Model identification with BPNN on restrictive ecological factors of SRB for sulfate-reduction

The model of back-propagation neural network (BPNN) was presented to demonstrate the effect of restrictive ecological factors, COD/SO 4 2- ratio, pH value, alkalinity (ALK) and SO 4 2- loading rate (Ns), on sulfate reduction of Sulfate Reducing Bacteria (SRB) in an acidogenic sulfate reducing reactor supplied with molasses as sole organic carbon source and sodium sulfate as electron acceptor. The compare of experimental results and computer simulation was also discussed. It was shown that the method of BPNN had a powerful ability to analyze the ecological characteristic of acidogenic sulfate reducing ecosystem quantitatively.

固定化SRB包埋颗粒组分优选及处理含SO_(4)^(2-)废水效果研究

赣南离子型稀土矿尾水存在SO42-含量高、pH偏低的问题,影响后续微生物对尾水其他组分(NH_(4)^(+)-N、NO_(3)^(-)-N)的处理,拟采用硫酸盐还原菌(SRB)包埋颗粒对水体中SO_(4)^(2-)进行去除,同时提升水体pH。通过对SRB包埋颗粒表面吸附材料、还原激活材料、内聚碳源和固体酸水解材料4个组分进行实验研究优选SRB包埋颗粒组分,结果表明,凹凸棒石粉作为SRB包埋颗粒表面吸附材料应用效果比较好,纳米零价铁对SRB的还原激活作用相对更好,内聚碳源及固体酸水解材料组合以玉米芯、花生壳与沸石粉、磁铁矿粉的组合效果比较理想。在此基础上筛选制备出4种包埋颗粒,通过厌氧三角瓶验证其对模拟废水中SO_(4)^(2-)的去除效果,发现制备的4种包埋颗粒经过10 d的实验对SO_(4)^(2-)的去除率都在60%以上,去除率最高的是花生壳-Fe_(3)O_(4)组合包埋颗粒,为80.20%。

Treatment of simulated wastewater from in situ leaching uranium mining by zerovalent iron and sulfate reducing bacteria

Batch and column experiments were conducted to determine whether zerovalent iron (ZVI) and sulfate reducing bacteria (SRB) can function synergistically and accelerate pollutant removal. Batch experiments suggest that combining ZVI with SRB can enhance the removal of U(Ⅵ) synergistically. The removal rate of U(Ⅵ) in the ZVI+SRB combining system is obviously higher than the total rate of ZVI system and SRB system with a difference of 13.4% at t=2 h and 29.9% at t=4 h. Column experiments indicate that the reactor filled with both ZVI and SRB biofilms is of better performance than the SRB bioreactor in wastewater basification, desulfurization and U(Ⅵ) fixation. The results imply that the ZVI+SRB permeable reactive barrier may be a promising method for treating subsurface uranium contamination.

The Microbial Metabolic Characteristics in the Course of Sulfate-Reduction

Acid-producing phase reactor of two-phase anaerobic treatment process has remarkable advantages treating sulfate-laden wastewater. In order to investigate SRB population's capability of utilizing substrate and the microbial acidification type formed during the course of sulfate reduction, continuous-flow and batch tests were conducted in a continuous stirred tank bio-film reactor supplied with sodium sulfate as electron acceptor. The experimental results demonstrated that the acidification type formed b...

Effect of Sulfate-reducing Bacteria on Corrosion Behavior of Mild Steel in Sea Mud

Microbiologically influenced corrosion （MIC） is very severe corrosion for constructions buried under sea mud environment. Therefore it is of great importance to carry out the investigation of the corrosion behavior of marine steel in sea mud. In this paper, the effect of sulfate-reducing bacteria （SRB） on corrosion behavior of mild steel in sea mud was studied by weight loss, dual-compartment cell, electronic probe microanalysis （EPMA）, transmission electron microscopy （TEM） combined with energy dispersive X-ray analysis （EDX） and electrochemical impedance spectroscopy （EIS）. The results showed that corrosion rate and galvanic current were influenced by the metabolic activity of SRB. In the environment of sea mud containing SRB, the original corrosion products, ferric （oxyhydr） oxide, transformed to iron sulfide. With the excess of the dissolved H2S, the composition of the protective layer formed of FeS transformed to FeS2 or other non-stoichiometric polysulphide, which changed the state of the former layer and accelerated the corrosion process.

