Aeration by on-site produced pure oxygen


Project title: Conservation of energy in activated sludge systems of industrial wastewater treatment plants by on-site produced pure oxygen
Project leader: Günter Müller-Czygan (HST)
Co-operation partner: HST Hydro-Systemtechnik GmbH;  Air Products GmbH
Sponsor: Deutsche Bundesstiftung Umwelt (DBU)
Reference number: 26353
Project term: September 2008 - June 2012


Short abstract


The insertion of oxygen into the aeration tank of sewage treatment plants plays an important role in the biological procedures of waste water clarification. As the aeration causes the highest energy consumption of a wastewater treatment plant (with 40 to 80% depending on the procedure), innovations in this area have a great impact on the total energy balance of the plant.

An approach to reduce the specific energy consumption is the application of pure oxygen (technical oxygen with a proportion of oxygen higher than 90%). Compared to conventional aeration systems, previous systems with use with pure oxygen have often been uneconomical and to complex in terms of logistic and technical requirements. Because of that such installations have been limited only to the industrial sector or special applications.

An innovative system on the basis of vacuum technology (VSA = Vacuum-Swing-Adsorption) allows an on-site production of pure oxygen, independent of external gas suppliers. In combination with an increasing price for energy, this technology offers new application potentials for the use of pure oxygen also on smaller industrial and communal wastewater treatment plants.

Vergleich herkömmlicher mit Reinsauerstoffbelüftung

Figure: Comparison of conventional (left) and pure oxygen aeration (right)  (Photos: Air Products)

Apart from energy savings, there are further advantages to be realized in the field of environmental protection and plant management by using pure oxygen for aeration. The better oxygen transfer does not only results in a massive reduction of the volume of inserted gas and the following reduction of emissions like escaping, smell loaded gas and particulate material out of the aeration tank to more than 90%. It also allows a significant higher degradation rate by reason of a fivefold higher availability of the oxygen. In addition, by reducing the accumulation of excess sludge also the sludge disposal can be reduced.

Within the DBU-sponsored research project together with the industrial partner HST Hydro-Systemtechnik GmbH, the application as well as the technical and economical limitations of the new technology for on-site production of pure oxygen shall be scientifically investigated. By a pilot installation of the system supplier Air Products GmbH the demand for adjustment to the specific circumstances of wastewater treatment and the practical capability of the system shall be demonstrated. Afterwards, HST Hydro-Systemtechnik GmbH intends to distribute the innovative technology into the wastewater sector.

Downloads

Project Abstract (90 KB)