Studies on membrane scaling during water desalination by direct contact membrane distillation

摘要

The formation of deposits on the membrane surface during membrane distillation (MD) of tap and ground saline water was studied. The effect of feed composition on the intensity of membrane scaling was discussed. Scanning electron microscopy observations indicated that a deposit, which precipitated during brine desalination, covered the entire surface of membranes, resulting in a decline of the membrane permeability. The impact of membrane morphology on the pores wetting was investigated in detail. It was found that hydrophobic membranes with small pores and thicker walls were recommended for commercial MD applications. They were found to be more resistant for wetting, especially if the scaling phenomenon occurred. A feasibility of freshwater production from brines was evaluated. During desalination of saturated NaCl solutions, almost 99% salt rejection was achieved.