Methane Digesters
For Fuel Gas and Fertilizer

With Complete Instructions For Two Working Models


L. John Fry
Santa Barbara, California

"Methane Digesters" is also published, independently, as Newsletter No. 3, Spring 1973,
by The New Alchemy Institute, Box 432, Woods Hole, Massachusetts 02543, price $3.00.

Eighth Printing

© 1973 L. John Fry
Richard Merrill

Inspiration: L. John Fry
Contributors: L. John Fry, Richard Merrill
Editors: Richard Merrill, Yedida Merrill
Artwork: Beth Amine
Thanks to: Earl Barnhart
Kim Mitchell

Table of Contents

1 Background
Methane-Gas Plant: Synergy at Work

2 History

3 Biology of Digestion
Bio-Succession in the Digester

pH and the Well-Buffered Digester

4 Raw Materials
Digestible Properties of Organic Matter
Amount of Manure Collectable
Manure Production and the Livestock Unit
Carbon to Nitrogen Ratio (C/N)
Calculating C/N Ratios

5 The Gas

Fuel Value
Amount of Gas From Different Wastes

6 Digesters
Basic Digester Design

Raw Materials and Digester Design
Loading Rate, Detention Time and Digester Size
Heating Digesters
Insulating Digesters

7 Using Gas
Properties of Methane

Uses of Methane
Efficiency of Digestion

8 Using Sludge

Sludge as a Fertilizer

Sludge Gardening and Farming
Sludge-Pond Cultures

9 Building a Sump Digester
Making Starter Brew

10 Building an Inner Tube Digester
Inner Tube Digester Parts List
1. Main Chamber of the Digester
2. The Plastic Insert
3. Attaching the Cylinder to the Inner Tube
4. Inlet Fittings and Attachment of the Slurry (Feeding) Bucket
5. Fitting the Effluent Pipe
6. Fitting the Gas Outlet
7. The Scum Collector
8. Gas Yield Indicator
9. Pressure Release Bottle
10. Inner Tube Storage
11. Burner
12. Temperature
13. The Bacterial Brew
14. Feeding
15. Removing Scum and Effluent
16. Safety Precautions
17. Lighting the Flame
18. pH

11 Necessity is the Mother of Invention

Design of the First Full Scale Displacement Methane Plant
Digester Description

12 References

Next: 1 Background

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