Sealer holding member for membrane element and membrane element using the same

A sealer holding structure for a spiral-type membrane element, comprising:

• (i) the spiral-type membrane element having an upstream end and a side circumference, said spiral-type membrane being disposed inside an outer vessel;
• (ii) an outer-cover member that covers the side circumference of the membrane element and extends in an upstream direction from the upstream end of the membrane element;
• (iii) an annular sealer for sealing a space between the spiral-type membrane and the outer vessel at the upstream end of the membrane element;
• and
• (iv) a sealer holding member for holding the annular sealer comprising a first annular portion, an annular projection, a second annular portion, and a third annular portion, wherein
• the first annular portion is engaged with an inner wall of the outer-cover member without contacting the side circumference of the membrane element;
• the annular projection stops an end of the outer-covering member;
• and
• the third annular portion is a second annular projection, and the second annular portion is defined between the annular projection and the third annular portion where the annular sealer is fitted.