Firstly, due to long cycles, drying causes the manure to have a high solid content. This often means using large amounts of water (up to 6:1 water to manure) to make digestion viable. Also, pine shavings are often used as bedding in chicken houses. Wood contains a bi-polymer known as lignin, which requires energy to be digested (as opposed to producing energy). This therefore decreases viability of digestion. The high protein content of chicken manure can cause excessive build up of ammonium during the digestion phase. At high levels this becomes toxic to the methane-producing bacteria.
We have the technology to successfully digest pure chicken manure without the addition of additional substrates. We also have large facilities currently running some of which have an installed capacity of up to 5MW. That’s innovation.