Water Treatment

1. Explain how water is filtered and cleaned in a city for drinking.
There are four processes used to purify water. The first process is screening which keeps the debris out. The next process is called coagulation and settling this is where the water is mixed with aluminum sulfate and Chlorine. it transforms into a sticky substance that attracts bacteria and impurities. In the next step the water moves into a sedimentation basin where the aluminum sulfate substance falls to the bottom and is taken out of the water. The last process is the disinfecting process which chemicals are added to kill any lasting germs.

2. Explain how sewer water is treated and returned to the river or lake.
The first thing in this process is holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface where they will be taken out. the next step may require a separation process to remove the micro-organisms from the treated water prior to discharge or tertiary treatment. the last thing that happens is the water is sometimes disinfected chemically or physically before discharge.

3. 2 good questions to ask tomorrow.
What are the names of the chemicals put into the water?
How long does the process take for both of them?