Hospital waste water should be treated separately
LAUSANNE, SWITZERLAND – A startling discovery made by researchers at Vidy, in Lausanne, has led to recommendations that waste water dumped into Lake Geneva be given complementary treatments and that waste water from hospitals be treated separately. The research team from Eawag, the Swiss aquatic research institute in Lausanne, has found that while water treatment programmes reduce the overall number of germs, they appear to create an environment which actually encourages the most resistant bacteria.
The Eawag team set out to learn if the lake water environment is also affected by the increasing animal, including human, resistance to bacteria that is being shown by a number of studies.
A preliminary report was recently published by Frontiers in Microbiology.
About 15 percent of Switzerland’s waste water is dumped into lakes after being treated. The situation in Vidy is far from an isolated case, Eawag says. Once waste water from the Lausanne area is treated, some 90,000m3 a day, it is released into Lake Geneva ab0ut 700 metres from the shore via a pipe that ejects it at a depth of 30m in the Vidy bay.
Lausanne has no pharmaceutical industry, the researchers point out, nor does it has related industries, but the 214,000 inhabitants of the region use a number of small medical centres and hospitals and the large university hospitals centre, the Chuv, is linked to the city’s waste water treatment system.
The team studied the resistance to antibiotics in parallel with classic tests, looking at growth rates in the water environment and using sophisticated genetic research tools.
The study created a previously unequaled quantity of data about waste water and lake sediment. It showed that there is a particularly high number of bacteria-resistant germs in the waste water coming from the Chuv.
And while 75 percent of the germs are eliminated through current treatment, the multi-resistant ones that are left are encouraged in their new environment.
Recommendations: further treatment and separate hospital waste water
The Eawag group says there is no reason for alarm, since measurements show the resistant germs tend to remain in the sediment rather than in the water near it, but they are recommending two changes. Additional water treatment is needed in selected stations to neutralize a large number of the resistant germs, and hospital waste water should be treated separately.