BIOFILM FORMATION AND CONTROL IN REMINERALIZED DESALINATED SEAWATER

Abstract

This study investigated impacts of remineralized desalinated seawater on biofilm formation and control. Common organic pipeline materials and biofilm reactors could release organic contents into desalinated seawater, which could support biofilm growth. A new glass biofilm reactor which did not leach organic contents was hence designed and used. Calcium and magnesium could enhance biofilm cells growth and protect them from nutrient depletion. Although only magnesium could enhance polysaccharide production, both cations showed enhancement on extracellular polymeric substance (EPS) matrix structure. Hydraulic shearing and disinfection as biofilm control approaches were tested. A critical velocity was obtained. Calcium and magnesium showed protection against mono-chloramine. Free chlorine could reduce polysaccharide in EPS, which helped to reach and inactivate cells. Lastly, disinfection by-products (DBPs) formation potential by free chlorine and mono-chloramine with humic acid (HA), biofilm cells and EPS as precursors was studied. Calcium and magnesium showed enhancement or inhibition on formation potential of different types of DBPs with HA, while the effects on DBPs formation potential with bacterial materials were only enhancements. DBPs formation potentials of these precursors under various conditions were also compared.