Problem

The Mukilteo Water and Wastewater District faced a dual challenge in their biosolids management process. Their aged belt press yielded biosolids with insufficient cake dryness of 13% TS, compounded by escalating hauling costs. Plant supervisor Darin Janda explained that although the belt press's age was a factor, the district sought drier solids, especially with biosolids being hauled a considerable distance, even marginal dryness gains would translate to substantial cost savings.

Solution

They explored different solutions to tackle the problem. The district dismissed centrifuges due to high power consumption, polymer usage, and maintenance difficulties. The lead time for replacement parts also proved problematic. Initially leaning toward a screw press, the district found it couldn't attain the desired cake dryness through pilot tests. Finally, they came across the rotary press, and it seemed promising. Among different manufacturers, the Fournier Rotary Press emerged as the preferred choice, supported by favorable feedback from end-users and a consulting engineer's endorsement.

Results

After more than a year of operation, results exceed expectations. The press consistently achieves over 17% and as high as 19%, with better solids capture, reduced return of solids to the process, and less wasting. Janda highlights an unforeseen benefit: much less washwater usage resulting in energy savings and a drier press room environment. “It used to be damp in there; mold was growing on the ceiling and walls, and it was terrible. With all the advantages of our Fournier Rotary Press, we would never go back to a belt press.” 

Learn more at www.fournierdewatering.com or call 800-463-6328

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