HOW COMPOSTING WORKS

Working in a similar way to the compost heap in the backyard, but odorlessly, and many times faster, "SUN-MAR" toilets and toilet systems break down human waste and toilet paper through the natural process of decomposition. Heat, oxygen, moisture, are organic material are needed to facilitate this breakdown, and allow natural organisms called microbes to transform the waste into useful garden fertilizer. Heat is generated by the compost itself, assisted by the heating element (on electric models); while oxygen is provided by the ventilation system, and the tumbling action of the composting drum.

Organic material in the form of SUN-MAR peat mix is added manually. This provides an excellent form of organic carbon which is biologically active, absorbent, entraps oxygen, and speeds the composting process. Peat moss may be used as an acceptable substitute. Moisture is obtained directly from human waste, while the last and most important "ingredient", the microbes, are contained in rich top soil which is added to the compost to start the process.

SUN-MAR's insulated composting drum (we call it a Bio-drum) provides the best possible environment for aerobic microbes to thrive and dominate. This Bio-drum is uniquely able to provide a warm, moist, oxygen rich environment which allows fast, odorless, aerobic microbes to degrade the waste and toilet paper back to its basic minerals. Organic carbon is converted to carbon dioxide and hydrogen to water vapor. It is this high speed composting efficiency, made possible by the Bio-drum, which accounts for SUN-MAR'S ability to handle heavy or residential/commercial needs.

A composting toilet system has three completely separate tasks:

• compost the waste and toilet paper quickly and odorlessly;

• ensure that the finished compost is safe and easy to handle, and

• evaporate the liquid.

Many years ago "SUN-MAR" engineers realized that each of these tasks required a separate chamber with its own independent environment.

This revolutionary three chamber approach proved so successful, that we were able to double the composting speeds of the old single chamber units with mechanical mixers. Today only one single chamber unit, the lower capacity "TROPIC", remains in the "SUN-MAR" product line. All other units work on the same three chamber principle first developed by SUN-MAR in 1979.

"SUN-MAR" engineers found that the ideal conditions for fast, odorless composting could only be provided in a rotating drum,(we call it the Bio-drum). The Bio-drum is uniquely able to keep the compost completely oxygenated, mixed, moist and warm, and so provide perfect conditions for fast, aerobic (and therefore odorless) composting. Waste enters the composting drum through an entry port located in the top of the Bio-drum. By adding peat moss, and periodically turning the handle on the front of the unit, the drum rotates, and the compost tumbles, (assisted by a mixing baffle) thereby thoroughly and completely oxygenating and mixing every part of the compost. The Bio-Drum is ideally rotated 4-6 revolutions about every third day while the toilet is in use. More frequent rotation of the drum is not recommended. The Bio-drum is fitted with a door which closes automatically to keep the waste inside as the drum rotates. After turning, a lock automatically maintains the Bio-drum in a top dead center position ready to receive new material. To ensure that the compost cannot get saturated, a screen at the rear of the drum filters any excess liquid directly into the evaporating chamber. At the same time, by protecting the compost from direct heat, the Bio-drum keeps the compost uniformly moist. Lastly, the Bio-drum has the volume to hold the necessary mass of material to retain the natural heat developed in the core of the compost. On some models, insulation on the drum prevents heat loss.

The warm, moist, oxygen rich conditions in the Bio-drum allow the microbes to quickly break down the waste into its essential minerals. In the spring time, or when the drum gets 2/3 full, some compost is extracted into the finishing drawer. This is done simply by pulling the drum lock, and rotating the drum backwards. Now, the drum door remains open, and compost falls into the second chamber; the compost finishing drawer.

The compost finishing drawer, the second independent chamber, is immediately below the composting drum, and just above the evaporating chamber. Compost in this drawer is totally isolated from material in the Bio-drum. Although it is no longer subject to contamination from fresh waste, it should not be used on edible vegetables. While in the finishing drawer, the compost is surrounded by a stream of drying air, and absorbs the radiant heat from the evaporating chamber. It is here that composting and sanitation are completed, and the compost becomes safe to handle.

The finishing drawer can be pulled out and removed by hand (no tools or screws are needed) and the sanitized compost emptied whenever it is necessary to extract more compost from the drum.

The third chamber, which forms the base of the toilet, is the evaporating surface from where any excess liquids which cannot be absorbed by the compost are evaporated or drained. Liquid is evaporated by drawing air through the intake holes at the base of the toilet, over the evaporating surface, and up the vent stack. On electric models air is drawn in by a fan, while non electric models use natural draft induced by chimney effect of a 4" vent stack. In both cases a partial vacuum is maintained which ensures that no odors can escape. Electric models also have a thermostatically controlled heating element which is located in a sealed compartment underneath the evaporating chamber. This heater keeps the floor of the chamber hand warm to assist evaporation.