Effect of Inorganic Ions on Biofilms Component and Activity in the Recirculating Cooling Water System

In this research a laboratory model recirculating cooling water system was applied to investigate the effects of four kinds of inorganic ion concentrations on extracellular polymeric substances (EPS) content, the ration of proteins and polysaccharides ratio in EPS (PR/PS) and dehydrogenase activity (DHA) in the attached biofilms. The results showed that the low Na+ concentration was beneficial to EPS production and biofilms DHA. With Ca2+ concentration increasing, EPS content first increased and then decreased as a whole. Mg2+ showed no obvious effect on biofilms EPS content, while had the effect on PR/PS and DHA. The increase of Fe3+ concentration was beneficial for EPS formation and DHA when Fe3+ concentration was below 1.5 mg/L.