Waste Reclamation is one of the most vital---and most under-appreciated---environmental systems aboard any starship or station. For millenia, any species that has taken to the stars has had to develop a way to deal with the by-products of beings existing in space. Most learned quickly that recycling what you brought with you was the most productive and efficient means of storing what resources were needed for extended travel. This was also true of Starfleet, and their early ships employed numerous mechnical and chemical means by which to reuse the waste created on a day-to-day bases.
The development of transporter technology in the mid-22nd Century went far to improve the waste management systems of ships and stations. Much of the bulky, high-maintenance systems of ducts, piping, and conveyors were no longer needed. Waste could be easily and safely transported to recycling locations. Although this did require more energy consumption, the trade-off for more room, less personnel, and smaller recycling centers was deemed more beneficial. The real boon in waste management tech came with the standardization of the Replicator. Trash, sewage, and other wastes could now be dematerialized into either organic or non-organic compounds and stored for later matter replication. Again, the issue of power consumption remained. Today, Federation vessels and posts use replicators alongside more traditional mechanical/chemical recycling equipment.
Waste management falls into four recycling categories:
Sewage & Water
The recovery and reuse of water and sewage generated by the crew still relies on more conventional means such as hydrodynamics, mechanical filtration, osmotic/electrolytic fractioning, and thermal sterilization. The resulting organic sludge, however, is reprocessed into a particulate suspension that serves as raw material for the food replicators. Anything deemed unfit for this process (which is less than 2 percent), is sent over to Matter Replication Recycling.
Solid waste that cannot be readily dematerialized are collected through a system of linear induction utility conduits to processing units. They are scanned, sorted, sterilized, and reduced into a more general recyclable form. Hazardous materials are conveyed to specialized processors (see below) and unrecoverable portions are converted into raw material for matter replication.
Foodstuffs and any waste that cannot be recycled using mechanical or chemical means is automatically slotted for matter replication fodder. Matter replication recycling centers use industrial replicators with a variable molecular matrix to dematerialize waste and either A) remake them into needed or desired materials, or B) convert them into raw materials for later use by the replicators. Although clearly the safest and quicker method of recycling, it is also by far the biggest user of power.
Waste determined to be toxic, reactive, radioactive, or a biohazard is immediately separated from general waste and put in replicators. This comprises less than 5% of daily waste. Here, the waste is converted into inert carbon particles and stored for later recycling in the matter replicators.
Starbases, outposts, and larger ships usually have more than one of each of the above mentioned recycling centers, spread out over several decks. They are manned by Operations personnel. The entire waste reclamation system can be monitored and controlled from a Bridge or Operations Center's Environmental Systems station, as well as from Main Engineering.