Sample Extended Abstract：示例扩展摘要

Sample Extended Abstract：示例扩展摘要 MICROBIAL RISK ASSESSMENT ASSOCIATED WITH TREATED WASTEWATER REUSED FOR IRRIGATION 1312Ana C. Espinosa-García, Miguel Silva-Magaña, Alejandra Fonseca-Salazar, Fernando González-Villarreal and 1Marisa Mazari-Hiriart 1Instituto de Ecología, Universidad Nacional Autónoma de México (UNAM), Mexico City, Mexico acespino@ecologia.unam.mx, fonseca.maalejandra@gmail.com, mazari@unam.mx 2Instituto de Ingeniería, UNAM, Mexico City, Mexico fgv@iingen.unam.mx 3Instituto de Biotecnología, UNAM, Cuernavaca, Mexico miguelsm@ibt.unam.mx ABSTRACT Wastewater treatment is the fundamental requirement for water reuse because the contaminants can become an important source of hazards to exposed persons. The quality of water for reuse must comply with the limits stipulated in regulations in order to protect public health. Therefore, quality as well as the microbial contaminants in relation with the potential health risk is key management issues in the assessment and monitoring of treated wastewater. Our aim was to assess the health risk associated with fecal coliforms, coliphages, enterovirus and adenovirus presence in reused irrigation water. Microbial detection from wastewater and treated wastewater samples was performed with methods such as membrane filtration, double agar layer, and qPCR. The risk matrices show that bacterial and viral presence in water reused for irrigation, as well as in grass must, be resolved because the counts found were above doses that can cause infection in the users exposed. At present, a renovated Residual water treatment plant (WWTP) is being stabilized and initial analyses show improvements in the WWTP regarding the ability of bacteria and virus removal. Keys: water quality, health risk, water reuse, exposure 1. INTRODUCTION The relationship between environmental matrices and human health was recognized a long time ago. However, characterization of the relationship has been difficult to establish due to the pathogens that are transmitted via water but that are not exclusively dispersed by it. Pathogens transmitted by water include bacteria, viruses, and parasites with different characteristics that allow a different survival and dispersion rate [1]. Microorganism indicators have been very useful for water quality monitoring and control; however, there are studies showing traditional indicator bacteria failure because their presence or absence is not related with important water-related pathogens water such as protozoa and viruses. The World Health Organization (WHO) recommended integrating risk assessment analysis as a tool to understand what the health risk related with microorganisms present in water that are consumed or when individuals are exposed to these could be [2]. The qualitative approach of microbial risk assessment permits the development of a focused proposal that quantifies and characterizes the microbial risk. The purpose of this study was to analyze the presence of Fecal coliform (FC), Fecal enterococci (FE), Coliphage (CoF), Enterovirus (EV), and Adenovirus (AdV) in treated wastewater that is used for the irrigation of green areas of the National Autonomous University of Mexico (UNAM) and to evaluate the health risk implications of their presence in areas that are used intensively, mainly by university community. 1 2. MATERIALS AND METHODS The water produced at the National Autonomous University of Mexico (UNAM) Wastewater treatment plant (WWTP) is reused for the irrigation of the 54 hectare green area of the campus. Irrigation is performed through sprinklers, from which we collected 10 L samples. The samples were concentrated following the ultrafiltration method and processed to detect FC and FE, both by membrane filtration [3]; CoF was detected by the double agar layer method using Escherichia coli strains K12-Hfr 3000 and HSpFamp as host cells [4,5]; EV and AdV were detected using PCR amplifying 5’UTR [6] and hexon region [7], respectively. Five g of grass samples were also processed for the detection of the same microorganisms on the grass surface. Samples correspond to on campus green areas intensively used by the university community. The semi-quantitative method to evaluate the risk [2] related with the presence of microorganisms in reused water and grass was applied. 3. RESULTS The presence of data for each microorganism detected was organized by frequency of positive events. A microbial risk matrix was integrated considering positive data for all microorganisms. Bacteria and viruses were considered separately for integrating risk matrices. Criteria for assessing the risk level comprised the quantity detected for each microorganism and the dose-response reported for bacteria and enteric viruses. The matrices show that bacterial and viral presence in water reused for irrigation, as well as in grass, must be resolved because the counts were above doses that can cause infection in the users exposed. The activities that take place in the green areas would be important for determining the level of exposure, i.e., food consumption with respect to walking or to studying. WWTP capacity with respect to microbial removal was not sufficient to produce safe water for reuse in irrigation. This comprised important information to support WWTP remodelation. Currently, a renewed WWTP is being stabilized and the first analyzes show improvements in WWTP in terms of the ability of bacteria and virus removal. REFERENCES 1. Maier R., Pepper I. L., Gerba C. P. (2009). Environmental Microbiology. American Public Health Association. China: Academic Press. p. 598. 2. World Health Organization (WHO). (2011). Guidelines for drinking water quality. Fourth ed. Geneva, Switzerland: WHO Press. 3. American Water Works Association, Water Environmental Federation (APHA). (2005). Standard Methods for Examination of Water and Wastewater. 21 ed. Washington, D.C., USA: United Book Press. 4. EPA. (2001). Method 1602: Male-specific (F+) and somatic coliphage in water by Single agar layer (SAL) procedure. Washington, D.C., USA: Environmental Protection Agency. 5. ISO. (1995). 10705-1: Water quality-detection and enumeration of bacteriophages. Part 1: Enumeration of F-specific RNA bacteriophages. Geneva, Switzerland: International Organization for Standardization. 6. Monpoeho, S., Dehee, A., Mignotte, B., Schwartzbrod, L., Marechal, V., Nicolas, J. C., Billaudel, S., Ferre, V. (2000). Quantification of enterovirus RNA in sludge samples using single tube real- time RT-PCR. Biotechnology. 29, 88-93. 7. Xagoraraki, I., Kuo, D. H.-W., Wong, K., Wong, M., Rose, J. B. (2007). Occurrence of human adenoviruses at two recreational beaches of the Great Lakes. Applied and Environmental Microbiology. 73: 7874-7881. 2