Construct a Biogas Plant

Construction time and labour resources required to build a 3-CUBIC METER BIOGAS PLANT will vary depending on several factors. The most important consideration is the availability of people interested in doing this project. The project may in many circumstances be a secondary or after-work project. This will of course increase the length of time needed to complete the project.

The construction times given here are at best an estimation based on limited field experience. Skill divisions are given because some aspects of the project require someone with experience in metalworking and/or welding. Make sure adequate facilities are available before construction begins.

A biogas digester is the apparatus used to control anaerobic decomposition. In general, it consists of a sealed tank or pit that holds the organic material, and some means to collect the gases that are produced. Many different shapes and styles of biogas plants have been experimented with: horizontal, vertical, cylindrical, cubic, and dome shaped. One design that has won much popularity, for reliable performance in many different countries is presented in this book.

It is the Indian cylindrical pit design. In 1979 there were 50,000 such plants in use in India alone, 25,000 in Korea, and many more in Japan, the Philippines, Pakistan, Africa, and Latin America. There are two basic parts to the design: a tank that holds the slurry (a mixture of manure and water); and a gas cap or drum on the tank to capture the gas released from the slurry. To get these parts to do their jobs, of course, requires provision for mixing the slurry, piping off the gas, drying the effluent, etc. In addition to the production of fuel and fertilizer, a digester becomes the receptacle for animal, human, and organic wastes. This removes from the environment possible breeding grounds for rodents, insects, and toxic bacteria, thereby producing a healthier environment in which to live.

Some applications for the biogas:

• Gas can be used for heating, lighting, and cooking
• Gas can be used to run internal combustion engines with modifications
• Effluent can be used for fertilizer.

Some advantages:

• Simple to build and operate
• Virtually no maintenance–25-year digester lifespan
• Design can be enlarged for community needs
• Continuous feeding
• Provides a sanitary means for the treatment of organic wastes.

If you are considering this book, the 80 page document Biogas Plant Design(for only $9.00 dollars) is also worth having.

TABLE OF CONTENTS
I.              WHAT IT IS AND HOW IT IS USEFUL

II.             II. DECISION FACTORS
Applications
Advantages
Disadvantages
Considerations
Cost Estimate

III.            III. MAKING THE DECISION AND FOLLOWING THROUGH

IV.           IV. PRECONSTRUCTION CONSIDERATIONS
By-Products of Digestion
Location Size
Heating and Insulating
Digesters
Materials
Tools

V.            V. CONSTRUCTION
Prepare Foundation and Walls
Prepare the Gas Cap Drum
Prepare Moisture Trap
Prepare Mixing and Effluent Tanks

VI.           VI. OPERATION
Output and Pressure

VII. VARIOUS APPLICATIONS OF BIOGAS AND DIGESTER BY-PRODUCTS
Engines
Fertilizer
Improvised Stove
Lighting

VIII. MAINTENANCE
Possible Troubles

IX. TEST GAS LINE FOR LEAKS

X. DICTIONARY OF TERMS

XI. CONVERSION TABLES

XII. FURTHER INFORMATION RESOURCES A Listing of Recommended Resource Materials Useful Information for Methane Digester Designs

APPENDIX I. DECISION MAKING WORKSHEET

APPENDIX II. RECORD KEEPING WORKSHEET

NOTE: The 3-Cubic Meter Biogas Plant manual is a downloadable e-book. No physical products will be shipped. After you order, you will get instant access to download the e-book. The e-book format is adobe acrobat PDF, which can be viewed on Mac or PC.  This document was developed by Volunteers in Technical Assistance (VITA).  It makes available to individuals and groups technical resources aimed at fostering self sufficiency. The complete document is available for download at a facilitating cost of $9.00, which covers our bandwidth usage and site maintenance.