Bad Sassendorf is using new ozone treatment technology to eliminate pharmaceuticals from its wastewater.
THE LITTLE GERMAN SPA town of Bad Sassendorf, renowned for its salt and mud cures, has no less than six hospitals. Not surprisingly, pharmaceuticals –from antibiotics to pain killers – collect in its wastewater far more than average, and residents worry about the long-term eff ects of trace pollutants, which traditional wastewater treatments cannot eliminate.
That’s where Xylem’s ozone treatment technology comes in. In January 2010, Bad Sassendorf became one of the world’s first municipal sewage plants to eliminate pharmaceuticals from its wastewater by using a supplemental wastewater treatment involving ozone to break down the complex drug compounds. “The expectations are big,” says Michael Ziegler, sales engineer for Xylem in Herford, Germany.
Bad Sassendorf’s initiative is part of a larger trace-pollutant cleanup program for the Ruhr River. In the summer, the river comprises up to 40 percent wastewater. The same water gets recycled for drinking purposes. “It’s a very short cycle between discharging and using,” says Daniel Rohring, product manager for ozone in Herford.
“In the 1990s investigators began finding estrogenic substances – hormones – in Germany’s rivers, lakes, and seas,” says Arne Wieland, an Xylem application engineer in Herford. These hormones appeared to be causing the ‘feminization’ of male fish, a troubling find.
Researchers evaluated various technologies that might reduce the amount of hormones and pharmaceuticals in the water, a major source of which was effluent from wastewater treatment plants. Ozone drew particular attention as a treatment solution because it oxidizes very efficiently.
When people take medicines such as antibiotics, hormones or anti-epilepsy drugs, they excrete as much as 50 percent of what they ingest. If left untreated, many of these drugs, which typically have a long molecular structure, break down very slowly in the environment.
During Xylem’s treatment, ozone attacks drug compounds by breaking them down directly or indirectly. Normally the reaction process completely consumes ozone (comprising three oxygen atoms), releasing only oxygen.
The result? “You get cleaner water,” says Wieland. Effectiveness depends on several factors, including the drug involved, the ozone concentration and the reaction time. The Bad Sassendorf plant uses a concentration of 4.6 kilograms of ozone per hour, and a 13-minute treatment cycle, believed to provide maximum efficiency.
Ozone breaks down too rapidly to be stored or transported. Because of this, Xylem supplied Bad Sassendorf with an ozone generator that creates ozone atoms to do the work. Xylem supplied all the equipment, already factory-tested, in container housing in order to minimise startup time and costs.
“It’s more or less a ‘plug and play’ system,” says Michael Ziegler. In the end, Bad Sassendorf only had to build the concrete tank where the ozone is introduced (via diffusers that make tiny bubbles to increase surface contact with pollutants).
The Bad Sassendorf plant is one of three plants along the Ruhr River to install Xylem ozone treatment systems; the other two will begin in the spring of 2011.