18-Env-B9 Environmental Chemistry and Microbiology · May 2016
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — May 2016 — 04-Env-B9, Environmental Chemistry/Microbiology. 3 hours duration; closed-book exam (one 8.5×11" aid sheet, both sides, permitted; any non-communicating calculator permitted). The paper has two sections — Section 1: Chemistry (8 questions, 50 marks) and Section 2: Microbiology (12 questions, 50 marks) — twenty 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, BOD/SRT/F–M); Guidelines for Canadian Drinking Water Quality (Health Canada); MWH's Water Treatment: Principles and Design (3rd ed.) (advanced treatment, UV disinfection, potable reuse).
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.
2.1 FALSE. Fungi are predominantly aerobic (obligate or facultative aerobes); relatively few are true anaerobes. They require molecular oxygen for efficient respiration in almost all environmentally-significant species.
2.2 FALSE. Algae are photoautotrophic — they fix inorganic carbon (CO2) into cell material using light energy (photosynthesis), producing oxygen as a by-product, rather than consuming organic carbon from the environment.
2.3 TRUE. Aerobic respiration (using O2 as the terminal electron acceptor) releases far more energy per unit of substrate oxidized than anaerobic pathways (fermentation or anaerobic respiration on a weaker acceptor), which supports faster growth and substrate metabolism rates — the reason aerobic activated sludge processes achieve much shorter treatment times than anaerobic digestion.
2.4 FALSE. By definition, procaryotic cells (bacteria, archaea) lack a membrane-bound nucleus; their genetic material lies free in the cytoplasm as a nucleoid. A true membrane-enclosed nucleus is the defining feature of eucaryotic cells (algae, fungi, protozoa).
