Quantification of salmonella in treated biosolids from municipal wastewater treatment plants in four cities in Turkey using culture-based techniques

Aytaç, Begüm
Large quantities of biosolids are produced every day from wastewater treatment plants. In Turkey, because there is no legally permissible use for this sludge, it is mostly sent to landfills for disposal. Land application of biosolids is a useful and valid alternative for making use of this huge amount of sewage sludge. However, it must be assured that it is adequately safe for human contact and use. In this study, biosolid samples from four Turkish treatment plants (Ankara, Eskişehir, Kayseri and Yozgat) were analyzed for presence and concentration of Salmonella, one of the key pathogens present in biosolids. Quantifications were carried out using a culture-based method established by the U.S. EPA (Method 1682). Additionally, a novel molecular method (propidium monoazide assisted Taqman qPCR) was employed to explore more vi accurate and rapid quantification. Based on the culture-based method, Yozgat biosolids were found to contain highly variable quantities, reaching up to 693 MPN/4g, higher than would be expected for such a treatment system. Salmonella in the biosolid samples from Ankara, Eskişehir, and Kayseri fell mostly in the range of 0-50 MPN/ 4 g dry weight, values consistent with both the published literature values from similar treatment plants around the world, indicating that usage of the biosolids from these treatment plants for agricultural purposes is reasonable in terms of this pathogen. These quantities of Salmonella proved too low to be efficiently detected by molecular methods, indicating that the current EPA method is the most applicable for this rare but virulent pathogen.


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Citation Formats
B. Aytaç, “Quantification of salmonella in treated biosolids from municipal wastewater treatment plants in four cities in Turkey using culture-based techniques,” M.S. - Master of Science, Middle East Technical University, 2016.