A refresher (or 'fresher) was a term for a commode, or, more generically, a lavatory. (TOS novel: The Lost Years; DS9 - Worlds of DS9 novel: Andor: Paradigm, et.al.) 24th century refreshers disposed of waste material with transporter-based dematerialization process, breaking waste into simple inert compounds, which could then be utilized in other replication systems within an integrated system. Portable 'freshers could also be deployed on temporary emergency basis, safely keeping the inert matter in storage. (TNG novel: Losing the Peace)