Question

Decentralised Waste Water Treatment (DEWAT) system has\(\underline{\hspace{2cm}}\).
(A) Low primary investment.
(B) Easy to operate and maintenance.
(C) Baffled filter reactor filled with stone for filtration.
(D) First three chambers for sedimentation of sludge.
Choose the correct answer from the options given below:

• A. (A), (B) and (D) only
• B. (A), (B) and (C) only
• C. (A), (B), (C) and (D)
• D. (B), (C) and (D) only

Hint:

Think of DEWATS as the "simple, local, and natural" alternative to big city sewage plants. Key concepts are low cost, low tech, easy maintenance, and use of natural filtration/treatment methods like baffled reactors and anaerobic digestion.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Decentralized Wastewater Treatment Systems (DEWATS) are small-scale, locally-based systems designed to treat wastewater close to the source. The question asks for their key characteristics.

Step 3: Detailed Explanation:
DEWATS are characterized by several features that make them suitable for communities, small industries, or institutions where large centralized systems are not feasible. \[\begin{array}{rl} \bullet & \text{(A) Low primary investment: Compared to large, centralized sewage treatment plants, DEWATS typically have lower capital costs.} \\ \bullet & \text{(B) Easy to operate and maintenance: They are designed to be simple, often using gravity flow and natural processes, which reduces the need for complex machinery, electricity, and skilled operators, making them easy to maintain.} \\ \bullet & \text{(C) Baffled filter reactor filled with stone for filtration: This is a common component in DEWATS. The baffled reactor is an anaerobic treatment stage where wastewater flows up and down through baffles, and the attached growth on filter material (like stones or gravel) helps in treating the wastewater.} \\ \bullet & \text{(D) First three chambers for sedimentation of sludge: A typical DEWATS plant starts with a primary treatment phase, often a settler or septic tank with multiple chambers, where solids (sludge) settle out through sedimentation.} \\ \end{array}\] All four statements accurately describe common features and advantages of DEWATS.

Step 4: Final Answer:
All the given statements (A), (B), (C), and (D) are characteristics of a DEWAT system.