18-Env-B5 Industrial & Hazardous Waste Management · December 2016
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); Canadian Nuclear Safety Commission (CNSC) regulations on radioactive waste; 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.
Hazardous to what/to whom? A hazardous waste threatens: human health (workers who handle it and the public via inhalation, ingestion or dermal contact, both acutely and chronically); the environment (soil, groundwater and surface-water contamination, air emissions, and ecological/aquatic toxicity to non-human receptors); and property/infrastructure (corrosion, fire or explosion damage from ignitable/reactive/corrosive wastes). Because many hazardous constituents (heavy metals, chlorinated solvents, PCBs, dioxins) are persistent and do not readily degrade, the hazard can also extend to future generations through long-term, hard-to-reverse contamination of soil and groundwater.
| Industry | Waste (liquid / solid) | Type of hazard | Potential management strategies |
|---|---|---|---|
| Electroplating / metal finishing | Liquid (spent plating baths, rinse waters); solid (sludge) | Toxic heavy metals (Cr, Ni, Cd), cyanide (acute toxicity) | Cyanide destruction (alkaline chlorination), chemical precipitation/pH adjustment, metal recovery/recycling, sludge dewatering to a secure hazardous landfill |
| Petroleum refining | Liquid and solid (API-separator sludge, spent catalysts, tank bottoms) | Ignitability, toxic PAHs/benzene (carcinogenic) | Dewatering, thermal desorption/incineration, licensed land treatment where permitted, source reduction through improved housekeeping |
| Pulp and paper | Liquid (bleach-plant effluent) | Persistent, bioaccumulative toxic chlorinated organics (dioxins/furans) | Process substitution to ECF/TCF bleaching, biological treatment, activated-carbon polishing |
| Dry cleaning | Liquid and solid (spent solvent, still-bottom residue) | Toxic/carcinogenic solvent (perchloroethylene), DNAPL groundwater threat | On-site solvent recovery/distillation, licensed hazardous-waste incineration, secondary containment/leak prevention |
| Battery manufacturing/recycling | Solid and liquid (lead paste, spent electrolyte acid, cadmium) | Toxic heavy metals, corrosive acid | Acid neutralization, metal recovery/smelting, secure landfill for non-recoverable residuals |
| Pharmaceutical manufacturing | Liquid and solid (spent solvents, API residues, expired product) | Toxic/carcinogenic, ecotoxic (e.g. endocrine-disrupting) constituents | High-temperature incineration, solvent recovery, reverse-distribution/take-back programs |
