Recycling
Recycling was the process of using unused materials and substances and waste to produce something new. 

Early Starfleet survival training included a trip to the Australian outback. Jonathan Archer and  underwent such an excursion, which included drinking recycled sweat and eating snake meat. ()

During a discussion among the senior staff of Deep Space 9 about the feasibility of a Bajoran solar sail traveling from Bajor to Cardassia, Chief Miles O'Brien doubted that such a journey could have been made, seeing as, aside from lacking replicators, "[t]hey would've had to store their air supply and there's only enough room on board for a few weeks' worth." Major Kira Nerys, theorized that "maybe they recycled [the air] somehow, used some kind of photosynthetic plant." ()

Space travel was one of many factors in reclamation technology, as recycling was key in situations were energy and materials were a premium.

While energy conservation was at times essential, energy itself, like residual antimatter, was recycled to use as power components from life support to replicators. ()

Aside for energy, nearly all matter, most especially waste, was recycled for conservation purposes.  explained that aboard  "we recycle pretty much everything on a starship. That includes waste, and the first thing that happens to the waste is it gets processed through a machine called a bio-matter resequencer. Then [...] the waste is broken down into little molecules and then they get transformed into any number of things we can use on the ship. Cargo containers, insulation, boots, you name it." ()

In an alternate 2374, Commander Chakotay gave Captain Kathryn Janeway a pocket watch as a gift for her birthday. Janeway appreciated the sentiment, but told him she couldn't keep it, and it should be recycled, because they couldn't " afford to waste energy on nonessentials," and "[t]hat watch represents a meal, a hypospray, or a pair of boots. It could mean the difference between life and death one day." ()

By the 24th century replicators became, perhaps, the most common means of recycling used materials. When The Doctor mentioned the fast growing of Naomi Wildman to her mother Samantha, she told him that it felt like everytime she turned around, she had to recycle her clothing back in the replicator. () 

Kathryn Janeway placed a stack of books in her replicator and asked the computer to recycle them in 2376. ()

Upon returning to  later that same year, Lyndsay Ballard was glad to see that Harry Kim had saved her personal effects, including the pair of ice skates she owned, rather than recycling them. () 

In 2377, when The Doctor was serving aboard Dinaali Hospital Ship 4-2, one of his patients, Tebbis, had repaired a medical scanner that one of the ship's technicians was going to recycle because it had no longer worked. ()

Later that year, The Doctor – while posing as Seven of Nine – suggested to Ensign Harry Kim the construction of a holographic stomach for him which could store food for eventual recycling. This would allow him to eat like other crewmembers. ()

See also 
 Water reclamation

External link 
 

Energy