Neptune cleans up waters
Clean-up of a stagnant pool (Unteres Heustadelwasser)
The Unteres Heustadelwasser today is a long, narrow pool of stagnant water, which is extremely rich in nutrients. To improve the water quality of the pool quickly, the City of Vienna has installed the so-called "Neptune plant" - a facility which removes organic matter and phosphorus from the water.
Once part of the Danube river system, the Unteres Heustadelwasser is today cut off from the river mainstream. Its water is extremely rich in nutrients, which leads to excessive growth of algae. This has frequently caused the oxygen content of the water to drop to dangerously low levels, in some cases even resulting in the death of fish populations.
The Municipal Department - Water Management (MA 45) worked to identify counter-measures which would result in a rapid improvement of water quality. A decision was taken to install the socalled "Neptune water treatment plant" to reduce the nutrient content of the Heustadelwasser and effect a substantial clean-up. The Neptune plant removes organic substances and phosphorus, an important trigger of algal growth, from the water. The reduced level of algal nutrients keeps algal growth at bay.
The working cycle of the "Neptune plant" starts with water from the Heustadelwasser, which is rich in algae and nutrients, being pumped up through an underground pipe to the surface of a gravel layer. The water is distributed to multiple nozzles and spray-dispersed over the gravel bed, which acts as a filter, much like the filters of water treatment plants. Through the spraying process, the water becomes enriched with oxygen so that aero bic bacteria can become active and digest organic substances and algae. After the water has trickled through the gravel layer, it passes through an additional special filter where residual phosphorus is precipitated. The cycle is closed with clear, low-nutrient water being discharged back into the Heustadelwasser pool.
The "Neptune plant" has quickly solved previous problems with lack of oxygen, and substantial amounts of phosphorus have been removed from the water.
As a result, 2010 witnessed a significant reduction of phosphor and plankton algae in the water, subsequently enabling the growing of submerged plants, which are competing with plankton algae for nutrients, in 2011. The next years will bring further improvements in the water quality.
Facts & Figures
- Reduction of phosphorus by up to 60%
- Reduction of suspended solids by 90%
- Start of operation: May 2007
DI (FH) Volker Schaffler
Tel. +43 1 4000 84269
Fax +43 1 4000 7997