- Public Works
- Water & Wastewater
- Wastewater System
What is the Wastewater (Sewer) System?
Everyone generates wastewater. The typical home uses 75 to 100 gallons of water per person per day. When people "use" water it doesn't go away; it becomes dirty and is wastewater or sewage; and, it can stink. Wastewater contains pathogens (disease organisms), nutrients (nitrogen, phosphorus, etc.), solids (organic, inorganic), chemicals (from cleaners, disinfectants, medications) and water. Wastewater must be cleaned up before it is returned to the environment to be recycled for future generations.
What is Wastewater Treatment?
Wastewater treatment protects human and environmental health. No one wants to live in a place that stinks, is full of deadly bacteria and cannot support aquatic life. That's why communities build wastewater treatment plants and enforce laws against the release of raw sewage into the environment. There are two basic wastewater treatment systems - decentralized systems (on-site septic systems) and centralized systems which cities use in treating wastewater to meet water quality standards in a cost-effective manner. In cities where people are packed closer together and where there is a lot more wastewater to treat, the community will construct a sewer system that collects wastewater and takes it to a wastewater treatment facility.
How the Sewer System Works
To get the wastewater from your house to the wastewater treatment plant requires a system of pipes (called mains and laterals) and lift stations (to overcome changes in flow elevations).
Once the water reaches the wastewater treatment plant, it goes through one, two, or three stages of treatment which are closely monitored by the U.S. Environmental Protection Agency (EPA) and the Texas Commission on Environmental Quality (TCEQ):
- Primary treatment allows the solids to settle out of the water and the scum to rise. The system then collects the solids for disposal as sludge (either in a landfill or an incinerator).
- Secondary treatment removes organic materials and nutrients. This is done with the help of bacteria - the water flows to large, aerated tanks where the bacteria consume everything they can. The wastewater then flows to settling tanks where the bacteria settle out. Secondary treatment might remove 90% of all solids and organic materials from the wastewater.
- Tertiary treatment uses chemicals to remove phosphorous and nitrogen from the water, but may also include filter beds and other types of treatment. Finally, chlorine added to the water or ultra violet treatment of the water kills any remaining bacteria, and the water is discharged; normally, into an existing stream or large body of water.
Questions concerning the City of Edna's Water or Wastewater System should be directed to the Director of Public Works at 361-781-3122.