Saving municipal energy through efficient aeration in the clarifier

Wastewater treatment plants often account for up to 20 per cent of a municipality's electricity consumption. In times of sharply rising energy prices, they are therefore often at the centre of the search for avoidable municipal kilowatt hours. The strip diffusers from AQUACONSULT Anlagenbau show that innovative technologies can realise high savings potential in the wastewater treatment plant process. The so-called AEROSTRIPs are considered a key to many optimisation projects in wastewater treatment.

The technology of the company from Lower Austria has also been tried and tested in numerous German sewage treatment plants. Among others, AEROSTRIPs have been optimising the Zweibrücken wastewater treatment plant in Rhineland-Palatinate (70,000 PE) for five years now - with enormous savings in energy and CO2: the conversion has almost halved the specific electricity consumption of the wastewater treatment plant from over 30 kWh/E/a to 18 kWh/E/a. ‘This current value is far below the DWA performance comparison of recent years and shows how highly efficient the aeration technology can be used,’ confirms Norbert Meyer, Managing Director of the engineering firm BITcontrol GmbH, which planned the modernisation of the wastewater treatment plant for UBZ (Umwelt- und Servicebetrieb der Stadt Zweibrücken). Today, the Zweibrücken site is a showcase example for the economical operation of wastewater treatment plants throughout Germany. ‘In order to achieve this performance, both the process technology and the machine and EI&C technology were optimised between 2016 and 2018. The result was better cleaning performance with lower resource consumption,’ explains Meyer.

Wide-area aeration with 440 AEROSTRIP strip diffusers

The optimisations carried out read like a guide for increasing the efficiency of municipal sewage treatment plants through innovative aeration technology. For aeration, 440 AEROSTRIP strip diffusers were installed with sufficient aeration density. Modern blowers now take over the air supply, which are operated in stages in the optimum efficiency range. A load management system for the aeration optimises the cleaning processes and the required air input. In addition to these measures, the biological stage was converted from intermittent/downstream denitrification to upstream/intermittent denitrification.

The AEROSTRIP strip diffusers from the Austrian company AQUACONSULT Anlagenbau GmbH play an essential role in this system. ‘Thanks to the extensive aeration and the small distances between the aeration elements, oxygen can be introduced effectively and agitators can be dispensed with in many cases,’ emphasises Norbert Meyer. Circulation through aeration shocks requires considerably less energy than agitators.

Innovative technology - a global success story

‘Of course, this saving makes the electricity meter of every wastewater treatment plant very happy,’ says Rüdiger Vrabac, Branch Manager at AQUACONSULT Anlagenbau in Germany, based in Rinnthal, Rhineland-
Palatinate. ‘The investment in our AEROSTRIPs pays off immediately. The average return on investment is currently three years.’ The flat design of the strip diffuser, for example, also contributes to energy savings. With an installation height of just five centimetres - in combination with installation directly on the pool floor - the entire water depth can be used for oxygen input. This in turn favours high-yield surface aeration regardless of the pool geometry and size. ‘Thanks to ongoing research and development work and regular performance tests, our AEROSTRIP can now be regarded as one of the most efficient representatives of fine-bubble deep diffusers,’ says Vrabac.

The innovative strip diffusers from Traiskirchen in Lower Austria are now used in more than 2,500 industrial and municipal wastewater treatment plants around the world. AQUACONSULT can currently look back on some very special references, such as the Jeddah Airport 2 wastewater treatment plant (Saudi Arabia) or Lynetten, Damhusåen and Avedore (three wastewater treatment plants in Copenhagen) and the ‘Alte Emscher’ in Duisburg, one of the largest wastewater treatment plants in Germany. The decision of the respective operators to use AEROSTRIPs in their plants always results in impressive energy and CO2 savings.