18-Env-A6 Solid Waste Engineering and Management · May 2013
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.
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.
11.1 Solid wastes — all discarded (non-liquid, non-gaseous) materials arising from residential, commercial, institutional, industrial, agricultural and municipal activities that the generator no longer wants and that require collection, processing or disposal, excluding wastes regulated separately as hazardous or radioactive.
11.2 Municipal solid waste (MSW) — the subset of solid waste generated by households, and by commercial/institutional sources of similar character, that is collected and managed by (or on behalf of) a municipality; it excludes industrial process waste, construction/demolition debris (often tracked separately), and hazardous waste.
11.3 Pyrolysis — thermal decomposition of organic material in the substantial absence of oxygen, converting waste into a combustible gas (syngas), a liquid (bio-oil/tar), and a solid char residue; unlike combustion it does not oxidize the feedstock, so the products retain chemical energy for later use.
11.4 Wet oxidation — oxidation of organic material suspended or dissolved in water at elevated temperature and pressure (typically well below the water's critical point) using injected air or oxygen, used to destroy organics in sludges or concentrated liquid wastes (e.g., leachate) without the need to dewater first.
11.5 Darcy's Law — the empirical relation for laminar flow of a fluid through a porous medium, $q = -K\dfrac{dh}{dl}$, stating that the specific discharge (flux) $q$ is proportional to the hydraulic gradient $dh/dl$ through the hydraulic conductivity $K$; it is the governing equation for groundwater/leachate seepage through soil, liners and refuse.
