Silva Digester Bundle – Paca digestora Silva (One-cube-meter Silva digester)
An organic waste compression system.
The system has been implemented in Colombia. However, the designer states it can be applied anywhere if there is organic waste.
The system is open-source and it can be implemented by anyone.
Target users include households and communities in general that have access to organic waste.
This product can be locally manufactured following the following steps:
a) Build the box: The process starts by building a 1 m x 1 m x 1 m box using wood planks. The planks of minimum length 1 m and varied width and thickness can be assembled using nails, wood screws, and hand tools.
b) Start the base: Place the box on the ground in an open space preferably outdoors (e.g., yard, parks, farms, or urban gardens). Place tree branches inside the box at the base to build support for organic waste. The space formed by the branches will allow draining rainwater.
c) Gather organic waste from your garden: This type of waste will form the first layer inside the box, on top of the three branches. Press this layer of waste using an earth rammer or stepping on it. The goal is to get very well-compressed organic garden waste.
d) Gather organic waste from your kitchen: Build the second layer forming a “nest” with organic waste from the garden and place organic waste from your kitchen inside the “nest.”
e) Cover the kitchen waste: Using another layer of garden waste, cover the kitchen waste very well, and compress the material until getting a compact compound.
f) Repeat the process until reaching the top of the box.
g) After a month, remove the planks and start a new bale.
Users can build their own Silva Digester Bundle by following the instructions published at this website
How much organic waste/how often added
Volume out compared to volume in
Time to decompose
Amount of nutrients recovered at the end of processing
Additional disinfection or other processes needed
The digester bundle uses a box made of wood planks. The dimensions of the box are 1 m x 1 m x 1 m and the size and thickness of the wood planks can vary. Wood strips can be used to join planks. Large plastic containers can work as an alternative to wooden boxes.
There is no technical support provided and users are expected to maintain the product on their own.
Wood planks can be replaced with plywood or any other kind of solid board.
According to the designer, the 1 m³ wood box allows users to process up to 500 kg of organic waste (combined garden and kitchen waste at a 50/50 proportion). After six months, the compound is transformed into approximately 150 kg (330 lbs.) of organic fertilizer.
The Silva Digester Bundle was tested at the “Villa del Socorro” neighborhood in Medellin (Comuna 2), Colombia but the results were not reported. However, the website shows images of the process of working with the community.
Testing performed by a research team from “Universidad de Antioquia in Medellin”, Colombia, to analyze the physical, chemical, biological, environmental, and sanitary aspects of 1 m³ digested bundles reported the following results:
- pH between 6, 11-8, 9
- Humidity 30.1%-67.3%
- Minimum internal temperature 25°C, maximum internal temperature 57°C at an ambient temperature between 19-24°C
- No ammonia, methane or hydrogen sulfide during the sampling process
- No rodents, flies, or domestic cockroaches found
- All decomposition process carried out by fungi, bacteria, and decomposer arthropods
- At the end of the process, 76% of the 1 m³ bundle was converted to compost
The same investigation implemented a survey on 101 people from the community and the results showed an elevated perception of the system as “healthy, easy-to-handle, and useful technique to develop recreational and teaching/learning activities.”
The engineering school and Centro de Extension Academica at the Universidad de Antioquia in Medellín, Colombia, have investigated about digester bundles and organized workshops to train students, faculty, and staff to build and replicate the system.
No known safety hazards are related to this product.
Ossa-Carrasquilla, L., 2016. Aplicación de la tecnología de las Pacas Biodigestoras para el tratamiento ecológico de los residuos orgánicos de la Universidad de Antioquia. Tesis de grado, Universidad de Antioquia.
Ardila Delgado, J., et al., 2015, Descomposición de residuos orgánicos en pacas: aspectos fisicoquímicos, biológicos, ambientales y sanitarios. Producción + Limpia, 10(2): 38-52.
The Universidad de Antioquia in Medellín conducted monitoring of pH, humidity, weight, temperature, volume, leachate, gases, microorganisms, arthropods, and rodents were carried out. 101 members of the educational community were surveyed. Database and analysis were performed using Epi-Info and Excel.
Several videos (in Spanish) with tutorials on how to build a digester bundle can be found on Youtube.
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