Volatile Fatty Acid and Water Extraction from Rumen Fluid by Forward Osmosis

Publication Type:
Issue Date:
Full metadata record
Nature offers elegant, efficient, and sustainable solutions to most of our problems. One such problem is to convert the most abundant natural resource of lignocellulosic biomass into a fermented solution for subsequent biochemicals extraction. An efficient, economical and eco-friendly technique or system has not been developed yet to address this problem. Nature has offered a robust solution to this problem in the form of ruminant's digestive system where a fermented solution (rumen fluid) is produced from the digestion of biomass in the fore-stomach (or rumen) with the help of diverse microbiota followed by volatile fatty acids (VFAs) absorption from the rumen fluid in the small intestine along with water absorption in the omasum and large intestine. This study aims to replicate the two important processes taking place inside the ruminant's digestive system with a membrane-based forward osmosis (FO) process. First is the use of FO for acetic acid extraction from rumen fluid by mimicking the VFAs absorption in the small intestine. Under the optimum conditions, the FO process using the cellulose triacetate (CTA) membrane exhibited negligible water flux and extracted 27% of the maximum attainable acetic acid from the synthetic solution within 8 hours of operation. The optimised conditions were used to elaborate the FO extraction of acetic acid from a real rumen fluid. The second is employing FO for dewatering rumen fluid by simulating the water absorption in the omasum and the large intestine. High water flux and a low reverse solute flux (RSF) were observed using concentrated artificial saliva as a draw solution and clean water as the feed. Membrane fouling was observed with the deposition of mainly biomolecules from the rumen fluid on the membrane surface. Besides, this study also covers the membrane biofouling that can occur as a result of resource recovery from rumen fluid in a long term FO operation and evaluates the various membrane cleaning strategies for flux recovery. The results suggest that fouling is driven mostly by the gravity-driven deposition of foulants on the membrane surface. DNA sequencing showed that key microbial taxa from rumen fluid such as Prevotellaceae, Ruminococcaceae, and Acidaminococcaceae were also identified within the fouling layer. A combination of chemical cleaning using 0.1% NaOCl and osmotic backwashing using NaCl 1M solution was most effective with 70.0% flux recovery while hydraulic cleaning was the least effective and could only recover 14.1% flux.
Please use this identifier to cite or link to this item: