For what it's worth, a friend of mine has a company that installs septic systems on boats. It's basically a garbage disposal and a fuel injector. The "masserator" pump grinds up all the "stuff" and then sends it to an injector system that injects the slurry into the exhaust pipe of the diesel engine. Obviously, there are some control logic on the system--it will only start injecting if the engine is running and is at least a certain temp. The exhaust gases burn all the stuff up and there is no odor out the pipe other than the normal exhaust smell. They also claim (EPA backs this up) that the emmissions are also lower when it's burning the sh1t......
They are also working on a system for RV's and buses. Do you think that's worth anything to anybody not to have to empty out the holding tank?