Heavy Metals in Water and Wastewater Treatment Plant Sludges in Milwaukee Area

The purpose of this research program was to evaluate the heavy metal concentrations in the sludges generated at the Milwaukee Jones Island and South Shore wastewater treatment plants, and the Howard Avenue and Linnwood Avenue water purification plants. Various sludge samples were obtained from 13 sites at these four plants, during a one year period that included 21 test runs. The heavy metals analyzed were cadmium, copper, chromium, lead, nickel and zinc. Including duplicates, over 3500 metal analyses were performed in this study. Through all water plant sludges contained measurable amounts of heavy metals, the concentrations were lower than for the wastewater plant sludges. Except for cadmium, the South Shore sludges, in general, had higher concentrations of the other five metals. No discernible upward or downward trend was noted in heavy metal concentrations at any of the sampling sites during the one year test period. Ancillary tests on the variability in heavy metal concentrations in repetitive tests on the sane sludge sample demonstrated the difficulty of obtaining a representative aliquot for analysis with this type of Material