Sanitary wastewater treatment, of course!
Maybe you never once thought about wastewater systems or perhaps you said, “Just dump that; it’ll go to the wastewater treatment facility anyway.” In terms of wastewater treatment, an educated and conscientious public helps keep recreational and drinking water supplies free of contamination. Let’s find out what happens in the sanitary system we use and take for granted every day, and why we should think twice before sending something down the drain.
Wastewater from homes and businesses travels through pipes to larger sewers below ground. The sewers are accessible for inspections and maintenance through manholes, and lead to a publicly-owned treatment works (POTW) facility, which is designed to treat primarily one thing: human waste.
Of course, many other wastes enter the system including “untreatables” such as dental floss, chewing gum, hygiene products, and children’s toys, to name a few. Accidents happen but placing as much untreatable waste as possible into household garbage ultimately saves resources and sewer bill costs because those items must be screened at the POTW entrance (called the headworks) then hauled away.
As repulsive as human waste is to humans, it is nothing less than the most delectable feast to many bacteria. These bacteria, known collectively as activated sludge (are you getting hungry?), are the heart stomach of the POTW.
Under tightly-controlled conditions, sludge digests wastewater organic matter. When the smorgasbord is complete, liquid and sludge solids are separated. Liquid continues through a final disinfection (reaching near drinking water quality) before discharge to a nearby river, lake, or ocean. The dewatered solids are often sold as fertilizer. Other byproducts such as methane gas are produced and can be reclaimed as renewable resources to power the POTW.
Despite my simplification of POTWs, their true complexities are proven by regulations that require designs licensed by professional engineers, permits approved by government agencies, and systems operated by experienced and certified personnel.
Ask if your local POTW offers tours and you can see how much happens “behind the scenes” to keep our waters safe.
Now that you have a basic understanding of sanitary wastewater treatment, will you think twice about what you dump, flush, or rinse down the drain? What do you think happens to other potentially harmful “stuff” that gets into the system? Check back here for more insight.