Abstract
Conventional water treatments have several successive processes in series to produce potable water. This chapter talks about the conventional water treatment processes which are mainly used to treat water originated from freshwater sources. Besides, the discussion covers some typical water quality, both raw and treated, as well as the standards of water quality. One of the highlighted topics in this chapter is the common issues that are frequently happening in the conventional water treatment facilities around the rural regions experiencing tropical climate, which is centred on the issues affecting the raw water quality and treatment processes. The major issue during post-treatment which is on sludge management is also discussed by underlining some alternative to the traditional way of using sludge lagoons. Topics in this chapter provide a better perspective to the water treatment operators and students who are interested in this topic of major processes used in conventional water treatment plants as well as the common issues encountered.
TopSources Of Water
Water is a tasteless, odourless, and transparent substance that occurs naturally on earth in all three physical states: solid (ice), liquid (liquid water), and gas (steam). Surface water and groundwater are the main sources of potable water. The surface water includes freshwater from streams and lakes, brackish water, and seawater from the ocean. The groundwater is a type of freshwater that lies under the ground surface and can be recovered by digging a well. Although around 70% of the earth’s surface is covered with water, only about 2.5% of its total is drinkable freshwater, while the rest is seawater. The earth holds about 1.4 quintillion (1.4 x 1018) m3 of water of which 97.5% are composed of seawater, around 1.7% frozen in glaciers, ice caps, and ice sheets, while the other 0.8% exists as liquid water found in lakes, rivers, swamps, atmospheric water vapour, and underground (Caldecott, 2008).
Key Terms in this Chapter
Sludge: Viscous mixture of solid and liquid compounds discharged from the water treatment process.
Dewatering: Process of removing water typically from a mass of sludge.
Water Quality: Variables or parameters which limit water use, for examples the chemical, physical, biological, and radiological properties of water.
Raw Water Supply: Water resource found in the environment that has not been treated which contains impurities and microbes making it unsuitable for direct consumption, such as rainwater, groundwater, and surface water of river and lake.
Conventional Water Treatment Plant: Water treatment facility which consists of several unit processes, typically seven to ten-step process to deliver safe drinking water to consumers.
Microalgae: Microscopic-size algae which can be frequently found in freshwater and marine ecosystems.
Drinking Water: Water having the quality that is suitable and safe for drinking.
Tropical Country: Country experiencing tropical climate which is situated within the region known as the tropics.
Potable Water: See Drinking Water.