In which of following step large and small particles are removed from sewage through sequential filtration and sedimentation?

Options

A. Primary treatment
B. Secondary treatment
C. Biological treatment
D. Tertiary treatment

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the specific step in sewage treatment where large and small particles are removed through sequential filtration and sedimentation.

2. **Identifying the Treatment Steps**: The sewage treatment process consists of several steps: primary treatment, secondary treatment, biological treatment, and tertiary treatment.

3. **Defining Primary Treatment**: The primary treatment is also known as physical treatment. It involves the removal of large and small particles from sewage.

4. **Process of Primary Treatment**: In this step, floating debris (large particles) is removed through sequential filtration. After that, smaller particles are removed through a process called sedimentation, where the particles settle at the bottom.

5. **Conclusion**: Based on the definition and process of primary treatment, it is clear that the removal of large and small particles occurs during this step.

6. **Final Answer**: Therefore, the correct answer to the question is **primary treatment**.

---