Concept design class under the guidance of Prof. Tom Philipps
The usage process starts with the use of the toilet, which is a waterless system due to its individual sealing in fermentable bags. Once the business has been completed, the „flush“ is triggered and the excrements are placed in a bag produced from corn starch, which can be decomposed without leaving any residue, sealed and collected in a collecting container underneath the toilets. When this is full, the filled bags are placed in module two, where they are fermented at an operating temperature of 30-40°C and the gases are extracted to be stored in a gas storage tank for further use.
The biogas produced by anaerobic fermentation has a methane content of 60-70% and can therefore be used as fuel for the combined heat and power plant.
On the outside, it defines the design language of the individual modules, with large radii on the outer shell and small radii on handles and doors. The orange „bumper“ protects the cabin from transport damage and is made of aluminium. It is visible from a distance and detaches itself from the mostly miserable surroundings of the camps. The cabin is entered through a swing door whose surface is illuminated by a homogeneous LED panel. This shows the way at night and illuminates the area in front of the toilets, which is intended to counteract abuse and harassment, which often occurs in refugee camps on or near the toilets. In addition, the panel illuminates the interior of the cabin and bathes it in a pleasant warm light that harmonises well with the curves of the interior.
The biomass is permanently moved by a rake, which accelerates fermentation.
Acidogenesis: Further degradation of the shorter compounds formed during hydrolysis to organic acids (mainly carboxylic acids) and alcohols. This produces substances such as butyric, propionic and acetic acids, but also substances undesirable for the quality of the biogas such as hydrogen sulphide and ammonia (mainly due to the nitrogen of the proteins).
Acetogenesis: The substances produced by hydrolysis and acidogenesis are degraded by microorganisms to acetic acid and its dissolved salt (acetate). Due to the disappearing alcohols and further increase in acids, the pH value drops.
Methanogenesis: Methane is formed in two different ways. First (A) from acetic acid, which is broken down into methane by methanogenic bacteria. Second (B), methane and water are formed from elemental hydrogen and CO2.
(A) CH3COOH -> CO2 + CH4
In the combined heat and power plant, the biogas is converted into electrical energy and forced thermal energy by combined heat and power generation. The latter is either used to heat public places, such as the hospital ward, or is further converted into electrical energy. This can then be used by residents to charge their mobile phones, laptops, radios and other electronic devices.