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 task is to keep ammonia levels low. The ammonia level is controlled by regulating the inlet of air to the aeration tanks. Oxygen regulation is carried out 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 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'.
Benefits using electric actuators
In Esbjerg, it was not only precision and energy consumption that led operations management to choose 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 (a neighboring town) they had a positive experience replacing a traditional actuator solution with an electric actuator from LINAK. So, we decided to follow suit'.
Operations 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 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 management is always looking for areas where they can optimize processes and become more efficient. Currently they are 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'.
Currently operations management is devising a master plan to optimize Renseanlæg Vest further. The plan evolved from Esbjerg Municipality's desire to reduce the overflow from the plant and to achieve better resource utilization.
'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 operations management at DIN Forsyning.
Read more about the the knife gate valve for precise airflow.
