Working like the compost heap in the backyard, but without odour and much faster, Sun-Mar toilets break down human waste and toilet paper through the natural process of decomposition. Because most of this waste is evaporated, only a very limited quantity of finished compost is produced.

Many commerical composting plants rely on windrows for proper composting. Quite a lot of money is invested in these municipal plants in completely turning a compost pile - and there is a reason. Forced air static pile composting dries out the compost (agitators may be used in these systems, but agitation is frequently confused with aeration), which renders the bacteria ineffective without moisture. Windrows also require a certain amount of forced air in order to work properly, which has to be taken into account in a proper composting toilet design.

The combination of turning the compost evenly in a drum simulates the windrow environment, and the fan on an electric unit or passive venting on a non-electric unit allows more oxygen to move through the pile when the unit isn't being turned, without sacrificing the vital component of moisture.

The combination of all of these factors ensures a rich environment for aerobic bacteria to break down every part of the pile. It just makes good sense.

Oxygen, moisture, heat and organic material are needed to allow minute natural organisms to transform the waste to fertilizing soil.

• Oxygen is provided by drum rotation and by the ventilation system. The drum is easily rotated via a handle at the front of the unit.
  
• Moisture is obtained directly from human waste.
  
• Organic material in the form of peat mix is added manually, since this organic carbon is absorbent, holds oxygen, and is cheap and readily available.
  
• Heat is generated by the compost itself, assisted by the heating element (on electric models).
  
• Microbes are contained in the rich top soil which is added to the compost.
  
  

Odor Free

The engineered air flow within Sun-Mar units ensures that a partial vacuum is maintained within the unit at all times. Air is drawn in by a fan, or on non-electric units by the vent chimney, over the evaporating chamber and up the vent stack. Not only does this evaporate excess liquid, but, by continuously pulling air in we ensure no smell escapes from the unit.

In addition, the tumbling action of the composting drum results in such a moist and beautifully oxygenated compost that an aerobic breakdown takes place which is both fast and odorless. Breakdown is odorless because aerobic microbes produce only carbon dioxide and water vapor, quite unlike the unpleasant anaerobic smell often found in a septic tank, outhouse, or backyard compost.

Sun-Mar's unique Bio-DrumTM has been developed to provide the optimum conditions for aerobic composting. Using such design, Sun-Mar has been able to ensure that the compost in the drum is maintained in the moist, warm, well mixed, oxygen rich condition which aerobic bacteria need for optimum performance.

Sun-Mar has also found that such approach avoids the anaerobic activity which occurs wherever there is insufficient oxygen. This is important because anaerobic activity is slow and produces offensive odors. The use of this revolutionary Bio-Drum^TM results in composting speeds double those of the old single chamber units with mechanical mixers.

Start Up and Use

Sun-Mar units require very little maintenance. Peat moss should be added at the rate of one cupful per person per day. Toilet paper is decomposed easily by Sun-mar units and should be added as usual. The compost should be mixed and aerated every third day (or at the end of the weekend) while the toilet is in use, simply by turning the drum handle and rotating the drum 4-6 complete revolutions. In cottage use, some composted material may only need to be extracted in the spring. In residential or commercial use extraction will be more frequent.

Winter Use

Sun-Mar makes its units out of fiberglass and marine grade stainless steel, so freezing temperatures will do no damage even if the compost freezes in the drum. Composting action decreases with temperature, so for extended winter use, all piping should be well insulated and the unit should be kept at a minimum temperature of about 55-60 degrees Fahrenheit (13-15 Celsius). 

For periodic use in winter, the toilet may be used as a holding tank, until the compost warms up, and the microbes emerge from dormancy. Electric units should be plugged in on arrival so the ventilation system is working and there will be no odor. When the compost is frozen, the drum should not be rotated.