First we need to divide between continuous and discontinuous systems. Discontinuous systems are filled, digest and emptied. Lot of work. Pretty useless for a toilet.
Continuous systems are usually filled with water so that the entire environment is anaerobic. One the one side something goes in, while the same amount gets out on the other side.
So a flush toilet that comes with water is ideal because if you want to get the shit into the system water is the ideal transport medium.
The digestion process is not exothermic. It needs to get on temperature to function properly.
With the humanure of one family you are not getting far. There is not that much energy left in humanur. If you can combine it with compostable non-lignin containing material you will get far better results.
In my opinion humunur in a biogas system is always just an addition to the other stuff that you are feeding in when we talk family scale digesters.
Tom OHern wrote:I saw that you also posted in the Humanure toilet vs biogas digester? thread. Did you read all of that before posting this question? There are a lot of good thoughts there. One of the reasons I don't think it isn't done more often is that in order to produce enough cooking fuel for 1 or 2 people, it takes almost 1000lbs of human waste and an adult produces about 1lbs per day so that is a lot of input for very little output. It just isn't a cost effective system for biogas production. Now, if you already have a biodigester set up, it can handle any human waste that you add up to its capacity, but if you just have human waste, you are probably better off composting it via the Humanure method.
There are large scale system that have been done, but they are not cheap nor simple. They involve heat treatments systems for the inputs and UV sterilizations for the effluent output. When you say a "large number" how many are you saying?
Hi Tom OHern,
Thank you for your prompt reply. We have 500 people working in a industry 24/6 and 365 days. We want to use this biogas into the burner of a 100 Kg/hr Boiler.