Modifying Supports Surfaces by Dairy Wastewater Conditioning Film and Relationship with Initial Bacterial Adhesion

Abstract

The choice of the best support for microbial adhesion can improve the start-up speed and efficiency of dairy wastewater treatment by biofilm bioreactors. In this study, three substrates were tested: PP (polypropylene), PET (Polyethylene terephthalate), and PVC (polyvinyl chloride). By using the contact angle method, the surface physicochemical characteristics of the bacterium, inert substrates, and substrates after dairy wastewater (DWW) conditioning film were measured to understand its impact on adhesion as well as the most suitable material to optimize bacterial adhesion. DWW conditioning film affects the physicochemical characteristics of plastic supports and improves the initial adhesion of bacteria to substrates. Results of initial adhesion tests for untreated and treated supports showed differences in how bacterial cells adhered to substrates. Before treatment, PVC and then PP showed a significant adhesion capacity, double that of PET. After modifying by DWW, initial bacterial adhesion increased by 106 (105 to 1011 CFU/cm2) and PVC demonstrated the highest adhesion capacity, followed by PP and finally PET. Therefore, before the modification of the supports by DWW, PP and PVC are in the same rank for the initial bacterial adhesion and after the modification, PVC seems to be the best for initial bacterial adhesion.