Wednesday, 8 October 2008: 2:25 PM
George R. Brown Convention Center, General Assembly Theater Hall A
Farmland application of biosolids is the most sensible and cost-effective option for many municipalities and it provides tremendous savings in fertilizer costs to the farmers. However, environmentalists continue to raise concerns about the safety of this practice because biosolids may contain pharmaceuticals and personal care products (PPCPs) at various levels. PPCPs enter the wastewater stream via domestic and industrial wastewater. During the wastewater treatment process, some PPCPs partition into biosolids due to their high affinity for organic carbon. In this presentation, case studies on the accumulation and transformation of selective PPCPs in biosolids-amended soils will be presented. Our laboratory studies suggested fast photodegradation of 4-NP in surface soils while biological processes were important for transformation of antibacterial agents. In addition, sorption of PPCPs to biosolids may also significantly retard their transformation. Although detectable levels of many PPCPs have been reported in biosolids, the information about their concentrations in soil after long-term land application of biosolids is scarce. We evaluated concentrations of 4-NP, PBDEs, and antibacterial agents in soil samples from our long-term plots that have been receiving annual applications of biosolids since 1973. At the end of 2005, the cumulative biosolids loadings were 0 (control), 554, 1109, and 2218 Mg dry biosolids per hectare in the plots receiving annual biosolids applications at the rate of 0, 16.8, 33.6, and 67.2 Mg dry biosolids per hectare. Our field investigation has shown that < 5% of 4-NP and antibacterial agents but > 90% of PBDEs applied to the soils during the past 33 year were accumulated in the top 48-inch soil. Up to date, most of the research has focused on accumulation and transformation of PPCPs in biosolids-applied soils. Research on plant uptake of PPCPs in biosolids-applied soils is needed.