Fang Li has completed his PhD at the age of 27 years from Donghua University and postdoctoral studies from the University of Texas at Austin. He is the Vice Director of Textile pollution controlling Engineering Centre of Ministry of Environmental Protection. He has published more than 50 papers in reputed journals .
The feasibility study of utilizing direct contact membrane distillation for the treatment of industrial dyeing wastewater and their characteristic pollutants were demonstrated. Two commercial hydrophobic membranes made of polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) were comparatively studied. The results suggest that PTFE membrane always demonstrates enhanced flux and rejection performance for selected characteristic pollutants of dyeing wastewater compared with that of PVDF counterpart, which can be caused by its enhanced porosity, hydrophobicity and reduced wettability. Additionally, the PTFE membrane shows excellent stability with an average sulfanilic acid (one selected non-volatile characteristic pollutant of dyeing wastewater) rejection efficiency of 99.8±0.1% over 48 h continuously running. The effects of several key operational parameters (e.g., operational temperature, time, feed concentration and flow rate) on the treatment performance were also systematically studied. When challenging the industrial and synthetic dyeing wastewater, the DCMD system demonstrate different performances in terms of flux and rejection efficiency, which are closely related to the sample compositions and concentration. The relevant COD and color removal efficiency over 48 h continuous operation was, respectively, 90% and 94% for sample 1# (from discharge outlet of the dyeing vat wastewater), 96% and 100% for sample 2# (from discharge outlet of the wastewater treatment plant after physicochemical and biological treatment), and 89% and 100% for sample 3 (synthetic dyeing wastewater after bench-scale membrane bioreactor treatment). Furthermore, various advanced characterization techniques, (e.g., field emission scanning electric microscopy, energy-dispersive spectrum, Fourier transform infrared spectroscopy, 3-dimensional excitation−emission matrix fluorescence spectroscopy, contact angle, and gas chromatography-mass spectrometry) were employed to study the fouling properties and performance of the PTFE membrane. These overall findings suggest that direct contact membrane distillation (DCMD) process is a promising option for the treatment of dyeing wastewater with limited energy consumption and high performance.