That's an excellent and increasingly common question! The short answer is yes, the liners for urban trash cans *can* be biodegradable, but whether they *should* be, and how effectively they work in a city's waste system, involves some important nuances.
In theory, biodegradable liners, often made from materials like cornstarch (PLA), PBAT, or other plant-based polymers, are designed to break down much faster than conventional plastic bags in specific composting conditions. For a household with a backyard compost bin, they can be a great fit.
However, the reality for *urban* public trash cans is more complex. Most city waste ends up in landfills, which are intentionally designed to be dry and anaerobic (without oxygen) to prevent decomposition and leachate. In this environment, even "biodegradable" bags may not break down significantly faster than regular plastic, negating their core benefit. If a biodegradable bag contaminates a recycling stream, it can actually harm the recycling process.
For these liners to be truly effective, a city needs a robust industrial composting facility that accepts them. The liner must be certified for that specific composting process (look for standards like ASTM D6400). Without this end-system, the bag's eco-claim is largely nullified.
So, what's the solution? Forward-thinking cities are exploring:
1. Certified Compostable Liners in bins paired exclusively with organic waste collection.
2. Liner-Free Designs for certain dry waste streams, with easy-to-clean bins.
3. Durability Focus, ensuring a bag's strength to prevent litter, even if it means using less plastic overall.
In conclusion, while the technology exists, switching to biodegradable liners requires a systemic change, not just a product swap. The most sustainable choice depends entirely on your city's waste processing infrastructure. The best step is to contact your local waste management authority to ask about their capabilities and recommendations.