Because of the denser active use of the spectrum, and because of higher radio telescope sensitivities, radio frequency interference (RFI) mitigation has become a sensitive topic for current and future radio telescope designs. In this paper, we consider different interference mitigation options which take advantage of both time-frequency and spatial RFI signatures. After specific subspace decompositions, these RFI spatial signatures are estimated and applied to pre- or post-correlation data by means of spatial filtering techniques based on projectors. We provide some performance analysis through simulations and Cramer-Rao Lower Bound derivations. In addition, recent results on real data from the LOFAR and EMBRACE radio telescopes are presented.