Sewage sludge treatment at Garmerwolde wastewater treatment plant

Transfer and transport of sludge

In 2021, the Noorderzijlvest Water Authority commissioned a study into how the transfer and transport of sludge can be carried out in a sustainable, reliable, and efficient manner. The study also looked at how the outdated installation at the Garmerwolde wastewater treatment plant can be replaced.

Administrative decision-making

In November 2021, based on the results of the study, the Board of Directors of the water authority decided to have the proposed preferred implementation version developed into an implementation plan. A preparatory credit has been made available for this purpose.
The Board of Directors made a follow-up preparatory credit available for the design process in February 2023. In July 2023, the Board of Directors made an implementation credit available for the construction of a new sludge cake transfer facility.  

Tender for sludge cake transfer

New tower silos need to be installed to store the sludge cake at the wastewater treatment plant in Garmerwolde. The tender was put out to market at the beginning of this year. The contract was awarded to machine factory Jansen & Heuning (J&H). The agreement was signed recently.

SNON collaboration

The Noorderzijlvest, Hunze en Aa’s, and Drents Overijsselse Delta water authorities have signed a 20-year agreement with Slibverwerking Noord Oost Nederland B.V. (GMB/EEW consortium) for the final processing of their sewage sludge as of 2021.

Water authorities enter into partnership with sludge processing Slibverwerking Noord Oost Nederland B.V.

New sludge cake transfer

In April 2024, J&H will start building the new sludge cake transfer facility. To do this, they will first build a temporary facility. This will allow two trailers to be filled with sludge cake at the same time. The existing sludge cake transfer facility will then be demolished. The new sludge cake transfer facility will be built on the site of the old one. The filter presses will be fitted with new troughs and screw conveyors that will be connected to the temporary facility. The entire facility will be ready for use at the end of April 2024. The sludge cake will then be transported by trailer lorries to the SNON processing site.

Effects of the new sludge cake transfer

The larger capacity of the trailer lorries halves the number of transport movements compared to container transport. On average, over the course of a year, there will be six trailer lorry transports per working day between 7:00 and 19:00 to SNON's processing location. The silos are closed, and odours and other emissions are extracted by a fan and treated by a filter. The area where the lorries are parked under the silos is screened off. 
The materials used for the new sludge cake transfer facility can be reused later. The existing sludge cake transfer facility will be demolished with the possibility of reuse. The total energy consumption of the new sludge cake transfer facility is low. 

The transport of sludge cake 

SNON will start transporting the sludge cake to its processing location by container lorry on 1 January 2024. Container transport will gradually be phased out in the second quarter of 2024. Trailer orries will then be used to transport the sludge cake.