  We consider two-species exclusion processes on the d-dimensional discrete
torus taking the effects of exchange, creation and annihilation into account.
The model is, in general, of nongradient type. We prove that the (charged)
particle density converges to the solution of a certain nonlinear diffusion
equation under the diffusive rescaling in space and time. We also prove a lower
bound on the spectral gap for the generator of the process confined in a finite
volume.
