A horizontal decanter centrifuge for enhanced recovery of drilling mud from drilling mud solids. Oilfield decanters will always suffer some drilling mud losses because they can only achieve a certain effectiveness with respect to solids dryness. The embodiment describes a process to mitigate the financial burden of drilling mud losses by adding a less expensive sacrificial fluid to take the place of drilling mud in the solids phase. A process and apparatus for drilling mud displacement is described including flowing the drilling mud into a horizontal decanter centrifuge, wherein the stresses imposed within the decanter act to force a sacrificial fluid to displace the drilling mud. The embodiment also describes a process wherein vapours or mist are prevented from escaping and becoming airborne into the external atmosphere.