Back in July, the City of Ottawa made a shift to allow its residents to put plastic bags in the compost bin. People noticed.   After the plastic bag bill passed, many people took to Twitter to voice their disapproval, calling it a "stupid policy" for "the lazy," and "idiotic at a time when in many jurisdictions, plastic bags are trying to be phased out."   While it may seem odd to allow plastic bags in the green bin, many people find it makes the process of capturing household organic waste a little more tidy. Municipalities that allow it skim plastic bags off early in the disposal process.   Many jurisdictions actually encourage the use of biodegradable bags, and consumers buy them with the belief that they will decompose with the rest of the organic waste. But that isn't always true.   Even in the landfill, compostable plastics may not degrade, according to a study done by the University of Plymouth in the U.K. The study tested five types of commonly used plastic bags, including ones labelled "compostable" and "biodegradable," to see how well they break down in different conditions. They tested the bags in both soil and sea, where they remained intact, exactly like regular plastic.   Tom Szaky, CEO of TerraCycle, a U.S. business that has gained a reputation for recycling the "non-recyclable," has written about this. In his book Linear to Circular: The Future of Packaging, he writes that most consumers "don't realize … that biodegradable bioplastics will break down only under the right conditions — those of a specific industrial composting facility."   Szaky emphasized that "even if that happens, [the bags] won't contribute value to the compost, unlike coffee grounds or leaves, which have a wide range of micro- and macronutrients as well as a living ecosystem of bacteria and other microbes."   Even if they could create those perfect conditions, some municipalities have banned compostable plastics from green bins, including Toronto.   The City of Toronto website says:  "There are many types of products that call themselves 'degradable.'   "They may be degradable in the presence of certain components … and are made to degrade in a certain time period. This time period and conditions may not match the actual conditions in a processing facility."   The Metro Vancouver solid waste site states that "plastics, including those marked biodegradable, do not belong in the compost as they do not break down properly during processing."   People who are confused or concerned about any kind of plastic have other options. Many municipalities suggest lining your bin with newspaper for an easier clean or simply not lining the bin at all. They also suggest washing out your bins regularly and putting them on the curb consistently, even when they're not full.   Or you could simply call your municipality's facility and ask what they accept.   — Taylor Logan