1. biological filtration mechanical filtration

2. Sludge/Biosolids Solids that settle out in the primary & secondary settling tanks. The digestion of sludge is completed in heated, anaerobic tanks called digesters. The methane produced during digestion is used to heat the digester.

3. Digested sludge can be used as fertilizer (e.g.- milorganite), Incinerated, or sent to a landfill.

4. http://www.thestar.com/Article/459085 Is Sludge Safe to Use as Fertilizer? http://www.thestar.com/News/Ontario/article/459345 http://healthzone.ca/health/article/459606 http://www.thestar.com/News/Ontario/article/460264

5. Chlorine Chlorine is used at both the sewage treatment plant and the water purification plant to kill disease- causing microorganisms. At the water purification plant, it is the secondary disinfectant. Chlorine is also used at the water purification plant to kill zebra mussels. In large numbers, zebra mussels might clog the intake pipe that brings the water from Lake Ontario into the plant.

6. The sewage treatment plant will be switching to UV light because chlorine can kill fish. The water purification plant uses ozone as the primary disinfectant.

7. Chlorine can react with organic compounds to forms trihalomethanes. Trihalomethanes are carcinogenic (cancer-causing). Ground-level ozone is a component of smog. Calcium thiosulfate is used at the water purification plant to “neutralize” the excess chlorine and ozone.