Is it possible to have an odorless/near odorless indoor vermicompost system?
Somewhere in the range of 3-7 gallons.
What about purposing something like this on the scale of 65 gallons? Does size have an impact on odor? (That particular one may not be well oxygenated but imagine if it were aerated on all sides)
Yes. Decomposition smell comes from anaerobic decomposition. Keeping your compost oxygenated should eliminate odors. For my normal compost I do this by flipping it regularly, more at first (every 2 weeks) tapering off to every other month. Slimy sections are an indicator of anaerobic decomposition. Aerobic decomposition should produce no (low) smell, but it will produce heat.
Yes, it is possible. The kind I use in the house (for cooked food, which worms eat better than raw) is called 'The Worm Factory®'. It is a good prototype. The worms start in the bottom tray, and you add food on top until the tray is nearly full of worms, compost, and bedding, then you add the next tray with bedding and some food. By the time the top tray is used, the bottom tray (which will have few worms by that time) will be fully composted.
There is no smell whatsoever, except for a faint smell of earth, and sometimes the current food sources (especially apple cores, I've noticed - they can smell like cider for a bit).
On a larger scale, tumblers are not best; they are for mixing/aerating the ingredients of regular (non-vermicultural) compost so that they decompose properly. This is most useful while the compost is hot. Once it cools, it is piled so that it can cure and finish the decomposition process. This is entirely wrong for worms, which require a bedding material (where they spend their time when not eating) and an area where the food goes (they do best when this remains the same, so they don't have to search).
So for that much volume, people generally use a bin, with drainage of course, with openings at the bottom to remove the compost from. The food is placed on the top, under a layer of bedding material, and the worms build the compost up slowly until some is removed.
In any method, the biggest thing I see people running into is overfeeding. Worms only eat a certain amount per day. You should give them as much each day as they will eat, or add more, and wait until i is nearly gone before adding more. Even if there is enough bedding material for a good ratio for regular compost, don't go adding lots of food.
In addition to lack of oxygen and over feeding as already noted, unpleasant odor can also a result of too much nitrogen or too much moisture. If does start smelling, turn it and add some carbon to it (dry shredded newspaper as an example). Composting is sometimes a balancing act between carbon and nitrogen, and some experimentation may be in order. Good luck!
