No effluent or solids recycle is required with the anaerobic filter because biological solids remain in the filterand are not lost with the effluent.

For processes requiring almost complete solids recycle, the liquid phase removed from the reactor was centrifuged to pellet the solids,and then the pellets were returned to the reactor.

Solids recycle is the return of solids to a liquid-solid operation so that they can be processedor used again.