18-Env-A1 Principles of Environmental Engineering · December 2016
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — December 2016 — 04-Env-A1 / Principles of Environmental Engineering. 3 hours duration; closed book with a candidate-prepared 8.5×11 in double-sided aid sheet; Casio or Sharp approved calculator only. Any five questions constitute a complete paper (first five answers marked); all seven are solved below for completeness. Each question is worth 20 marks.
Reference texts. Davis & Cornwell, Introduction to Environmental Engineering (6th ed.); Metcalf & Eddy, Wastewater Engineering: Treatment and Resource Recovery (5th ed.); MWH’s Water Treatment: Principles and Design (3rd ed.); Sawyer, McCarty & Parkin, Chemistry for Environmental Engineering and Science; Guidelines for Canadian Drinking Water Quality (Health Canada); Canadian Council of Ministers of the Environment (CCME) water-quality and municipal solid-waste guidelines; Canadian Environmental Protection Act, 1999 (CEPA) and Canadian Environmental Assessment Act (CEAA 2012); ISO 14040/14044 (Life Cycle Assessment); Bies & Hansen, Engineering Noise Control; Andrews, Canadian Professional Engineering and Geoscience (professional ethics).
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.
Approach. For each growth area, the two required impact/solution pairs are placed against the category (air emissions, water demand, or wastewater treatment) each most directly stresses, using the source’s 3×3 matrix layout; the remaining category is addressed briefly in the surrounding text so all three environmental categories are still covered for every growth driver.
| Growth Area | Category | Major Environmental Impact | Environmental Engineering Solution |
|---|---|---|---|
| (i) Population increase | Water Demand | Rising aggregate potable demand outstrips aquifer/reservoir safe yield, lowering water tables and reducing environmental (in-stream) flows. | Demand management (low-flow fixtures, tiered/volumetric pricing, leak detection in distribution mains) plus reclaimed water for non-potable reuse to diversify supply. |
| Wastewater Treatment | Increased sewage flow and BOD/nutrient loading exceeds existing plant hydraulic and treatment capacity, risking effluent exceedances and combined-sewer overflows. | Staged treatment-capacity expansion (additional bioreactor/clarifier trains) combined with inflow-and-infiltration reduction in the collection system to free existing capacity first. | |
| (ii) Wastewater generation increase | Wastewater Treatment | Higher hydraulic and pollutant loading overwhelms the treatment train (clarifier solids loading, disinfection contact time), risking non-compliant effluent quality. | Upgrade to higher-rate biological treatment (MBR/MBBR) and enhanced biological nutrient removal (BNR) sized for the increased load. |
| Air Emissions | Anaerobic digestion and biosolids handling generate odour (H₂S) and fugitive methane emissions that scale with treated flow. | Covered anaerobic digesters with biogas capture and flaring or combined heat-and-power reuse, plus biofilter odour control at plant headworks. | |
| (iii) Industrial intensification | Air Emissions | Increased industrial combustion/process emissions (VOCs, PM, NOₓ, SO₂) degrade local and regional air quality. | Best-available control technology (scrubbers, baghouses, catalytic converters) plus cleaner-fuel switching or process electrification. |
| Water Demand | Industrial process and cooling-water withdrawal competes directly with municipal and ecological demand. | Closed-loop process/cooling-water recirculation and water-reuse conditions attached to development/discharge permits. |
Read across the matrix, all three growth drivers stress the same three categories to different degrees: population growth is dominated by demand-side and downstream-treatment pressure; incremental wastewater generation stresses the treatment plant directly, with a secondary air-quality (odour/GHG) impact from the biosolids side of treating that extra flow; and industrial intensification is dominated by point-source air emissions and competing process-water demand, with wastewater treatment impacts (industrial pretreatment for metals/toxics before sewer discharge) addressed through pretreatment bylaws rather than repeated here. In every case, meeting "strict environmental requirements" after further growth means sizing and permitting the engineering solution ahead of the growth, not retrofitting after a capacity or emissions exceedance occurs.
