Lessons Learned: A Happy Ending to a Poopy Story

My new motto: “Without big problems, we wouldn't have great solutions” (said Daniel Lujan from my biodigester committee). This is the story of my experience exploding a biodigester.

A biodigester is a large “stomach” that converts animal (or in some cases human) manure into liquid fertilizer (biol) and methane gas through a natural anaerobic decomposition process. There are two main designs: a long-tubular biodigester design, usually made out of plastic, and Chinese concrete dome-design. The most important part - there is no air in the biodigester where the biological process is taking place. As long as there is no air, the natural bacterias that are in the mixture of animal manure and water will begin to decompose, producing methane gas in the process.   

Now back to our project...last year all signs were “go”: we had a hard-working committee, an approved grant, and a lot of animal poop. Early on we encountered some obstacles, including but not limited to, massive boulders that were hiding in the ground in the way of our trench, drawings that had the wrong dimensions, and flexible tubing that had a tendency to “kink” and not allow gas to pass through. We completed the biodigester in time for a late summer heat wave to bake the heck out of the biodigester, rapidly produce gas, and explode the biodigester bag. Needless to say, we all stood there staring at the hole in the biodigester, and we were heart-broken.

My community partners have often like to joke during the course of this project that our obstacles are just another part of our “grand biodigester adventure” (and another reason why I should marry a Peruvian and stay in Peru and work on this project forever). After we ripped the biodigester bag, we removed over 5,000 liters of manure-water-slurry and got the bag out of the trench. We then patched the 1-meter long hole with a liter of glue and 4m2 of patch material. After we repaired the hole, we leak-tested the patch by blowing up the bag with air and rubbing soapy water on the seams and checking for bubbles from escaping air. After leak-testing the bag it was ready to be re-installed in the trench, and commissioned for the second time.

Leak-testing the biodigester bag 

There we were, two months later, and we had a working biodigester producing liquid fertilizer and burnable methane gas for a stove. There were times throughout this process that we felt that we were never going to finish this project. Yet there we were, happily ever after. 

My lessons learned – worry less, don’t give up, and remember, as long as you didn’t get covered in animal poop during the course of your project, things probably aren’t really all that bad.  

Re-filling the biodigester

Repairing the hole

Back in business!