Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China; School of Environment, Tsinghua University, Beijing 100084, China.
Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China; State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (MARC), Tsinghua University, Shenzhen 518055, Guangdong, China.
Water Res. 2015 Mar 15;71:207-18. doi: 10.1016/j.watres.2014.12.056. Epub 2015 Jan 13.
To understand the role bacterial communities play in corrosion scale development, the morphological and physicochemical characteristics of corrosion scales in raw and disinfected reclaimed water were systematically investigated. Corrosion tubercles were found in raw reclaimed water while thin corrosion layers formed in disinfected reclaimed water. The corrosion tubercles, composed mainly of α-FeOOH, γ-FeOOH, and CaCO3, consisted of an top surface; a shell containing more magnetite than other layers; a core in association with stalks produced by bacteria; and a corroded layer. The thin corrosion layers also had layered structures. These had a smooth top, a dense middle, and a corroded layer. They mostly consisted of the same main components as the tubercles in raw reclaimed water, but with different proportions. The profiles of the dissolved oxygen (DO) concentration, redox potential, and pH in the tubercles were different to those in the corrosion layers, which demonstrated that these parameters changed with a shift in the microbial processes in the tubercles. The bacterial communities in the tubercles were found to be dominated by Proteobacteria (56.7%), Bacteroidetes (10.0%), and Nitrospira (6.9%). The abundance of sequences affiliated to iron-reducing bacteria (IRB, mainly Geothrix) and iron-oxidizing bacteria (mainly Aquabacterium) was relatively high. The layered characteristics of the corrosion layers was due to the blocking of DO transfer by the development of the scales themselves. Bacterial communities could at least promote the layering process and formation of corrosion tubercles. Possible mechanisms might include: (1) bacterial communities mediated the pH and redox potential in the tubercles (which helped to form shell-like and core layers), (2) the metabolism of IRB and magnetic bacteria (Magnetospirillum) might contribute to the presence of Fe3O4 in the shell-like layer, while IRB contributed to green rust in the core layer, and (3) the diversity of the bacterial community resulted in the complex composition of the core layer, and gas producing bacteria (sulfate-reducing bacteria and methanogenic bacteria) played a role in the formation of the porous core layer.
为了了解细菌群落在腐蚀结垢发展中的作用，系统研究了原水和消毒再生水中腐蚀结垢的形态和物理化学特性。在原水中发现了腐蚀瘤，而在消毒再生水中形成了薄的腐蚀层。腐蚀瘤主要由α-FeOOH、γ-FeOOH 和 CaCO3 组成，由一个顶表面；一个壳层，比其他层含有更多的磁铁矿；一个与细菌产生的茎相关的核心；和一个腐蚀层。薄的腐蚀层也具有层状结构。它们具有光滑的顶部、密集的中部和腐蚀层。它们主要由与原水中瘤体相同的主要成分组成，但比例不同。瘤体中溶解氧（DO）浓度、氧化还原电位和 pH 的分布与腐蚀层不同，这表明这些参数随着瘤体中微生物过程的变化而变化。瘤体中的细菌群落主要由变形菌门（56.7%）、拟杆菌门（10.0%）和硝化螺旋菌（6.9%）主导。铁还原菌（主要是地杆菌属）和铁氧化菌（主要是噬水菌属）的序列丰度相对较高。腐蚀层的分层特征是由于结垢本身的发展阻止了 DO 的转移。细菌群落至少可以促进分层过程和腐蚀瘤的形成。可能的机制包括：（1）细菌群落介导了瘤体中的 pH 和氧化还原电位（这有助于形成壳层和核心层），（2）IRB 和磁细菌（磁螺旋菌）的代谢可能有助于壳层中 Fe3O4 的存在，而 IRB 有助于核心层中绿锈的形成，（3）细菌群落的多样性导致核心层的复杂组成，产气体细菌（硫酸盐还原菌和产甲烷菌）在多孔核心层的形成中发挥作用。
