[Research of PCDD/Fs pollution level in activated sludge and sludge amended soils]

The pollution level of PCDD/Fs of activated sludge in the different processing stages on Beijing Daxing Sludge Composting Plant and pollution level in the neighboring sludge amended soils were studied, and the pollution level was compared with the surrounding background soils. The concentration levels of PCDD/Fs of activated sludge samples in the different treatment stages were 3118.31-3617.36 pg/g, and the TEQ was 26.19-35.81 pg/g, which ranked in middle and lower level in worldwide studies. The concentration of PCDD/Fs of sludge amended soils and background soil samples were 55.05-72.07 pg/g, 8.69-18.06 pg/g respectively, and the TEQ were 1.20-2.64 pg/g, 0.28-0.39 pg/g. The agriculture application of sewage sludge increased the concentration level of PCDD/Fs and their isomers in sludge amended soils, and the total quantity increase ratio was 3.0-8.3. The concentration of PCDD/Fs in sewage sludge amended soils displayed positive correlation with application rates. The concentration distribution pattern of 17 kinds isomers of PCDD/Fs in sewage sludge amended soil was similar with activated sludge, and was very different from background soils. The activated sludge was the main source of PCDD/Fs in sludge amended soils. This study explored the affection of pollution levels of PCDD/Fs in the farmland soils because of the application of activated sludge, and revealed the sources of pollution and contamination patterns of PCDD/Fs in sewage sludge amended soils.