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Case story

Reducing aeration energy consumption

The city of Esbjerg is home to the fifth largest wastewater treatment plant in Denmark - Renseanlæg Vest. Here operation management decided to use linear actuators from LINAK to perform a stable and precise air flow control in the aeration tanks. The LINAK actuators were chosen because they add a number of benefits to daily operation, for example a lower energy consumption and easy mounting.

DIN Forsyning

Every day 20,000 m3 of wastewater enters Renseanlæg Vest in the Danish city of Esbjerg. The plant is part of the regional utility company, DIN Forsyning, and the water here must undergo a series of treatment processes before it can be released into the North Sea. Treatment at this particular plant is further challenged as approximately 60 % of the water comes from industry. The facility is designed for 290,000 PE, corresponding to a wastewater load from 290,000 people.

Precise regulation of the aeration process
An important and energy consuming process in wastewater treatment is aeration, where the objective is to keep ammonia levels low. The ammonia level is controlled by regulating the inlet of air to the aeration tanks. Oxygen regulation is done using a surveillance system, sending messages to the actuators to regulate the v-port knife gate valves, when there is either too much or too little ammonia in the water. For the operations management, it is essential to be able to perform very precise oxygen regulations:

'Aeration is an expensive process. About a third of the plant's energy consumption is spent exclusively on supplying the aeration compressor. That's why it's essential for us to be able to regulate our valves accurately, so that we don't waste energy on aeration. Here, using LINAK actuators has proven very beneficial as they are able to deliver the precision we need'.

Actuator DIN Forsyning

Benefits of using electric actuators
In Esbjerg, it was not only precision and energy consumption that led the operations management to choosing LINAK products:

'A couple of years ago we had to replace our existing valve solutions on the aeration tanks, and we asked around in our network. In Ribe (neighbouring town) they had a positive experience of replacing a traditional actuator solution with an electric actuator from LINAK. So, we decided to follow suit'.

Operation management at Renseanlæg Vest has not regretted the decision of trying the alternative solution rather than taking the traditional route: 

 'The LINAK system was somewhat cheaper to procure. Furthermore, the actuators don't require any maintenance or service. They are so robust that they can withstand all the stress they are subjected to here at the plant, without any problems. And they're also really easy to mount. Our valves are placed so that they are quite hard to access, but this wasn't a problem as the actuators are so small and light. The job took only two men, and no crane was needed'.

The future for Renseanlæg Vest
At the Esbjerg facility, the management is always looking for areas where it can optimise processes and become more efficient. They are currently testing LINAK® actuators in the city's other treatment plant, Renseanlæg Øst, and several other projects are in the pipeline:

 'We can see opportunities installing LINAK solutions in other areas of our plants. It could be in the clarifier tanks, at the inlet to the aeration tanks, or on the slide gates at the rainwater basins. That's something we'll take a closer look at when the current solutions need replacing'.

Operation management is currently devising a masterplan to further optimise Renseanlæg Vest. The plan evolved from Esbjerg Municipality's desire to reduce the overflow from the plant and to achieve better resource utilisation.

 'Just as we contacted Ribe about electric actuators, we have also been contacted by other colleagues. They wanted to hear about our experiences and we're happy to share them with anyone who is interested', says the operation management at DIN Forsyning.

Read more about the the knife gate valve for precise airflow.


Focus on wastewater treatment

In the wastewater industry easy control and monitoring are key elements for ensuring optimal day-to-day running of wastewater facilities. Learn more about LINAK actuator solutions for wastewater handling in this brochure.

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