AWWA WQTC55216

The goal of this research was to provide information regarding the possible interactions between biofilm, attached humic substances, iron oxides and the effects of common corrosion control techniques. Biofilm reactors consisted of small-diameter columns operated in an upflow mode. There were two replicate columns for each treatment type investigated. Two experiments were performed, each using a different type of media in the column reactors. The first experiment used iron-oxide-coated, 0.5-mm-diameter glass beads (IOCBs) and the second experiment used crushed and size-graded corrosion products (CPs) obtained from an unlined cast iron distribution system pipe section. Glass beads were coated with iron oxides using a technique described elsewhere. Based on scanning electron microscopy, the CPs had very irregular, crystalline structures typical of well-formed iron oxides, whereas the iron oxide coating on the glass beads was amorphous. Based on titrations from pH 11 to pH 3, the CPs had approximately 14 times more reactive sites per gram than the IOCBs, suggesting the CPs had much greater potential capacity to adsorb humic substance. Includes 12 references, table.