Assessment of Disinfection Efficiency of Chlorine and Bromine-Based Biocides for Marine Biofouling

Abstract

Marine biofouling is a significant challenge for industries that rely on seawater. This study examined the effect of structural materials, carbon concentration, and salinity on biofilm formation. Furthermore, it compares the disinfection efficiency of chlorine (NaClO) and bromine (NaBr) biocides and attempts to identify their optimal dosing. Among tested materials, PVC exhibited the highest microbial attachment (40%), followed by plastic (30%) and concrete (23%). Biofilm attachment and growth increased with higher concentrations of total organic carbon (TOC), which depends upon the seawater’s salinity. The simultaneous reduction of salinity and TOC concentration further enhanced the biofilm attachment and growth. A strong positive linear correlation (r = 0.98 and p = 0.003) was found between the initial cell count of seawater and biofilm formation. Disinfection experiments showed that NaBr (97.36%) was slightly more effective than NaClO (95.83%). Response Surface Methodology (RSM) identified optimal disinfection conditions: 0.6 mg/L biocide concentration and 138 min dosing period. Generally, there are three strategies for reducing biofilm growth: selecting appropriate materials, controlling carbon concentrations, or optimizing concentrations and dosing periods with biocides.