Effect of THPS on the microbial community in a simulated crude-oil storage tank environment

Tetrakis (hydroxymethyl) phosphonium sulfate (THPS) is commonly used due to its low environmental impact and its effectiveness in preventing sulfate-reducing bacteria (SRB) growth. The treatment effect with one THPS application on the microbial community was evaluated in a batch fractionated assay containing water from a crude oil storage tank, carbon steel coupons and crude oil. The effects of the treatment were monitored for 60 days. The total number of planktonic bacteria and archaea estimated by qPCR decreased at the beginning of the treatment with THPS, however, 60 days after the application the number was higher, as were the sulfate-reducing microorganisms (SRM) and methanogens (MA). From the diversity analysis of the 16S rRNA gene, the relative abundance of the genus Desulfovibrio was higher on day 8 in the system with THPS, but by day 60 there were no differences. Among the MA, the abundance of the genus Methanocalculus increased due to the presence of biocide. The presence of the biocide did not affect the number of bacteria and archaea attached to SAE 1010 carbon steel coupons. Corrosion rates revealed that THPS produced a decrease in corrosion initially, but the values were even high. The results suggested that the treatment with THPS produced the selection of a long-term resistant community with potential activity to induce corrosion of carbon steel.

四羟甲基硫酸磷（Tetrakis (hydroxymethyl) phosphonium sulfate, THPS）因环境友好且可有效抑制硫酸盐还原菌（sulfate-reducing bacteria, SRB）生长而被广泛应用。本研究采用包含原油储罐水样、碳钢试片及原油的分批分级实验体系，评估了单次THPS投加对微生物群落的处理效果，监测周期为60天。经定量聚合酶链反应（quantitative PCR, qPCR）估算的浮游细菌与古菌总数量，在THPS处理初期有所下降，但投加60天后该数量反而升高，硫酸盐还原微生物（sulfate-reducing microorganisms, SRM）与产甲烷古菌（methanogens, MA）的数量亦呈现相同变化趋势。基于16S rRNA基因的多样性分析显示，THPS处理体系中脱硫弧菌属（Desulfovibrio）的相对丰度在第8天更高，但至第60天时已无显著差异。在产甲烷古菌类群中，受该杀生物剂影响，产甲烷球菌属（Methanocalculus）的丰度有所上升。该杀生物剂的存在对附着于SAE 1010碳钢试片的细菌与古菌数量无显著影响。腐蚀速率测定结果表明，THPS初期可降低腐蚀程度，但后续腐蚀速率反而更高。研究结果表明，THPS处理会筛选出具有潜在碳钢腐蚀诱导活性的长期抗性微生物群落。