1. Safe Drinking Water

2. What is this a picture of?

4. The majority of people in the US get their water from public water systems that have to meet state or federal requirements for safety
Almost 20% of the world’s population does not have regular access to clean drinking water

5. Common water-borne diseases
Cholera
Transmitted by Vibrio cholera and causes gastrointestinal issues
Giardiasis
Transmitted by Giardia lamblia parasite and causes GI issues
Legionellosis
Caused by Legionella pneumophila bacteria and leads to flu like symptoms

6. Cholera
Giardia lamblia
Legionellosis

7. Organisms in the Water
Maximum Contaminant Level Goals (MCLG) are in place to prevent water borne illnesses
Zero tolerance for Giardia, Legionella and viruses
Indicator organisms like fecal coliform bacteria are used for water quality testing

8. Making Water Safe
If surface water or well water is contaminated there are a few methods that can clean it
Chlorination- chlorine can disinfect (kill) most microbes
UV Light- kills bacteria; more expensive than chlorination
Heat- water heated to a rolling boil for at least one minute can kill bacteria and protozoan cysts
Filtration- activated carbon filters remove organic chemicals from water

9. The Treatment Process

10. Waste Water Treatment
Most of the wastewater from residential areas is biodegradable
Industrial water and storm runoffs contain toxic chemicals that can interfere with treatments

11. Treatment Process 1. Screening:
Wastewater entering the treatment plant includes items like wood, rocks, trash and even dead animals.
The water is run through a screen to catch these solids
Most of these materials are sent to a landfill.

12. 2. Pumping:
The wastewater system relies on the force of gravity to move sewage from your home to the treatment plant. (So wastewater-treatment plants are located on low ground, often near a river into which treated water can be released).
If the plant is built above the ground level, the wastewater has to be pumped up to the aeration tanks

14. 3. Aerating:
The wastewater is sent to a tank where it is exposed to oxygen to allow decomposition to begin

15. 4. Removing sludge
Wastewater then enters the sedimentation tanks
Large particles (AKA the sludge) settles out of the wastewater and is pumped out of the tanks
Some of the water is removed in a step called thickening and then the sludge is processed in large tanks called digesters.

17. Lighter materials float to the surface
5. Removing scum:
Lighter materials float to the surface
This 'scum' includes grease, oils, plastics, and soap.
Slow-moving rakes skim the scum off the surface of the wastewater. Scum is thickened and pumped to the digesters along with the sludge.

19. 6. Killing bacteria:
Wastewater flows into a 'chlorine contact' tank, where the chemical chlorine is added to kill bacteria,
The chlorine is mostly eliminated as the bacteria are destroyed, but sometimes it must be neutralized by adding other chemicals
The treated water (called effluent) is then discharged to a local river, wetland or the ocean

20. The Sludge
Another part of treating wastewater is dealing with the solid-waste material
These solids are kept for 20 to 30 days in large, heated and enclosed tanks called 'digesters.'
Here, bacteria break down (digest) the material, reducing its volume, odors, and getting rid of organisms that can cause disease
The finished product is mainly sent to landfills, but sometimes can be used as fertilizer.

21. Wastewater Treatment Video

22. Summarizing Questions:10 points
Why is chlorine added to water during the treatment process?
Expand: Why is there more chlorination and filtration of water during summer months?