Modern Wastewater Treatment: The Marvel of Civil Engineering We Take for Granted?
“But…where does it go?” It’s a question we might hear from a toddler while potty training or seeing something rinsed down the drain. We rarely think about it in our daily lives, yet wastewater treatment plants (WWTPs) remain a crucial part of the modern human impact cycle, with a direct impact on ecological and human health, as well as climate change. At the start and end of our plumbing system, WWTPs represent a marvel of civil engineering firmly set to protect harmful impacts of the water to humans and ecology, as well as the harmful impacts of humans to the water.
Anything you buy that ends up in the sewer can be considered a down-the-drain product: shampoo, mouth wash, sunscreen, medicine, drain cleaner, even particles that wash off your clothes. If it goes down the shower, sink, toilet or washing machine within a US municipal district, it will end up at a WWTP.
At the WWTP, primary treatment involves removal of pollutants and contaminants through screening and settling out of large particles. Organic matter is then removed via microbial degradation during secondary treatment, with a disinfection step (e.g., chlorination) to remove the bacteria following degradation. Some communities also incorporate an advanced treatment process for removal of special concern pollutants, such as nitrogen or phosphorus. After treatment, the treated water is then released into local waterways, where it can be used again for any number of purposes, such as drinking water supply, crop irrigation, and sustaining aquatic life.
WWTPs must continually evolve, making sure their infrastructure is suitable for the populations served while integrating modern research for treatment of emerging contaminants. For example, research has shown that the presence of both antibiotics from hospital, veterinary, or local drains and pathogens that accompany waste is a continual driver of bacterial evolution and contributes to antibiotic resistance. Examples such as these make it clear that investment in improved, state-of-the-art WWTPs is an investment in our health, the environment, and our future.
What can we do to help?
Begin by understanding that that what goes down-the-drain has the potential to, quite literally, live on. This knowledge check will hopefully urge us to make mindful changes around our homes.
- Save water
- Turn off the water while brushing teeth or washing your face
- Run dishwasher and washing machine only when they are full
- Tend to leaky plumbing fixtures
- Practice proper disposal
- Dispose of hazardous products properly
- Never flush non-degradable products
- Do not flush old prescriptions or medication
Earth911.com is a great resource for searching your local recycling programs and hazardous waste disposal days by entering your zip code. You can also take an active role in understanding your local WWTP network, or learn more about how WWTPs function (https://www.youtube.com/watch?v=FvPakzqM3h8). You’ll be armed with a stronger answer the next time a child asks, “but…where does it go?”