18-Env-A6 Solid Waste Engineering and Management · May 2016
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Reference texts: Tchobanoglous, Theisen & Vigil, Integrated Solid Waste Management: Engineering Principles and Management Issues; Vesilind, Worrell & Reinhart, Solid Waste Engineering; Davis & Cornwell, Introduction to Environmental Engineering (6th ed.); CCME, Guidance Document on Landfill Gas Management; Canadian Environmental Protection Act, 1999.
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.
(1) Biological treatment (aerobic activated sludge or sequencing-batch reactor, or anaerobic treatment) targeting dissolved BOD/COD and ammonia — most effective early in a landfill's life, when leachate organic strength is highest. (2) Physical-chemical treatment (coagulation-flocculation, chemical precipitation of heavy metals, air stripping of ammonia) targeting inorganic and refractory constituents — increasingly relied upon as leachate matures and its organic fraction becomes harder to biodegrade. (3) Membrane treatment (reverse osmosis or ultrafiltration), which produces a high-quality permeate suitable for direct discharge, though the concentrated reject stream requires further management by recirculation to the landfill or off-site disposal.
