18-Env-A6 Solid Waste Engineering and Management · December 2017
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.); Freeze & Cherry, Groundwater; 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.
The greatest deterrent to reclaiming materials from solid waste is economics — specifically, the cost of collecting, processing and preparing recovered materials to a marketable specification frequently exceeds the revenue those materials command in a volatile secondary-materials market. Even where markets exist, contamination of the recovered stream (food residue in recyclables, commingled mixed materials) further depresses achievable price and processing yield, compounding the underlying economic gap. Because recycled-material prices are set globally and fluctuate with virgin-commodity prices, a materials recovery program that is marginally viable at one point in the commodity cycle can become a net cost at another, which is why stable end-markets (not just the physical ability to separate materials) are the binding constraint on how much material actually gets reclaimed rather than landfilled.
