Question 8 of 16: Separation at Home vs. Separation at a Materials Recovery Facility

Question 8: Separation at Home vs. Separation at a Materials Recovery Facility (10 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.

Both alternatives aim to recover the same broad material streams (paper, metal, glass, plastics, organics) but trade off differently across several factors that must be weighed together, not in isolation. Material quality and contamination — source separation at home generally yields cleaner, higher-value streams (less cross-contamination between recyclables and food waste) because the resident sorts before commingling, whereas centralized MRF separation from a mixed stream inevitably loses some quality to contamination and breakage, even with good technology. Capital and operating cost — home separation shifts the sorting "labour" to residents at near-zero direct capital cost to the municipality, but requires multiple collection streams/trucks (higher collection cost, the dominant SWM budget item, per Q3); a MRF is capital-intensive (conveyors, magnetic/eddy-current separators, screens per the Q10 process) but allows single-stream collection with fewer trucks and routes. Resident participation and convenience — home separation depends entirely on voluntary compliance and correct sorting behaviour, which is difficult to guarantee and enforce across a whole community, while a MRF removes this burden from residents (single-stream "just put it in one bin" convenience) and is not sensitive to household compliance. Recovery rate and market value — a well-designed MRF, precisely because it accepts commingled material, can often achieve a higher overall diversion rate (residents who wouldn't sort three separate bins will use one), but the resulting lower-purity material commands a lower price in recovered-material markets than cleanly source-separated material. Public education and outreach cost — home separation requires sustained, recurring public education to maintain sorting accuracy over time, an ongoing cost that a MRF-based system reduces (though some outreach on what is and isn't recyclable is still needed). A comprehensive system in practice often blends both: source separation of the most contamination-sensitive stream (organics, since contaminated compost has limited markets) combined with a MRF for commingled dry recyclables, balancing quality against convenience and cost.