Across
- 3. the process of adding air into wastewater to allow aerobic biodegradation of the organic materials.
- 4. the pipes that carry sewage
- 6. process of keeping places clean and healthy
Down
- 1. a polluting or poisonous substance that makes something impure.
- 2. the impurities present in wastewater
- 4. the solid accumulated in wastewater treatment plant
- 5. used water