Corrosion and Electrochemical Behavior of 316L Stainless Steel in Sulfate-reducing and Iron-oxidizing Bacteria Solutions

Corrosion and electrochemical behavior of 316L stainless steel was investigated in the presence of aerobic iron-oxidizing bacteria IOB and anaerobic sulfate-reducing bacteria SRB isolated from cooling water systems in an oil refinery using electrochemical measurement, scanning electron microscopy SEM and energy dispersive atom X-ray analysisEDAX. The results show the corrosion potential and pitting potential of 316L stainless steel decrease distinctly in the presence of bacteria, in comparison with those observed in sterile medium under the same exposure time. SEM morphologies have shown that 316L stainless steel reveals no signs of pitting attack in the sterile medium. However, micrometer-scale corrosion pits were observed on 316L stainless steel sur- face in the presence of bacteria. The presence of SRB leads to higher corrosion rates than IOB. The interactions between the stainless steel surface, abiotic corrosion products, and bacterial cells and their metabolic products in- creased the corrosion damage degree of the passive film and accelerated pitting propagation.

Synthesis of Chlorinated Bicyclic Adduct as Biocids for Sulfate-Reducing Bacteria

Synthesis of bicyclic systems containing chlorine atoms, and/or ether groups in aromatic rings can be con- sidered as an important method for building bicyclic system and production of new adducts. One of the most important types in the cycloaddition reaction is the Diels-Alder reaction (1,4 cycloaddition). In the present investigation a new ether of allylic type (dienophile) p-allyl bromo phenol was prepared and its structure was confirmed by molecular weight determination, refractive index, infrared spectra, and density. A new adduct was obtained by means of 1,4 cycloaddition reaction of hexachlorocyclopentadiene (HCP) and the new pre- pared dienophile. The reaction takes place without using solvent, catalysts, or elimination of any compound. The effect of variations in temperature, initial molar ratio and reaction duration were studied to determine the optimum conditions of the reaction. The optimum conditions reached were reaction temperature recorded 140?C, initial molar ratio diene: dienophile was 3:1 and the reaction duration time reached 6 h. Under these optimum conditions the maximum yield was 78%. The new adduct revealed very high biological effect as sulfate-reducing bacteria (SRB).

Biological treatment of wastewater with high concentrations of zinc and sulfate ions from zinc pyrithione synthesis

An enriched and domesticated bacteria consortium of sulfate-reducing bacteria(SRB)was used to treat wastewater from zinc pyrithione(ZPT)production,and the effects of different reaction parameters on sulfate reduction and zinc precipitation were evaluated.The single-factor experimental results showed that the removal rates of Zn2+and24SO?decreased with an increased ZPT concentration ranging from3.0to5.0mg/L.Zn2+and24SO?in wastewater were effectively removed under the conditions of30?35°C,pH7?8and an inoculum concentration of10%?25%.The presence of Fe0in the SRB system enhanced Zn2+and24SO?removal and may increase the resistance of SRB to the toxicity of Zn2+and ZPT in wastewater.A Box?Behnken design was used to evaluate the influence of the main operating parameters on the removal rate of24SO?.The optimum parameter values were found to be pH7.45,33.61°C and ZPT concentration of0.62mg/L,and the removal rate of24SO?reached a maximum of91.62%under these optimum conditions.

SRB-生物硫铁复合材料对废弃煤矿地下水的修复研究

酸性矿山废水(AMD)中含有高浓度的硫酸盐和金属离子,对矿山生态环境造成了严重的危害。硫酸盐还原菌(SRB)可以将SO_(4)^(2-)还原为S2-,沉淀金属离子,并生成生物硫铁,其处理效率较高。文章利用农业废弃物秸秆制备SRB的缓释碳源,考察了不同形式的碳源条件下SRB对酸性矿山废水特征污染组分的处理效果,并结合SRB原位生成的生物硫铁包覆颗粒,制备得到SRB-生物硫铁复合材料,通过批量实验和动态柱实验考查SRB-生物硫铁复合材料对高浓度模拟废水和实际矿井水的处理效果。结果显示:在pH为5.5时,将秸秆渣作为游离SRB的碳源是可行的,但与秸秆渣相比,秸秆生物炭的处理效率明显更高,将秸秆生物炭与乳酸钠结合制备的SRB碳源,激活SRB的时间更短,12 h内对SO_(4)^(2-)和Fe^(2+)的去除率分别达到了59.25%和79.56%。在此实验范围内,随着生物炭投加量的增大,去除效率逐渐提高,在pH为4.5~6.5的范围内,体系初始pH对SRB反应体系的处理效果影响不大。SRB-碳源与生物硫铁包覆颗粒结合后对高浓度的SO_(4)^(2-)和Fe^(2+)模拟废水能保持高效且持久的反应活性。动态柱实验表明SRB-生物炭-生物硫铁复合材料对酸性矿井水的特征污染指标有明显的修复效果,出水水质的大部分指标可满足地下水III类标准,运行15 d后仍能保持稳定的修复效果。

