Project 5 - More about SIRDO

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The association which invented the SIRDO


       G.T.A. (Grupo de Tecnología Alternativa, S.C.)

workshop address (no offices):

C.P. 53270
TEL. 344 - 0312        FAX. 343 - 3748
R.F.C. GTA-831117-G13

Inventor of the decomposition process called "SIRDO" (lntegral System for Recycling Organic Waste).
Patente Mexicana C.I. 6758
M.R. 338568, SECOFI

With 15 years of experience in recycling liquid and solid domestic waste.

Departing from ethnobiological principles developed by the Mexican Indians, the ATG has adapted such bio-chemical principles to modern life, in order to preserve and restore the soil for the new generations of Mexico and the world.

The ATG is proud that their system are now installed and operating in 7 states in Mexico.


webpage: - spanish texts only!

Arq. Josefina Mena-Abraham, M. Sc.
President and founder.

Alamo 8-16 Col. Los Alamos,
San Mateo, Naucalpan, Edo. de México
CP 53230 MEXICO.
Tel. (5) 344-0312 FAX (5) 343-3748

THE ALTERNATIVE TECHNOLOGY GROUP is an NGO created in 1978 to devolop alternate ecological systems for processing human waste into low cost primary productive components such as water for irrigation and bio-fertilizer.

Years of applied research and experimentation yield the "SIRDO", a biochemical system that decomposes waste. Its design grew out of an indigenous Mexican agricultural system known as "Chinampa" still practiced today in Xochimilco, the floating gardens on the outskirts of Mexico City.

As in the Chinampa the treatment of dark water generates sludge of such characteristics that enable its use as "inocula" for aerobic decomposition of solid orgnic waste. Solar energy and controlled environmental factors, within the system, remove pathogens. The process is a Mexican Patent able to produce high quality bio-fertilizer. It eliminates the sludge problem generated by residual water treatment, at the same time as the garbage pollution.

SIRDO can be used in rural or urban environments. The highly adaptable process ranges from an integrated system that recycles solid waste, dark and grey waters for a housing development to a sophisticated domestic solid waste processor.

Technological development of this process has generated: 2 wet and 3 dry systems, each processing different types of waste which produce several different products.

Faecal matter is the main pollutant of the environment and essentially of the water we drink, from a bacteriological and parasitical point of view. For this reason the Mexico City's authorities and the Xochimilco delegation, have joined efforts with ATG in order to implement an adequate alternative: ecological sanitation units.

It is ATG's policy to provide alternatives with leading edge technology at a low cost to respond to real social needs, in order to sustain the environment, for the new generations of Mexico and our planet.


  • Eliminate pollution generated by solid human and other organic waste
  • Produce on site decentralized solutions to solve the drainage problem, preventing the contamination of rivers, springs and the underground water table
  • Decrease public expenditure of transporting solid waste to dumps, while simultaneously reducing sources of contamination
  • Produce high quality bio-fertilizer with recycled organic and faecal matter


Processes mixed water from conventional sewerage collector networks; this system is connected to the last register. The sludge and scum generated are transformed into soil improvers within a dual chamber covered by a solar collector. The effluent can be used for irrigation or be delivered to receptive water sources.
These systems have been developed for horizontal condominiums, real estate developments, low-income housing, clubs, hotels and farms.


This system combines 3 basic principles which, previously seemed impossible to combine. These are:
  • the use of conventional toilets
  • aerobic decomposition of organic and fecal matter
  • recycling dark and grey water (in 2 separated networks)
The system processes dark water generating sludge that is appropriate for aerobiosis which "inoculate" solid organic waste and transforms it into bio-fertilizer within a dual solar heater chamber. The remaining effluent is used for aquaculture.
The grey water is processed through a slow acting biological filter generating water appropriate to irrigate crops and gardens.


This system processes human and animal excrement with solid waste in a dual compartment chamber which is used alternately for the filling and drying phases on semester cycles. It produces bio-fertilizer free of pathogens. It is a substitute for latrines and includes a dry toilet which eliminates the use of water for sewage.

Dry SIRDO type 6M

Processes only human or animal excrement. Produces fertilizer and soil improver. Includes a dry latrine and a single solar heated chamber.

CEI Chamber (induced stabilization)

Processes solid organic waste from gardens and kitchens, as well as animal excrement in a dual chamber used alternately on a semester cycle for the filling and drying phases. The "inocula" is cured early in the process by adding liquid bacteria.


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