Effects of olestra in sewage sludge on soil physical properties

This study investigated the potential effects of olestra, a fat replacer, on soil physical properties following amendment in sewage sludge. Liquid and solid forms of olestra, ranging the product formulation properties, were added to anaerobically digested sludge at concentrations of 5.7 and 4.4% by weight, respectively. Sludges, with and without the two olestra formulations, were dewatered to 45% solids by weight and uniformly mixed with four distinctly different soils: Miamian silt loam (fine, mixed, mesic, Typic Hapludalf), Kokomo silt loam (fine, mixed, mesic, Typic Argiaquoll), Hazleton sand (loamy-skeletal, mixed, mesic, Typic Dystrochrept), and Paulding clay (very fine, illitic, nonacid, mesic, Typic Haplaquept) at a rate of 25% by weight of sludge to soil. The mixtures were incubated in a greenhouse and samples were taken at 1, 6, 12, and 20 wk and analyzed for: bulk and particle densities; water retention at 0, -5.9, -33, and -1500 kPa matric potentials; saturated hydraulic conductivity (K-s); water-stable aggregates; shrinkage; Atterberg limits; and pocket penetrometer resistance. Results showed that the presence of olestra in sewage sludge at concentrations as high as 6% by weight should not exhibit any long-term effects on these soil physical properties.