EESA11 Lec 11 possible questions

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University of Toronto Scarborough
Environmental Science
Maria Dittrich

EESA11 Lec 11 KNOW:  “Some important world standards” o The World Health Organization (WHO)  Set up guidelines for drinking-water quality – become the internationoal reference point for standards setting and drinking water safety o The European Union (EU) o U.S. Environmental Protection Agency (EPA) o Presidency of Meteorology and Environment (PME)  Set up guidelines for Saudi Arabia  Types of Microbial Pathogens o Bacteria  Single-celled organisms  E.g. cholera, E. Coli  Detection needs growth in specific media; cell-division produces “colonies” or measurable enzymatic reactions; colony characteristics and unique metabolic abilities identify the organism o Viruses  Protein- packaged RNA or DNA  Norwalk, rotavirus  Detection requires cell-culture techniques or PCR (polymerase chain reaction); PCR cannot determine viability  Coliphage = type of virus that attacks E. Coli  is an indicator of the potential for a virus which is specific to humans to also be present o Protozoa  Single-celled organisms  E.g. giardia, cryptosporidium  Detection requires identification of individual organisms, usually by IFA (immunofluorescent antibody techniques); IFA can NOT determine viability  IFA techniques – concentrate particles from water, separate target from other particles, identify organism by epifluorescence  Solution to Pathogen Monitoring: o Indicator organisms – presence of an indicator organism indicates a pathogenic organism may also be present o Treatment techniques – protects the public health by providing treatment to control pathogenic organisms, even if undetectable  Treatment of drinking water o Chlorination – most common and technologically simple means of disinfection  Creates own contaminants, disinfection-by-products (DBPs):  Chloroform is made the most; animal carcinogen  Total trihalomethanes (THMs) – primary water pollutant  Alternative disinfectants o Chlorine dioxide – destroys pathogenic microbes, but creates chlorite o Chloramine – can lead to creation of nitrosamines – stronger carcinogens than THMs o Ozone disinfection – removes poor taste, colour, and odour from water and protozoan, cryptosporidium. If bromide is in the water, will create bromate – strong animal carcinogen and a regulated pollutant o UV light – kills pathogens but is expensive o Distillation – expensive and lacks minerals and taste Lecture 11 – Possible Questions 1. What is the definition of water drinking standard and their limiting concentrations? - Drinking water standard: water quality parameters established for public water supplies to define the limiting concentrations of various constituents - Limiting concentrations = those that can be tolerated for the intended use 2. Which are primary and secondary drinking water standards?
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