Of course, in our daily lives we use cleaning products, personal care items, and cosmetics; we paint walls and take medication. But what happens when we shower, after using the toilet, when we empty the mop 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 partly new, unknown compounds forms in the sewer system and ends up at the wastewater treatment plant. With 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 absorbed by organisms and thus enter the human food chain. These trace substances also make the purification of water for the production of drinking water from bank filtrate a complex process. Because they are difficult to degrade, micropollutants also accumulate in groundwater.

Micropollutants in Medicines

Accurately assessing whether a drug 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 broken down, transformed, or 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 quickly reach for painkillers. The Mombach wastewater treatment plant in Mainz alone receives the equivalent of about 270 tubes of the painkiller diclofenac every day. The Wirtschaftsbetrieb Mainz has determined that, even after wastewater treatment, the equivalent of approximately 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 (ICPR), up to 5,000 different chemicals are used in households. These include biocides, such as pesticides or disinfectants. Material protectants, which are designed to protect wood, masonry, boats, and other items from algae, fungi, chemical degradation, and water permeability, are also used in everyday life. The range of household chemicals is vast: 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 common household descaling agents.

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

When using household chemicals and medications, the following generally applies: 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 the number of antibiotic-resistant bacteria is increasing (e.g., multidrug-resistant germs in hospitals). Expired medications or leftover doses should be disposed of in the general waste bin.

Cleaning products should ideally be used 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 detergents and dishwashing liquids are often used in excessive amounts. Check with your water supplier 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 won’t use 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, rubbing alcohol (at least 75 percent alcohol) is a sensible alternative: inexpensive, effective, and a fully biodegradable natural product.

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

Wash your car only at designated car washes or in car wash facilities, 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 is happening in Mainz regarding micropollutants?

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