Acetic acid extraction from rumen fluid by forward osmosis

Abstract

This study evaluated the potential of extracting acetic acid from rumen fluid by forward osmosis (FO). Unlike other FO applications to extract water and reduce the feed water volume, this research used FO to mimic the ruminant intestines for extracting acetic acid from rumen fluid to a clean matrix with a minimum water flux. The FO extraction of acetic acid was optimised with a synthetic solution using cellulose triacetate (CTA) and thin film composite (TFC) polyamide membranes under different operating parameters (e.g. membrane orientation and stripping solution pH ). Under the same operating conditions the CTA membrane showed higher acetic acid transport than the TFC polyamide membrane. Increasing the stripping solution pH from 5.5–6.5 to 9.0–10.0 increased the acetic acid transport through both CTA and TFC membranes. On the other hand, the membrane orientation had no discernible effect on the transport of acetic acid. Under the optimum conditions, the FO process using the CTA membrane exhibited negligible water flux and extracted 27% of the maximum attainable acetic acid from the synthetic solution within 8 h of operation. The optimised conditions were used to elaborate the FO extraction of acetic acid from a real rumen fluid. Considerably lower extraction rate from the real rumen fluid was observed compared to the synthetic solution, suggesting the need for further research to address the complexity of the rumen matrix. • Acetic acid extraction was extracted by forward osmosis into a clean matrix. • Membrane properties and stripping solution pH govern the acetic acid extraction. • Acetic acid extraction from real rumen fluid was lower than the model solution. • Negligible water fluxes were observed under all extraction conditions.