Synergistic Effect of Monochloramine and Glutaraldehyde Biocides against Biofilm Microorganisms in Produced Water

Abstract

The synergistic effect of oxidizing biocide (monochloramine) and non-oxidizing biocide (glutaraldehyde) against biofilm microorganisms in produced water system have been investigated. Batch process was used for the investigation of biofilm attachment on polyvinylchloride slides with the aid of chocolate agar (enriched medium), in produced water. The effects of the biocides on biofilm mass were assessed by comparing the biofilm mass of the control samples (without the addition of biocides) to the biofilm mass of the test samples (after the addition of biocides). The organic constituents of the biofilm on each slide were evaluated as spectrophotometric analysis of protein and polysaccharide contents using modified Lowry method and phenol-sulphuric acid method, respectively. The synergy of monochloramine with glutaraldehyde caused a greater reduction in the final biofilm mass, protein and polysaccharide contents, respectively, than monochloramine or glutaraldehyde acting independently. Considering reduction in total protein contents and a 10 day old biofilm, the synergistic biocide caused a 69.6 % reduction, monochloramine caused a 62.9 % reduction, and glutaraldehyde caused a 59.1 % reduction. In terms of reduction in total polysaccharide contents and a 10 day old biofilm, the synergistic biocide caused a 66.6 % reduction, monochloramine caused a 60.6 % reduction, and glutaraldehyde caused a 54.7 % reduction. The result indicates strong antimicrobial value for the combination of oxidizing and non-oxidizing biocides against biofilm-microorganisms.

Keywords: Produced water, biofilm, Standard Curve, biocides, Spectrophotometer