ARS | Publication request: Reducing Phosphorus Runoff from Biosolids with Water Treatment Residuals

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 14, 2009
Publication Date: N/A

Technical Abstract: A large fraction of the biosolids produced in the U.S. are placed in landfills or incinerated to avoid potential water quality problems associated with non-point source phosphorus (P) runoff. The objective of this study was to determine the effect of various chemical amendments on P runoff from biosolids applied to small plots cropped to tall fescue. During the first year of the study, P runoff was evaluated from biosolids that had been treated with alum, ferric chloride, or alum-based water treatment residual (WTR). The WTR was mixed with the biosolids three days prior to application at a rate of 20% (wt/wt) during year 1. In year 2, WTR/biosolid mixtures of 15% and 30% (wt/wt) were allowed to incubate for three weeks prior to land application. During year 1, soluble P loads in runoff from biosolids treated with WTRs were 48% lower than with untreated biosolids and not significantly different than that from other chemical treatments. Soluble P loads in runoff during year 2 for the 15 and 30% WTR mixtures were 78% and 85% lower than untreated biosolids, respectively. The improved reductions in P runoff observed in year 2 indicate that longer incubation times may allow for greater P adsorption onto WTRs. We believe this is because the adsorption process is probably limited by the rate of P diffusion into micropores. Treating biosolids with WTRs results in an environmentally friendly fertilizer and allows for the agronomic use of these important resources.