Hi, the former lab tech is probably the first person you should contact. Aside from that I'd suggest dropping in on some local labs, and ask if they know of anyone who might be interested. They may even have someone willing to help out after hours.
Fwiw if you don't already know how to run the processes, etc., you probably won't be able to tell the difference between a real "expert" vs someone who knows just a bit more than you do. So a reference from a working lab has some value in this respect.
A commercial outfit is probably gonna need a sewering permit from the local municipality. Hopefully the studio owner is already on top of this. A regular photo lab tech is not likely to know much about this, or effluent control in general, but it's something that has to be dealt with. You can probably find information online with respect to local requirements. Fwiw this was one of the main reasons the so-called washless systems were developed, 1980s or so. No sewer hookup, so no permit needed - ALL waste was taken by licensed waste haulers.
Hopefully things will work out ok.