Putting orange and lemon peels down the garbage disposal makes the drain, sink, and entire kitchen smell fresh and clean. No one likes a smelly drain, and recycling these peels as air freshener can make your entire kitchen smell citrus fresh. Older citrus fruits that may be going partially bad, can still be cut up and put into the garbage disposal. I cut the peels into at least quarters of the whole to not make the disposal work so hard. If you don't have a disposal, orange and lemon juice with warm running water can keep your drains smelling fresh.