I work with sanitation in Africa so you can guess what the binder is. We pasteurize/hygienate feces with heat to deactivate pathogens. Poo, which has a high energy density, is a great binder for charcoal briquettes. I doubt that there will be tar problems in a gasifier.
Also, urine is a great nitrogen and phosphorus inoculant for biochar soil amendment. We are trying to create an ecological sanitation system that can be run as a business in villages of 500-1000 in rural areas. We think that we can deliver a very inexpensive service that creates fertilizer and cooking briquettes. This enterprise is two years old and we hope to have government approval later this year.
The carbonite is needed for a vehicle to transport the briquettes to a larger town where charcoal is the fuel of choice. Our customers still cook with dead sticks gathered from the national forest. The change over to charcoal cooking will take a while for our rural customers, but they really like our simple, odor-free, portable toilet.