海洋微生物对C40混凝土耐腐蚀性能的影响

将C40混凝土分别置于灭菌海水、富集硫酸盐还原菌(SRB)海水和富集铁细菌(IOB)海水中干湿循环2400 h,通过化学滴定法和交流阻抗谱(EIS)研究了SRB菌和IOB菌对混凝土耐腐蚀性能(氯离子扩散规律)的影响。结果表明:SRB和IOB微生物膜层均呈龟裂状态,无法有效阻隔海水侵蚀;SRB和IOB降低了混凝土内部的pH值;经SRB和IOB腐蚀后混凝土的氯离子扩散系数分别为4.65×10^(-10)m^(2)/s和4.20×10^(-10)m^(2)/s,比灭菌海水环境下分别提高了63.16%和47.37%。

不同稻虾模式对硫酸盐还原菌群落结构及多样性的影响

硫酸盐还原菌(SRB)作为一种土壤中普遍存在的微生物,在生物地球化学循环中发挥关键作用。本研究以常规水稻单作模式为对照(CK),无环沟式稻虾(水稻和克氏原螯虾)共作模式(RS_(0))、有环沟式稻虾轮作模式(RS_(1))与有环沟式稻虾共作模式(RS_(2))为研究对象,采用16S rDNA高通量测序技术,探究不同稻虾模式对土壤硫酸盐还原菌(SRB)群落结构及多样性的影响。结果表明:与CK相比,3种稻虾模式均显著降低了水稻成熟期土壤氧化还原电位(Eh)和硫化物、硫酸盐、全硫含量,提高了pH和有机质、速效钾、碱解氮含量,其中RS_(0)提升效果最为显著;3种稻虾模式SRB群落结构存在差异:RS1、RS2和RS0处理的δ-变形菌纲相对丰度比CK分别下降46.00%、63.61%和51.94%,而α-变形菌纲则分别提高402.52%、441.01%和584.17%。3种稻虾模式硫酸盐还原菌Observed_species指数、Shannon指数和Simpson指数与CK相比均显著提高,但不同稻虾模式间丰富度及多样性没有显著差异。RDA分析表明,速效钾、Eh、有机质、有效磷、碱解氮、硫酸盐、硫化物、全硫和pH是影响稻田土壤SRB群落结构的影响因子,其中全硫和硫化物是主要因子。综上,稻虾模式能维持或者提高稻田土壤养分状况和SRB群落丰富度及多样性,改善稻田土壤SRB群落结构,结果可为稻虾种养土壤生态健康及稻田综合种养土壤微生物研究提供参考和支撑。

电弧喷涂Zn和Al涂层在含SRB海水中的腐蚀行为与机理

利用电弧喷涂技术在Q235钢基体上分别制备了Zn、Al涂层,研究涂层在含硫酸盐还原菌(SRB)海水中的腐蚀行为与机理。采用EIS、PC等电化学方法研究Zn、Al涂层在SRB一个生长周期内的腐蚀电化学行为,采用SEM和EDS对浸泡15 d后的涂层表面微观形貌和化学成分进行分析。EIS和PC结果表明,Zn、Al涂层在含SRB海水中的腐蚀速率均表现出先增大后减小的趋势,在整个实验过程中,Zn涂层的腐蚀速率一直大于Al涂层;SEM分析表明,浸泡结束后,Zn涂层表面覆盖了一层由微生物(SRB)和腐蚀产物共同组成的混合膜层,而铝涂层表面的覆盖层主要为生物膜,腐蚀产物较少。EDS结果显示,Zn涂层表面的S元素含量远高于Al涂层,说明SRB的代谢活动对Zn涂层的影响相对较大。

