Use of an inorganic membrane comprising an oxide and/or hydroxide of an element M 1, wherein the element M 1 is silicon or a metal, for increasing resistance to fouling in filtration, wherein an antifouling treatment method is applied to the inorganic membrane, the antifouling treatment method comprising grafting the surface of said oxide and/or hydroxide with an organic moiety R 1 by contacting said surface with an organometallic reagent to obtain a functionalized membrane, wherein: the organometallic reagent is a compound of the formula R 1 -M 2, or of formula R 1 -M 2 -X, or of formula R 1 -M 2 -R 1 ', wherein - R 1 is C 1-6 alkyl, phenyl, or -R 7 [OR 8] n R 9; wherein R 7 and R 8 are independently from each other C 1-4 alkylene; n is an integer from 1 to 4; and R 9 is C 1-4 alkyl; - M 2 is Li or Mg, and X is halo; - R 1' is the same or different from R 1 and is selected from the group consisting of C 1-12 alkyl, C 6-10 aryl, C 7-16 alkylaryl, C 7-16 arylalkyl, -R 7 [OR 8] n R 9, C 3-8 cycloalkyl, C 3-8 cycloalkenyl, C 4-10 cycloalkylalkyl, C 4-10 cycloalkenylalkyl, C 2-12 alkenyl, 3- to 8-membered heterocyclyl, 5- to 10-membered heteroaryl, heterocyclylC 1-6 alkyl, heteroarylC 1-4 alkyl and C 2-12 alkynyl; optionally substituted with one or more groups independently selected from hydroxyl, -OR 4, amino, halo, sulfhydryl, -SR 5, -COOH, and -COOR 6, wherein R 4, R 5, R 6 are independently selected from C 1-6 alkyl, halo and C 6-10 aryl, R 7 and R 8 are independently from each other C 1-4 alkylene, n is an integer from 1 to 4, and R 9 is C 1-4 alkyl, wherein R 1 is optionally substituted with one or more groups independently selected from hydroxyl, -OR 4, amino, halo, sulfhydryl, -SR 5, -COOH, and -COOR 6; wherein R 4, R 5, R 6 are independently selected from C 1-6 alkyl, halo and C 6-10 aryl, wherein the functionalized membrane is less hydrophilic compared to the membrane before the antifouling treatment. the organometallic reagent is a compound of the formula R 1 -M 2, or of formula R 1 -M 2 -X, or of formula R 1 -M 2 -R 1 ', wherein - R 1 is C 1-6 alkyl, phenyl, or -R 7 [OR 8] n R 9; wherein R 7 and R 8 are independently from each other C 1-4 alkylene; n is an integer from 1 to 4; and R 9 is C 1-4 alkyl; - M 2 is Li or Mg, and X is halo; - R 1' is the same or different from R 1 and is selected from the group consisting of C 1-12 alkyl, C 6-10 aryl, C 7-16 alkylaryl, C 7-16 arylalkyl, -R 7 [OR 8] n R 9, C 3-8 cycloalkyl, C 3-8 cycloalkenyl, C 4-10 cycloalkylalkyl, C 4-10 cycloalkenylalkyl, C 2-12 alkenyl, 3- to 8-membered heterocyclyl, 5- to 10-membered heteroaryl, heterocyclylC 1-6 alkyl, heteroarylC 1-4 alkyl and C 2-12 alkynyl; optionally substituted with one or more groups independently selected from hydroxyl, -OR 4, amino, halo, sulfhydryl, -SR 5, -COOH, and -COOR 6, wherein R 4, R 5, R 6 are independently selected from C 1-6 alkyl, halo and C 6-10 aryl, R 7 and R 8 are independently from each other C 1-4 alkylene, n is an integer from 1 to 4, and R 9 is C 1-4 alkyl, - R 1 is C 1-6 alkyl, phenyl, or -R 7 [OR 8] n R 9; wherein R 7 and R 8 are independently from each other C 1-4 alkylene; n is an integer from 1 to 4; and R 9 is C 1-4 alkyl; wherein R 7 and R 8 are independently from each other C 1-4 alkylene; n is an integer from 1 to 4; and R 9 is C 1-4 alkyl; - M 2 is Li or Mg, and X is halo; - R 1' is the same or different from R 1 and is selected from the group consisting of C 1-12 alkyl, C 6-10 aryl, C 7-16 alkylaryl, C 7-16 arylalkyl, -R 7 [OR 8] n R 9, C 3-8 cycloalkyl, C 3-8 cycloalkenyl, C 4-10 cycloalkylalkyl, C 4-10 cycloalkenylalkyl, C 2-12 alkenyl, 3- to 8-membered heterocyclyl, 5- to 10-membered heteroaryl, heterocyclylC 1-6 alkyl, heteroarylC 1-4 alkyl and C 2-12 alkynyl; optionally substituted with one or more groups independently selected from hydroxyl, -OR 4, amino, halo, sulfhydryl, -SR 5, -COOH, and -COOR 6, wherein R 4, R 5, R 6 are independently selected from C 1-6 alkyl, halo and C 6-10 aryl, R 7 and R 8 are independently from each other C 1-4 alkylene, n is an integer from 1 to 4, and R 9 is C 1-4 alkyl, wherein R 1 is optionally substituted with one or more groups independently selected from hydroxyl, -OR 4, amino, halo, sulfhydryl, -SR 5, -COOH, and -COOR 6; wherein R 4, R 5, R 6 are independently selected from C 1-6 alkyl, halo and C 6-10 aryl, wherein the functionalized membrane is less hydrophilic compared to the membrane before the antifouling treatment.