Developing the wastewater treatment plants
At the wastewater treatment plants the treatment process is always working very well. But we don't rest there. We are involved in different projects which will make us even better and have a positive environmental impact. Here are a few examples of what we are currently working with:
OUR IMPORTANT BY-PRODUCT HAS BEEN QUALITY-CHECKED
In the wastewater treatment process digested sludge, which is an important by-product, is formed. Sludge from wastewater treatment plants is often used as fertiliser (plant nutrient), mainly as a phosphorus source, on farm land.
The sludge contains large amounts of biologically degradable material and plant nutrients.
Since June 2009 the sewage sludge from the wastewater treatment works in Sjölunda, Klagshamn, Källby and Södra Sandby is certified according to REVAQ, a certification system for sewage sludge. Even before this VA SYD had developed methods for sludge treatment and complied with all the legislative requirements.
WHAT DOES THIS CERTIFICATION MEAN?
The certification proves that VA SYD's treatment of incoming wastewater and sewage sludge fulfils the specified requirements in order to obtain higher quality and continual improvement. As nutrients are returned from the city to the countryside the nutrient cycle is closed.
WE CAN PRODUCE FUEL FOR CLEANER AIR IN THE CITIES
At the wastewater treatment plants, digester gas is formed. The digester gas is used internally at the plants but it is also possible to produce vehicle fuel from the biogas. Biomethane is a very eco-friendly, renewable vehicle fuel which is particularly interesting for city centre traffic. We have projects in both Lund and Malmö aiming at starting up this new application for our by-product.
WASTEWATER DIRECTED TO A MODERN WASTEWATER TREATMENT PLANT
There are nine wastewater treatment plants in the municipality of Lund, but not all of them have the capacity to treat the wastewater efficiently. For instance, not all of the plants have a denitrification process. To improve the wastewater treatment, some of the wastewater treatment plants will be phased out as soon as a sewer transferring the wastewater to the Källby WWTP in Lund has been built.
IMPROVING AND MAKING THE TREATMENT PROCESS MORE EFFECTIVE
Our wastewater treatment plants require energy and chemicals. By implementing and developing advanced process control we are creating safer and more resource-effective treatment processes.
In the biological processes the bacteria require a lot of air to prosper and we want to monitor the aeration in such a way that the bacteria are given exactly the needed amount of air, and not more. We are currently developing our metering and monitoring system to obtain even better control over the aeration, which is a large energy consumer.
Besides oxygen, the bacteria require other substances, for example carbon. Depending on the process configuration, an external carbon source may be needed. Ethanol or methanol is delivered to some of our plants. In order to reduce the need of external carbon sources we are developing methods for producing our own carbon source from the sludge which is formed in our treatment processes.
sludge liquor – WHAT IS LEFT
After digestion and final dewatering the sludge should have a high dry-solids content. The fluid remaining after the dewatering processes is called sludge liquor. At the Sjölunda WWTP we are developing methods for purifying this particular process stream which represents a big part of the load on the biological treatment stage of the plant.
In the chemical treatment we are trying to minimise the dosage of precipitation chemicals. In Lund the biological phosphorus removal is optimised in order to reduce the need of precipitation chemicals. With advanced process monitoring we are also optimising the purification in the final chemical treatment process.