Of course, we use cleaning products, personal care products, cosmetics, paint, and medication in our everyday lives. But what happens when we shower, use the toilet, empty the cleaning bucket, or when it rains on dried paint? You would think that the sewage treatment plant would take care of it—unfortunately, no! As soon as the dissolved substances contained in our everyday products leave their destination, i.e., are flushed down the toilet, carelessly thrown away, or disposed of incorrectly, we have an environmental problem. A cocktail of partly new, unknown compounds is created in the sewage system, which arrives at the sewage treatment plant. According to the current state of technology, 98% of all sewage treatment plants in Germany are unable to adequately eliminate such "micropollutants" from wastewater.

What exactly are micropollutants?

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

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

Micropollutants in pharmaceuticals

It is difficult to reliably assess whether a drug has an impact on the environment because some active ingredients are excreted unchanged by humans, while others are converted. In nature, they are either further broken down, converted, or they can react with other substances to form new compounds. For this reason, their effect 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 intake of hormone residues from birth control pills has been proven.

When we feel pain, we quickly reach for painkillers. The Mainz sewage treatment plant in Mombach alone receives the equivalent of approximately 270 tubes of the painkiller diclofenac every day. The Mainz municipal utility company has determined that, even after the wastewater has been treated, the equivalent of around 100 tubes of diclofenac still flow into the Rhine. On their way down the Lower Rhine to the North Sea, these substances then encounter many other substances that are already dissolved in the water.

Micropollutants affect us all

The above examples 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 and disinfectants. Material preservatives, which are designed to protect wood, masonry, boats, etc. from algae, fungi, chemical decomposition, and water permeability, are also used in everyday life. There is a wide range of household chemicals: preservatives and fragrances are found in cosmetics. Impregnating agents are applied to our outdoor clothing and shoes, for example. Corrosion inhibitors are found in common descaling agents.

How to avoid or minimize the introduction of micropollutants:

When using household chemicals and medicines, the following generally applies: use them sparingly, apply them correctly, and dispose of them properly.

To avoid overdosing on medication, it is advisable to use it with care. Antibiotics pose a double risk: they can damage ecosystems and increase the number of antibiotic-resistant organisms (e.g., multi-resistant germs in hospitals). Expired medication or leftovers should be disposed of in the residual waste bin.

Cleaning products are best used only when necessary. Often, household remedies such as soaking (for stains), citric acid (for limescale), spirit (for grease and mold), or boiling water (for grease) are sufficient. Mechanical cleaning aids such as scouring cream can also help.

Laundry detergents and dishwashing liquids are often overdosed. Ask your water supplier about the hardness of your tap water. If you take into account the degree of soiling and the amount of laundry or dishes, you will not overdose. Only use phosphate-free dishwasher cleaners and detergents.

When choosing shampoos and cosmetics, opt for environmentally friendly products without fragrances or preservatives.

It is sufficient to use disinfectants only selectively and carefully. Neither the kitchen nor the bathroom need to be disinfected regularly. If you do, 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 mechanically, and encourage beneficial insects by creating shelters for hedgehogs or birds, for example.

Only wash your car at designated washing areas or in car washes, never at the side of the road. Have your oil changed at a garage to ensure that no waste oil ends up in the environment.

Household chemicals must be disposed of properly via the hazardous waste collection vehicle or the hazardous waste collection point. For more information, please contact the Mainz waste disposal company (see list of links).

What is happening in Mainz with regard to micropollutants?

In Mainz, the introduction of a further, so-called "4th treatment stage" at the Mombach sewage treatment plant has been decided. The innovative solution that is being sought will remove most of the micropollutants from Mainz's wastewater. You can find more information in the list of links below.