The TED - Biodigester Design grew out of about 20 years of experience with biogas - digesters in developing countries. It is the successor of the Tanzanian CARMATEC digester. It is a fixed-dome digester with an expansion channel according to the so-called Chinese Principle.
The TED Design provides a template for digester volumes from 8m3 to more than 100m3. The construction procedure stays the same for all sizes.
The maximum gas-pressure for all digesters is 0.1 bar and is fixed hydrostatically by the position of inlet and outlet openings. The proper functioning depends mainly on the brick layed structure which has a life expectancy of several decades.
The recommended size for a digester depends on the expected input type (human feces, cow manure, wastewater) and the input volume. Generally the digesters are overdimensioned by at least factor 2 compared to the theoretical necessary size to ensure steady operation.
We provide you with here with the
Manual for the Construction off a Bio Digester, “LUPO” Design
that was written by Christopher Kellner in 2002. It is suited to give an excellent idea about how TED's digesters are constructed.
However: This document in itself is not suited to enable you to build a biodigester by yourself!
That said, here you go.
Another very good ressource is the book DEWATS - Decentralised Wastewater Treatment in Developing Countries, Ludwig Sasse (1998).