Arithmetic Macaulayfication of projective schemes

In this paper, we study arithmetic Macaulayfication of projective schemes and Rees algebras of ideals. We give a necessary and sufficient condition for a nonsingular projective scheme to have an arithmetic Macaulayfication. If the scheme is not necessarily nonsingular, we show that our condition give a sufficient condition for the existence of an arithmetic Macaulayfication. We also study truncated Rees algebra of an ideal. We show that the truncated Rees algebra R_\lambda(I) of an ideal I is alway Cohen-Macaulay for \lambda large enough in some important situations.