Comparison of sludge microbiological characteristics in Tehran Wastewater Treatment Plants

Application of sewage sludge to agricultural lands is increasing but the use of such sludge may cause outbreaks of disease due to the transmission of these organisms through the food chain. For these reasons, there is a need to control the levels of pathogens in sludge and its application to agricultural land. The aim of this study is to compare the important microbiological characteristics of dried sludge in three wastewater treatment plants (WWTPs) including Sharhrak-e-Gharb, Shoosh and Mahallati. Samples were collected during three seasons (fall, winter and spring (2006-07)) from drying beds of the WWTPs and Parasite eggs; FC and TC of samples were examined using standard methods. The results showed that the average amounts of FC for sludge of Shahrak-e-Gharb , Shoosh and Mahallati WWTPs were found to be 4.9 × 10 3 , 3.7 × 10 3 and 1.21 × 10 4 MPN/g.DS 4 , respectively. According to the obtained data, the sludge of all these wastewater treatment plants is classified into Class B of USEPA 40 CFR Part 503 regulations. Therefore, direct human exposure of the sludge would still pose a significant health risk and its application should be restricted.

کلیدواژه ها:

Dried sludge ، microbiological characteristics ، parasite egg ، Total and Fecal Coliform