Flexibility is a must for Suiker Unie
Suiker Unie, part of the agro-industrial Royal Cosun Group, develops, produces and markets sugar from sugar beet. Alongside other production sites in Netherlands and Germany, the sugar factory in Dinteloord (NL) is one of the largest and most modern sugar factories in the world. "Processing 1 tonne of sugar beets into crystal sugar, releases 600 litres of water which then has to undergo water purification treatment. They therefore treat around 2.5 million m3 water through their own water purification system each year. Sludge is released during this process, which builds up in the settling pond. Because this can result in leaching, regular sludge dewatering is required. Indaver Impex manages this task for us" explains Peter Gulden, Production Leader for Biomass Fermentation and Water Purification.
All Parts of the Beet are Re-used Including the Washing Water
"Every day, for 5 months, from September to January, 30,000 tonnes of beets are delivered to Suiker Unie at their site in Dinteloord, where they are washed, cut and (via a thickening process) converted into crystal sugar" Gulden explains. "Sustainability is important to Suiker Unie and they value every part of the beet: the clay soil, which is rinsed off, is used for building up land, the beet pulp becomes animal feed and the beet tops and washing water are converted into biogas. Thanks to this production process, Suiker Unie supplies 1/3 of the green gas production in the Netherlands. The sugar from the beet is reclaimed through the sap and following a purification and thickening process, is dried into sugar crystals, which are then cooled until they are ready for sale. The large amounts of water used during the process are also discharged again once they have been purified and checked. Around 800m3 of water therefore goes through Suiker Unie's own water purification plant every hour and then flows into a settling pond as effluent. The water stays in this buffer before being discharged. After a few years, an excess of settled sludge has built up in the pond and it has to be cleaned to prevent leaching. Indaver Impex is the right partner for the job", states Gulden.
Volume reduction and high dry matter content thanks to dewatering
Impex has been dredging and dewatering the settled sludge in the settling pond on a structural basis since 2013. Gulden explains: "In principle, the effluent that ends up in the buffer pond, is already clean, but it still contains small quantities of suspended matter. Before discharging this water, the suspended matter can continue to settle for 24 hours. Using a specialised dredging boat and dewatering equipment (a belt filter press) Impex reduces the volume of sludge that has built up in the pond considerably, which increases the content of dry matter from 4% in the dredged sludge to 30% in the dewatered sludge cake."
Sludge cake reused for elevating ground
"Impex removed and dewatered around 2,500 m3 sludge from the pond during the three-week-long campaign. With this regular sludge removal, Impex guarantees business continuity and ensures the settling pond can be used to its full capacity. Suiker Unie uses the dried sludge cake among other things as a material for building up the roads and dikes on its own site. A great example of material recovery. We use every part of the beet, there is no waste, only by-products. That's quite an accomplishment, don't you think?" beams Gulden full of pride.
Tight-knit organisation and a safe work environment
"Before Impex starts work", explains Gulden, "they compile an extensive Health and Safety and Environment Plan and come out to clarify it. They take away points for improvement from every campaign. That is how we realised that to come up with the best dewatering recipe, a sludge sample and analysis needed to be conducted first. Menno Koomen, our contact person at Impex was easy to reach if we had any questions or problems. Thanks to good agreements and Impex's focus on safety, the project ran smoothly. That is something my colleagues were also very aware of during a safety tour. Impex quickly adapts to the customer's environment. This flexibility is a must for a long and happy working relationship. I am a satisfied customer.
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