Yes, urban trash bins can be customized with different opening shapes to reduce contamination, but I would treat it as one useful tool rather than a magic fix. The basic idea makes sense: the shape of an opening can guide what people put in. A round hole can encourage bottles and cans, a narrow slot can discourage bags and food waste, and a shaped flap can make it harder to drop in the wrong item. In public spaces, those small physical cues often work better than signs alone, because people do not always stop to read instructions.
That said, opening shapes only work well when they match the local waste stream and the way people actually behave. If a city uses one bin for mixed recycling, a very restrictive opening may cause jams, litter, or people forcing items through the wrong slot. If the rules are complex, a clever opening cannot replace clear labels, colors, pictograms, and regular education. Accessibility matters too: openings should still be usable for people with limited grip strength, children, and people carrying items. Maintenance is another practical issue. Small openings can clog, and if bins are not emptied or cleaned often, people will lose trust and start leaving waste beside them.
The best results usually come from combining shape with context. For example, bottle-shaped openings can work well in busy public areas where drinks containers dominate. Flat slots may suit paper collection in offices or campuses. Separate flaps for food waste can help in places where food packaging is a common contaminant. But before rolling out a new design citywide, I would pilot it in a few locations, compare contamination rates, and watch for overflow, misuse, and accessibility problems. In short, customized openings can absolutely help reduce contamination, but they work best as part of a wider system that includes good signage, consistent rules, smart placement, and reliable servicing.