Manufactures and researchers/professors have been trying to push bioreactors onto civil engineers for wastewater treatment for years, because they're infinitely configurable and admittedly are neat, but they can't come remotely close to scaling up like a traditional WW treatment plant or even an activated sludge plant.

It's always seemed to be an inherent limitation of bioreactors.

Which tells me that the solution these people need to be looking for will resemble something between a wastewater treatment plant and an oil refinery, but in any case, steady state manufacturing, not bioreactors and batches.