Phosphorus Depletion as a Green Alternative to Biocides for Controlling Biodegradation of Metalworking Fluids

Abstract

Metalworking fluids (MWFs) are used as lubricants and coolants in the manufacturing operations. Their biodeterioration, while in operation, is a widespread problem leading to poor performance and worker health issues. Adding biocides, though effective in reducing microbial growth, leads to the production of more recalcitrant wastewaters that are difficult to dispose or recycle on-site. Increasing environmental concerns have led to robust legislation for reducing/eliminating the use of toxic biocides in MWFs, stimulating a growing interest in the development/application of alternative biological preservation strategies. In this study, inducing nutrient imbalance was investigated for controlling microbial growth in MWFs. Phosphorus was immobilized employing insoluble LaO to form LaPO. Concentrations of LaO greater than 0.08%w (%w = weight percent) completely inhibited microbial growth (from 1.4 × 10 to 0 CFU/mL) and hindered biodegradation. Raman spectroscopy suggested that LaO converted intracellular phosphorus into LaPO. The growth inhibition potentials of both 0.06%w La(NO) and LaO were found to be superior to formaldehyde. The antimicrobial property of LaO (i.e., inhibition) was tenable by adding sufficient phosphate, acting as an on/off switch for controlling microbial growth in MWFs. This technology offers the potential to reduce/eliminate the use of biocides in MWFs, improves the feasibility of end-of-life biological treatment, and closes the water loop.

Luminescent Microbial Bioassays and Microalgal Biosensors as Tools for Environmental Toxicity Evaluation

“…The extracted water from the plant with potential antimicrobial properties was exposed to different bacteria including E. coli HB101 (pUCD607) inhibiting their growth. In the same way, Azimi and Thompson (2017) investigated the nutrient imbalance for controlling microbial growth in metal fluids using La 2 O 3 (as phosphorus scavenger) and measured the bioluminescence inhibition of E. coli HB101 (pUCD607).…”

Luminescent Microbial Bioassays and Microalgal Biosensors as Tools for Environmental Toxicity Evaluation

“…coli HB101 (pUCD607) inhibiting their growth. In the same way, Azimi and Thompson (2017) investigated the nutrient imbalance for controlling microbial growth in metal fluids using La2O3…”

Quorum sensing inhibition as a promising method to control biofilm growth in metalworking fluids

“…Measures to combat microbial growth in MWFs typically involve the use of biocides, although alternative, more environmentally friendly approaches have also been investigated [1,2]. These measures are, nonetheless, insufficient at eliminating the microbial load in MWF circulation systems [14,23,27,50].…”