18-Env-B5 Industrial & Hazardous Waste Management · May 2014
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Reference texts: Nemerow & Dasgupta, Industrial and Hazardous Waste Treatment, 2nd ed.; Metcalf & Eddy, Wastewater Engineering: Treatment and Resource Recovery, 5th ed.; Davis & Cornwell, Introduction to Environmental Engineering, 6th ed.; LaGrega, Buckingham & Evans, Hazardous Waste Management, 2nd ed.; CCME, Guidelines for the Management of Biomedical Waste in Canada (1992); Canadian Environmental Protection Act (CEPA), 1999; provincial Environmental Protection / Hazardous Waste Regulations (e.g. BC's Hazardous Waste Regulation, O.Reg. 347 in Ontario).
All eighteen questions are compulsory on this paper and are answered in full below.
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.
Three well-established causes of toxicity/inhibition in a biological oxidation (e.g. activated-sludge) system are: (1) heavy metals (Cu, Zn, Cr6+, Ni, Cd, Pb), which denature microbial enzymes and, unlike a soluble organic, accumulate in the biomass over repeated small discharges rather than washing straight through; (2) cyanide, which binds the iron in cytochrome oxidase and blocks cellular respiration directly, so even a few mg/L can sharply depress the oxygen-uptake rate; and (3) un-ionized ammonia or high concentrations of phenolic/chlorinated organic compounds, which are specifically toxic to nitrifying organisms (ammonia, especially at elevated pH) or which denature proteins and disrupt cell membranes generally (phenols, chlorinated solvents).
