Heavy metals, PCDD/F and PCB in sewage sludge samples from two wastewater treatment facilities in Rio de Janeiro State, Brazil

Two sewage sludge samples collected from an urban as well as a rural area in Brazil and one sludge sample originating from the city of Balingen, Baden-Württemberg, South Germany, were investigated in respect to contamination with heavy metals, PCDD/F and PCB. The results were compared to PCDD/F and indicator-PCB mean values found in the region of Baden-Württemberg. The observed toxicity equivalents of PCDD/F found in the Brazilian samples, were below the upper limit specified by German legislation for final disposal or agricultural use in soils. Both the PCB and heavy metal values exceeded this limit. The PCDD/F congener/homologue profiles found in the Brazilian samples indicated that the urban sewage sludge shows a contamination where both chlorophenols and depositional sources appear to be contributing to the contamination pool. The enrichment of highly chlorinated PCDD/F groups in the sludge of semi-rural origin is probably due to transport phenomena effects. For the German sludge sample, depositional sources seem to be the main PCDD/F contamination pathway. Regarding PCB, both Brazilian samples show a homologue profile that indicates a contamination stemming from technical PCB formulations like Clophen A50 and Clophen A60 or equivalent.