Application of membrane technology and evaporating crystallization process in zero-discharge of high salinity wastewater from VB12 industry

Vitamin B12 pharmaceutical wastewater has the characteristics of high COD, high salinity, high ammonia nitrogen and high hardness, which is difficult to meet the relevant emission standards by conventional treatment processes. In this article, the process route of "biochemical treatment-concentration and separation of membrane system-evaporative crystallization” was adopted to realize zero-discharge treatment and utilization of vitamin B12 pharmaceutical wastewater. In this process, biochemical pretreatment of "hydrolysis acidification+anaerobic+aerobic” incubated by salt tolerance measure was adopted firstly, the membrane technology of "chemical softening+reverse osmosis preconcentration+nanofiltration for separating salt+reverse osmosis reconcentration+purification” was adopted subsequently. The purpose of concentrating salt and separating salt was achieved and the production water met the reused standard for reclaimed water. The concentrated liquor produced from membrane system was evaporated to crystallize, the purity of NaCl produced by the evaporation system could retain≥99.0%, and the purity of Na2SO4 could retain 96.0%, which met the corresponding standards in Industrial Salt (GB/T 5462-2015) and Industrial Anhydrous Sodium Sulfate (GB/T 6009-2014) respectively. This process has the characteristics of high removal efficiency and stable operation, which provides a reference as engineering case for the zero-discharge treatment and resource utilization of similar wastewater.