LIXue-mei,MAYan-qi,LIYao.Risk Assessment of PCBs and PCDD/Fs in Digested Sludge and Thermal Drying Sludge[J].China Water & Wastewater,2024,40(7):91-97.
Risk Assessment of PCBs and PCDD/Fs in Digested Sludge and Thermal Drying Sludge
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第40卷
Number:
第7期
Page:
91-97
Column:
Date of publication:
2024-04-01
- Keywords:
- sewage treatment plant; anaerobic digestive sludge; thermal drying sludge; polychlorinated biphenyls (PCBs); dioxins (PCDD/Fs); risk assessment
- Abstract:
- This paper determined the concentrations of polychlorinated biphenyls (PCBs) and dioxins (PCDD/Fs) in anaerobic digestive sludge and thermal drying sludge by isotope-dilution high-resolution gas chromatography-tandem high-resolution mass spectrometry, and assessed their the ecological risk by acute toxicity test of photoluminescence bacteria. The toxic equivalents (TEQs) of dioxin-like PCBs (DL-PCBs) and PCDD/Fs ranged from 1.50 pg/g to 32.50 pg/g (measured in dry sludge), which were lower than the standard value of 100 pg/g set by the European Union. Among them, PCB 28 and PCB 118 were the most abundant substances in indicative PCBs (I-PCBs) and DL-PCBs, respectively. The concentrations of PCB 28 and PCB 180 in thermal drying sludge were significantly positively correlated with the concentration of I-PCBs (P<0.05). The composition of PCDD/Fs in anaerobic digestive sludge varied greatly. Octachlorodibenzofuran (OCDF) had the highest concentration in samples S1-S6, accounting for 66.2%-88.9%, while octachlorodibenzodioxin (OCDD) had the highest concentration in other samples. Sludge age was the main factor affecting the concentration of PCDD/Fs. Different from anaerobic digestive sludge, OCDD was dominant in the thermal drying sludge. The results of acute toxicity test showed that the 50% effective concentrations (EC50) of anaerobic digestive sludge and thermal drying sludge against Vibrio fischeri were 76.3 g/L and 30.4 g/L at 15 min and 21.6 g/L and 12.5 g/L at 30 min, respectively. The inhibition rate of thermal drying sludge against Vibrio fischeri was higher than that of anaerobic digestive sludge, which was contrary to the results of TEQs(DL-PCBs+PCDD/Fs). Therefore, a single chemical analysis could not fully reflect the ecological risk of sludge, and multiple factors should be comprehensively considered.
Last Update:
2024-04-01