John Hader, researcher at the Department of Environmental Science

Organisms are used during the sewage treatment process to remove pollutants before release to the environment (e.g., the Baltic Sea). However, down-the-drain spills of industrial chemicals can kill these microorganisms at the treatment plant, resulting in a decrease in pollutant removal efficiency and thus sewage being released to the environment untreated — potentially for months. Within the ECORISK2050 EU project, the Department of Environmental Science is collaborating with the Käppala wastewater treatment plant to determine the risk of such disasters. Käppala started by collecting information on chemicals used at >100 industries in the Stockholm area that feed wastewater downstream (e.g., car washes, factories, hospitals). For these thousands of chemicals, researchers at the Department of Environmental Science are conducting a risk screening analysis, pairing these upstream chemical use data with toxicity data gathered using web scraping and predictive modeling techniques.

The result: a prioritization list of upstream chemicals that (if spilled) pose the highest risk to Käppala. Käppala’s staff can then engage with these high-risk clients and implement mitigation strategies to reduce the risk of these toxic chemicals being spilled. This will help keep the treatment process at Käppala running smoothly, something crucial for maintaining the excellent environmental water quality Stockholm is known for.

“We all play an important role in making sure the chemicals we use, both at work and at home, are disposed of properly to protect the sewage treatment process — and the environment.”

“The Käppala Association is pleased to co-operate closely with scientists at Stockholm University – the process has given us more insight in dealing with chemical spills and has saved us a lot of time.”

The Käppala wastewater treatment cleans water from more than half a milion people around Stockholm. Photo Käppalaförbundet