Abstract: A method and system for performing maintenance on a membrane having semi-permeable properties and is used in a pressure retarded osmosis PRO, the membrane having a high pressure first side and second side of lower pressure. A time controllable first valve or pump (31; 41; 51; 61; 71; 81; 91) is connected between an input (12) to the low pressure side of the membrane (13?) and an input (11) to the high pressure side of the membrane (13?), said first valve or pump operable to selectively deliver a plug (21) of a second type of water (FW) to the first side of the membrane to lower concentration of dissolved substance (s) in water of a first type (SW) thereat, thereby creating a PRO pressure backwash function with the water of the second type (FW) from the first to the second side of the membrane pressurized on said first side by high pressure supply of water of the first type (SW) upstream of said plug (21) of water of the second type (SW).

Abstract: The present invention concerns a semi-permeable membrane for use in osmosis consisting of one thin layer of a non-porous material (the diffusion skin), and one or more layers of a porous material (the porous layer), where the porous layer has a structure where porosity ?, thickness of the porous layer (m), and tortuosity ?, are related to one another as given by the expression: x·?=?·S wherein S is a structure parameter having a value equal to or less than 0.0015 meter. Further a method for providing elevated pressure by osmosis as well as a device for providing an elevated osmotic pressure and electric power is described.

Abstract: The present invention concerns a semi-permeable membrane for use in osmosis consisting of one thin layer of a non-porous material (the diffusion skin), and one or more layers of a porous material (the porous layer), where the porous layer has a structure where porosity ?, thickness of the porous layer (m), and tortuosity ?, are related to one another as given by the expression: x·?=?·S wherein S is a structure parameter having a value equal to or less than 0.0015 meter. Further a method for providing elevated pressure by osmosis as well as a device for providing an elevated osmotic pressure and electric power is described.

Abstract: The present invention concerns a semi-permeable membrane for use in osmosis consisting of one thin layer of a non-porous material (the diffusion skin), and one or more layers of a porous material (the porous layer), where the porous layer has a structure where porosity ?, thickness of the porous layer (m), and tortuosity ?, are related to one another as given by the expression: x·?=?·S wherein S is a structure parameter having a value equal to or less than 0.0015 meter. Further a method for providing elevated pressure by osmosis as well as a device for providing an elevated osmotic pressure and electric power is described.

Abstract: A method and system for performing maintenance on a membrane having semi-permeable properties and is used in a pressure retarded osmosis PRO, the membrane having a high pressure first side and second side of lower pressure. A time controllable first valve or pump (31; 41; 51; 61; 71; 81; 91) is connected between an input (12) to the low pressure side of the membrane (13?) and an input (11) to the high pressure side of the membrane (13?), said first valve or pump operable to selectively deliver a plug (21) of a second type of water (FW) to the first side of the membrane to lower concentration of dissolved substance (s) in water of a first type (SW) thereat, thereby creating a PRO pressure backwash function with the water of the second type (FW) from the first to the second side of the membrane pressurized on said first side by high pressure supply of water of the first type (SW) upstream of said plug (21) of water of the second type (SW).

Abstract: The present invention concerns a semi-permeable membrane for use in osmosis consisting of one thin layer of a non-porous material (the diffusion skin), and one or more layers of a porous material (the porous layer), where the porous layer has a structure where porosity ?, thickness of the porous layer (m), and tortuosity ?, are related to one another as given by the expression: x·?=?·S wherein S is a structure parameter having a value equal to or less than 0.0015 meter. Further a method for providing elevated pressure by osmosis as well as a device for providing an elevated osmotic pressure and electric power is described.

Abstract: The present invention concerns a semi-permeable membrane for use in osmosis consisting of one thin layer of a non-porous material (the diffusion skin), and one or more layers of a porous material (the porous layer), where the porous layer has a structure where porosity ?, thickness of the porous layer (m), and tortuosity ?, are related to one another as given by the expression: x·?=?·S wherein S is a structure parameter having a value equal to or less than 0.0015 meter. Further a method for providing elevated pressure by osmosis as well as a device for providing an elevated osmotic pressure and electric power is described.