Indoor plumbing is a great thing! It isn’t necessary to understand how it works to use it, but if you’re curious about what happens to waste after it goes down the drain, we have your answer.
After you flush your toilet or let something go down the drain, the waste is taken through the sewage pipe. We call that waste sewage. These pipes travel from your house and meet with the sewage from other homes and buildings to flow into a bigger pipe.
These larger sewer pipes take all the sewage to the sewage treatment plant. In San Antonio, the sewage treatment plant is operated by San Antonio Water Systems, or as you may know them, SAWS.
What happens once sewage arrives at the treatment plant?
After the sewage is taken to the treatment plant, it is put through a 3 stage process.
Stage 1: Primary Treatment
Step 1: Filtration (inorganic)
This is when large solid items are filtered. Fine springs filter the water of things that are larger than a quarter inch. These can be anything from baby wipes (yes, even the flushable ones) to discarded food wrappers. As these objects are filtered out, they are then collected and transported to the landfill.
Step 2: Grit Removal
Microorganisms are added to consume the remaining organic material found in water. This is when we get out the things smaller than a quarter of an inch. The grit is washed and collected into a dumpster to go to the landfill.
Step 3: Clarification
The water is slowed down, and the waste starts to settle out onto the floor of the chamber and the scum, such as oil, floats to the top and is then filtered out.
Stage 2: Secondary Treatment
Step 1: Aeration
Air is added into the wastewater to stimulate aerobic cellular respiration. This is the process of energizing and stimulating the right bugs in the water to eat the waste in the water and then each other.
Step 2: Final Clarification
The activated sludge is removed once more and used for food for the bugs or is sent to the digesters.
Stage 3: Tertiary Treatment
Step 1: Fine Filtration
Using diamond cloth filters, any remaining organisms are removed from the water.
Step 2: Disinfection
Chlorine gets added to the water in the reaction chamber to kill any remaining microorganisms for at least 20 minutes.
Then the chlorine is neutralized, and the water goes into the river (or ocean) or is used in the treatment plant’s recycle center.
That was quite a trip your plumbing waste went on. For a more in-depth explanation of the plumbing process, you can visit the SAWS website. For all your plumbing problems, call the San Antonio plumbers the city has trusted for over 40 years.