The Endress+Hauser Group

Media center

Events

Your career with Endress+Hauser

Product tools

Contact Information

E-direct Shop

E-direct complements our traditional offering by providing you with a quick, effective way to purchase easy-to-configure, entry-level instrumentation.

E-direct Shop

Controlled by Liquiline Control

Automated phosphate removal in Stadtlohn wastewater treatment plant

The Stadtlohn WWTP regulates phosphate elimination using the Liquiline Control. This control system doses the precipitant into the clarifiers depending on the current concentration of phosphate in the wastewater.

  • WWTP in the town of Stadtlohn, North Rhine-Westphalia ©Endress+Hauser

    WWTP in the town of Stadtlohn, North Rhine-Westphalia.

  • Precipitant tank at Stadtlohn WWTP ©Endress+Hauser

    Precipitant tank at Stadtlohn WWTP: An iron(III) chloride (FeCl3) precipitant is used in summer, while an iron-aluminum combination product is used in the winter months.

The results

  • Uniform phosphate concentration in outlet of only 0.5 - 0.6 mg/l.

  • Optimized precipitant usage.

  • High level of process transparency combined with ease of use.

  • The switching of the basins from parallel to cascade operation during a plant upgrade posed no problem for the control system.

  • The Stadtlohn WWTP is designed to handle wastewater from a population equivalent (PE) of 30,500. At present, a PE of approximately 21,000 is connected to the plant, roughly 15% of which is industrial wastewater. The plant‘s two intermittent basins are activated sequentially (in cascade formation). Commissioned in 1991, the facility has undergone extensive modernization works over recent years

  • Ewald Rathmer
    We can always rely on the Liquiline Control control system. Even in difficult inflow conditions, it works as specified, thus ensuring that the outlet parameters are always adhered to.

    Ewald Rathmer

    Plant Manager, WWTP Stadtlohn (Germany)

The challenge

The customer required a control system that automated phosphate precipitation while also ensuring compliance with the phosphate limit value of the plant (1 mg/l), as stipulated by regulations. The phosphate concentration in the outlet had to be as constant as possible during both peak- and low-load phases. The control system also had to be able to comply with much lower limit values, since a more stringent limit value of 0.3 mg/l is expected in the next few years.

An additional requirement was the ability of the control system to function after the clarifiers were switched from parallel to sequential operation. Furthermore, the solution had to be easy to operate, to ensure that staff could make settings quickly and easily when on standby duty during the night and at weekends

Our solution

The WWTP operator opted for a complete solution comprised of several different components:

  • State-of-the-art, low-maintenance phosphate analyzer.

  • Programmable logic controller (PLC) with Liquiline Control software.

  • Touchscreen display used to operate the system from the control room.

  • Various services, such as consulting, design and configuration of the controller, process integration, system training.

Load-dependent precipitant dosage in Stadtlohn

The customer wanted phosphate measurement to take place at three measuring points. A phosphate analyzer was therefore installed in a centrally located measuring container. The analyzer automatically analyzes samples from the measuring points every 10 minutes. The Liquiline Control uses the measured value from the inlet of the biological stage to adapt to the incoming load, thus balancing out peak- and low-load phases.

Based on the measured value from the outlet of the biological stage, the Liquiline Control regulates precipitant dosage until such point as the desired residual outlet concentration of 0.5 - 0.6 mg/l has been reached. In this way, precipitant usage is optimized.

Phosphate measuring points at Stadtlohn WWTP

  • Inlet of biological stage: Measurement of incoming load.

  • Outlet of biological stage: The effectiveness of phosphate precipitation is tested here.

  • Outlet of WWTP: Final check to verify if limit value has been observed.

Contact

Endress+Hauser Ltd
Floats Road M23 9NF Manchester United Kingdom
Tel.: +44 161 286 5000
Fax: +44 161 998 1841
Send email www.uk.endress.com

This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies. Find out more here close