The performance of different nanofiltration （NF） and reverse osmosis （RO） membranes was studied in treating the toxic metal effluent from metallurgical industry. The characteristics and filtration behavior of the processes including the wastewater flux, salt rejection and ion rejection versus operating pressure were evaluated. Then the wastewater flux of RO membrane was compared with theoretical calculation using mass transfer models, and good consistency was observed. It was found that a high rejection rate more than 95% of metal ions and a low Chemical Oxygen Demand （COD） value of 10 mg·L^-1 in permeate could be achieved using the RO composite membrane, while the NF rejection of the salt could be up to 78.9% and the COD value in the permeate was 35 mg·L^-1. The results showed that the product water by both NF and RO desalination satisfied the State Reutilization Qualification, but NF would be more suitable for large-scale industrial practice, which offered significantly higher permeate flux at low operating pressure.
Non-porous polyether sulfone hollow fibers(with a 5 μm poly(dimethylsiloxane)coating)were used as structured packing in the distillation of ethanol-water solutions.In this novel membrane contactor,liquid flowed through the lumens of the fibers,and vapor flowed countercurrently outside the fibers.The results showed that the new membrane contactor gave better,more productive separations than traditional packing in distillation.The minimal HETP of hollow fibers could reach as low as 5.8 cm,and the contactor worked well above the limit where flooding normally occurs in conventional cases.The overall mass-transfer coefficient and individual mass-transfer coefficients based on the gas side and liquid side were calculated respectively.The theoretical analysis indicated that the resistance in the liquid was responsible for more than half of the total resistance.
