In this article we will discuss about how to remove colour, odour and taste from water. Aeration: Aeration is a process in which water is brought in intimate contact with atmospheric air to promote exchange of gases between water and atmospheric air. The aeration of water serves the following purposes: (i) In the course of aeration, oxygen from atmospheric air [...]
A rapid sand filter (gravity type) consists of the following parts: 1. Enclosure Tank: It is an open watertight rectangular tank constructed of stone or brick masonry or concrete. The depth of the tank is about 2.5 to 3.5 m. The surface area of the tank may vary from 10 to 50 m2. Thus depending on the total surface area [...]
Permanent hardness of water can be removed by the following methods: Method # 1. Lime-Soda Process: In this method lime [Ca(OH)2] and sodium carbonate [Na2CO3] (or soda ash) are used to remove permanent hardness from water. The chemical reactions involved in this process are as follows: The compounds calcium carbonate CaCO3 and magnesium hydroxide Mg(OH)2 are insoluble in water and [...]
In this article we will discuss about the various operations involved in water treatment. 1. Sedimentation: Sedimentation is a process of separating from water by gravitational settling the suspended particles that are heavier than water. In water there are mainly two types of suspended solids: (i) Inorganic solids having specific gravity of about 2.65, and (ii) Organic solids having specific [...]
Depending upon the stage of treatment at which chlorine is applied to water and also upon the expected results of application of chlorine; chlorination may be of the following forms: Form # 1. Plain Chlorination (or Simple Chlorination): Plain chlorination (or simple chlorination) indicates that only chlorine treatment and no other treatment is given to raw water, and after giving [...]
Learn about the comparison between lime-soda and zeolite process for water softening. Comparison # Lime-Soda Process: 1. Size of Plant: Bulky and large. 2. Supervision Required: Skilled supervision is required for successful working. 3. Sludge Problem if any: Large quantity of sludge is formed which needs to be disposed off by some suitable method. 4. Post Treatment if Needed: Recarbonation [...]
The following are the minor methods of disinfection: Method # 1. Boiling: The bacteria present in water can be killed by boiling it for a long time. This is the most effective method of disinfection of water. However, this method cannot be used to disinfect water on a large scale for public water supplies, for economical reasons. Moreover, it can [...]
In chlorination method of disinfection chlorine (or its compounds) is used as disinfectant. Chlorine is an element, having the symbol CI with an atomic weight of 35.45, melting point -101.5°C and boiling point 34.5°C. Gaseous chlorine is greenish yellow in colour and is approximately 2.5 times heavier than air. Under pressure, it is a liquid with an amber colour and [...]
The continuous flow type of sedimentation tanks are widely adopted at present and hence, it becomes essential to study in detail some of the design aspects of these tanks. Following are the aspects of continuous flow sedimentation tanks: 1. Velocity of Flow 2. Capacity of Tank 3. Miscellaneous Considerations. 1. Velocity of Flow: The velocity of flow of water in [...]
For the purpose of designing, the continuous flow basin may be divided into following four zones: (a) An inlet zone, (b) A settling zone, (c) Sludge zone, and (d) An outlet zone. Before starting design work the following simple assumptions could be made: (i) The water in the settling zone acts as quiescent without any disturbance and the sedimentation takes [...]