Abstract: A membrane separation method is useful in purifying clear water, sewage, etc. and can reliably remove obstruction of an air diffusing apparatus by opening and closing valves, a submerged membrane separation apparatus to be used for the same, and a method for cleaning an air diffusing apparatus. The submerged membrane separation apparatus includes a separation membrane module, an air diffusing apparatus, and a gas supplying apparatus, wherein an air diffusing apparatus is arranged in one treatment tank, two header pipes (A and B) are placed as the gas supplying pipes, the connecting port a and the header pipe A and the connecting port b and the header pipe B for each of the air diffusing apparatuses are respectively connected, on-off valves are arranged in four parts, and the header pipes A and B each have an open end.

Abstract: A membrane separation method is useful in purifying clear water, sewage, etc. and can reliably remove obstruction of an air diffusing apparatus with a simple operation of only opening and closing a valve, a submerged membrane separation apparatus to be used for the same, and a method for cleaning an air diffusing apparatus. The submerged membrane separation apparatus includes a separation membrane module, an air diffusing apparatus, and a gas supplying apparatus, wherein an air diffusing apparatus is arranged in one treatment tank, two header pipes (A and B) are placed as the gas supplying pipes, the connecting port a and the header pipe A and the connecting port b and the header pipe B for each of the air diffusing apparatuses are respectively connected, on-off valves are arranged in four parts, and the end of downstream sides of the header pipes A and B are open to the atmosphere.

Abstract: Provided are membrane elements and membrane units capable of easily forming a space part surrounded with a frame body above the membrane elements regardless of the number of the membrane elements. That is, the membrane elements are membrane elements each comprising filtering membranes on both surfaces of a plate-like supporting plate, wherein spacer parts are formed in both side parts for keeping the membrane face distance to adjacent membrane elements being prescribed intervals, and the spacer parts have through bolt insertion holes and are extended upward from the upper end part of the supporting plate. The membrane units are configured by arranging a plurality of the membrane elements in such a manner that the channel parts formed in the spacer parts are brought into contact with each other, seal panels are installed in the outermost parts of the arranged membrane elements, and a frame body is formed by surrounding the space above the filtering membranes by the spacer parts and the seal panels.