The fact that waste water treatment does not necessarily consume energy but can even produce it is a new, innovative approach that is already being implemented in Hengelo, the Netherlands.
The Vechtstromen wastewater association is responsible for wastewater treatment, flood defence and surface water quality in 23 municipalities in the east of the Netherlands (Drenthe, Overijssel and Gelderland). That alone is a big task. What distinguishes this association from others, however, is that it generates more electricity than it consumes through state-of-the-art technology and innovative processes in wastewater treatment at the Hengelo wastewater treatment plant.
Sustainable energy generation ensures cost savings and environmental protection
One of the first steps in plant optimization was the consolidation of almost all wastewater treatment plants belonging to Vechtstromen. The next step was a thermal pre-treatment of the sludge, which enabled considerable optimizations in the digestion process. This in turn significantly improves the dewatering properties of the sludge and reduces the volume of sludge to be removed. A total of 500 truckloads less sludge are to be transported annually.
In addition, biogas is produced in the course of this process, which in turn is used to generate electricity. This saves costs on the one hand and generates revenue from the feed-in of electricity on the other. At the same time, the production of green energy and reduced transports also protect the environment.
Hiller decanter ensures reliable sludge dewatering
The dewatering of the digested sludge will be carried out by a Hiller decanter of size DP574 from the beginning of 2020. The capacity here is 1,100 kilograms of dry matter per hour.
Hiller is proud to be part of this key reference. The competition for this project was correspondingly high; after initial technical assessments by the client, there were still four well-known decanter manufacturers left. The contract was now awarded on the basis of both an economic evaluation and on-site tests. Further decision bases were then the costs for sludge processing as well as for polymer consumption and future maintenance costs (prerequisite was a 5-year maintenance contract). In the end, Hiller GmbH from Vilsbiburg was able to assert itself in all the points mentioned above. In September, two decanters of the DP574 series will be delivered to Hengelo, one of the two decanters will go into operation immediately, while the second will serve as a reserve to ensure uninterrupted operation in 24-hour service.
Generation of around 6 million kWh of electricity after completion of the plant
When the plant is completed in the course of 2019, approximately 6 million kWh of electricity will be produced with this plant. Only a third of this electricity will then be used to purify the wastewater, the rest being fed into the grid.
This extraordinary project can certainly be called a lighthouse project, which achieves great results for mankind and the environment through a combination of state-of-the-art technology and innovative processes and thus attracts a lot of international attention.