THE HISTORY OF SUN-MAR IS THE HISTORY OF COMPOSTING TOILETS

 What SUN-MAR Composting Toilets do

SUN-MAR composting toilets recycle waste on-site by evaporating the liquids, and converting the solids to a fertilizing soil which is perfect for uptake by plants. SUN-MAR composting toilets use naturally occurring aerobic bacteria to convert the carbon atoms in the waste to carbon dioxide, and the hydrogen atoms to water. In this way the waste is oxidized and reduced to its essential minerals. Since waste is some 95% moisture, after the liquid has been evaporated and the solid waste composted, the residual is only about 3% of the starting volume. 

 This recycling process avoids the need for sewers and central treatment plants. It also avoids invasive on-site treatment systems such as septic systems.

SUN-MAR composting toilets are recycling marvels that are odorless, leave no footprint, do not pollute in any way, and can be installed anywhere a toilet is needed. Indeed a SUN-MAR is so obviously good for the planet that at SUN-MAR we wonder why everyone is not using them!

The First Generation Waterless Composting Toilet

The founder of SUN-MAR, Hardy Sundberg, developed the first self contained composting toilet in 1971. This waterless toilet had a fan and heater at the top, blowing hot air onto the waste pile which was agitated by mechanical mixers. As the compost in the bottom was agitated it fell though a screen into a collection chamber.

While at the time this toilet represented a big step forward in the development of composting toilets, in hindsight it can be seen to suffer from a number of weaknesses. Firstly, this composting toilet design was what we now call a single chamber unit, which means that the operating conditions were the same throughout the whole toilet and not optimized for the different needs of composting, evaporation or finishing. Secondly, the fact that heat was being blown in from the top meant that the compost tended to get dried out, while the liquid in the bottom was not evaporated efficiently. Thirdly, the compost in the bottom was not isolated and was subject to contamination from fresh waste.

Even today, over 30 years later, some waterless composting toilets can still be found which feature a top mounted heater with all the attendant problems this brings. However, subsequent SUN-MAR composting toilet designs have been successful in solving the inherent problems evident in this first waterless toilet design.

The Second Generation

In 1977, the second generation composting toilet was born. Known as the Tropic, this waterless toilet featured one highly significant improvement;- the heater was located in a sealed compartment in the base of the toilet. This base heater was able to evaporate the excess liquid in the base, while allowing the compost pile to remain moist, an improvement which dramatically increased composting speed and ease of operation

This heater arrangement therefore overcame the big problem with top mounted heaters, namely that in evaporating liquid they also dry out the compost pile. Drying out the pile has two undesirable affects. Firstly, aerobic microbes are reduced to the point where composting slows to a halt, and secondly the waste cakes to a consistency somewhat like an adobe brick where it becomes impossible to agitate the pile.

The First Central Composting Toilet System was Marketed

In 1977 SUN-MAR extended the concept of domestic composting by offering a composting toilet system that was outside and several feet away from the bathroom, but connected to a 1 pint toilet in the bathroom. This allowed users to have a ”normal” looking bathroom, while still having all the benefits of composting. The use of a low flush toilet meant that compost was much easier to keep moist. However because this toilet was not waterless, it was not always possible to evaporate all the liquid. Consequently, the small amount of excess liquid has to be handled by an old septic, recycling bed, or other approved system.

The Third Generation

In 1979, a further major improvement was launched. The difficulty of aerating, and providing oxygen for the aerobic microbes was solved by replacing the pile and mechanical mixers by a Bio-drum. The Bio-drum had a door which when open allowed the waste into the Bio-drum, and when shut allowed the Bio-drum to stay sealed when rotated. This Bio-drum arrangement gave rise to a huge performance improvement because by rotating the drum compost could now be well mixed, and perfectly oxygenated, while also allowing the moisture to be evenly distributed throughout the compost.

This Bio-drum had a screen in the rear, which allowed any excess liquid to drain into the evaporating chamber in the base of the composting toilet, thus ensuring the waste did not get saturated. Saturated waste is undesirable in a composting toilet because it dramatically slows composting down by driving out the oxygen the aerobic microbes need to survive. A saturated compost provides good conditions for anaerobic microbes, which are slow and odorful.

Another major benefit to the Bio-drum arrangement was that by rotating the Bio-drum backwards, the Bio-drum door would remain open so that the compost would drop automatically into a finishing drawer. In the drawer, compost was isolated, no longer exposed to fresh waste, and was able to finish composting while gradually drying out. The drawer could be easily removed without exposing the user to liquid or fresh waste.

This was the first three chamber composting toilet, where composting was taking place in the Bio-drum, liquid was being evaporated in the evaporating chamber and compost was being finished in a finishing drawer. All these essential processes could now be optimized, a development which gave SUN-MAR the leadership position in the field of composting toilets,-  one which it has maintained to the present day

The Advantages of a Three Chamber Composting Toilet

Some of the advantages have been described above. Hopefully repetition will do no harm!

1. The three different chambers allow for optimizing the three different requirements for composting, evaporating and finishing.

2. The Bio-drum allows compost to be properly and completely oxygenated, rather than the partial aeration achieved by composting toilets with fixed mechanical mixers.

3. The Bio-drum ensures there is no excess moisture, since any excess is automatically drained to the evaporating chamber.

