERATURE REVIEW
2.1 CONCEPTUAL FRAMEWORK
2.1.1 WATER SOURCES AND THE HYDROLOGICAL CYCLE
The need for understanding the hydrological cycle is essential for knowing the various water sources and it also helps in the exploring of the different factors that affect the quality water (Michael, 2006) and the quality of water from the source contributes to the treatment process that is going to take place for the removal of water contaminants. Hydrological cycle is a process that describes the continuous movement of water in the environment i.e. on, above and below the surface of the Earth. Figure 1. The hydrologic cycle (Ward and Robinson, 1990).
The hydrological cycle cannot be said to have a particular beginning or an end, but

Since water quality is dependent on the level of contaminants there is the need to regulate the amount of contaminants in water. Water treatment is the process of removing or reducing the level of contaminants present in water so that it is safe for consumption.
The general water treatment from the Environmental Protection Agency (EPA, 1999) is as follows.
- Flocculation
Contaminant particles (metals, organic material, and microorganisms) are most times small in size, therefore without assistance these particles cannot be filtered out easily. In this process coagulating compounds are added to the water, these compound causes the suspended contaminants to stick to the compound to create bigger particles. Alum and iron salts or synthetic organic polymers (which are either used unaided or in combination with metal salts) are generally used to promote coagulation.
- Sedimentation
In the process the heavy particles created from the flocculation process are allowed to settle out.
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It is measure of the degree of acidity or alkalinity of water. The pH value is affected by the presence of different admixtures. The pH value also influences several water quality parameters. Extreme values of pH can lead to problems with the use of sense organs.
• Alkalinity
It is measured in mg/l CaCO3. It is the ability or capacity of water to neutralise the acids when they come in contact with water, it is due to the presence of bicarbonates. It is not directly a physical parameter but a bulk parameter.
• Salinity
It is usually measured in parts per million or parts per thousand. It is the measure of salt content present in water. It is most time gotten from the value of conductivity, it also affect sense organs depending of the concentration or amount present in water.
• “Total dissolved solid” (TDS)
It is defined as the amount of inorganic salts and dissolved materials (solids) in water. It can be used to check the salinity of water and is sometimes measured with conductivity. It is measured in parts per millions or parts per thousands and may lead to organoleptic problems in high concentrations.
2.2.2.2 CHEMICAL PARAMETERS
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