Drausy® in focus

The Hessischer Jägerhof Foundation has opted for a gentle watercourse restoration method in which perforated hoses are laid between the water and the mud layer. A compressor pumps air into the hoses, which bubbles up through the fine openings. This oxygen supply in the water near the bottom causes the sludge layer to compost and thus also improves the water quality.

The Foundation became aware of Drausy® through a paper on the rehabilitation of a stretch of water in the park: Mr. Dietz had given a hint in his work on page 34: "For the new conception of the Luisengraben, desilting is necessary in any case due to the heavy silting up. An interesting method is a procedure in which air is fed into the organic sediments via special hoses. This aeration ensures aerobic decomposition of organic matter. The method has been successfully applied at the tank ditch in the municipality of Malsch, among other places".

The regular measurements show that sufficient oxygen has been stored in the sediment since work began. The intensive biological activity of the natural bacteria in the sludge causes the oxygen content to drop again. This indicates that more and more bacteria are formed that mineralise the existing organic sludge - this is comparable to composting. Over time, the organic content decreases, so that the bacteria also receive less and less nourishment.

It is a sustainable and cost-effective method.

The intensive conversion and decomposition processes of the organic substances that have been sedimented for years, brought about by aeration, are largely complete or have been reduced to the "usual" level. Of course, organic substances and nutrients continue to enter the system via surface inputs (leaf fall, flying insects, dust, pollen, etc.) and via groundwater (agriculture), or are produced in the water body itself (algae). The sediments no longer show any black colouration in the layers near the surface. The field and laboratory measurements also show that the oxygen-free reduced areas have become significantly less in their vertical extent and can only be found in deeper layers. The sediments are almost free of algal and bacterial growth.

The water body becomes healthy again and deeper due to the decomposition of the organic digested sludge. This is because the biological degradation products are converted into fine sand, which compacts the sediment of the water body. The system does not affect the animals living in the water body. If we had had to dredge the pond and dispose of the sludge, we would have paid at least double.

By using the DRAUSY system, the service life of the sewer can be extended by 25 years. The costs of the DRAUSY system are significantly lower compared to conventional rehabilitation techniques. In addition, a significant improvement of the wastewater quality can be expected due to the addition of oxygen. By using the DRAUSY system, the odour nuisance can be stopped immediately. The costs of the DRAUSY system are comparable to those of the conventional process. The addition of oxygen can also reduce the pollutant load of the industrial wastewater and thus enable compliance with the limit values of the Indirect Discharger Ordinance.

Committed project managers awarded Golden Sewer Lid: Baxpehler's project offers an environmentally and citizen-friendly solution to the difficult problem of odour generation in sewers, especially in the vicinity of sewage pressure pipes. Technical innovations are reflected in the combination as well as in the technical implementation of the individual measures.