A waste collection bag may be used by an autonomous cleaning robot (e.g., an autonomous vacuum) to store waste during a plurality of cleaning processes. The waste collection bag comprises a top portion and a bottom portion. The top portion includes an opening for waste to enter the waste collection bag. The top portion is composed of a porous material to filter air through the porous material. The bottom portion is composed of a non-porous material configured to hold liquid waste and includes an absorbent for interacting with liquid waste to form semi-solid waste.