Improvements in biological conversion processes and associated apparatuses are disclosed for the generation of useful end products such as ethanol, through metabolic pathways of C1-fixing bacteria that utilize, as a nutrient, a C1-carbon source from a C1-containing substrate such as an industrial waste gas. Particular aspects of the disclosure relate to the downstream recovery of ethanol and/or isopropanol from bleed and permeate streams and more particularly to performing such recovery with improved efficiency that can advantageously reduce capital (e.g., equipment) and/or operating (e.g., utility) costs. Particular aspects related to the downstream recovery of ethanol and/or isopropanol using a low pressure separator having an internal divider.