An installer wrote asking whether polymers present in soaps and body washes could cause clogging in effluent filters and on media filter surface areas. He had observed this problem in systems that his company installs and maintains. This is an interesting question and a little different take on a problem that has been observed elsewhere. It was ascribed to excessive use of antibacterial cleaning products interrupting septic tank biology, causing excessive solids to accumulate, clogging effluent filters and having the potential to move solids downstream.

         We are not organic chemists, and our only association with polymers is in a rudimentary knowledge of their use in conditioning septage for dewatering in treatment facilities. We looked at the ingredient labels of some cleaners and fabric softeners in our homes and found words like “biodegradable softening agents (cationic).” This is interesting because the definition of a polymer is simply “a substance made up of a large number of smaller molecules that link together to form larger molecules.” An example of a synthetic polymer is plastic. An example of a natural polymer is rubber. The softening agents referred to are polymers. Each product has its own set of proprietary compounds to enhance its cleaning or softening ability.

         Whether we realize it or not, polymers play a large role in our everyday life. As indicated, enough forming polymer chains have given us all kinds of plastic products. And as we looked at their role in household cleaning products, we found they are playing an increasing role in those products.

POLYMER USE IN WASTEWATER

         Here is what one company said about its products and polymers: Its product “offers a comprehensive range of specialty chemicals to enhance the performance of fabric-, dish- and surface-care products. The innovative ingredients and additives we produce modify physical properties and offer a range of functional benefits such as stain removal, hygiene improvements, fabric softening and surface modification for easier cleaning. In partnership with customers in the home products industry, we innovate products that help people to live a more comfortable life.”

         One of the main reasons for polymers in cleaning products is to use less harsh chemicals that are biodegradable to protect both the user and the environment. In another area of its company write-up, it highlights the cleaning and disinfectant nature of some of its products. Protecting human health and the environment are our goals as well, so we both want the same things.

         As I indicated earlier, polymers are used in our industry to condition septage to thicken the solids and remove water, leaving the solids behind to be treated or land-applied. Conditioning can increase sludge solids to 15% to 30%. The process removes the bulk of the water for further treatment or discharge more quickly than using other chemical or heat methods to reduce the moisture content. The main advantage of using polymers as opposed to iron or lime is that they do not increase the volume of solids left to be treated or disposed.

         The fundamental objective in septage treatment is to cause the aggregation of fine solids through flocculation. During the process, individual particles aggregate into clotlike masses or precipitate into small lumps. Accomplishing this in septage treatment facilities is part science and part art to get the right mix of polymer to the incoming septage to accumulate the solids and remove the water.

         Could polymers be part of the problem in premature effluent and media filter clogging? The answer appears to be yes, it seems possible. We do not know the exact chemical composition of the polymers used in the cleaning and softening products, and we do not know what other polymers are going to be created and used in the future in these products.

THE GOOD AND THE BAD

         The chemists creating these products look at if they improve the product from a cleaning perspective and will they break down in the environment. They are not necessarily looking at what happens when the product is introduced directly into a wastewater system with little time to degrade.

         Whether these products are or will cause problems in your systems goes back to the level and frequency of use within the house, as we discuss with use of antibacterial products. From my perspective, if the polymers act in the tank to accumulate solids, it is not all bad because we catch them at the effluent screen. By bringing smaller particles together into larger particles, we can reduce suspended solids headed to the drainfield. However, if the polymer is not activated until it passes through the tank and plugs other pretreatment devices or drainfields, it can become a large problem.

         Unfortunately, we do not have a good way of predicting or anticipating what happens, so encouraging less use at the source (homeowner) appears to be the best route. It also means we as an industry should have conversations with the companies formulating cleaning products. They should ask, as part of their testing protocols, what happens when the product is added to a wastewater stream.