Methods for using a liner in a waste sorting and disposal system are provided. The liner includes an internal space and an opening that provides access to that internal space. In some embodiments, the liner may also include a machine-readable identification key that is configured to identify a type of waste that the liner may receive. In some embodiments, the machine-readable key is optical, color-coded, alphanumeric or graphical. The liner can include one or more closure members to allow a user to securely seal the liner when it is removed from the container. In some embodiments, the liner can include a flange, lip, hook or other protrusion to secure its position relative to a container.