Across
- 2. Used water form combination of domestic, commercial, industrial or agricultural activity
- 5. To remove the stuff which makes something dirty.
- 6. Single-celled microscopic animals,
- 9. A governmental agency that protects people and the environment from significant health risks.
- 11. To make something clear.
- 13. A loosely clumped mass of fine particles
- 14. A cleaning process used to destroy bacteria.
- 15. Not made of living matter.
- 16. A living thing you can only see with a microscope
- 17. Matter that settles to the bottom of a liquid
- 18. The most common chemical element in our air.
Down
- 1. The air treatment cause the microorganisms to take this up.
- 3. Thick soft wet mud, commonly the product of a refining process.
- 4. The study of ecosystems.
- 7. A member of a large group one celled microorganisms
- 8. Third in the order.
- 10. The process in which organic substances are decomposed by microorganisms into simpler substances.
- 12. The study of living things.