What are the buoys for monitoring the water quality

Better water quality: Poisonous algae will soon be without a chance

With a multi-sensor system and hyperspectral cameras, lakes and rivers can soon be completely monitored. Then high concentrations of nutrients that allow the algae to proliferate are recognized without any time delay, so that countermeasures can be taken.

Too late: Poisonous blue-green algae had already spread so widespread on this lake that they had to be vacuumed - and bathing in the lake was not allowed.

Photo: Michael Bahlo / dpa

Sewage treatment plants often fail to remove all nutrients such as nitrates and phosphates from the wastewater. Like fertilizers, they end up being too generously distributed by farmers in their fields, in rivers, lakes and ultimately in the sea. If it becomes too much, a fatal cycle begins: cyanobacteria, better known as blue-green algae, begin to proliferate. They remove oxygen from the water, which other living things then lack. And to top it all off, they also produce toxins that pose problems for the waterworks. Such a development is often recognized so late that countermeasures are no longer effective. This is due to the fact that bodies of water cannot be completely monitored.

The sun and wind provide electricity for the sensors

That should change now. Researchers at the Karlsruhe Institute of Technology (KIT), together with the sensor specialist ADM Elektronik in Sauerlach, Bavaria, and the biotechnology company bbe Moldaenke from Schwentinental near Kiel, are developing a monitoring system that continuously monitors the quality of water.

Current method of application of the multi-algae sensor - in future it will be operated automatically from buoys in conjunction with other sensors.

Source: bbe Moldaenke GmbH

It determines parameters such as temperature, oxygen concentration, algae content and greenhouse gases on the surface and at various depths. The data are transmitted by radio to a monitoring center. The buoy supplies itself with solar energy or wind power. Water samples can also be taken remotely for more detailed investigations in the laboratory.

"Enormous social importance"

"A good condition of our waters is of enormous social importance", says Andreas Holbach, who coordinates the joint project "Waquavid" together with Professor Stefan Norra at KIT. “The flowers of cyanobacteria in particular can release toxic substances that are dangerous for humans and the ecosystem.” So far, water has been monitored with a large number of independently operating sensor systems. This complicates and slows down integrated data evaluation, says Norra.

Multisenor measuring buoy plus hyperspectral cameras

The depth profiling multisensor measuring buoy, as the developers call their device, only monitors a limited area. Hyperspectral cameras, which are located on board aircraft, drones and satellites, should also be used to obtain information about the condition of larger bodies of water.

In June 2016, bathing was temporarily prohibited there because of blue-green algae at Dümmer See: Together with partners from industry, KIT researchers are now developing a monitoring system that continuously monitors the quality of water.

Source: Ingo Wagner / dpa

They record light reflections that occur when the area to be examined is bombarded with laser flashes. Depending on the constituents of the water, some of the light is swallowed or its frequency changed. From this, combined with the data supplied by the measuring buoy, the water quality can be determined, as well as the regions into which pollutants are discharged.

Leaf of the swimming fern species Salvinia molesta. The ends of your hair are tied together in the shape of a whisk. This allows the plant to absorb oil very well.

Source: KIT

Another KIT research team has developed a material based on the model of swimming ferns that does not absorb water, but instead absorbs large amounts of oil. Then the nano fur can simply be fished out of the water - with its oil load.

A contribution by:

  • Wolfgang Kempkens

    Wolfgang Kempkens studied electrical engineering at RWTH Aachen University and graduated with a diploma. He worked for a daily newspaper and magazine before establishing himself as a freelance journalist. He mainly deals with environmental, energy and technology issues.