Three Generations of Dry Toilets

First-generation toilets were the latrines or backhouses of our grandparents: a simple hole or pit in the ground, above which there was a floor or board with a hole, with or without a proper seat. These toilets were smelly and very polluting due to anaerobic fermentation (absence of air). Agricultural reuse of the effluent did not however seem to present a major problem. This was current practice for centuries, indeed millennia.

Second-generation toilets developed in the 20^th century are mainly characterized as source-separating Scandinavian-type toilets. They aimed at the outset to improve dry toilets’ convenience. In fact, they constitute a technical improvement on the traditional chamber pot to make dry toilet use possible within the home, similarly to water closets. To minimize the frequency of the required emptying of the waste, urine is first separated from the faeces: this is the toilet’s most important characteristic. Urine, which represents about 90 % of the excreta, is diverted to a separate storage tank while the faeces are collected in a main compartment. To reduce their volume, these are usually dried with a heating element, a hot air current or solar energy. A forced air ventilation system is usually provided to control odours that ultimately appear after waste separation. The ventilation system almost always works electrically. The dried faeces and the urine are then commonly used in the garden and/or for agricultural use. To avoid burning plants, urine must first be diluted to 8 times its volume.

Third-generation toilets differ from the others on how they work, biologically. Smell is inhibited thanks to the addition of a litter composed of plant matter that is rich in cellulose. This is the basis of the biolitter toilet or BLT. In this toilet, plant cellulose biologically inhibits the enzymatic reactions in the excreta that are responsible for the odours. This can only work in the presence of urine. To prevent anaerobic fermentation (with the consequent odours), the toilet’s «receiving» capacity cannot be expected to exceed the volume of one week’s «production». Therefore, the emptying of the container is more frequent. Note that a BLT, even though it is placed within the home, does not require mechanical ventilation. Before reuse for agricultural or gardening purposes, the BLT’s effluent must be composted in a two-stage process, over a two-year period. The compost thus obtained is suitable for all plants, without any health risk.

The Biolitter Toilet or BLT

Not so long ago, I was annoyed to observe that people reduced my overall thinking to the sole biolitter toilet – pejoratively called a « cat litter box » by some – of which I was said to be the inventor. Now, « invention » is a big word for something which’s time was long overdue. It now appears I was not the only proponent of this type of toilet, at about the same period in time [1]. It’s true that I was the first to launch the biolitter toilet in Europe, mainly France and Belgium (and eventually my native Hungary) under the name « toilette à litière biomaîtrisée » which translates as a biocontrolled litter toilet. The launch came in 1992 after about 10 years of personal use at home as well as laboratory testing more than 20 years after my first tinkering with dry toilets. To my credit, I simply provided the scientific explanation to how odours are controlled, and I proposed the biological means of returning our dejecta back into nature’s great natural cycles. Nevertheless, I claim the authorship of the name « toilette à litière biomaîtrisée » known in short as the TLB in francophone Europe (now known as the BLT in English). The name came to me in 1995 during a symposium organized by the « Ecole d'Agriculture de Ath » (Ath Agriculture School) in Belgium where many speakers presented case studies of worldwide experiments on livestock quality in production facilities where livestock was raised in biocontrolled-litter housing systems (better known as deep-litter or deep-bedding housing systems in the English-speaking world). It became obvious to me that the lack of odours in these facilities was based on the same principles as those applying to the litter toilet that I had launched 5 to 6 years previous. Before 1990, practically no one in the French-speaking world seemed interested in dry toilets. I believe I was among the first scientists (if not THE first) to actively and publicly promote these toilets (via conferences and lectures, documentaries and interviews), and to research the scientific aspects of odour control by the use of cellulose litter. My first conferences on the subject provoked outright laughter : at the start of the 90’s, no one, absolutely no one, took me seriously.

Since then, the rise of water problems has helped change attitudes towards dry toilets. The number of websites devoted to the subject is inexhaustible. Unfortunately, there is a tendency to consider all dry toilets as equal to the BLT. Any toilet that does not involve the use of water to evacuate excreta is defined as a « dry toilet ». This is a vast category that covers set-ups or systems that are sometimes even more polluting that flushable WC’s. To call the biolitter toilet a « dry toilet » will tend to confuse the issue, between a toilet that is truly respectful of the biosphere, and all those others that are less environmentally friendly, if not outright un-ecological.

In the English-speaking world, the third-generation toilet I promote is better known as a «°sawdust toilet°», a term popularized by another proponent of such toilets, the American Joseph Jenkins. The term itself is somewhat restrictive, since sawdust is only one of the possibilities available as a litter cover material – and it is not the best, even though it can work well [2]. I prefer the term «°biolitter toilet°» (simpler than «biocontrolled litter toilet»), which calls to mind the litter’s biological action in the toilet’s modus operandi, similar to the French version term I coined in 1995 and that is currently used in French-speaking Europe.

Esperanto-speaking people have a proper term : the «°pajlaĝnecesejo°», although I prefer the term «°pajlaĝejo°». In Hungary, the toilet is suitably called «°alomszék°» (or litter toilet).

