Whole Systems Approach to Ecological Design

Appropriate Technology: Water

Organic Agriculture and Local Food

Appropriate Technology: Energy

Green Building & Retrofitting

Appropriate Technology: Water

Composting Toilets

Composting toilets are excellent for a small number of ecovillagers in a settlement.  In villages with centralised facilities, many such toilets can be built in a block.

There can be cultural taboos against dry toilets, and the community should be consulted before adopting this technology.

There are also hybrid systems that use normal flushing toilets followed by solids separation by centrifuge.  The solids are then composted in a separate digestor, while the liquids are disinfected (where necessary) and discharged with the grey water system.

Chart from Aquatron


The Aquatron uses a normal flushing toilet and the Aquatron separator, which enables the flow of water to be diverted to a treatment and disposal system and the solids to be composted.  The system has the benefits of a flush toilet, mainly public acceptability and convenience, with some of the benefits of composting toilets, particularly no sludge and the creation of humus.

1. Aquatron uses standard Water Closets (flushing volume 3-6 litres) or special models where the urine is mechanically diverted from the flushing water and the solid waste in the bowl itself.

2. When the toilet is flushed, the contents of the bowl are transported to the Aquatron Separator where approx. 98 % of the liquid fraction is separated by using the momentum of the flushing water, centrifugal force and gravity. The Aquatron Separator needs no moving parts.

3. The solid waste (paper and faeces) falls down into the Bio Chamber where it is composted by bacteria and, if desired, by worms. If using worms, the volume of the solid waste will be reduced by approx. 95 %. The need for emptying and handling the waste is therefore reduced to a minimum. Optionally, after installing an Aquatron System, some 250-300 worms are placed into the Bio Chamber. The number of worms needed to maintain the composting process will be adjusted automatically by nature. Optimal temperature for the composting is 12-25 degrees Celsius, a temperature level recommended for year-round inhabited homes. Freezing will kill the worms. The composting process is free from odour and flies because the Bio Chamber is ventilated and the small amount of liquid following the paper down into the Bio Chamber is removed by a drain at the base of the Bio Chamber. When the Aquatron 90 and 400 models are emptied, the refuse must be composted to soil in the garden together with the normal garden and kitchen waste.

4. The liquid proceeds to the UV unit where it is exposed to Ultra Violet light, which kills bacteria and viruses. The liquid may then be treated as Grey Water (bath, dish washing and laundry water), which means that the toilet wastewater may be infiltrated into the ground or into a suitable receptacle. Since the liquid fraction is separated from the solid waste, Aquatron Systems are not sensitive to peak load usage.

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Composting toilet construction in Bolivia

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