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López A, Baguer B, Goñi P, Rubio E, Gómez J, Mosteo R, Ormad MP. Assessment of the methodologies used in microbiological control of sewage sludge. Waste Manag 2019; 96:168-174. [PMID: 31376961 DOI: 10.1016/j.wasman.2019.07.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 06/28/2019] [Accepted: 07/14/2019] [Indexed: 06/10/2023]
Abstract
Sewage sludge usually contains potentially polluting substances such as heavy metals, organic pollutants and various organisms including bacteria, protozoa, helminths, viruses and algae, some of which may be pathogenic. Certain of these pathogens could be transferred to the soil if the sludge is used on agricultural or land recovery applications. For its application on agricultural land, sewage sludge must comply with the limits established in the legislation, which in Europe does not include quality standards regarding microbiological parameters. Nevertheless, the presence of pathogens could limit its agricultural use, as it could pose a risk to human, animal and environmental health. This study compares 4 different methodologies used in microbiological analysis in order to identify the most efficient and reliable method on determining bacteria in sewage sludge. Escherichia coli and Enterococcus faecium are used as bacterial indicators. The results obtained in this work indicate that results obtained with three different plate count methods cannot be comparable with those obtained with the MPN method. The membrane filtration method is recommended for its high precision and sensitivity, both in low and high bacterial loads. It is also concluded that it would be necessary to establish the quality standard in concordance with the method used.
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Affiliation(s)
- A López
- Water and Environmental Health Research Group, Environmental Sciences Institute (IUCA), Department of Chemical Engineering and Environmental Technologies, School of Engineering and Architecture, University of Zaragoza, Calle María de Luna 3, 50018 Zaragoza, Spain.
| | - B Baguer
- Water and Environmental Health Research Group, Environmental Sciences Institute (IUCA), Department of Chemical Engineering and Environmental Technologies, School of Engineering and Architecture, University of Zaragoza, Calle María de Luna 3, 50018 Zaragoza, Spain
| | - P Goñi
- Department of Microbiology, Preventive Medicine and Public Health, Water and Environmental Health Research Group, Environmental Sciences Institute (IUCA), Faculty of Medicine, University of Zaragoza, Calle Domingo Miral, 50009 Zaragoza, Spain
| | - E Rubio
- Department of Microbiology, Preventive Medicine and Public Health, Water and Environmental Health Research Group, Environmental Sciences Institute (IUCA), Faculty of Medicine, University of Zaragoza, Calle Domingo Miral, 50009 Zaragoza, Spain
| | - J Gómez
- Navarra de Infraestructuras Locales S.A (NILSA), Avenida Barañain 22, 31008 Pamplona, Spain
| | - R Mosteo
- Water and Environmental Health Research Group, Environmental Sciences Institute (IUCA), Department of Chemical Engineering and Environmental Technologies, School of Engineering and Architecture, University of Zaragoza, Calle María de Luna 3, 50018 Zaragoza, Spain
| | - M P Ormad
- Water and Environmental Health Research Group, Environmental Sciences Institute (IUCA), Department of Chemical Engineering and Environmental Technologies, School of Engineering and Architecture, University of Zaragoza, Calle María de Luna 3, 50018 Zaragoza, Spain
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