Food Wastes: Vermicomposting and Food Digestors

Vermicomposting or worm composting is the easiest way to recycle food wastes and is ideal for people who do not have an outdoor compost pile. Composting with worms avoids the needless disposal of vegetative food wastes and enjoy the benefits of a high quality compost. It is done with “redworms” (Eisenia foetida) who are happiest at temperatures between 50= and 70= F and can be kept indoors at home, school, or the office. As with outdoor composting, it is best to avoid putting bones, meats, fish, or oily fats in the worm box as they emit odors and may attract mice and rats. When cared for properly, worms process food quickly and transform food wastes into nutrient-rich “castings.” Worm castings are an excellent fertilizer additive for gardens or potted plants.

The redworms are placed in a box or bin which can be built or purchased, along with “bedding” of shredded cardboard and/or paper moistened to about 75% water content. The container should be wide enough so that food scraps can be buried in a different location each time. The dimensions of the container and the amount of worms required initially will depend on how much organic food waste will need to be composted each week.

The worms will gradually reproduce or die according to the amount of food they receive. A sudden addition of a large amount of food waste may attract fruit flies, so increases should be made gradually. In a healthy box, worms can build large populations and consume four to six pounds of food scraps per week. About four to six months after the box has been started, the worms will have converted all of the bedding and most of the food waste into “castings” which will need to be harvested so the process can begin again.

Food waste digestors are an option for people who want to reduce the amount of food waste they produce but do not have a compost pile. These units resemble commercially produced compost bins, but differ in purpose. They are designed to accept food wastes otherwise inappropriate for composting such as meats, fish, fats, or oily food scraps. In general they are built to prevent odors from being released and prevent rodents from entering the unit. Food waste digestors are fundamentally different from worm boxes and compost piles, because the digestors do not ultimately produce a soil enhancing product. Their purpose is to cut down on the volume of food waste generated. Food waste digestors are not a “magic hole in the ground” however, and the decomposed food residue must periodically be emptied into the trash.