18-Env-B9 Environmental Chemistry and Microbiology · May 2013
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — May 2013 — 04-Env-B9, Environmental Chemistry/Microbiology. 3 hours duration; closed-book exam (approved Casio or Sharp calculator only). The paper has two sections — Section 1: Chemistry (11 questions, 50 marks) and Section 2: Microbiology (14 questions, 50 marks) — twenty-five questions constitute the complete exam and all are answered below. Total examination mark 100.
Reference texts. Davis & Cornwell, Introduction to Environmental Engineering (6th ed.) (water chemistry, disinfection, water/wastewater microbiology, indicator organisms); Metcalf & Eddy (Tchobanoglous, Stensel, Tsuchihashi & Burton), Wastewater Engineering: Treatment and Resource Recovery (5th ed.) (chemical unit processes, chemical phosphorus precipitation, biomass stoichiometry, activated-sludge microbiology); Guidelines for Canadian Drinking Water Quality (Health Canada); MWH's Water Treatment: Principles and Design (3rd ed.) (chlorine disinfection, contact-tank sizing).
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
Four significant waterborne diseases, each caused by a different pathogen class transmitted via the faecal–oral route: (1) cholera, a severe acute diarrheal illness caused by the bacterium Vibrio cholerae, historically responsible for major epidemics tied directly to contaminated drinking-water supplies; (2) typhoid fever, caused by the bacterium Salmonella Typhi, producing sustained fever and systemic illness; (3) giardiasis, caused by the protozoan Giardia lamblia, whose environmentally resistant cysts survive typical chlorine doses and require filtration or UV/ozone for reliable control; and (4) cryptosporidiosis, caused by the protozoan Cryptosporidium parvum, whose oocysts are even more chlorine-resistant than Giardia cysts and were responsible for the 1993 Milwaukee outbreak, the largest documented waterborne-disease outbreak in North America.
