Polyhydroxybutyrate-calcium alginate/carboxyl multi-walled carbon nanotubes composite nanofibrous filtration membranes (PHB-CaAlg/CMWCNT) were prepared by electrospinning technique combined with redissolving the top hydrogel nanofibrous layer to form dense thin film as barrier layer on PHB nanofibrous substrate through suitable water mist wetting process and Ca2+ cross-linking. The obtained PHB/CaAlg nanofibrous membrane by synchronization electrospinning could improve the hydrophilic property as middle layer and closely integrate with the top hydrogel layer. The morphology of the membranes was observed by SEM. The hydrophilic property, tensile mechanical property, dye adsorption and filtration properties were characterized. The results showed that the tensile mechanical property and hydrophilic property of PHB-CaAlg/CMWCNT membrane were significantly improved, and the dye Brilliant blue adsorption capacity was twice higher than PHB-CaAlg membrane. The flux and rejection rate of PHB-CaAlg/CMWCNT membrane for Brilliant blue were 32.95 L/m(2) h and 98.20%, respectively. The thickness of PHB-CaAlg/CMWCNT membrane was about 40-50 mu m and the membrane consisted of 20 mu m PHB nanofibrous substrate, 10 mu m PHB/CaAlg membrane and 10-20 mu m CaAlg/CMWCNT membrane. The optimum time of water mist wetting process and Ca2+ cross-linking was 5 min and 8 h, respectively. This PHB-CaAlg/CMWCNT membrane has promising applications as nano-filtration membrane with high flux and rejection rate for small organic molecules in wastewater under low operating pressure. (C) 2016 Elsevier B.V. All rights reserved.