Who Uses the BLT?

Once you recognize that continued use of flushable WC’s is leading us to an environmental dead end, you can thenceforth consider switching to a BLT, as has been done by thousands of households in Belgium, France and other European countries since my public interventions. (I have no doubt that a similar phenomenon has also occurred in North America since the publication of Joseph Jenkins’ book [1].) A survey that was carried out [3] revealed that families having adopted the BLT no longer want to have anything to do with conventional WC’s, feeling that the BLT provides comparable convenience while satisfying their environmental concerns. The survey also confirmed that BLT use was not exclusive to those with « back-to-the-earth » or other fringe lifestyles. In fact, the majority of users have a college degree or equivalent, sometimes living in upscale homes or at the least in very comfortable ones.

It is noteworthy to add that the biolitter toilet also applies to animals. Livestock raising in organic deep-litter housing systems is a proven technique that produces high-quality meat. By composting the litter-bedding over which livestock is raised, we now have the means of preventing water pollution caused by liquid pig manure. Should we not convince pig farmers of the soundness of this approach?

How the BLT Works?

A purpose of the BLT is to restore our dejecta into the process of humus formation under the best possible conditions. For this, we must first prevent urease – an enzyme in our excreta – from transforming precious organic nitrogen into ammonia, unusable for humus synthesis. This phenomenon was first understood thanks to laboratory observations [4] : that plant cellulose inhibits the enzymatic reactions that mineralize dejecta’s organic matter. Now, these reactions constitute the origin of obnoxious smells. An idea became obvious : add plant cellulose to our dejecta in order to block enzymatic reactions, and in so doing, prevent odours. Another benefit of this gesture is to increase our dejecta’s carbon / nitrogen ratio to a level that is ideal for exterior aerobic composting. [5] .

An important detail: the inhibition of enzymatic reactions can only take place in a moist environment, therefore in the presence of urine. This is the reason you must absolutely not separate urine from faeces. Another important detail : the introduction of plant cellulose in the BLT’s process (i.e. the litter) must occur immediately after defecation or urination, to prevent the start-up of mineralization.

What Does the BLT Look Like

Once you have adopted a BLT, you don’t need to attempt to imitate conventional WC’s, unlike what most commercially-sold dry toilets do. It’s no longer necessary. You can design a beautiful piece of furniture which’s style can match that of the rest of the home. You can apply the same principle to a biolitter urinal.

Technically, simplicity is of the essence. The BLT is a simple bucket placed within a piece of furniture that can evoke a simple chair with a hole in the middle. Important detail : a protective baffle must be mounted under the cover. For added comfort, you can even add armrests and upholstering. You need not provide water supply (except for a lavatory), nor a drain, nor mechanical venting for the BLT. The BLT can be placed within the home, in either the toilet room or bathroom. For added convenience, some even put a BLT in the guest bedroom, behind a folding screen. It is also quite appropriate for a sickroom. Also, it is important to provide a litter container, either separate from the BLT or integrated in the BLT design.

When used as recommended, the BLT does not generate more odours than a conventional WC.

How to Build your BLT?

The BLT does not benefit from any commercial advertising. The basic idea is that anyone and everyone should have access to a toilet that is truly environmentally friendly. It can obviously be built by your average handymen or «do-it-yourselfers» using the plans provided within this website. You may also want to look-up Joseph Jenkins’ drawings and sketches in his book on sawdust toilets. Here is a finished example.

An elegant solution can also consist in setting a sanitary bucket in a chair seat : an inexpensive and efficient solution, and very presentable. 

However, if you are not handy with tools, you can find BLT’s already available on the market in some regions of the world. This is particularly true in France and Belgium, where the EAUTARCIE website has had considerable success. One can only hope that BLT manufacturers will sprout worldwide.

The BLT in Tropical Regions

We have experimented with BLT’s in tropical regions. Providing the proper precautions are taken, the BLT can also be used in the tropics.

The higher temperatures in these regions appear to shorten the time span within which the BLT can properly function in controlling odours. There are no problems up to 25°C. Above this, the toilet starts to give off whiffs of ammonia. But the smell increases after a few hours on a very hot day. Above 30°C (within the home), you’re better off to have you BLT in a well-ventilated exterior shed, apart from the house.

If you absolutely want to put the BLT within the house, than you must stick to stainless steel or enamelled steel buckets : plastic buckets are quite inadequate.

The bucket must be emptied twice a day. After each use, make sure to moisten the litter cover material in your BLT. On this matter, also read the BLT instruction manual. For litter, you need material that is highly absorbing. Sawdust gives good results. However, sawdust and wood shavings from certain tropical species of wood emit unpleasant odours when wet. In Africa, they use shredded cardboard boxes as litter (first wetted, than shredded into small pieces). Printing inks completely degrade during composting, leaving no residues. Tall savannah grass clippings giver lesser results. If the litter is slightly moist, odour control becomes easier.

In tropical regions, composting is much quicker than in temperate Europe. After 3 to 4 months, you can already empty your compost bin to start the second stage of composting. Read more on this at Composting human dejecta.

