Decline in PCDD and PCDF Levels in Sewage Sludges from Catalonia (Spain)

Abstract

Nineteen sewage sludges from rural and urban wastewater treatment plants (WWTPs) in Catalonia (Spain) were analyzed for PCDDs and PCDFs using HRGC-HRMS to determine the present levels of contamination. Total I-TEQ values for these samples ranged from 7 to 160 pg/g, with a mean value of 55 pg/g and a median value of 42 pg/ g. Moreover, archived sewage sludge samples collected and stored between 1979 and 1987 from 15 WWTPs were analyzed to gain some insight into temporal trends and possible variations in source inputs. Total I-TEQ values for archived samples ranged from 29 to 8300 pg/g, with a mean value of 620 pg/g and a median value of 110 pg/g. Our findings show that contemporary sewage sludge PCDD/F concentrations have declined since the 1980s. In addition to the variations in PCDD and PCDF concentrations, there were also some changes in the isomeric patterns. These variations in levels and isomeric patterns could reflect changes in PCDD and PCDF sources to the environment over time.

A comparison of TEQ contributions from PCDDs, PCDFs and dioxin-like PCBs in sewage sludges from Catalonia, Spain

“…The ratio R TEQ PCDD/TEQ PCDF was calculated, and the values ranged between 0.5 and 1.4, with a mean value of 1.0. Generally, sewage sludge samples are characterized by a R TEQ PCDD/TEQ PCDF >1 (Eljarrat et al, 1997 and1999). However, from the eight samples analysed in our study, four presented a R TEQ PCDD/TEQ PCDF <1.…”

“…The calculated TEQ PCDD/F values in the samples collected in the 80s ranged from 29 to 8300 pg/g d.w. with a mean value of 620 pg/g d.w., whereas sludges collected during the 90s showed levels between 7 and 160 pg/g d.w., with a mean value of 55 pg/g d.w. (Eljarrat et al, 1999). In the present study, we reported concentrations of sludges collected in 2000, and a slightly decline was observed when comparing with levels during the 90s.…”

“…corresponding to the different sewage sludges studied Eljarrat et al (1999) b Results from Eljarrat et al (1997) c Results from Pauné et al (1994) Figure 1 Percentage contribution to the total WHO-TEQ from non-ortho and mono-ortho PCBs, and …”

“…The contamination of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in sewage sludge is well documented. Analytical results have been reported from the United States (Tiernan et al, 1997), Germany (Gihr et al, 1991;Hagenmaier et al, 1992), Sweden (Broman et al, 1990), the United Kingdom (Sewart et al, 1995) and Spain (Eljarrat et al, 1997 and1999).…”

“…A further objective was to compare the PCB, PCDD and PCDF levels in these sludges with results obtained from samples taken in the 80s (Eljarrat et al, 1997 and1999) in order to detect temporal trends.…”