documentclass[twocolumn]{book}
usepackage[utf8]{inputenc}
usepackage{lipsum}

%usepackage{showframe}
usepackage[paperwidth=297mm,paperheight=210mm,left=25mm,right=25mm,top=30mm,bottom=30mm]{geometry}


usepackage{scrpage2}
pagestyle{scrheadings}
clearscrheadfoot
ofoot[pagemark]{pagemark}
setheadsepline{0.2pt}
setfootsepline{0.2pt}

begin{document}

lipsum
lipsum

end{document}

usepackage[paperwidth=297mm,paperheight=210mm,left=25mm,right=25mm,
          top=30mm,bottom=30mm,footskip=5mm,headsep=0mm]{geometry}