You are here:
RECYCLING OF WATER TREATMENT PLANT SLUDGE VIA LAND APPLICATION: ASSESSMENT OF RISK
Citation:
Jain, P., Y. Jang, T. Tolaymat, M. Witwer, AND T. G. Townsend. RECYCLING OF WATER TREATMENT PLANT SLUDGE VIA LAND APPLICATION: ASSESSMENT OF RISK. Eliot Epstein and Aarne Vesilind (ed.), JOURNAL OF RESIDUALS SCIENCE AND TECHNOLOGY. DEStech Publications, Inc, Lancaster, PA, 2(1):13-23, (2005).
Description:
Water treatment sludges (WTS) offer potential benefits when applied to soil and recycling of the waste stream via land application has been proposed as a management option. Recycling of WTS to the land helps conserve landfill disposal capacity and natural resources, but potential environmental and human health risks must be properly evaluated. In this study, alum, ferric and lime WTS samples were collected from 34 water treatment facilities in Florida, US. The concentrations of several inorganic and organic pollutants were analyzed. The results were compared to risk-based soil contaminant thresholds to assess possible human health risk. Leached concentrations were compared to water quality thresholds to examine the potential for groundwater contamination. Although arsenic concentrations did exceed contaminant thresholds in some lime WTS samples, as a whole the land application of lime WTS was found to pose minimal risk. Several elements in the ferric and alum WTS samples exceeded the soil and groundwater thresholds. These include the iron and aluminum from the chemical coagulants themselves, as well as trace elements such as arsenic and vanadium. Coagulant analysis suggested that a major source of the arsenic and vanadium in the alum and ferric WTS could be the treatment chemical itself. Other factors are recommended for consideration when evaluating the risk posed by ferric and alum WTS land application, including the rates of application (and thus the final concentration of the amended soil) and the elemental content of existing soil amendments that the WTS might replace or supplement.