Presented: Thursday Mar 3, 2011 Lesson 2 CHAPTER 3–Section 3.4 Presented: Thursday Mar 3, 2011 Lesson 2

3.4 Protecting the Environment by Separating Mixtures WHAT IS SEWAGE? WHAT HAPPENS TO IT WHEN YOU FLUSH? Sewage is a mixture of water and waste that is flushed down the sink or toilet. It passes through drains and pipes until it reaches a sewage treatment plant. It goes through one or more stages of treatment to remove the solids, break down organic material, kill disease causing organisms

PRIMARY TREATMENT Half the solids are removed, sewage passes a metal grid which sieves out objects that don't decompose easily, like fabric and plastics. It then goes into a large pool and is allowed to settle for many hours - solids settle to the bottom and floating components like oil and grease rise to the top. Solids are removed and can be used as fertilizer, burned or sent to landfill.

SECONDARY TREATMENT Dirty water passes through tanks containing bacteria – oxygen gas is bubbles through the mixture and the bacteria breaks down remaining human waste and plant material. Water settles again and the bacteria settle to the bottom and are removed.

TERTIARY TREATMENT Phosphorus and Nitrogen are removed. Bacteria that grows inside the wastewater and passes through filters. Ozone is bubbled through the wastewater or it could be exposed to ultraviolet radiation. Chlorine is added to water to kill the remaining organisms and then the water is returned to oceans.

Gulf of Mexico Oil Spill

LETS EXPERIMENT You will be working in groups Each group will get a beaker with water and oil, a few plates, cotton balls/swabs, detergent, soap, spoon, popsicle sticks, etc. As a group you need to use the material given plus any other material you would like to use with my approval to try and remove as much oil as possible from the water I will be looking for group participation, fairness, helpfulness, cooperation Safety Answer the questions on the bottom of your handout and hand it in