Environmental and Microbial Influences on Corrosion of Selected Types of Petroleum Industry Steel

This study explored the influence of brackish water sediment, mangrove swamp sediment, clayey/lateritic soil, and river water (freshwater) sediment on the corrosion rates of carbon, mild, and stainless steels and the species of sulphate reducing bacteria (SRB) and iron bacteria associated with the process. The material loss following burial of the steel samples for a 9-month period was assessed. Standard and specialised microbiological techniques were employed in the characterisation of the bacterial species. Qualitative assessment for corrosion was done via optical microscopy and macroscopy. Corrosion was highest on steel buried in brackish water sediment and lowest in that from river water sediment. Carbon steel was the most susceptible to corrosion while stainless steel was the most resistant. Sulphite, sulphide, nitrate and phosphate concentrations had a strong impact on corrosion rates. Thiobacillus, Leptothrix and Gallionella dominated amongst the iron bacteria while Desulfobacter and Desulfovibrio dominated amongst the SRB. There were significant differences in corrosion rates and bacterial abundance from one environment to the other. Iron bacteria showed greater abundance than SRB across the different environments and steel types. Iron bacteria counts, however, did not correlate positively with corrosion rates. The findings suggest that oil industry facilities in brackish water environments are more liable to corrosion than those located in fresh water ecosystems.

Treatment of water inflow from flooded underground mines

The study focuses on the adverse effect exerted on the environment by temporary shutdown and closure of underground mines by means of flooding. Closure of underground mines only terminates the structural and technological transformation of geological rock mass while detrimental effect on the natural environment of underground mines remains and even becomes more severe sometimes. Some hazards are revealed, which initiate new phenomena and processes, and are mainly connected with flooding of underground mines. Such hazards are groundwater rise, flow of water from flooded mines to operating mines, ground surface deformation due to subsidence and entry of pollutants in underground aquifers and surface water bodies. In terms of a flooded mine in East Donbass, the method of catchment of water outlet from the flooded mine and dispersion to a man-made biological pond is described. The biological pond is split into zones. First, there is a shallow place with planting for activation of growth of iron bacteria; here, removal of iron ions from mine water takes place. Then, water flows to the pond for the further bio-oxidation and treatment of water up to the standard MAC. The article offers recommendations on making of the biological pond and a trench for water flow from mine. The required volumes and sizes of the biological pond, trench and activation zone for iron bacteria are calculated. Treated mine water, via a dam, will be fed to a water storage reservoir.

Preventing the growth of iron bacteria in water wells by copper and silver coating

The growth of iron-related bacteria and their deposition of iron oxides often impedes the operation of water wells, resulting in costly rehabilitation measures. The microbicidal potential of a silver and copper coating was investigated. Field-scale experiments on a riser pipe showed that silver coating only slightly subdued the growth of iron bacteria, while copper coating was highly effective. However, the coating was eroded and oxidized over the course of the experiment, rendering it ineffective. Model experiments with different types of copper coatings showed that only polished copper metal was able to prevent the growth of an iron bacteria biofilm for a longer period of time, while thinner coatings were overcome after some months. While the coating of screens, casings and riser pipes might thus not be sustainable, protecting parts of the submersible pump prone to iron oxide deposition by a copper coating could be an interesting option.

Properties of the Iron Bacteria Biofouling on Ni–P–rGO Coating

Biofouling on heat exchange devices can decrease heat transfer efficiency, corrode materials, and even lead to safety accidents. Most heat exchange devices are made of carbon steel that efficiently produces biofouling. However, in this paper, a nickel–phosphorus–reduced graphene oxide (Ni–P–rGO) coating was prepared on carbon steel by electroless plating to investigate the properties of iron bacteria biofouling. The surface coating was analyzed via scanning electron microscopy and Raman spectroscopy. After the carbon steel and the Ni–P–rGO coating were immersed into an iron bacteria solution for 120 h, the weight of the iron bacteria biofouling on the Ni–P–rGO coating sharply decreased when compared with the carbon steel. We can conclude that the concentration of graphene can affect the weight of iron bacteria biofouling. We also found that the coating solution with 40 mg/L of graphene performed the best in inhibiting biofouling by decreasing the weight of the biofouling by 97.2% compared to carbon steel.

Properties of Iron Bacteria Biofouling on Ni-P-rGO Coating under Flowing Conditions

Biofouling on heat exchange devices can decrease heat transfer efficiency, corrode materials, and even lead safety accidents. Most heat exchange devices are made of carbon steel, which produces biofouling easily. In this paper, nickel-phosphorus-reduced graphene oxide (Ni-P-rGO) coating was prepared on carbon steel by electroless plating as a kind of advanced material to study the properties of iron bacteria biofouling under flowing conditions. The coating was analyzed via scanning electron microscopy and Raman spectroscopy. The properties of iron bacteria biofouling on carbon steel and Ni-P-rGO coating were then compared under flowing conditions. Compared with carbon steel, the asymptotic value of fouling resistance on the Ni-P-rGO coating significantly decreased. Additionally, the induction period and the time of reaching the asymptotic value greatly increased. The inhibition properties of biofouling of advanced materials Ni-P-rGO coating under different temperatures, flow velocities, and initial concentrations was also studied.