Effects of shear and surface roughness on reducing the attachment of Oscillatoria sp. filaments on substrates.

The effects of surface roughness and shear on the attachment of Oscillatoria sp. algal filaments onto SS314 stainless steel coupons were investigated. Average surface roughness was used to systematically characterize the surface condition. An annular biofilm reactor with a spinning inner cylinder was used to create a uniform shear flow over the coupons. As far as the authors are able to establish, these systematic methods have yet to be used in the study of microalgae deposition. It was postulated that increasing average surface roughness would lead to an increase in the amount of algae deposited, whereas an increase in shear would lead to a decrease in algae deposition and reduce the algae lengths by way of fragmentation. The results indicate that an increasing surface roughness would increase the amount of algal strands that might deposit on the coupons, whereas shear was found to have the effect of reducing the amount of algae that might attach on the coupons.