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.