The comparison of practical efficiency of formaldehyde and non formaldehyde biocides on predominant microbial population in metal working fluids

Metalworking fluids (MWFs) are extensively used in the metalworking industry to cool and lubricate the tool work piece interface and protect the work piece from corrosion. The aim of this study was to survey the microbial load of MWFs rate and evaluate the effectiveness of formaldehyde and non formaldehyde biocides on microbial elimination in a molding unit at Sarcheshmeh copper complex. During a period of 9 months، two samples were collected per week from sump of molding unit at Sarcheshmeh copper complex by Grab sampling procedure. Using emulsification، surface tension and HPLC tests، MWFs deterioration were detected. Finally، the efficiency of four selective biocides on dominant microbial populations and biocide efficiency were assessed by HPLC. Among formaldehyde and non formaldehyde biocides، glutaraldehyde had the ability for complete removal of MWFs microbial contamination. Therefore this biocide in a dose higher than 20 ppm is recommended in MWFs.