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ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Publications at this Location » Publication #241733
Title: Drinking water treatment residuals: A Review of recent uses

Author
item Ippolito, James
item BARBARICK, K - Colorad0 State University
item ELLIOTT, H - Pennsylvania State University

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/2010
Publication Date: 1/3/2011
Citation: Ippolito, J.A., Barbarick, K.A., Elliott, H.A. 2011. Drinking water treatment residuals: A Review of recent uses. Journal of Environmental Quality. 40(1):1-12(2011).

Interpretive Summary: Water treatment residuals (WTR), waste products of drinking water purification, are either recycled or landfilled. The most reported effect of WTR is their large capacity to adsorb and reduce plant-available phosphorus. This is a detriment if soil-phosphorus levels are lowered below plant requirements. Conversely, WTR land application could be an advantage in reducing excessive levels of phosphorus in organic wastes (e.g. poultry litter, manures, biosolids) or in fields with excessive phosphorus accumulation. Removal of the other potential environmental contaminants, such as perchlorate, selenium, mercury, and arsenic, by WTR has been documented. While WTRs are wastes, proper management can allow WTR to provide environmental and agronomic benefits.

Technical Abstract: Coagulants such as alum [Al2(SO4)3•14H2O], FeCl3, or Fe2(SO4)3 are commonly used to remove particulate and dissolved constituents from water supplies in the production of drinking water. The resulting waste product, called water-treatment residuals (WTR), contains precipitated Al and Fe oxyhydroxides, resulting in a strong affinity for anionic species. Recent research has focused on using WTR as cost-effective materials to reduce soluble phosphorus (P) in soils, runoff, and land-applied organic wastes (manures and biosolids). Studies show P adsorption by WTR to be fast and nearly irreversible, suggesting long-term stable immobilization of WTR-bound P. Because excessive WTR application can induce P deficiency in crops, effective application rates and methods remain an area of intense research. Removal of other potential environmental contaminants [ClO4 -, Se(+IV and +VI), As(+III and +V), and Hg] by WTR has been documented, suggesting potential use of WTR in environmental remediation. Although the creation of Al plant toxicity and enhanced Al leaching are concerns expressed by researchers, these effects are minimal at circumneutral soil pH conditions. Radioactivity, trace element levels, and enhanced Mn leaching have also been cited as potential problems in WTR usage as a soil supplement. However, these issues can be managed so as not to limit the beneficial use of WTR in controlling off-site P losses to sensitive water bodies or reducing soil-extractable P concentrations.