Of course, in our daily lives we use cleaning products, personal care products, and cosmetics; we paint with paint; and we take medication. But what happens when we shower, after using the toilet, when we empty the cleaning bucket, or when rain falls on dried paint? You’d think the wastewater treatment plant would take care of it—but unfortunately, no! As soon as the dissolved substances contained in our everyday products leave their intended destination—that is, when they’re flushed down the toilet, carelessly thrown away, or improperly disposed of—we have an environmental problem. A cocktail of compounds—some of them new and unknown—forms in the sewer system and ends up at the wastewater treatment plant. Based on current technology, 98% of all wastewater treatment plants in Germany are unable to adequately remove such “micropollutants” from the wastewater.

What exactly are micropollutants?

The term “micropollutants” or “trace substances” refers to dissolved, synthetic substances found, among other places, in our water bodies. They are invisible because they occur in low concentrations ranging from one-thousandth to one-billionth of a gram per liter. Even at this scale, they are so dangerous that they can harm aquatic organisms and, ultimately, humans.

Micropollutants enter surface waters indirectly from households via wastewater treatment plants or directly from agriculture and industry. There, they are taken up by organisms and thus enter the human food chain. These trace substances also make it difficult to purify water for drinking purposes from bank filtrate. Because they are difficult to break down, micropollutants also accumulate in groundwater.

Micropollutants in Medicines

Accurately assessing whether a medication impacts the environment is complicated by the fact that some active ingredients are excreted by humans unchanged, while others are metabolized. In nature, they are either further degraded, transformed, or they can react with other substances to form new compounds. For this reason, their impact on the aquatic environment cannot yet be reliably predicted in many cases.

It is known that the accumulation of pharmaceuticals in fish leads to organ damage and behavioral changes. For example, the feminization of male fish due to the ingestion of hormone residues from the birth control pill has been documented.

When we feel a twinge, we’re quick to reach for painkillers. The Mombach wastewater treatment plant in Mainz alone receives the equivalent of approximately 270 tubes of the painkiller diclofenac every day. The Wirtschaftsbetrieb Mainz has determined that, even after wastewater treatment, the equivalent of about 100 tubes of diclofenac still flows into the Rhine. On their journey down the Lower Rhine to the North Sea, these substances then mix with many other substances already dissolved in the water.

Micropollutants Affect Us All

The examples above show that micropollutants affect us all. According to the International Commission for the Protection of the Rhine (IKSR), up to 5,000 different chemicals are used in households. These include biocides, such as pesticides and disinfectants. Material preservatives—which are designed to protect wood, masonry, boats, and other items from algae, fungi, chemical degradation, and water penetration—are also used in everyday life. Household chemicals cover a wide range: Preservatives and fragrances are found in cosmetic products. Water-repellent treatments, for example, are applied to our outdoor clothing and shoes. Corrosion inhibitors are found in everyday descaling agents.

Here’s how you can avoid or minimize exposure to micropollutants:

When using household chemicals and medications, the following general guidelines apply: use them sparingly, apply them correctly, and dispose of them properly.

To avoid overdosing on medications, it is advisable to handle them with care. Antibiotics pose a twofold risk: they can harm ecosystems, and antibiotic resistance is on the rise (e.g., multidrug-resistant bacteria in hospitals). Expired medications or leftover doses should be disposed of in the general waste bin.

It’s best to use cleaning products only when absolutely necessary. Often, household remedies such as soaking (for stains), citric acid (for limescale), rubbing alcohol (for grease and mold), or boiling water (for grease) are sufficient. Mechanical cleaning aids like scouring cream can provide additional help.

Laundry detergent and dishwashing liquid are often used in excessive amounts. Check with your water utility to find out the hardness level of your tap water. If you take into account the level of soiling and the amount of laundry or dishes, you’ll avoid using too much. Use only phosphate-free dishwasher detergents and laundry detergents.

When choosing shampoos and cosmetics, opt for eco-friendly products free of fragrances and preservatives.

Using disinfectants only when necessary and with care is sufficient. Neither the kitchen nor the bathroom needs to be disinfected regularly. If you do need to, rubbing alcohol (at least 75 percent alcohol) is a sensible alternative: inexpensive, effective, and a completely biodegradable natural product.

Avoid using chemical pesticides in the garden. Instead, use home remedies, remove weeds by hand, and encourage beneficial organisms by, for example, creating shelters for hedgehogs or birds.

Wash your car only at designated car wash stations or in car washes—never on the side of the road. Have your oil changed at a repair shop to ensure that no used oil enters the environment.

Household chemicals should be disposed of properly via the hazardous waste collection truck or at a hazardous waste drop-off point. For more information, contact the Mainz Waste Management Authority; see the list of links.

What’s happening in Mainz regarding micropollutants?

In Mainz, a decision has been made to introduce an additional, so-called “4th treatment stage” at the Mombach wastewater treatment plant. This innovative solution will remove the majority of micropollutants from Mainz’s wastewater. You can find more information in the list of links below.