I think you could use the macerator instead. You would have to be careful, even though it is extremely low flush by flush standards, it could add way too much liquid.
Subject: Pumping into a Biogas digester with Flushing Toilet
Hello all, I'm new to the forum and loving the discussions on here.
I've gone down the Biogas rabbit hole over the last couple months and I'm very intrigued!
I'm interested in building an off-grid cabin at some point, so all the systems are on the table and the more integration the better.
I've already decided that aside from an outhouse, I will also want an indoor toilet for when the elements are harsh.
While I could build a dry toilet or composting toilet and make some form of humanure with it, I'm interested in knowing if there is a more hands off way of dealing with the poop.
I don't want to carry buckets of poop in and out of the house on a regular basis.
Also, the idea of a septic system, while more hands off requires excavation and just seeps into the ground eventually, not providing usefulness along the way.
Since I want to have a biodigester anyway for methane production as my cooking fuel, I will have a lot of other biomass available to me. SO, I might as well put the poop in there too.
I am aware that there are issues with biogas like pathogen management, sufficient warmth, and large amount of biomass to methane ratio, but please save those discussions for a different post.
I don't want to be pouring blended poop down a funnel manually. And I want to minimize smells from any openings.
I would be using grey water in my toilet that has been recirculated through some solar heating tubes.
Also, if the macerating toilet works and is a good idea, maybe I would have a second one outside with an other sealed inlet tube into the biodigester for animal manure, food scraps and other organics.
I think my main area of uncertainty is the pumping action going to the digester. Most systems I've seen are gravity fed with a funnel and some sort of push tube. Would pumping introduce too much oxygen into the digester with each flush?
Is there a way to prevent effluent from violently flushing out with each toilet flush?