Photo: Tomas Jarnetun /Azote.

This year's theme for World Water Day is wastewater. And there are good reasons for it. Globally, over 80 percent of the wastewater generated by society flows back into the ecosystem without being treated or reused.

Therefore, the UN initiated campaign focus on improving wastewater treatment to reduce pollutants entering the ecosystem.

Baltic Eye will also focus on wastewater on World Water Day. The treatment of sewage water in the Baltic Sea region has certainly improved over the past decades. But demands on water treatment increase as society's consumption and production patterns change.

– There is a chemical intensification in society. The production and use of various types of chemical substances are growing rapidly, which also affects how much of the different types of chemicals that end up in the wastewater and run the risk of being further transported into the sea, says environmental chemist Emma Undeman.

The recent Baltic Eye policy brief, Advanced wastewater treatment - a proactive protection of the Baltic Sea, explore the possibilities of using new and improved treatment technologies to meet these new requirements and to protect sensitive aquatic environments.

– We have looked specifically at the Baltic Sea coastal area. It is home to about 28 million people, living closer than 20 kilometers from the coastline. Approximately 70 percent of all their wastewater passes through the 45 largest treatment plants in the coastal area. If these major plants were upgraded with techniques for more advanced water treatment, the total chemical emissions from sewage treatment plants in the coastal area to the sea could be reduced by about 50 percent, says Emma Undeman.

What is advanced wastewater treatment?

- There are various techniques that can improve the treatment of so-called micropollutants, particularly synthetic organic chemicals, such as pharmaceuticals. A common technique is to break up the molecules using ozone gas. Another is to separate the chemicals from the water by either adding powdered activated carbon which binds the molecules, or make the sewage water pass through an activated carbon filter.

Can today's sewage treatment plants not capture chemicals?

- The common plants are not built to remove contaminants such as organic chemicals or metals, although many substances are removed anyway. But persistent and water-soluble substances can pass more or less unaffected through the treatment plants, and many pharmaceuticals fall into this category. To clean this type of substances, and also improve the treatment of most chemical pollutants in general, require more advanced treatment methods.

Should we not focus on reducing the use of hazardous substances instead?

Better treatment doesn’t affect the "chemical intensification". Should we not focus on reducing the use of hazardous substances instead?

- Yes, absolutely. But we should do both. Cleaning wastewater doesn’t protect us from exposure in our homes or workplaces. Nor does it affect the flow of chemicals that do not go through treatment plants. But it is one of the few options to protect the Baltic Sea's sensitive environment and be extra cautious with perhaps the most important natural resource we have, water. Without relying solely on regulations and prohibitions of all individual substances.

- A dream scenario would of course be not having to clean wastewater at all because it simply did not contain any hazardous substances. But, unfortunately, we are still far from that scenario. Therefore, we should consider taking the precautions that are available now, and work both upstream and downstream.

Text: Henrik Hamrén

FACTS: World Water Day

In 1993, the United Nations General Assembly officially designated March 22 as World Water Day.

In 2017, the theme is Wastewater, and the campaign, Why waste water?, is about two specific measures:

• Reduce – improve wastewater treatment to reduce pollutants entering the ecosystem
• Reuse – treat and use wastewater for green space irrigation and municipal cleaning

This year’s theme connects to the UN Sustainable Development Goal (SDG) target 6.3, that require us by 2030 to “improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials, halving the proportion of untreated wastewater and substantially increasing recycling and safe reuse globally”.

World Water Day is coordinated by UN-Water in collaboration with governments and partners.