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, localized systems treating wastewater near its origin. The query seeks their defining attributes.

Step 3: Detailed Explanation:
DEWATS possess several features making them suitable for communities, small industries, or institutions where centralized systems are impractical.\[\begin{array}{rl} \bullet & \text{(A) Low initial investment: Compared to large, centralized sewage treatment plants, DEWATS generally have lower capital costs.} \\ \bullet & \text{(B) Simple operation and maintenance: Designed for simplicity, often employing gravity flow and natural processes, they require less complex machinery, electricity, and skilled operators, facilitating easy maintenance.} \\ \bullet & \text{(C) Stone-filled baffled filter reactor for filtration: This is a common DEWATS component. The baffled reactor is an anaerobic treatment stage where wastewater moves up and down through baffles, with attached growth on filter media (e.g., stones, gravel) aiding treatment.} \\ \bullet & \text{(D) Initial chambers for sludge sedimentation: A typical DEWATS plant begins with primary treatment, often a settler or multi-chambered septic tank, where solids (sludge) separate via sedimentation.} \\ \end{array}\]All four statements accurately describe common features and benefits of DEWATS.

Step 4: Final Answer:
Statements (A), (B), (C), and (D) all represent characteristics of a DEWAT system.