SRB对X100管线钢在西北盐渍土壤中应力腐蚀开裂行为的影响

采用慢应变速率拉神(SSRT)实验和SEM研究了SRB对X100管线钢在典型的西北盐渍土壤(库尔勒土壤模拟溶液)中应力腐蚀开裂行为的影响。结果表明,X100管线钢母材和焊缝在无菌的库尔勒土壤模拟溶液中具有较高的SCC敏感性,其断口模式为穿晶+沿晶SCC混合断裂;X100管线钢母材和焊缝在含有SRB的库尔勒土壤模拟溶液中的SCC敏感性低于无菌时的,其断口模式为穿晶SCC断裂,说明SRB的存在抑制了X100管线钢的脆变,致使X100管线钢的SCC敏感性降低,这可能是由于SRB能在X100管线钢表面快速繁殖并形成生物膜,该生物膜随时间的增加会不断的堆积并变得致密,一定程度上阻隔了活性阴离子Cl-进入X100管线钢基体表面,致使X100管线钢的SCC敏感性减小。

游离和固定化SRB污泥处理含锌废水比较研究

采用聚乙烯醇(PVA)-硫酸铵包埋法对硫酸盐还原菌(SRB)进行固定化处理。以含锌废水为处理对象,利用内聚营养源固定化小球与游离污泥做对比实验,考察硫酸根去除率、锌离子去除率、出水COD值等因素,并借助EDX分析小球内部锌离子含量。实验结果表明,采用内聚营养源固定化小球,硫酸根去除率为55.7%,锌离子去除率达98%,出水COD<100mg/L,进行多次循环实验,出水锌离子浓度仍达到污水综合排放二级标准;采用游离污泥,硫酸根去除率为46.1%,锌离子去除率为98.2%,出水COD1800mg/L以上,用于二次处理废水,锌离子去除率仅为60.4%。固定化小球循环处理废水四次后,每克固定化小球内部锌离子含量为0.04364mg。

硫酸盐还原菌腐蚀防治技术研究

自然环境中硫酸盐还原菌的广泛发育易引起诸多腐蚀性问题,严重影响生态环境质量并危及相关工业安全生产,因此备受广大学者关注。通过梳理文献,对硫酸盐还原菌腐蚀防治技术进行综述。首先基于微生物的代谢过程,简单介绍了硫酸盐还原菌介导的腐蚀行为;其次针对其介导腐蚀,简要概述了物理、化学和生物等防治方法,总结了各方法的应用特性及发展前景;随后主要从微生物活性抑制和产物消耗这2个角度,重点分析归纳了基于硝酸盐还原作用的硫酸盐还原菌腐蚀防治机理,并综述了相关的实践应用研究情况。最后,针对硫酸盐还原菌腐蚀防治技术提出几点思考,并对其进一步发展做出展望。

生物竞争技术防治油田采出水中SRB引起的腐蚀

新疆彩南油田产出水富含SRB、NRB及硫酸根离子,生产系统腐蚀严重。研究了利用SRB和NRB之间的生物竞争防止SRB引起的腐蚀的方法。在厌氧培养基中加入化学处理剂,在40℃培养7天,由N80钢片腐蚀速率确定了化学处理剂的适宜加量：现用杀菌剂（1227＋戊二醛）为80 mg/L,SRB抑制剂（硝酸铵＋亚硝酸钠）为1 mg/L,缓蚀剂ZC-503为20 mg/L。在彩南C2104井产出水样中加入1%磷酸氢二铵、0.1%酵母膏、适宜加量的一种或一组化学处理剂,在40℃密闭培养不同时间（4-96小时）后测SRB、NRB菌数和S2-浓度,培养120小时后测钢片腐蚀速率,结果如下：加入抑制剂可抑制SRB生长,促进NRB生长,防止S2-生成,使腐蚀速率由0.102 mm/a降至0.064 mm/a;加入缓蚀剂不影响两种菌的生长,可推后S2-的生成,使腐蚀速率降至0.038 mm/a;同时加入抑制剂和缓蚀剂可完全抑制SRB生长,防止S2-生成,促进NRB生长,使腐蚀速率降至0.035 mm/a。建议彩南油田生产系统采用这种低费用的生物竞争和化学缓蚀结合技术防治SRB引起的腐蚀。