双极膜电渗析分离发酵液中L-乳酸

采用三室型双极膜电渗析装置将发酵液中的L-乳酸钠转化为L-乳酸。探讨操作电压、流速、进料L-乳酸钠质量浓度等工艺参数对转化过程的影响，考察电渗析过程参数对转化率、物料损失率、电流效率和能耗等技术指标的影响。在最优操作条件下（流速40L／h，电压15V）对2L的100．25g／L乳酸钠发酵液进行分批重复电渗析处理。结果表明：整个过程的转化率为81．22％，损失率为1．5％，能耗为0．81kW·h／kg，电流效率为91．8％，得到的L-乳酸质量浓度可达144．31g／L．电渗析残液补糖后可回到发酵罐中用于发酵生产L-乳酸.

Separation of L-lactic acid from fermentation broth by bipolar membrane electrodialysis

The separation of L-lactic acid was proposed from fermentation broth by bipolar membrane electrodialysis with three-chambers. Effects of operation voltage, flow rate and initial concentration of sodium L-lactate on some parameters were studied, such as conversion ratio of sodium lactate, loss rate, energy consumption and current efficiency in the processes. Results showed that the final L-lactic acid concentration was 144.31 g/L when fed-batch electrodialysis was performed to produce L-lactic acid from the broth containing 100.25 g/L of sodium L-lactate under the optimum conditions of operation voltage at 15 V and flow rate at 40 L/h. The conversion ratio of sodium lactate, loss rate, energy consumption, and current efficiency were 81.22%, 1.5%, 0.81 kW·h/kg, and 91.8%. Electrodialysis waste water su-pplemented with glucose was reused as a fermentation medium for L-lactic acid production.