What it does
This project aims to increase the recycling rate by using the physical properties of materials. The bin automatically sorts recyclable materials using the lightness of vinyl and the density difference between plastic and aluminum, without complex technology.
Your inspiration
Around the world, we’re still not sorting recyclable materials well. Statistically, only about 32% of people do it. Some countries show high rates, but they’re the exception. So why don’t more people do it? While many know recycling is important, most avoid it because it’s inconvenient—or because they aren’t sure what goes where. Some even practice “wishcycling,” tossing items in the recycling bin just hoping they’re recyclable. That uncertainty often leads to frustration and contamination. We were inspired by that feeling—"This is too annoying.” This project began with a simple idea: what if the trash bin could do the annoying part for us?
How it works
Users push in the drawers, place recyclables on top, turn on the bin, then pull the drawers out. From there, the bin works automatically. The bin has two floors. The upper floor has turbo blower fans and holes placed alternately. Wind starts when powered, but is blocked until the drawers are pulled. Then, fans blow left, lifting vinyl into the ceiling box. Heavier waste drops through the holes to the lower floor. The lower floor has three zones: aluminum (left), water (center), and plastic (right). A sliding panel forms a floor to divide top and bottom layers. A sloped base gathers aluminum to one side. Motors open both collection boxes to retrieve plastic and aluminum. Water drains through four outlets—under the aluminum box, plastic box, and two in the tank. And the bin uses a water level sensor to trigger automatic refilling. After that, it shuts down by itself. To control the system, an Arduino operates all motors and a sensor.
Design process
The idea began with an environmental mindset. To take advantage of the natural properties of materials, we first had to decide on the classification criteria. Our initial idea was to use magnetic fields for a strong sorting method. However, we found that very few materials are magnetic. So we shifted our focus to density—a basic property that varies across materials. But this introduced a new problem: the density difference between vinyl and plastic is minimal. To solve this, we came up with a two-stage sorting method. By first separating vinyl using its lightness, we could then more reliably distinguish between plastic and aluminum using density. This two-step process became a key feature of our design. Next, we faced the challenge of how to collecting the recyclable materials. At first, we considered using a robotic arm. It often missed low-friction items during testing, so we found it unreliable. As an alternative, we also explored the idea of using a net, like fishermen scooping fish. However, that mechanism would have made the trash bin more than twice the intended size, so we ruled it out. In the end, we chose to push plastic and aluminum aside mechanically, allowing vinyl to naturally gather in the wind. That’s how we arrived at the final version of our project.
How it is different
Our project is unique in three key ways. First, it operates without AI. Most sorting systems rely on cameras and image recognition, which increase cost and complexity. By removing them, we reduce expenses and make the system easier to build and maintain. This also eliminates the need for frequent updates or calibration. Second, the sorting relies on continuous physical forces—wind, gravity, and density. These natural properties allow the system to function with fewer sensors and moving parts, making it simpler and less prone to failure. It requires no external power source or computational control, which enhances stability and reduces maintenance. Third, user involvement is almost unnecessary. Waste can be thrown in as usual, and the bin sorts it automatically. Since the process happens without additional steps, it encourages consistent recycling in everyday use.
Future plans
The goal of this project is to let anyone throw away waste comfortabely. So we plan three main improvements. First, we’ll expand sorting to more recyclables. For example, we’re exploring magnetic properties to separate ferrous and non-ferrous metals. Second, we’ll add vibration and cleaning-fluid systems to wash waste and keep the bin clean, as cleaner waste improves recyclability. Third, we’ll install a flexible base that lifts wet or clumped vinyl using vibration, so it can float slightly and be carried by wind. These upgrades will make the bin smarter and more effective, with strong potential for further innovation.
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