Water Treatment


Water Treatment

Water Treatment

Question 1


Turbidity can be defined as the measure of water clarity based on how much the water suspended material reduces the light passage through the water. In this case, suspended materials consist of microbes, plankton, algae, soil particles (sand, silt, and clay) among other substances. Turbidity can have an effect on the water colour, and higher turbidity heightened water temperatures for the reason that the suspended particles take in more heat. As a result, this decreases the dissolved oxygen concentration since water with high temperatures holds less dissolved oxygen as compared to cold water (Davis & Cornwell, 2013). Furthermore, higher turbidity decreases the amount of light that has penetrated the water, which as a result, reduces the production of dissolved oxygen as well as photosynthesis. Turbidity sources include: urban runoff, soil erosion, too much growth of algal, waste discharge, corroding stream banks, among others.

Whereas small quantities of water somewhat seem to be colourless, the tint of the water happens to a deeper blue as the examined sample thickness heightens. The water’s blue hue is an inherent property and is brought about by scattering and selective absorption of white light. Besides that, impurities suspended or dissolved in water can offer distinct coloured appearances to the water. The colour of water can make known bacteriological, chemical and physical conditions. Green colour in drinking water can depict leaching of copper from copper plumbing and also can indicate a growth of algae. Blue colour in water can be a sign of copper, or may be attributed by industrial cleaners’ syphoning in the commodes tank, usually identified as back-flowing.


. (Davis & Susan, 2013) considering that differences in water density and temperature result in stratificationwater density, or motion energy, and therefore, increasing the water temperature depicts heightening molecular motion, energy of water. What’s more, water temperature has an effect on the reproduction as well as growth of living organisms. Scores of animals make use of temperature as an indication for the right time to migrate as well as reproduce. Commonly, at warmer temperatures plants and animals grow faster, even though the temperature limit for all living beings is higher. Importantly, water temperature has a great effect on kinetic energyexpresses the hotness and coldness of the water. In principle, heat is a sign of the water Water temperature

PH can be defined as the measure of how the water is acidic or basic and it ranges from 0 to 14, with PHs below 7 indicating acidity, while PHs above 7 indicating a base, at 7 the water is neutral. Davis and Cornwell (2013) posit that PH is in actual fact the relative amount measure of free hydroxyl and hydrogen ions in the water. Therefore, water having more free hydroxyl ions is basic while water with more free hydrogen ions is acidic. Given that PH can be influenced by water chemicals, PH is a vital sign of water that is chemically changing.

Inorganic – Iron:

Inorganic Iron in water is mostly present in two forms: either the insoluble ferric iron or soluble ferrous iron. In this regard, water having ferrous iron is colourless and clear for the reason that the iron is entirely dissolved. Therefore, when open to air in the atmosphere or pressure tank, the water becomes cloudy and a substance which is reddish brown starts forming. Water as it penetrates the underlying geologic formations as well as soils it dissolves iron, making it to leach into aquifers that double as groundwater sources for wells. Even though present in water, inorganic iron is hardly ever found beyond a concentration of 10 mg/L, but even as small as 0.3 mg/l can change the colour of water to reddish brown.


Water hardness as per Davis and Susan (2013) is the natural feature and is caused by the area’s geology, being mostly limestone.  Minerals like magnesium as well as calcium in the ground dissolve into the moving. Evidently, hard water can result in the formation of limescale in both hot as well as cold water systems and it increases soap or detergent amount utilised. What’s more, limescale will as well form in home appliances used for heating the water like irons as well as kettles. There are two types of harness: temporary hardness brought about by the existence of dissolved bicarbonate minerals while Permanent hardness is water having lasting mineral content that cannot be taken out through boiling.

Question 2


Screening as mentioned is the initial process of water treatment, and it fundamentally entails the removal of large floating and non-biodegradable solids that often penetrate the wastewater works, like wood, containers, tins, plastics, papers, and rags. Basically, successful removal of such constituents will save the downstream equipment and plant from any likely damage, needless pipe blockages, wear and tear, as well as the build-up of unnecessary material that may mess about with the processes of water treatment. In this regard, screening is by and large grouped into either fine screening or coarse screening. The screens could be mechanically or manually cleaned, with just the smaller and older treatment facilities making use of screens that are manually cleaned as their only and main device for screening. In this regard, coarse screens are usually utilised as devices for primary protection, and normally have their openings is 10mm and above (Davis & Cornwell, 2013). On the other hand, fine screens are utilised to get rid of material that could result in operation and maintenance setbacks in downstream processes, especially in water systems that do not have primary treatment. The majority of contemporary water treatment plants use a combination of fine and coarse screening.

Coagulation and Flocculation

Coagulation and flocculation entails removing turbidity as well as suspended solids from water in preparing it for consumption or for advanced treatment. This stage normally makes use of the difference in density between the suspended material as well as the water for separation. In this case, the process of coagulation and flocculation is utilised every time the rate of natural settling for suspended material is extremely slow to offer successful clarification. Coagulants are for that reason utilised to neutralize the suspended solids change, by bringing together the particles to generate a minute pin floc. To create bigger flocs or particles for quicker settling, organic flocculant is usually utilised together with a coagulant. Tentatively, coagulation as well as flocculation is a three step process, which involves flash mixing, coagulation, as well as flocculation.  Still, there are just two steps in the treatment plant during the process of coagulation and flocculation process. First the water flows into the chamber for flash mixing, and afterward flows into the flocculation basin. 


The process of sedimentation removes scores of particles, which includes silt and clay based turbidity as well as other related impurities. Such impurities consist of humic substances, manganese, iron, synthetic organic chemicals, toxic metals, and microbial contaminants. In this case, humic substances derive from soil are created within natural water as well as sediments by biological and chemical processes like vegetation decay. Getting rid of humic substances from water is advantageous given that when chlorine is poured to the water they create disinfection by-products like trihalomethanes. Sedimentation may as well take place as part of the pre-treatment process, termed as pre-sedimentation.  Basically, pre-sedimentation can as well be acknowledged as plain sedimentation for the reason that the process relies only on gravity as well involves no coagulation together with flocculation.  Devoid of coagulation and flocculation, plain sedimentation can get rid of material such as grit which will quickly settle out of the water exclusive of adding chemicals.


Davis, M., & Cornwell, D. (2013). Introduction to Environmental Engineering. New York: McGraw-Hill Education.

Davis, M., & S. M. (2013). Principles of Environmental Engineering & Science (3rd ed.). New York: McGraw-Hill Higher Education.