The
conversion of organic waste into value-added chemicals provides
a sustainable pathway toward a circular economy, but anaerobic digestion
(AD) as an established technology has faced great challenges primarily
due to the low value of its primary productbiogas. Recent
developments on arrested methanogenesis allow the AD process to be
rewired to suppress methanogenesis and promote the production of higher
valued volatile fatty acids (VFAs). However, the separation and recovery
of VFAs from the mixed reactor constituents (microbes, salt, and organic
solids), remains a challenge. Membrane-based separation processes
are showing increased promise compared to other methods, as recent
studies reported high yield, high selectivity VFA recovery with low
energy consumption and reactor footprint. However, competing membrane
processes have not been quantitatively reviewed or compared, making
it difficult to understand the current state-of-the-art. This study
provided the first such analysis, comparing nanofiltration (NF), reverse
osmosis (RO), pervaporation (PV), membrane contactors (MC), and membrane
distillation (MD) for VFA separation and recovery. The study offers
a comprehensive characterization of the different membrane’s
selectivity and permeability under different conditions and compares
them side-by-side using normalized measures. In addition, the energy
demand and fouling potential were also analyzed. New opportunities
such as mixed matrix pervaporation membrane, antifouling electroactive
membrane, solar-heating membrane distillation, and integrated processes
were also explored to provide insights on technology advancement and
synergistic benefits.