INVESTIGATION OF ZEBRA MUSSEL ADHESION STRENGTH USING ROTATING-DISKS

Zebra mussels adhere tenaciously and gregariously to hard surfaces, thereby fouling water-processing facilities and equipment. At present, there are few data on zebra mussel adhesion strength to common substrates. A rotating disk test system (RDTS) was used to measure the adhesion strength of small mussels (almost-equal-to 1 mm) to four materials [polyvinylchloride (PVC), polymethylmethacrylate (PMMA), stainless steel (SS), and aluminum (AL)]. Adhesion strength varied significantly with material but only marginally with residence time (one, two, seven, 14, 21, and 28 days). The estimated shear stress required to remove 95% of mussels (tau95%) averaged 62 +/- 5 Pa (mean +/- standard error, n = 6 disks) on PVC, 50 +/- 3 Pa on PMMA, 48 +/- 4 Pa on SS, and 31 +/- 1 (n = 4) Pa on AL. Tau95% peaked on the second day (85 Pa on PVC, 65 Pa on PMMA, 57.5 Pa on SS, 32.5 Pa on AL), then decreased to a constant level. Ultimately, this research should provide insight into material selection and designs that minimize attachment and facilitate removal of zebra mussels.