Visit the Aquatron website at www.aquatron.se for a full explanation. But you are basically looking at a very simple composting toilet, that can take a conventional flushing toilet as an input (or in my case 9 toilets) - rather than the usual point of use, sit over a hole and drop some wood shavings down when you are finished. Nothing against them, but incorporating them into a new build let alone an existing property not very easy - especially a you may have 4 or 5 toilets in a typical reasonable sixed new build.
The other alternative, which is often a planning / building regs requirement if you are a new build and aren’t able to connect onto mains sewage is to use a Biobubble / Ecodigester / Klargester Biodisc unit which generally has an electrical demand (generally very low), some form of bacteria media, and the need to empty the unit generally 1 to 2 times per year at an estimated cost of £150 + the initial cost of the unit of £2500 + install. Moving parts and lots of tubes and ductwork equals potential blockages.
Aquatron solves all this - with no moving parts, no electrical requirement, just one kilogram of worms from www.wrigglyworms.co.uk. A bit of wood shavings thrown into the main chamber every few weeks, and a veggie patch in about 8 years time to empty your compost onto.