Green treatment of turbid traditional Chinese medicine (TCM) wastewater: Optimization of UF-MD coupling process

In this paper, a hybrid system of ultrafiltration and membrane distillation was used to study the resourceful reuse of active compounds and water resources in traditional Chinese medicine wastewater. Pre-treatment of turbid wastewater by ultrafiltration (UF) was found to maximise the retention of macromolecular organic matter in the wastewater using a 10 kDa ultrafiltration membrane at a trans-membrane pressure of 0.15 MPa. The UF filtrate was subjected to vacuum membrane distillation (VMD) at 60 °C, 95 kPa, 36 L·h −1 , and pH = 3, which ultimately recovered about 85 % of chlorogenic acid as well as about 74 % of baicalin. The UF-MD system can effectively separate the large organic molecules, small molecules of active compounds and water in the turbid wastewater of traditional Chinese medicine, so as to realise the recovery and reuse of valuable resources in the turbid wastewater of traditional Chinese medicine. • Conventional processes focus only on the treatment of wastewater. This study not only enabled the wastewater to meet the discharge standard, but also further recovered the active substances in the wastewater of traditional Chinese medicine. • The UF process can significantly reduce the COD concentration of wastewater without affecting the concentration of active compounds. • The effects of temperature and pH on VMD flux and active compounds are more pronounced.