To improve the treatment process and eliminate micropollutants in the wastewater flow, the City of Greven decided to build an additional 4th treatment stage for its wastewater treatment plant, with an estimated investment requirement of €4.5 million. The egeplast egeXXL large-diameter pipe system made of durable and operationally reliable PE 100-RC, as well as precisely manufactured segmented bends, were used. The welded joints were made using a butt-welding machine from the egeplast rental fleet. The innovative treatment technology using cloth filtration and powdered activated carbon (PAC) in combination with buried PE-100 pipelines guarantees permanently safe and effective wastewater treatment in Greven.
Continuous monitoring of discharge parameters prompted the City of Greven (Westphalia) as early as 2013 to consider improving the treatment process. Greven has operated its wastewater treatment plant in its current form since 1981 for approx. 60,000 population equivalents. Around 50% of the wastewater volume to be treated is attributable to industrial discharges. The treated wastewater is ultimately discharged into the Ems. The wastewater treatment plant had a conventional 3-stage treatment system with a polishing pond designed as a buffer basin. The pipe material of choice for buried installation at the time was the commonly used AZ pipes. As early as 2014, the city council passed a resolution which, taking into account possible state funding, aimed to eliminate micropollutants in the wastewater flow. An external feasibility study supported these considerations and led to the decision to use powdered activated carbon (PAC) with downstream cloth filtration as an additional 4th treatment stage. This technology is capable of retaining fine particles down to 10 micrometres.
After the application had been submitted, the grant notification from the State of NRW was issued in 2016 from the RESA II programme (resource-efficient wastewater disposal). Due to the innovative approach of the treatment process, the fund
ing rate reached 80% of the investment volume, and thus more than the otherwise usual funding rate of 70%. The cost estimate resulted in an investment requirement of €4.5 million. In 2017, the approval planning was advanced and the application for approval was submitted to the Münster District Government. Subsequently, in March 2018, the City of Greven received approval for the construction of the 4th treatment stage. In summer 2018, the polishing pond was dismantled and the construction site prepared by Stückenschneider. In November 2018, civil engineering work began, carried out by Kögel Bau from Bad Oeynhausen. The preliminary planning was undertaken by the engineering office Rummler + Hartmann from Havixbeck.
All buried pipelines were specified in durable and operationally reliable PE 100RC. The egeplast egeXXL large-diameter pipe system was used in diameters up to 1,000 mm. A total of 350 m of pipes were supplied in SDR class 17. The segmented bends required for the numerous changes of direction on the wastewater treatment plant site were also manufactured by egeplast with precise angles. Butt welding was selected as the joining method for the PE 100-RC pipes and fittings. A suitable butt-welding machine was provided from the egeplast rental fleet.
Following the planned commissioning of the 4th treatment stage towards the end of 2019, scientific monitoring will take place for a further year during the run-in phase. Based on these findings, the City of Greven expects final commissioning towards the end of 2020.
