16-Civ-A3 Elementary Environmental Engineering · May 2018
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Paper format. National Exams, May 2018 — 16-Civ-A3 Elementary Environmental Engineering. Three hours; closed book with one candidate-prepared 8½ × 11 double-sided aid sheet; approved Casio or Sharp calculator only. Seven problems are printed, each worth 20 marks, and any five constitute a complete paper (maximum 100 marks). All seven are solved here, because the set is intended as a study resource rather than an exam script. Section marks are shown in brackets at the left margin of each question and are reproduced from the final-page Marking Scheme.
Reference texts.
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.
Technical strategies. (1) Intensify the biological process on the existing footprint — convert conventional activated sludge to a high-rate process: add fine-bubble aeration and step-feed, or retrofit to MBBR/IFAS (attached-growth media in the existing tanks) or membrane bioreactors (MBR), which carry 2–3× the biomass in the same volume and produce a higher-quality effluent. (2) Debottleneck clarification and add tertiary polishing — convert secondary clarifiers to high-rate ballasted or lamella settling, add chemical precipitation for phosphorus and filtration/UV for the tightened effluent limits, so the plant meets discharge standards at the higher load.
Non-technical strategies. (1) Reduce the incoming load through demand management — water conservation and inflow-and-infiltration (I&I) reduction shrink the hydraulic and organic load reaching the plant, effectively creating capacity; industrial pre-treatment by-laws and source control keep difficult loads out. (2) Manage flows institutionally — equalization/peak-shaving operating strategy, water-reuse programs that divert flow to non-potable use, and phased capital planning with an environmental compliance-monitoring program so the retrofit is staged and verified over the 20 years.
With only five years of landfill life at the current rate, diversion is urgent: halving the disposed stream roughly doubles the remaining landfill life while a longer-term solution is developed.
Technical strategies. (1) Organics diversion — curbside green-bin collection with centralized composting or anaerobic digestion; organics are typically the single largest divertible fraction (30–40% of MSW) and their removal alone approaches the 50% target. (2) Materials-recovery infrastructure — a materials-recovery facility (MRF) for expanded recycling plus construction-and-demolition and e-waste recovery, capturing the recyclable fraction that would otherwise be landfilled.
Non-technical strategies. (1) Economic and regulatory instruments — pay-as-you-throw / volume-based tipping fees, disposal bans on organics and recyclables, and extended-producer-responsibility (EPR) programs that shift packaging responsibility to producers. (2) Public education and participation — sustained outreach, clear sorting guidance, and diversion targets with public reporting; behavioural participation is what actually delivers the captured tonnages the technical systems can process.
