Principal Investigator: Gian S. Ghuman (Savannah State College)
Sponsor: GWRI
Start Date: 1984-08-01; Completion Date: 1985-08-01;
Keywords: groundwater, contamination, leaching, sludge, water quality
Description:
A study was conducted on the City of Savannah’s Water Pollution Control Plant to determine the efficiency of wastewater treatment in the removal of heavy metals. Four periodic samples of influent water, effluent water and sewage sludge were collected in October, December, 84 and March, June, 85 and were analyzed for the concentrations of Mn, Zn, Cd, Cu, Ni and Cr. The concentrations of dissolved heavy metals were slightly greater in the treated effluent water than in the influent water. Separation of sludge was effective in the overall removal of heavy metals from the wastewater. The activated sludge component of effluent water had high concentrations of heavy metals and must be fully removed to minimize the heavy metal content in the discharged water. Among the heavy metals, the total concentrations of Zn, Cu and Ni in the effluent water (both the aqueous and the sludge phases) were decreased, which indicated a material balance of zero for these metals when removal in the separated sludge is considered. On the other hand, the total concentrations of Mn, Cd and Cr were increased in the effluent water as compared to the influent water and it may be possibly due to the influent water samples collected from the outlet in the plant not being truly representative of the material, going in for treatment. A leaching study in PVC columns packed with sludge ash (pH 10.4) was conducted using de-ionized water, lagoon water, and acetic acid 5000 ppm (pH 5.0) as the leaching solutions. All leachates contained very low amounts of heavy metals and the incineration of limed sewage sludge into ash appears to be an efficient method of disposal. High concentrations of heavy metals as insoluble oxides in the sludge ash may prove to be a commercial source in the future for chemical separation.