  We consider an interacting particle system with two species under strong
competition dynamics between the two species. Then, through the hydrodynamic
limit procedure for the microscopic model, we derive a one-phase Stefan type
free boundary problem with non-linear diffusion, letting the competition rate
divergent. Non-linearity of diffusion comes from a zero-range dynamics for one
species while we impose the other species to weakly diffuse according to the
Kawasaki dynamics for technical reasons, which macroscopically corresponds to
the vanishing viscosity method.
