University of California Water Resources Center

The copper in the saturation extract of dried Davis sewage sludge was mainly in a complexed form. A Cu2+ specific ion electrode was used to determine the extent of complexation. Absorption experiments showed that the Kd value of 90 cc g-1. Paper electrophoresis was used to define the complexes according to their mobility in an electric field. Six fractions of positive, negative and neutral charge were isolated. The fraction of Cu in the sludge which was water soluble was found to increase significantly upon drying. The low Kd values on soil and the large percentage of complexed Cu suggested that sewage sludge may be a potential source of contamination of water and plant systems.