The Interaction of Biofoulants and Calcareous Deposits on Corrosion Performance of Q235 in Seawater

Abstract

An understanding of the interaction of calcareous deposits and biofoulants on the corrosion performance of steel during the fouling stage is both interesting and necessary. So, the effects of these factors on Q235 carbon steel were investigated and discussed for 20 weeks under real ocean conditions. The results indicate that calcareous deposits are favorable for the attachment of marine microorganisms. However, macroorganisms prefer adhering directly to the substrate. The generations of calcareous deposits have priority over the biofilm attachment under the condition of cathodic protection. Calcareous deposits can prevent steel against corrosion for four weeks without cathodic protection.

Understanding biofouling and contaminant accretion on submerged marine structures

“…As cathodic protection is a long-time and essential component of marine structures 2 , there is a need to understand the co-occurrent interactions that inevitably occur between electrochemical and microbial deposition 4 , as well as the settlement of subsequent biofouling communities on submerged infrastructure 10,58 . Within the marine environment, only a handful of marine biocalcifying bacterial strains from genera Bhargavaea, Epibacterium, Planococcus, Pseudidiomarina, Pseudoalteromonas, and Virgibacillus have been isolated from calcareous deposits formed from cathodic protection 3,57 .…”

“…Another vital area for understanding fouling mechanics is the interaction between marine growth involved in biofouling and their settlement on cathodically protected marine surfaces. A study by Zhang et al 10 found that calcareous deposits provided favorable conditions for microbial attachments due to the strong adsorption of bioadhesives to calcium carbonate. In comparison, it was more advantageous for macro-fouling organisms to adhere directly to the surface substrate as they are more susceptible to hydrological scouring by adhering to the calcareous deposits instead 10 .…”

“…A study by Zhang et al 10 found that calcareous deposits provided favorable conditions for microbial attachments due to the strong adsorption of bioadhesives to calcium carbonate. In comparison, it was more advantageous for macro-fouling organisms to adhere directly to the surface substrate as they are more susceptible to hydrological scouring by adhering to the calcareous deposits instead 10 . On cathodically protected surfaces, the accretion of calcareous deposits appeared to take priority over the biofilm formation, with deposition progressing even after the biofilm has been established 10 .…”

“…In comparison, it was more advantageous for macro-fouling organisms to adhere directly to the surface substrate as they are more susceptible to hydrological scouring by adhering to the calcareous deposits instead 10 . On cathodically protected surfaces, the accretion of calcareous deposits appeared to take priority over the biofilm formation, with deposition progressing even after the biofilm has been established 10 . Another study by Erdogan and Swain 58 explored impressed current cathodic protected and nonprotected steel panels exposed to the intermittent tide, completely immersed in seawater, and half buried in marine sediment.…”

“…The calcareous material can be broadly distinguished as either (1) calcareous deposition, which is from scaling due to cathodic protection or the accumulation of carbonates from microbial biomineralization 4 or (2) calcareous organisms, which usually consist of marine invertebrates 9 . Calcareous deposition and marine growth often co-occur on submerged surfaces, and there is a need to understand how the biotic and abiotic sources interact to produce broader countermeasures against marine fouling 10 . This is crucial as there may be potential differences in adhesion dynamics on surfaces with cathodic protection where the formation of the initial conditioning film is calcareousbased 2,4,11 , compared to the organic material-based film in typical biofouling successional models 9,12 .…”