What is (not) the purpose of the sanitary sewer?

February 28, 2018

By Laura Rectenwald, Ph.D., P.G.

Louis Pasteur connected the dots between germs and disease in the mid-19th century, a realization that would eventually provide the impetus for cleaning up our act with regard to management of human waste. Nowadays, the public doesn't think much about sewage treatment plants unless they are faced with a sewer problem.

From the time we are children, we are taught to flush or pour waste down the drain. Barring the occasional stoppage, the system works pretty well until it doesn't.

Our wastewater treatment plants are designed to remove small bits of solids and a specific amount of nutrients and microorganisms from wastewater. Although conventional wastewater treatment processes reduce the concentration of chemicals that pass through, they are not designed to handle petroleum products, cooking oil, pesticides, or concentrated chemicals. When slugs of "non-H2O" such as these reach our publicly owned treatment works (POTWs) they create havoc. Slugs of chemicals can easily interfere in the biological treatment process. The wastewater authority has responsibility to permit and restrict discharges as necessary to insure its proper operation, but it can take months to identify and pinpoint the source of a new and damaging input. On a day-to-day basis, each wastewater authority is largely dependent upon the integrity of the domestic users and industrial permittees to be judicious in what they pour or flush down the drain.

We have the ability to construct wastewater treatment facilities that discharge perfect water, but among all infrastructure needs, wastewater treatment is unglamorous at best. Here in Northeast Texas where we have "plenty of water," "toilet to tap" recycling is not even on the table.

Be aware that the greatest portion of rainwater that flows through streets, rooftops, lawns and parking lots goes straight to our waterways. All the chemicals and particulate that this water contacts is potentially washed right into our waters used for recreation and drinking water, along with the water that the POTWs treat to the best of their ability.

Chemical products are typically safe as long as they are used according to the label instructions. Educate yourself on the toxicity of chemicals you use and be mindful that most sewage treatment facilities were not built to remove chemicals. Even in your workplace, you have a personal responsibility to educate yourself regarding the chemicals that you use and how they must be handled and disposed in order to protect your health as well as our natural resources. Be aware that is not uncommon for products to be labeled "green" even when they contain chemicals that are not good for people or the environment, since this label "sells." POTW's were built to remove germs from wastewater so that our lakes and rivers do not make us sick, not to remove commercial chemical products.

Laura Rectenwald, Ph.D., P.G. is a consultant at Titanium Environmental Services, LLC. In addition to conducting environmental audits and remediation, she assists small cities and private industry with pretreatment programs and permitting. www.titaniumenvironmental.com


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