Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — December 2018 — 18-Env-A4 / Water and Wastewater Engineering. 3 hours duration; closed book with one double-sided aid sheet; approved Casio/Sharp calculator permitted. Question 1 is compulsory; the paper instructs candidates to attempt any three of the remaining four questions — all five are solved below for completeness.
Reference texts. Metcalf & Eddy, Wastewater Engineering: Treatment and Resource Recovery (5th ed.) — trickling filters, activated-sludge SRT/yield design, nitrogen speciation; Davis & Cornwell, Introduction to Environmental Engineering (6th ed.) — discrete particle settling theory, water-quality parameters; MWH’s Water Treatment: Principles and Design (3rd ed.) — coagulation-flocculation, adsorption, chlorine chemistry, water treatment plant process design; Guidelines for Canadian Drinking Water Quality (Health Canada/GCDWQ) — sulfate, nitrate and chloride aesthetic/health-based limits.
