摘要 |
A method of operating a pressure-retarded osmosis plant, the plant comprising at least one osmosis element having a semi-permeable membrane, the semi-permeable membrane defining a feed side and a permeate side of the osmosis element, the method comprising, in a first mode of operation, supplying a feed stream having a relatively high concentration of solute to the feed side, supplying a permeate stream having a relatively low concentration of solute to an inlet of the permeate side, and receiving a feed outlet stream from the feed side wherein permeate has passed through the semi-permeable membrane from the permeate side to the feed side, in a second mode of operation, supplying a backwash stream having a relatively low concentration to the feed side of the osmosis element such that water passes through the semi-permeable membrane, and receiving a permeate outlet stream from an outlet of the permeate side, the method further comprising alternately performing the first mode of operation, to perform a production step, and performing the second mode of operation, to reduce fouling of the semi-permeable membrane. |