CHARACTERIZATION OF ALUMINUM-BASED DRINKING WATER TREATMENT RESIDUALS COLLECTED FROM VARIOUS PARTS OF THE UNITED STATES

Previous research has demonstrated high affinity of Aluminum based drinking water treatment residuals (Al-WTR) to immobilize nutrients and metals from both water and soil solutions. Fifteen Al-WTR’s from various water treatment plants across the U.S. were collected and characterized to investigate the safe and universal applicability of this promising waste by product, irrespective of its geographic origin, within the United States. The Al-WTR samples were characterized and examined for leachate composition using toxicity characteristic leaching procedure (TCLP) and synthetic precipitation leaching procedure (SPLP) tests. Their sorption affinities for metals, such as As, Pb, Cu, Zn, and nutrients, such as P were determined through batch sorption experiments. Optimum sorption conditions, e.g., pH, Al-WTR application rate, and equilibration time were first determined, and the sorption ability of all fifteen Al-WTRs were tested for each metal/nutrient at 0.5, 1, 5, 10, 50, and 100 mg L^-1 contaminant levels. Results obtained from the leaching data showed that all fifteen Al-WTR samples were below the USEPA safe limits for RCRA 8 metals, as well as Ni, Zn, and Al. Batch sorption studies showed that regardless of the geographic origin of the Al-WTRs, they were all effective at removing metals and nutrients from water even at exaggerated contamination levels. For P, Pb, Zn, Cu, at all six levels of concentrations studied, more than 97% was removed from the solution. For As, the Al-WTRs were able to remove more than 87% from the solution up to 100 ppm, after which 81% was removed. Results from this study showed that regardless of their geographic origin, Al-WTRs generated in the United States are safe and effective sorbents that can be considered for “green” remediation purposes.