Across
- 3. A large pipe or channel that carries sewage (5)
- 7. Microorganisms that require oxygen to survive (15)
- 8. Liquid waste carried off by sewers (6)
- 10. Microorganisms that do not require oxygen to survive (17)
- 11. The maintenance of hygiene and prevention of disease (10)
Down
- 1. The semi-solid material produced as a byproduct of sewage treatment (6)
- 2. A network of pipes that carry sewage (8)
- 4. A process to treat waste by converting it to methane gas (6)
- 5. Refers to anything that is not useful and is discarded (10)
- 6. The process of introducing air into a substance (8)
- 9. A substance that pollutes something (11)