Effect of Fungus, Aspergillus sp. F1-1, on the Corrosion Behavior of PCB-HASL in Humid Atmospheric Environment

Fungi, as one of the serious factors causing microbiologically influenced corrosion (MIC), can shorten the service life of electronic materials which are wildly used in the atmospheric environment. In this study, the effect of Aspergillus sp. F1-1 (A. F1-1) isolated from PCB samples after the exposure test in Xishuang Banna on the corrosion behavior of PCB-HASL was investigated. The presence of the A. F1-1 posed a threat of local corrosion on PCB-HASLs. An obvious decrease of pH was observed in PCB with A. F1-1 due to the various organic acids secreted by A. F1-1. The presence of the fungi also led to serious surface cracking and delamination. Creep corrosion and micro-hole corrosion were accelerated in the presence of A. F1-1 compared to the control. Additionally, the metabolic activities of A. F1-1 were associated with enrichment of Cu-containing corrosion products under the hypha.

Inhibitors of Corrosion Induced by Sulfate-Reducing Bacteria

Currently, a lot of researcher’s attention is devoted to the problem of microbiologically influenced corrosion (MIC), since it causes huge damages to the economy, initiating the destruction of oil and gas pipelines and other underground constructions. To protect industrial materials from MIC effects an organic chemical inhibitors are massively used. However, the problem of their use is associated with toxicity, dangerous for the environment that caused the need for development the alternative methods of MIC repression. At the review, the data about different types of inhibitors-biocides usage has provided. The chemical inhibitors features are given and the mechanisms of their protective action are considered. The screening results and use of alternative and eco-friendly methods for managing the effect of corrosion caused by sulfate-reducing bacteria (SRB) are highlighted. Methods of joint application of chemical inhibitors and enhancers, such as chelators, biosurfactants, which contribute to reducing the concentration of chemical inhibitors, are discussed. The possibility of disruption of the quorum sensing interaction in the bacterial community to prevent the biofilm formation is considered. The information about the use of natural plant extracts, food waste, as well as by-products of agro-industrial production to combat MIC is provided. The development of biological corrosion control methods (to combat MIC) is of great importance for creating the best alternative and eco-friendly approaches to managing the effect of corrosion caused by SRB. The analysis of the literature data indicates the need to find the best alternatives and environmentally friendly solutions.

Microbiologically Influenced Corrosion of Iron by Nitrate Reducing Bacillus Sp

Iron has played a crucial role in the human ecosystem currently in transportation, manufacturing, and infrastructure. Iron oxide is known as rust, usually the reddish-brown oxide formed by iron and oxygen reactions in moisture from water or air. Microbiologically influenced corrosion (MIC) is a significant problem to the economic damage, especially in industrial sectors and its direct presence with nitrate/iron-reducing bacteria. This paper aims to explore the MIC of iron by nitrate-reducing Bacillus sp. including the redox reaction occurs, microbiologically influenced corrosion, iron/nitrate-reducing and mechanisms of microbial iron/nitrate reduction.

Microbiologically influenced corrosion inhibition of carbon steel via biomineralization induced by Shewanella putrefaciens

Microbiologically influenced corrosion inhibition (MICI) of Q235 carbon steel by biomineralization was investigated via a combination of surface analysis, electrochemistry, and scanning electrochemical microscopy (SECM). The results showed that Shewanella putrefaciens used the cell walls as the nucleation sites to induce the formation of a protective biomineralized layers which contained calcite and extracellular polymeric substances on the steel surface. The potentiodynamic polarization results demonstrated that the corrosion current density (icorr value) of the biomineralized steel surface was 0.38 μA cm−2, which was less than one-tenth that of the blank steel in a sterile medium (4.86 μA cm−2) after 14 days. The biomineralized layers presented wear resistance and could self-repair after undergoing mechanical damage under microbial conditions as verified by morphological and SECM observations. This work reveals that microbial-induced carbonate biomineralization, as a MICI approach, may be considered as a reliable, low-cost, environmentally friendly corrosion inhibition strategy.

Metagenomics Microbial Characterization of Production and Process Fluids in the Powder River Basin: Identification and Sources of Problematic Microorganisms Associated with SWD Facilities

Inconsistent bacterial control and monitoring led to variability in Salt Water Disposal (SWD) well performance and injectivity creating excess costs in biocide applications and remedial work. A metagenomics study using Whole Genome Sequencing (WGS) was conducted to determine the source(s) of problematic microorganisms throughout the process life cycle: Freshwater> Drilling> Completion> Flowback> Produced water> SWD. A total of 30 metagenomes were collected from the 6 process stages and identification and quantification of the major microbial taxa from each of these stages were identified. "Taxonomy to Function" associations were identified for all the major taxa found in the SWD fluids. WGS was performed on positive Sulfate Reducing Bacteria (SRB) and Acid Producing Bacteria (APB) media bottles inoculated in the field for a Flowback sample. Four of the six major taxa found in SWD samples are considered groups of microorganisms known to cause microbiologically influenced corrosion (MIC): Clostridia, methanogens, SRB and Iron Reducing bacteria. Thermovirga and Thermotagae, were the two most abundant taxa found in SWD samples, both thermophilic halophilic fermenting bacteria. The Fe reducing bacteria Shewanella was only detected in Drilling and SWD fluids suggesting its source was Drilling fluids. Completion fluid metagenome profiles from two separate sites followed similar patterns. During middle of completions Proteobacteria phyla were dominant taxa represented mostly by Pseudomonas. Other abundant phyla were all characteristic of polymer degrading bacteria. None of these taxa were dominant populations identified in SWD waters. Fresh water only shared similar taxa with Drilling and Completion fluids. A few minor taxa from Drilling and Completion stages show up as significant taxa in SWD fluids. The majority of taxa found in SWD samples appear to originate from Flowback and Produced waters, although at lower abundances than found in SWD samples. It cannot be determined if the microorganisms found in Flowback and Produced waters were endemic to the formation or come from contaminated source waters, i.e. process equipment used to store and transport water sources. Petrotoga mobilis was the dominant population of bacteria that grew in both media bottles, 96% and 77% for SRB and APB, respectively, while Petrotoga was detected at 14% in the field sample. The most abundant bacteria detected in field sample were Clostridia (38%) while only 2.7% were detected in APB media. SRB media bottle had 0.18% SRB detected by WGS; APB media had 9% SRB population abundance. No SRB were detected in corresponding field sample or below detectable limits (BDL) for WGS methods (<0.01%). WGS was forensically used to successfully identify type and source of problematic microorganism in SWD facilities. Results from media bottle and field sample comparisons stress the importance of developing improved field monitoring techniques that more accurately detect the dominant microorganisms.