  A Gribov-type dispersion relation is treated as an effective description of
interacting gluons forming a hot medium. Temperature dependence of the Gribov
parameter is determined from the fit to the lattice Yang-Mills results
describing thermodynamic functions. To maintain thermodynamic consistency of
the approach, a temperature dependent bag pressure is introduced. The results
obtained for equilibrium functions are generalised in the next step to
non-equilibrium conditions. We derive formulas for the bulk and shear viscosity
coefficients within the relaxation time approximation. We find evidence for
largely enhanced bulk viscosity in the region of the phase transition.
