If this technology is for real, I can see cities building refineries on-site at their sewage treatment plants, and then using it to run, well.... whatever diesel engines it works best for.
Of course, there's still solid waste to get rid of, but I think there's probably a lot less of it.
I beleive everything gets rendered to oil/gas, water, carbon, and minerals (basically, any non-hydrocarbons in the feedstock). As long as you can separate and collect the minerals, you should be able to return them straight to agricultural or industrial use, rather than having them as waste.
What interests me about this technology is if it could be used to, say, recycle city garbage into cheap heating oil it could do for the Northeast and Midwest what air conditioning did for Dixie.
According to other articles, human and animal sewage are one of their projected feedstocks. The efficency would be less because of the relative lack of lipids in sewage, but the avoided costs and environmental benefits are even more attractive.
As an aside, sewage plants already use methane extracted from the sewage to drive generators. Our little town does, generating enough electricity to mainly run the plant, but other cities generate enough to sell back to the grid.