Continuous processes for the anaerobic bioconversion of syngas to oxygenated hydrocarbonaceous products, in particular lower alkanols, are disclosed in which nutrients, including micronutrients, and lower carboxylate anion are recovered from at least a portion of an aqueous distillation fraction from a distillation unit operation to recover lower alkanols by using a “tight” ultrafiltration membrane. At least about 75 percent of the water permeates the ultrafiltration membrane. The tight ultrafiltration membrane rejects sufficient components that are adverse to the microorganisms used in the bioconversion that continuous fermentation operations over long durations can be achieved.