Reducing micropollutants with DynaSand filters

In Germany, wastewater treatments plants (WWTPs) that discharge into the River Isar need to meet strict effluent standards for suspended solids and micropollutants such as nitrogen and phosphorus. In Freising, the plant has been equipped with DynaSand filters that enable the site to meet the latest requirements and protect the sensitive local environment.

The ability to add aluminum or ferric salts ensures that phosphorus levels can also be managed within consent levels, ensuring the River Isar remains healthy and free from eutrophication.

“The DynaSand filters enabled the wastewater treatment plant to achieve key objectives for water quality. Now the River Isar is thriving, and the treatment plant has a reliable and cost-effective solution for the future.”

Sonja Winandi, Sulzer

The challenge
Local environmental concerns led to a demand for a reduction of suspended solids, nitrogen and phosphorus levels in effluent from a number of WWTPs around the River Isar.

Any additional equipment needed to fit within the existing footprint of the site and integrate easily with the original processes. The installation could not impact operation of the site.

The solution
30 DynaSand filters were designed and installed as a compact and effective solution. The new process removes suspended solids, biological nitrogen and low levels of phosphorus. If higher phosphorous concentrations are detected at the inflow, ferric salts are added to enable precipitation.

The total filter area of 180 m² can handle a maximum flowrate of 2’123 m³/h and deliver a suspended solids figure of less than 5 mg/l and phosphorus levels below 1 mg/l.

Customer benefit
The additional filtration equipment operates with minimal maintenance requirements, ensuring extended availability and reliable performance. The efficient continuous filtration process delivers consistently high treatment results while keeping operational costs low.

The real benefits are experienced by the environment, especially the local river, which now has a thriving aquatic ecosystem and consistently low concentrations of suspended solids, nitrogen and phosphorus.