ASSESSING THE EFFECT OF NATURAL ATTENUATION ON SEWAGE SLUDGE USING FABA BEAN (VICIA FABA) TEST AND GC-MS ANALYSIS

Sewage sludge (SS) is the final product of wastewater treatment its accumulation can cause serious environmental problems; however, it may be used as agricultural fertilizer. Our objective was to evaluate the effect of natural attenuation on SS by studying the cytotoxicity and genotoxicity potential of different concentrations of SS extract and soil mixtures using the Vicia faba L. test, and to study the microbiological biodiversity and presence of toxic furans and dioxins during natural attenuation. Cytological investigation of treated V. faba roots after 12 months of natural attenuation revealed that the percentage of different types of mitotic abnormalities increased with the concentration of raw SS from induced DNA damage in V. faba roots. However, this effect declined during the attenuation periods. Although after the natural attenuation period, significant effects were detected for the highest tested concentration (100% SS). Nine different bacterial colonies were observed in SS, but only three colonies remained after 12 months. Moreover, Gas Chromatography-Mass Spectrometry analysis showed that the concentrations of toxins were reduced during the natural attenuation periods. Therefore, we concluded that raw SS should not be used as soil fertilizer without detoxification, and its toxic potential must be formally assessed.

Automated summary

The study found that raw sewage sludge can induce DNA damage in Vicia faba roots, but this effect diminishes during natural attenuation. Additionally, concentrations of toxins decreased during the natural attenuation periods.