4. By being separated from any direct heat, the material in the drum does not dry out as it would in composting toilet designs where heat is aimed directly at the pile

5. The drum offers simplicity of operation. Tumbling the Bio-drum ensures mixing is easy and complete,.( like a cement mixer or clothes dryer)

6. Removing compost is merely a question of rotating the Bio-drum backwards. There is no concern with sealed bases, secured by screws and thee is no exposure to liquids and flooding

7. The Bio-drum offers the ideal environment for aerobic bacteria to prosper

8. The evaporating chamber is heated by a heater below it. The advantage this gives is similar to the advantage gained by heating a saucepan with an element beneath, as opposed to heating with a hair dryer from above.

9. The heater is on when there is liquid to evaporate and off most of the time when there is no liquid.

10. The evaporating chamber offers the ideal environment for evaporation with air being pulled by a fan over a large surface area of liquid warmed from beneath.

11. While in the drawer the compost is surrounded by a stream of drying air, and gradually dries out prior to removal rather than being exposed to, and contaminated by, fresh waste and liquid.

12. The drawer is removed merely by pulling it out by hand

The First Self-contained Non Electric Waterless Composting Toilet

So successful was the 3 chamber concept that in 1981 SUN-MAR introduced the first self-contained non-electric composting toilet. This was identical to the electric unit of its time, except for a few important differences:

1. The non-electric toilet had a 4" vent stack rather than the 2" vent on electric units

2. There was no fan on the non-electric unit, although a 12V fan could be inserted in the vent stack if additional air movement was needed.

3. There was no heating compartment in the base of non-electric toilets

4. The non electric composting toilet had a larger drain than the emergency safety drain on electric units

This concept proved so successful that SUN-MAR’s non-electric composting toilet remains the standard for those living off the grid.

The First Non-electric Central Composting Toilet System 

In 1987, SUN-MAR offered the first Non-electric Central Composting Toilet System. This unit incorporated similar differences that distinguished the non-electric self-contained toilet, namely a 4" vent stack with 12V fan, and no heating compartment in the base

The First Self contained Composting Toilet to Pass North American Operating Standard

In 1989 SUN-MAR’s Excel became the first self-contained composting toilet to pass the National Sanitation Foundation (NSF) Standard #41. This was a 6 month residential test where no odor was permitted even under overload conditions, and only a negligible fecal coliform count was permitted in the composted output. This meant that from 1989 regulators could confidently permit use of a waterless SUN-MAR composting toilet.

Today, SUN-MAR composting toilets are the only such toilets listed and certified by NSF under the new updated NSF  Standard #41 (1999) for residential and for cottage use.

The First Dual-vented Waterless Composting Toilet

In 1991 Sun-Mar introduced a dual vented self-contained composting toilet, which operated as an electric unit when power was available, but defaulted to non-electric operation using the 4" vent stack when it was not. This model proved to be popular for those who had no power now but were expecting it in the future; for those operating a generator for most, but not all the time; and for those with an insecure power supply.

1993 The Compact and the Centrex are launched 

1993 was a big year for SUN-MAR. At this time the Compact and Centrex models were both launched.

The Compact was a lower profile version of the long established Excel. It had a patented variable diameter Bio-drum and an elegant look which made this waterless composter at home in any bathroom.

The Centrex was an all new Central composting unit with a Bio-drum slung side to side rather than for and aft. This allowed for a lower profile making it easier to be fit into places where there is little headroom. In addition to the regular 1 pint flush version, this configuration also allowed SUN-MAR to offer a waterless Central unit which featured a SUN-MAR Dry Toilet positioned directly above the composting unit.

In addition, the new design lent itself to being scaled up, an advantage which was to result in the subsequent launching of the Centrex 2000 and 3000 series units

The First Composting Toilet Designed Specifically for Mobile Use

The SUN-MAR Mobile, introduced in1994 was the first waterless, self-contained composting toilet designed for use in marine and RV markets, and for that matter, for use in anything that moves. The key feature of the mobile unit was that at only 19" wide it could be installed virtually anywhere.

Other than the width, what was new in this composting toilet was the 3" vent stack with a special fan/filter box which scrubbed the vented air so as to avoid any inconvenience on deck. In addition the finishing drawer was gasketed in place so that liquid could not escape even during violent motion, and the footrest folded back into the unit which is only 23" deep.

In addition a shore based waterless composting toilet was introduced with a 2" vent with a special fan assembly, and a 160 watt heater in the base compartment. This unit, the Spacesaver, is ideally suited for installation in cupboards or small corners where a toilet is needed but space is a problem.

The Centrex 3000, the First Continuous Flow Composting Toilet System 

In 1997 SUN-MAR unveiled the first continuous flow central composting toilet system. This meant that as the Bio-drum rotates compost moves along and through the unit before falling automatically into a collection chamber at the end of the unit. On this unit, the high capacity 3000, the collection chamber replaces the finishing drawer as the 3rd chamber. This unit is the highest capacity Composting toilet system in SUN-MAR’s line and has been subject to continuous improvement since its introduction. It is available in either waterless or 1 pint flush configurations, and in electric, non-electric and dual vented versions.

The Mid Capacity Centrex 2000

The last new major family of Central Composting toilet systems, the Centrex 2000, was SUN-MAR’s millennium baby, born in 2000. This unit was designed as a medium to high capacity composter suitable for residential use and for heavy cottage use. In fact its Bio-drum is so large that most families only have to remove compost on an annual basis. Despite its high capacity the 2000 is a low profile unit which fits into spaces with limited headroom. Like the 3000, it is offered in waterless or 1 pint flush versions, and in electric, non-electric and dual vented models.