This document provides instructions for building a biodigester system to produce biogas from food and animal waste. It details the necessary materials which include PVC piping, buckets, tubing, and stakes. Steps include digging a trench, lining it with plastic, installing gas outlets and valves, filling it with water and initial inputs of manure and water. Regular daily inputs are recommended to get the system functioning properly within 30-60 days, producing biogas that can be piped to a kitchen stove for cooking fuel.

1. BIODIGESTORES

2. Materials
1. 1 PVC macho adaptor ½”
2. 2 five gallon buckets with the bottoms removed
3. 1 PVC hembra adaptor ½”
4. 2 non-corrosive washers (4-6 inch diameter) with a ½” hole
5. 2 rubber spacers 1 inch of equal or greater diameter than the
washer
6. 1 PVC Tee conjunction ½”
7. 1 PVC ninety degree conjunction ½”
8. 1 ½” metal valve
9. 4x4 inch piece of metallic screen
10. 3-4 feet of ½” PVC tubing
11. 1 roll of plastic hose ½” (amount determined by distance of the
biodigestor from the kitchen)
12.1 two liter plastic bottle
13. 4 one meter sturdy stakes
14. 2 two meter posts
15. ¼ gallon PVC glue
16. Rope 5-10 feet longer than the biodigestor bag
17. Saw (to cut PVC), scissors, machete, pick axe, shovel, hoe,
twine or string

3. SIGHT PREPERATION
A ditch 8m x 1m x 60cm with an approximate
difference of 5cm from entrance to exit
(ditch dimensions will vary according to plastic)

4. Clear ditch of any debris that could puncture
the plastic.

5. Walls of ditch spackled with mud to cover
protruding root ends.

6. 2. Excavate a stair at both ends of the ditch
(approximately 20cm deep, 45cm wide).
(1. Provisional, well secured posts need to also be installed
at both ends of the ditch (approx. 2ft. behind the stairs).

7. Extend 10m of plastic over a clean concrete surface
(note: no shoes on the plastic).

8. After cutting the first 10m, extend an equal amount of
plastic again through the cut portion.

9. After extending the second portion, take care to align
the two bags so as to avoid any folds or bunching.

10. Once the two bags are aligned, extend a rope
(approximately 15m) through the double bag and tie it
off at the secured posts on both ends of the ditch so as
to leave the bag hanging, however, touching the
ground.

11. Once the bag is in place the gas outlet can be installed.
You’ll need two non-corrosive palm size washers, and
two rubber spacers of equal or greater size.

12. Insert a ½ inch PVC hembra adaptor with the rubber
spacer on top of the non-corrosive washer, and
likewise with the ½ inch PVC macho adaptor.

13. The location of the gas outlet will depend largely on the general
surroundings of the ditch. The hole does not need to be in the
middle of the bag, it can be placed towards one end or another so
as to take advantage of hanging branches for the outlet’s support.
If there are no surrounding branches to support the outlet tubing, a
post may be installed to serve the same purpose.
Once the location has been chosen,
make a small cut, no bigger than a
½ inch, through the double bag.

14. The hembra adaptor is placed inside the bag, tightened
with the macho adaptor on the outside.

15. Once the gas outlet is in position, the bag is
filled with unchlorinated water to
approximately 4 inches below the stairs on
both ends of the ditch.

16. As the bag fills with water, the rope sustaining it is
removed and the outlet tubing is glued into place,
taking into consideration the direction of the kitchen
and the height of any supporting branches.
Note: take special
care that no glue
touches the bag.

17. After cutting a ½ inch size hole in a 2 liter bottle, a tee conjunction
is placed at a distance determined by the supporting branch. The
2 liter is then filled approximately half full with water to submerge
the PVC extension. The submersion allows for excess gas to
escape while preventing air from entering the system.
A small metal screen is inserted into
the tee conjunction to prevent the
flame from passing into the system.

18. Once tied to the supporting branch, the primary valve is
installed at a short distance from the excess gas release.

19. Two stakes are hammered securely in place at a distance the width
of the bucket on both ends of the ditch. The plastic is then pulled
through the bucket, folded over, and tied to both bucket and the
stakes with a long 2 inch wide strip of rubber (any rope will do).

20. It is essential that each bucket be submerged in at least 3-4
inches of water to prevent gas from escaping. The entrance
bucket rest in an up-right position while the exit bucket is tilted
at a 45 degree angle to allow the passage of excess liquids.

21. The suggested initial input to bring the biodigestor up to a functional
level is 20 buckets of two shovels of cow manure (one shovel of pig
manure) mixed with five gallons of water. The same mixture is added
once a day for at least eight consecutive days following the original
mixture; after which point the input may continue as such or decrease
to every other day. One can expect a period of at least 30-60 days until
the biodigestor is operating at full capacity.
Note: all mixtures should
be well liquefied, any
incorporated fruit should
also be well shredded.

22. In the Kitchen

23. Two valves are secured to the stove, then depending
upon the placement of the stove and the direction of
the incoming tubing, a 90 degree and tee conjunction
are placed accordingly.

24. A small piece of PVC is measured and
cut to bridge the two conjunctions.

25. To avoid reaching across an open flame to
close the valves, recommended valve
placement is between the burner and the stove
operator.

26. ¡Buen Provecho!