Method of Filtering Water

A filtration unit comprising:

• a filtration vessel containing at least one dead-end filtration element, wherein the at least one-filtration element comprises a plurality of hollow fibre microfiltration or ultrafiltration membranes wherein each hollow fibre has a first inlet and a second inlet at the first and second ends thereof, respectively, in fluid communication with the inside of the hollow fibre, and wherein the at least one filtration element has an outlet at one or both of the first and second ends thereof in fluid communication with the outside of the hollow fibres;
• wherein:
• (i) the first inlets of the hollow fibres of the at least one filtration element are connected either directly or indirectly to a first dedicated feed line via a first dedicated feed port in the filtration vessel and the second inlets of the hollow fibres of the at least one filtration element are connected either directly or indirectly to a second dedicated feed line via a second dedicated feed port in the filtration vessel;
• (ii) the outlet of the at least one filtration element is connected either directly or indirectly to a filtrate line via a filtrate port in the filtration vessel;
• wherein the first and second dedicated feed lines and the filtrate line each have a valve provided with an actuator wherein the actuators are independently actuatable to move the valves between an open and closed position.

A filtration unit comprising:

• a filtration vessel comprising at least two dead-end filtration elements arranged in a row, wherein each of the at least two dead-end filtration elements comprises a plurality of hollow fibre microfiltration or ultrafiltration membranes, wherein each hollow fibre comprises a first inlet and a second inlet at first and second ends thereof, respectively, in fluid communication with the inside of the hollow fibre, wherein each of the at least two dead-end filtration elements has an outlet at one or both of the first and second ends thereof in fluid communication with the outside of the hollow fibres, wherein each of the at least two filtration elements comprises an inner perforated pipe fluidly connected with the outside of the hollow fibres of that filtration element and wherein the inner perforated pipes of adjacent filtration elements are connected together via tubular pipe members;
• a first dedicated feed line fluidly connected with the filtration vessel at or near a first end thereof, a second dedicated feed line fluidly connected with the filtration vessel at or near a second end thereof, and one or more dedicated side feed lines, wherein each of the one or more side feed lines is fluidly connected with the filtration vessel via a feed port with a filtration element arranged on either side of each of the one or more side feed ports,
• a first filtrate line arranged at or near the first end of the filtration vessel and fluidly connected via a tubular pipe member with a terminal end of a perforated pipe of a first filtration element in the row, and a second filtrate line arranged at or near the second end of the filtration vessel and fluidly connected via a tubular pipe member to a terminal end of a perforated pipe of a final filtration element in the row;
• wherein the first and second dedicated feed lines, the one or more dedicated side feed lines, and the first and second filtrate lines each comprise a valve provided with an actuator whereby the actuators are independently actuatable to move the valves between an open and closed position such that, during back-washing of each of the at least two dead-end filtration elements, back-wash water can be fed to the outside of the hollow fibres through the outlet thereof and, in a first back-wash cycle, back-wash water containing entrained particulate material can be discharged from the inside of the hollow fibres through the first inlets thereof;
• and, in a second back-wash cycle, back-wash water containing entrained particulate material can be discharged from the inside of the hollow fibres through the second inlets thereof.