| abstract |
An object of the present invention is to provide a method for producing purified lactic acid for producing lactic acid suitable as a polymer raw material by desalting and purifying lactic acid obtained by fermentation by an ion exchange method. A lactic acid solution sent from a solid-liquid separation step 22 is supplied to a first cation exchange column 32, then supplied to a second cation exchange column 37, and discharged to a solid-liquid separation step 24. . When the adsorption capacity of the first cation exchange column 32 is consumed, alkali metal ions leak and are adsorbed and removed by the second cation exchange column 37. When calcium ions start to leak from the first cation exchange tower 32, the calcium ion leakage monitor 47 detects this. As a result, the valves 31, 34, 39, 42 are closed, and the valves 51, 54, 59, 62 are opened instead. At the same time, the pumps 36 and 41 are stopped, and the pumps 56 and 61 are operated instead. [Selection] Figure 5 |