Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — May 2018 — 04-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.) — population equivalent, oxygen sag/Streeter–Phelps, activated-sludge process control (RAS/WAS, HRT/SRT), secondary clarifier design; Davis & Cornwell, Introduction to Environmental Engineering (6th ed.) — turbidity, alkalinity chemistry, digester fundamentals; MWH’s Water Treatment: Principles and Design (3rd ed.) — coagulation-flocculation mechanisms, ozonation, disinfection by-products, pH.
