DIY Biogas: March 2014

It really is just two plastic barrels, one inverted inside the other, with three pipes -- one to get the food in, one to take the liquid fertilizer out and one at the top to deliver the gas to your cookstove or generator. 1000 liter tanks should get you about 2 hours of cooking gas a day if you live in a warm climate.

Cows eat food, not manure, and the bacteria in the cows stomach and intestines also eat that food, mixed with saliva and water. The goal is to replicate the inside of a cow's digestive tract to help the bacteria get the most energy from the food.

We only use the dung/manure to"innoculate" the system on the first day because it is the easiest non-invasive way of getting the "bacterial biogas experts" out of the animals' guts and into the tank.

In many respects making biogas is similar to making yoghurt. If you have a friend who has an active culture of methanogens from their own biogas digester (or from a septic tank, or from their baby's diaper just put them in. If you don't use manure, however, I'm not sure what or how much to feed them in the beginning.

Start up:

The process working with mesophils from animal dung, however, is started very simply by taking about 40 or 50 kg (maybe 4 to 6 10 or 15 liter buckets) of manure (we used horse manure in Germany, cow manure in Egypt, but any manure will do) and mix it into the bottom container with water (this is per 200 liters of water but we just go ahead and fill the whole thing even up to a 1000 liters of water; it may make the wait time for first flammable gas a bit longer as it takes the bacteria time to reproduce and fill that volume, but it worked fine for us as we didn't want to haul in more manure.). Then put the top barrel on and open the top valve so all the air escapes and the top barrel sinks down into the bottom barrel all the way.
You then close the valve at the top so no air can get in and just let it sit there for anywhere from 2 weeks to a month (depending on climate). During this boring period the bacteria will multiply. At first they will just produce CO2. After a few weeks open the valve and flame test with a candle (we didn't use a flashback arrestor! Doh! :) ) . The first couple of times the escaping gas will blow out the candle. Eventually, after a few days, the methane content will exceed 50%.
Once the gas starts to burn you can start feeding your digester ground up food waste (mixed in a blender with water, about 1 to 2 Kg a day, but start slowly so as not to overwhelm the bacteria; start with 200 grams then 400 the next day etc.). Soon the CH4 content at the top of the tank will exceed 60% (since CO2 is water soluble it can get up to 70%) and can be directly used in cook stoves and engines. Hope that helps explain it. It works well and is fairly simple you'll find. Give it a try !

Note:

Remember you only have to put the manure in THE VERY FIRST DAY. After this no more manure is needed.

The current process of biomethanation, which uses feedstocks like cattle dung, human feces, distillery effluents etc. is highly inefficient, because the nutritionally available calories and nutritive value of those substances is quite low.

ARTI developed in 2003 a new biogas technology which uses high calorie feedstock, consisting of starchy or sugary material. This material is capable of producing about 250 kg of methane per ton of feedstock (on a dry weight basis) and the reaction takes only 1 day to complete. In the case of a household biogas system, application of daily just 1 kg of feedstock is enough to provide a family with sufficient biogas to cook all the meals. The material that can be used as feedstock in the new biogas system consists of waste grain, seed of any plant species, oilcake of non-edible oilseeds as well as nonmarketable or nonedible fruits (wild species of ficus, overripe mango and banana). Even the flour mill can be used as feedstock.

Read full story here: http://solarcities.blogspot.com/2009/09/animation-of-simple-telescoping-biogas.html

DIY Biogas

Mini methane digester

The uses and equivalent of biogas

ARTI Style Methane Generator System

Biogas fuel without end