Water Treatment Processes Explained
Water treatment involves several steps to remove impurities and make water safe for consumption or other uses. These processes can be broadly categorized into physical, chemical, and biological methods. The question asks specifically for a chemical treatment process.
Understanding Chemical Treatment in Water Purification
Chemical treatment processes involve the addition of specific chemicals to the water to achieve purification goals. These chemicals react with impurities, altering their state or facilitating their removal through other processes.
Analyzing Treatment Options
Let's examine each option provided:
- Sedimentation: This is a physical process. It relies on gravity to allow heavier suspended particles in the water to settle down to the bottom of a tank or basin. No chemicals are typically added solely for the purpose of settling in this primary step, although coagulation might precede it.
- Coagulation: This is a chemical treatment process. It involves adding chemicals called coagulants (like alum or ferric chloride) to the water. These chemicals neutralize the negative charges on suspended particles, allowing them to clump together (forming larger particles called flocs) which can then be removed more easily by sedimentation or filtration.
- Filtration: This is primarily a physical process. Water is passed through filter media (like sand, gravel, or membranes) that physically block and remove suspended solids, including the flocs formed during coagulation.
- Grit Chamber: This is a physical treatment unit. It's designed to slow down the flow of water, allowing heavier inorganic materials like sand, gravel, and silt (grit) to settle out due to gravity, while organic materials remain suspended and are carried forward.
Identifying the Chemical Process
Based on the analysis, coagulation is the only process listed that fundamentally relies on the addition of chemicals to alter the properties of impurities for removal.
| Process Name | Type of Process | Primary Mechanism |
|---|---|---|
| Sedimentation | Physical | Gravity settling of solids |
| Coagulation | Chemical | Chemical addition neutralizes particle charges, promoting flocculation |
| Filtration | Physical | Physical straining/sieving of solids using filter media |
| Grit Chamber | Physical | Gravity settling of dense inorganic solids |
Therefore, Coagulation is the correct answer as it is a chemical treatment process used in water purification.
Important Questions from Water Treatment
- Choose the correct statements about coagulation process.
A. Coagulation makes smaller colloids to adhere to each other to form large floc particles
B. Colloids are continually involved in Brownian moment.
C. Colloids are stable because of their surface charge.
D. Coagulants are preferably trivalent cations.
E. Coagulants are soluble in neutral pH.
Choose the most appropriate answer from the options given below: - Hardness of water is due to the presence of
- Which of the following is used as a coagulant for removal of phosphates in water ?
- Given the following parameters of a primary settling chamber :
Diameter = 50m, Depth = 2.5m, average detention time = 2 hours.
How much quantity of waste water is being treated ? - Calculate hardness in units of mg/l as CaCO$_3$ of a ground water sample having Ca$^{++}$ ion concentration of 100 mg/l.
