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.
Three variables that govern landfill gas production are waste composition (the proportion of readily biodegradable organic material sets the ultimate methane yield of the waste mass), moisture content (water is required for microbial activity and substrate transport, so wetter waste generates gas faster and to a higher total yield), and temperature (anaerobic decomposition rate roughly follows an Arrhenius-type increase with temperature up to the thermophilic range, which is why deep, well-insulated cells that self-heat generate gas faster than shallow, cold cells). These three are the variables most directly built into first-order LFG generation models used for gas-collection-system design.
