There's a wastewater treatment facility, known as 'Klärwerk Steinhäule' and located in Ulm, Baden-Württemberg, Germany.
Klärwerk Steinhäule
The wastewater treatment plant 'Steinhäule' at the Danube cleans the wastewater of 440,000 inhabitants in the region. Currently, the waste water is released in 3 purification stages and supplied to the water cycle. A Fourth - adsorptive - purification stage which is currently in the construction phase is to filter out micro pollutants, pharmaceuticals and partly bacteria and viruses from the wastewater.
Around 40 million cubic meters of waste water flowing annually from the cities and towns to the wastewater treatment plant on the Danube. Through mechanical processes, the water is up to 25% cleaned before it further enters the biological part of the plant. When mechanical cleaning process, the substances that have a different specific gravity to water removed as a deductible or floating substances. The wastewater first passes through the grit and grease, then the fine screen and finally the primary clarifiers.
In the biological part of the pre-cleaned water flows through the aeration system and the secondary clarifier. Tightly coupled with the biological treatment is the elimination of nutrients, are in certain substances, such as phosphorus and nitrogen are eliminated.
The pre-screened wastewater flows into the aeration tank. The actual cleaning process is carried out by microorganisms (bacteria), largely through their metabolism consume the dissolved and finely dispersed contaminants or attach to the cell substance, thus forming sludge flakes. A portion of the carbon in the sludge is converted in this way by the bacteria to carbon dioxide. For this, the bacteria require oxygen which is sparged with compressed air via a blower station in the wastewater.
In treated wastewater are after a mechanical-biological and chemical wastewater treatment still micropollutants contained. The micro-pollutants in addition to the so-called "inert organic residual contamination", in particular deemed to be very problematic drug residues, X-ray contrast agents and hormones. Because of demographic changes and advances in medical care, this share continues to grow. The substances get through the sewage plant operations in the waters, affect where the aquatic environment and arrive ultimately back into the food chain.
When wastewater annually occur approximately 1,000,000 m³ of wastewater sludge. The sludge treatment has the task to separate the water from the sludge in the sewage works Steinhäule. The sludge fraction without water has a weight of approximately 10,000 tonnes per year. In the sludge treatment plants the amount of sludge is reduced to around 2,500 tonnes of ash after the dehydration and thermal treatment in fluid bed systems.
Gone are in Ulm / Neu-Ulm, the times in which the wastewater sludge was applied by the farmers in the fields - often with harmful effects to soil and groundwater. Thermal sewage sludge treatment facility today provides a safe, environmentally friendly and at the same time economical disposal of the sludge. The residuals of the fluidized bed combustion are supplied to a recycling. The carbon dioxide produced during combustion of cargo "biomass" sewage sludge is CO2 neutral, as in the burning of wood or other renewable resources.
source: [DE] Klärwerk Steinhäule