为解决柠檬酸行业的发酵废水污染问题，提出了柠檬酸沼气双发酵耦联工艺。前期研究发现，采用电渗析对厌氧消化液进行脱盐时，浓水易发生结垢现象；空气吹脱需要将厌氧消化液升温并维持在55 ℃，从而消耗大量能源。为解决上述问题，引入石灰软化-超滤技术以避免浓水结垢，并代替原先的空气吹脱工序。研究发现， Ca(OH)2最佳投加量为2.5 g/L，超滤最佳操作压强和膜面流速为0.20 MPa和4.023 m/s，此时，浓水朗格利尔饱和指数(Langelier saturation index, LSI)小于0，结垢现象得以消除。电渗析淡水作为配料水回用于柠檬酸发酵时，柠檬酸产量为(134.67±4.72) g/L，基本与去离子水发酵水平持平。

To solve the problem of fermentation wastewater in citric acid industry, the laboratory had proposed integrated citric acid-methane production process. Previous research indicated that scale formation was observed in anaerobic digestion effluent with electrodialysis treatment, and air stripping consumed energy to heat anaerobic digestion effluent to 55 ℃. In order to solve the above problems, lime softening-ultrafiltration technology was introduced to eliminate scale and replace air stripping. The optimal lime dose was 2.5 g/L. The optimal operating pressure and crossflow velocity respectively was 0.20 MPa and 4.023 m/s. The Langelier saturation index (LSI) of concentrate was less than 0 and the scale was removed. The citric acid production with the dilute of electrodialysis (134.67±4.72 g/L) was comparable to production with freshwater.