Chain-elongation routes to caproic acid toward industry-ready continuous operation and low-energy recovery

Chain elongation converts organic waste into caproate. Wider application depends on stable, predictable performance at scale. This review examines the operational and engineering factors that underpin process robustness. It highlights how reactor configuration, process control, and microbial community management govern stability under variable feedstocks. It also discusses how these factors shift pathway competition and carbon flow. Product removal is central to feasibility. Effective separation relieves inhibition and enables continuous operation, while reducing downstream processing costs. Electrochemical and adsorption-based methods are promising. However, long-term durability and regeneration remain concerns. Key barriers remain: substrate inconsistency, community instability, and material performance limitations. To support industrial deployment, the review outlines priorities for tighter pH/redox control and closer reaction-separation integration. It also calls for clearer techno-economic evaluation to define feasible scale-up windows.