Behavior of Sewage Sludge-Derived PAHs on Pasture

Abstract

A field experiment was set up to investigate the retention of PAHs by pasture grass following sludge application. In addition to information on compound-specific loss rates, the influence of meteorological variables and sludge-pasture contact time on the weathering process were investigated. The rates of loss were compound specific with half-lives ranging from < 1 to 10 d. The lighter PAHs were rapidly lost from the grass surface primarily by volatilization. For the intermediate and heavier PAHs, loss was slower with rain playing an important role in the weathering process. Growth dilution was also important in reducing the contaminant levels in the grass. The effect of sludge-pasture contact time prior to weathering by rain on the residual levels remains unclear. In terms of risk of exposure, there is the potential for persistent organic contaminants to be introduced into the grazing animal food chain if sewage sludge is applied to pasture land.

Effect of Composting on Polycyclic Aromatic Hydrocarbons Removal in Sewage Sludge

“…The differences observed in the behavior of individual PAHs compounds during the sludge composting could be related to various interactions of pollutants with compost matrix. The obvious reduction of PAHs with high molecular weight (N>4) could be explained by their strong adsorption to compost matrix such as ligno-cellulosic material and the resultant decrease of their extractability by solvent, probably due to their greater hydrophobicity compared to the PAHs with low molecular weight (N<4; Smith et al 2001;Amir et al 2005;Cai et al 2007b;Oleszczuk 2007).…”

“…Therefore, many people regard land application as a cost-effective method for the beneficial use of sludge. However, the presence of toxic potentially chemicals such as heavy metals and persistent organic pollutants in sludge pose some risk to the environment and human health (Smith et al 2001;Gale 2005). Over the past 5 years, heavy metal concentrations in sewage sludge have been decreased dramatically due to the separation of most industrial wastewater from domestic wastewater, with organic contaminants becoming the pollutants of most concern (Lee et al 2006).…”

Spatial distribution and sources of polycyclic aromatic hydrocarbons (PAHs) in soils from typical oil-sewage irrigation area, Northeast China

“…The Environmental Protection Agency (EPA) of USA has fixed 16 PAHs as priority pollutants (16 EPA-PAHs) in 1997 (US-EPA 1997). PAHs in soils arise mainly from a number of sources, including hydrocarbon spillage (Benner et al 1990), incomplete products of combustion of fossil fuels (Freeman and Catteil 1990), organic waste or wastewater used as compost and fertilizer (Smith et al 2001), and power plants and blast furnaces (Van Brummelen et al 1996).…”

Polycyclic aromatic hydrocarbons in Niger Delta soil: contamination sources and profiles

“…Some PAHs can also be derived from biogenic precursors such as pigments and steroids (Wakeham et al, 1980). PAH in soils can arise from a number of sources, and these include hydrocarbon spillage (Benner Jr. et al, 1990), products of incomplete combustion of fossil fuels, e.g wood burning (Freeman and Catteil, 1990), use of organic waste as compost and fertilizer (Smith et al, 2001) and power plants and blast furnaces (van Brummelen et al, 1996). There are also evidence to indicate that PAH are transported over long distances by atmosphere movement (Lunde and Bjorseth, 1977;Aamot et al, 1996;Bakker et al, 2001;Halsall et al, 2001).…”