The present invention relates to a process for removing dry surface biofilm from a surface. The process comprises: (i) dissolving a powder-based composition into water wherein the powder-based composition comprises: a) a hydrogen peroxide source, b) an acetyl donor, c) an acidifying agent, and d) a wetting agent; (ii) allowing the solution to generate a biocidally effective concentration of peracetic acid; (iii) contacting the dry surface biofilm contaminated surface with the solution of peracetic acid for a period of time; and (iv) removing the solution.