Method for separating acetic acid in fermentation liquid for biohydrogen production by bipolar membrane electrodialysis technique

Abstract

The present invention relates to a method for separating acetic acid in fermentation liquid for biohydrogen production by bipolar membrane electrodialysis technique. The invention solves the problem that the prior method for separating acetic acid has complex technology, low current efficiency, large energy consumption and long operation time. The method comprises a first step of circularly pumping the pre-treated fermentation liquid for biohydrogen production into a separation chamber of a bipolar membrane electrodialyzer; a second step of circularly pumping pure water or acetic acid solution into an enriched chamber of the bipolar membrane electrodialyzer; and a third step of circularly pumping Na2SO4 electrolyte with the mass concentration of 5% into an anode chamber and a cathode chamber, and performing bipolar membrane electrodialysis so as to accomplish the separation of acetic acid in fermentation liquid for biohydrogen production. The operation time in the invention is decreased by more than 80%, the technology is simple, a separation system is of closed cycling, no pollutant is discharged, and the method is green and environment-friendly. The removal rate of acetic acid in the invention is more than 85%, the recovery rate of acetic acid is more than 85-95%, the current efficiency is up to 60-70%, and the energy consumption is reduced.

Description

technical field

[0001] The invention relates to a method for separating acetic acid in a biological hydrogen production fermentation liquid. Background technique

[0002] In the process of biological hydrogen production by fermentation, the optimum pH for the growth and hydrogen production of hydrogen-producing bacteria is 4.5-5.5. When hydrogen is produced, a large amount of organic acids are generated, which makes the pH of the fermentation system drop rapidly. Hydrogen fermentation produces strong inhibition, resulting in a decrease in the yield of hydrogen gas and liquid phase end products (volatile acids and alcohols). Generally, the pH of the fermentation system is controlled by adding alkali, which requires a large amount of alkali consumption, and the labor intensity and production cost are very high; traditional acetic acid separation methods, such as extraction methods, easily bring the extractant into the wastewater, causing secondary pollution ; Adsorption metho...