SEWAGE SLUDGE AND POTENTIAL GROUNDWATER CONTAMINATION WITH HEAVY METALS

Sewage sludge has been applied to farm fields to enhance soil productivity for years. Sewage sludge may contain heavy metals and other chemicals from industrial facilities, and repeated applications on a particular field may lead to the buildup of metals in the soil, and subsequent movement of these metals to the groundwater system. This study was designed to determine if metals from sewage sludge could be in the groundwater. We collected groundwater samples from households in Wood County, OH at increasing distances from fields permitted for class B sewage sludge. A filtered and unfiltered sample of groundwater was collected 30 seconds after pumping began. A second set of samples were collected after temperature, pH and DO had stabilized. These samples were analyzed for major and trace elements and heavy metals using the ICP-OES in the Department of Geology at Bowling Green State University.

Major and trace element data were collected to characterize the groundwater and to exclude those wells in which the water was treated, either with water softeners or other treatment, prior to collection. These data show that there is very little difference in the composition of water collected 30 seconds after pumping began and after temperature, pH and DO had stabilized. We also show that the major and trace element chemistry of groundwater in Wood County is quite variable, with some major and trace elements varying by an order of magnitude from one well to the next. Results of this study show that there is no detected contamination of groundwater in the filtered samples obtained in this study. The concentrations of Cd, Co, Ni, and Tl are all below detection limit, and the average concentration of Zn is approximately 30 ppb, the same order of magnitude as Zn in surface water samples collected in Northwest Ohio.