Integrated Membrane Process for the Purification of Lactic Acid from a Fermentation Broth Neutralized with Sodium Hydroxide

Abstract

Lactic acid, mainly produced by fermentation, has been widely used in the food, chemical, and pharmaceutical fields. Because of the high downstream processing costs in traditional technology, the cost-effective production of high-purity lactic acid has remained a challenge for decades. This study provides an integrated membrane process to recover lactic acid from sodium salt fermentation broth that consists of ceramic membrane filtration, nanofiltration (NF), and bipolar membrane electrodialysis (BMED). In the ceramic membrane process, the flux changed with the membrane pore size in the order of 50 nm > 200 nm > 500 nm > 20 nm. At an operating pressure of 0.1 MPa, the flux of the membrane with a pore size of 50 nm reached a maximum of 192 L·m–2·h–1, and the removal rate of cells was up to 99.3%. In the subsequent NF step, the flux increased linearly with the operating pressure from 0.5 to 2.0 MPa, whereas the rejection rates of Mg2+, Ca2+, and Na+ increased with increasing TMP, and a flux of 5.0 L·m–2·h–1 was obtained at the operating pressure of 2.0 MPa, with 87.7% of Ca2+, 95.0% of Mg2+, and 98.9% of protein being retained. The BMED process was developed for the conversion of 95.0% NaL into NaOH and HL, and the energy consumption was 1.05 kWh·kg–1 under a current density of 400 A·m–2. Our results indicate that the proposed integrated membrane process is technically feasible for lactic acid production from fermentation broth.

Toward Resource Recovery from Textile Wastewater: Dye Extraction, Water and Base/Acid Regeneration Using a Hybrid NF-BMED Process

“…Similar with BMED stack run at constant current density mode, a quasi-steady stage for BMED operation at constant voltage mode was obtained. 50 During the steady operation, the increase in acid/base concentration in the BMED stack was observed to compensate the increase in the electrical resistance of the feed compartment, keeping the electrical resistance of the BMED stack constant. In the ultimate stage, the full exhaustion of salt in the feed resulted in a high resistance of the membrane stack (see Figure 4A) with a sharp decrease of the current.…”

Highly efficient synthesis of cumene via benzene isopropylation over nano-sized beta zeolite in a submerged ceramic membrane reactor

“…The filtration rate increased as the transmembrane pressure was increased from 0.1 to 0.3 MPa, and then almost kept stable with further increase in transmembrane pressure. The enhanced transmembrane pressure is known to proceed the reaction mixture passing through the membrane more quickly [29]. Meanwhile, the cake layer on the membrane surface was compressed more tightly.…”

Lactic acid production in a membrane bioreactor system with thermophilicBacillus coagulans: fouling analysis of the used ceramic membranes

“…(44,45), flux decline during filtration processes can be caused by different factors. The hydraulic resistance-in-series model is applied for analysis and prediction of the filtration behavior of fermentation broth, where the membrane resistance (R m,0 ), solute concentration polarization resistance (R cp ), gel layer resistance (R g ), solutes adsorption resistance (R a ), pore blockage resistances (R p ), and cake layer resistance (R c ) are taken into account in the following (46,47):…”