为解决柠檬酸行业废水对环境的污染，本文提出将厌氧消化液循环回用生产柠檬酸的工艺。研究发现，厌氧消化液直接作为工艺配料水循环回用对原料的液化没有影响，但对柠檬酸发酵产生抑制。进一步研究证明在厌氧消化液中的氨氮、钠离子、钾离子均会抑制柠檬酸发酵，其相应的临界抑制浓度分别为100、200、300 mg/L。本文采用超滤和纳滤的组合膜技术对厌氧消化液进行资源化处理，厌氧消化液中的抑制物得到了有效的去除，其中钾、钠离子的去除达到90%以上，氨氮的去除率也在80%以上。经过资源化处理后的厌氧消化液循环回用后其柠檬酸产量为139.25±1.85 g/L，达到了去离子水的发酵水平（138.70±2.46 g/L），经过资源化后厌氧消化液循环回用生产柠檬酸的新工艺是可行的，该工艺不仅减少了废水污染问题又节约了淡水资源，具有较高的经济效益、环境效益和社会效益。

A novel process for reuse of anaerobic digestion effluent in citric acid fermentation was investigated to resolve wastewater pollution in citric acid industry. Studies showed that anaerobic digestion effluent directly reused had no effect on liquefaction of raw materials, but produced inhibition for citric acid fermentation. Further experimental studies proved excess ammonia-nitrogen, Na+, K+in the anaerobic digestion effluent can inhibit citric acid fermentation and its corresponding critical inhibition concentration respectively 100, 200, 300 mg/L. In this paper, the combination of ultrafiltration and nanofiltration membrane technology was adopted to deal with the anaerobic digestion effluent, and these inhibitors have been effectively purified, including Na+, K+removal rate reached 90%, ammonia-nitrogen removal rate is over 80%. The anaerobic digestion treated by a combination ultrafiltration and nanofiltration reused in citric acid fermentation, citric acid production was 139.25±1.85 g/L，which was comparable to the control(138.70±2.46 g/L). The novel reusing process is feasible and not only reduces wastewater pollution problem and saves fresh water resources, has high economic benefit, environmental benefit and social benefit.