18-Env-B5 Industrial & Hazardous Waste Management · May 2015
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; Basel Convention on the Control of Transboundary Movements of Hazardous Wastes (1989); provincial hazardous waste regulations (e.g. BC's Environmental Management Act and Hazardous Waste Regulation).
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.
(1) Sample representativeness — whether a single grab sample or a flow-proportional composite sample is used, and how well either captures a batch process's true variability over a shift or production cycle; a grab sample taken at the wrong moment can badly misstate the true average. (2) Sample preservation and holding time — failing to cool, acidify, or otherwise preserve a sample immediately, or exceeding the maximum holding time before analysis, allows biological activity, volatilization or chemical reaction to change the sample's composition before it reaches the lab. (3) Sampling location — a sample collected before complete mixing of two waste streams, or too close to a point source, does not represent the combined discharge the result is meant to characterize. (4) Laboratory analytical technique and quality control — matrix interferences specific to an industrial (versus domestic) wastewater, calibration error, and inadequate QA/QC (blanks, spikes, duplicates) can all bias the reported result independently of the sample itself.
