18-Env-B6 Agricultural Waste Management · December 2019
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams, December 2019 — 18-Env-B6, Agricultural Waste Management (3 hours, open book, all 15 questions to be attempted, 100 marks total).
Reference texts: Rynk et al., On-Farm Composting Handbook (NRAES-54); OMAFRA, Nutrient Management Act, 2002 and O. Reg. 267/03 / Nutrient Management Protocol (NMAN); Metcalf & Eddy, Wastewater Engineering (anaerobic digestion chapter); ASABE Standards (manure storage, land application equipment); Environment and Climate Change Canada / Canada–Ontario Lake Erie Action Plan.
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. High capital cost and long payback period. A farm-scale digester, gas handling/upgrading equipment and a combined heat-and-power unit represent a large upfront investment relative to typical farm revenue, and payback periods of a decade or more are common without a strong incentive program.
2. Uncertain or insufficient economic incentives. Revenue depends heavily on electricity feed-in tariffs, renewable natural gas pricing, or carbon-offset markets, all of which have shifted significantly in Canada over the past decade (e.g., the end of Ontario's FIT/microFIT programs); without a stable, adequate price for the biogas/electricity produced, the economics are marginal even where the technology works well.
3. Technical complexity and operating/maintenance burden. A digester is a biological process that needs consistent feeding, temperature control (especially through a Canadian winter, which adds a real parasitic heating load), and a skilled operator to avoid upsets (souring, foaming, inhibition); many farms lack in-house expertise and access to specialized service providers is limited in rural areas.
Other contributing factors sometimes cited include feedstock supply uncertainty (co-digestion partners nearby) and permitting/approval time for NASM receipt, but the three above are the most consistently cited barriers in Canadian on-farm digester adoption studies.
