NivaarExam PrepOfficial exam papers ↗

18-Env-A6 Solid Waste Engineering and Management · December 2014

Question 13 of 29: Purpose of Measuring Biodegradability of the Organic Fraction

Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)

Notes on this paper

National Examination, December 2014 — 04-Env-A6 / 18-Env-A6, Solid Waste Engineering and Management. 3 hours duration, closed book, one non-communicating calculator, one letter-sized aid sheet (both sides) permitted. All 29 questions constitute a complete paper (100 marks total).

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.

Note on source parsing

This paper prints marks IN FRONT of the question number on every line (e.g. "5 1. What are the elements…", "4 16. All 29 questions are answered in full.

Question 13: Purpose of Measuring Biodegradability of the Organic Fraction (2 marks)

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.

Biodegradability (commonly estimated from volatile solids content or, more precisely, from lignin content via $BF = 0.83 - 0.028\,LC$) predicts how readily the organic fraction will decompose biologically. This is used to predict and size landfill gas generation (rate and total yield, for gas-collection system design and GHG/energy-recovery estimates) and to design and size biological treatment processes (composting retention time, anaerobic digester loading and detention time) — a highly lignified (low-biodegradability) fraction decomposes slowly and generates gas over a much longer timeframe than a readily biodegradable fraction such as food waste.