BLT’s for Collective Use

The BLT is perfectly adapted to grouped collective set-ups. However, there are certain needed precautions to avoid eventual failure. Such set-ups require added supervision when compared to WC’s. A person must be ever-present to ensure litter and toilet paper supply, but also to remove and replace the filled-up buckets in proper time. For this purpose, each toilet should be assigned 2 or 3 containers for temporary containment to provide extra time between actual waste removals. The waste can be dumped in a container that then needs to be transported to a proper composting facility. The collective set-up can even include biolitter urinals.

In France and Belgium, there are companies that even sell or lease portable BLT’s as «  Johnny-on-the-spots  » for construction sites, festivals and other public gatherings. As an example, look up the following French websites :

http://www.ecotoilettes.net/

http://aquaterre.canalblog.com/archives/accueil/index.html

http://www.toiletteacompost.org/

http://blog.terhao.org/images/M_images/techni.pdf

A Next Generation BLT: the Turbo-Toilet or TT

In our modern world, after close to a century of domination by the flush toilet, the convenience of WC use will certainly be hard to get by for many, if not for most people at present, especially in high-density housing where BLT’s may be somewhat difficult to manage. For the biosphere’s sake, it is high time we look into finding a solution to this dilemma.

With this in mind, it is realistic to conceive a project that helps define the next generation of toilets, which would have to work along the same principles as the BLT. These new toilets, which we will call turbo-toilets or TT’s, would be appropriate in large city apartment buildings. They would combine the advantages of a standard WC with those of the BLT, while minimizing any inconvenience.

The TT’s proper mode of operation would rely on diluting excreta as little as possible: in other words, of maintaining excreta as concentrated as possible. This is the most critical aspect to the process for it to work. From the outside, a TT would resemble micro-flush toilets used on trains, buses and airplanes (ideally in a more spacious toilet room!). These toilets are usually made of stainless steel, porcelain or enamelled steel. After relieving oneself, the toilet bowl would be rinsed out with a high-pressure jet (from 20 to 30 bars or 300 to 450 psi). Thanks to this high pressure, each toilet use would only consume between 100 and 200 ml (3½ to 7 oz) of water.

The next condition is to be able to easily convey this concentrated black water to its treatment centre, be it in an absorption tank located within the apartment building, or to a municipal compost facility. Thus, the concentrated toilet effluent is to be liquefied into slurry with the help of a pulverisor (or grinder) and injected under low pressure (a few hundred millibar or 10’s of kPa) into a separate small-section conduit. To minimize mineralization of organic matter, its length of stay in the conduit would have to be a short as possible in conjunction with the shortest and most direct run of conduit possible between the toilet and the absorption tank. The tank’s impregnated cellulose litter would then need to be transported or conveyed to a municipal compost centre.

In cities equipped with T-T’s, the conventional sewers would be reserved exclusively for grey water conveyance, and water treatment would become much simpler and less expensive than that of actual sewage. For further reading on this, go to Traiselect in an urban context.

Some toilets equipped with grinders already exist (although they are not called « turbo-toilets »), but they usually come with a standard volume flush, which represents much too much water. It’s to reduce this water volume that the water flush must be pressurized. Train and airplane toilets come close to this objective. Otherwise, pressure pumps that can do this job already exist in domestic pressure washers (e.g. manufactured by « Kärcher »). A TT would therefore use two existing and proven technologies. To come to fruition, the TT project needs to be «invented» and properly tried and tested.

To continue reading, go to The BLT Instruction Manual

Return to Why use dry toilets

[1] Joseph JENKINS, The Humanure Handbook : A Guide to Composting Human Manure », 1st published in 1994, 3rd edition in 2005

[2] In his book, Joseph Jenkins describes the sawdust’s ideal characteristics, and although sawdust is somewhat limitative per se, his «recipe» apparently works quite well. Nevertheless, it remains that I have witnessed numerous toilets that use sawdust. I personally have tried many kinds of sawdust : from softwood, hardwood, exotic wood, treated wood, finely or coarsely ground sawdust, etc. In all cases, without exception, the compost and even the toilet had a tendency to become smelly due to the lack of aeration. Some women complained to me about the dust in the toilet. As for sawdust from exotic tropical wood species, obnoxious smells eventually appeared, due to these species’ essential oils. I have even tried hemp, which doesn’t work well to control odours. A mixture of sawdust with wood shavings (non tropical) is the best.

[3] Christine ROUSSEAU, Toilette à litière biomaîtrisée : psychologie et motivation. (The biocontrolled litter toilet : psychology and motivation) Final thesis, Institution d’Enseignement de Promotion Sociale de la Commission Française de Peruwelz 1996.  

[4] Réf.: NIMENYA H., et coll., Ann. Méd. Vét., vol. 143, pp. 409-414 (1999)

[5] Our dejecta’s C/N ratio is about 7, whereas that of plants is between 200 and 300. To start composting, the C/N ratio should be around 60. Combining animal-sourced nitrogen (dejecta) and plant carbon (the litter) creates the ideal conditions for humus formation, without unpleasant odours.