污水管道的硫化氢腐蚀及其控制

论述了硫化氢腐蚀的机理及影响因素,提出了预防和控制硫化氢腐蚀的方法。硫化氢腐蚀是造成污水管道结构损坏的主要原因之一。在厌氧条件下,厌氧微生物将污水中的硫酸盐还原成硫化物,并与水中的氢根离子结合产生硫化氢。在微生物作用下,硫化氢被氧化生成硫酸,进而对污水管道材料产生极强的腐蚀作用。这是导致管道腐蚀的主要原因,而硫化氢直接对管道的腐蚀作用要小得多。污水中溶解氧、硫酸盐、pH值的含量,以及管道中的水位与温度是影响硫化氢对管道腐蚀的重要因素。通过降低污水中溶解性硫化物的浓度,是防止硫化氢腐蚀的理想措施。通常的控制技术包括:氧化法、沉淀法和pH值法。     

谈埋地输水PCCP管道外防腐措施的重要性

从水泥砂浆层腐蚀破坏与钢骨腐蚀破坏两个角度分析了埋地输水PCCP管道腐蚀的主要原因,对PCCP的防腐措施进行了探讨,提出了改善水泥砂浆和混凝土品质、涂覆外防腐层、阴极保护等措施,指出PCCP管道多用于大型输水工程,管径大,输水量高,提高其运行的耐久性与安全性至关重要。     

盐渍土地区混凝土腐蚀状况调查分析

为了研究盐渍土地区混凝土抗腐蚀性能,在青海省格尔木市察尔汗盐湖盐渍土地区进行实地走访,调研盐渍土地区混凝土结构构件的腐蚀状况,收集了多种混凝土防盐蚀的有效措施,对防盐蚀措施和防护效果进行了分析,针对不同的工程结构总结出相应有效可行的防腐措施.结果表明:工程结构与盐渍土或卤水接触部分的腐蚀最为严重,采取了防腐措施的混凝土结构构件腐蚀较轻,提高混凝土强度等级和增加保护层厚度可以适应各种类型的混凝土结构防腐.研究结果可为新建混凝土结构构件的防腐提供参考.     

庭院燃气管道弯管开裂和腐蚀穿孔分析与措施

通过对某庭院燃气管道弯管开裂和地下车库上方燃气管道腐蚀穿孔两个典型案例的分析,提出成型工艺造成的金相组织变形和残余应力是弯管开裂的主要原因,管道防腐层因潮湿环境破损导致管道外壁发生电化学腐蚀是地下车库上方管道腐蚀穿孔的主要原因。从钢管金相组织控制、成型工艺和管道防腐层改进3个方面提出了相应的措施。     

多种内防腐措施对提高混凝土耐久性的作用效果对比研究

对多种混凝土内防腐措施的防腐效果进行对比,并结合混凝土耐久性设计的要求,提出不同腐蚀环境下混凝土适用的防腐措施。结果表明,高性能混凝土在满足强度设计前提下,耐久性大幅提升;混凝土防腐剂提高了混凝土密实性,对提高抗氯离子渗透和硫酸盐腐蚀都有一定的效果;引气混凝土对提高干湿循环的抗硫酸盐腐蚀有一定效果,在弱腐蚀环境单独使用简单有效,在强腐蚀环境时可以作为辅助措施与其它措施共用;抗硫酸盐水泥对抗硫酸盐腐蚀具有良好的效果,但对抗氯离子渗透性无明显作用,2种腐蚀因素环境下不宜单独使用。     

人工煤气管道内壁腐蚀分析及防腐措施

分析了煤气管道内壁局部腐蚀的机理和原因,煤气管道的内应力和煤气中的杂质是造成煤气管道腐蚀的主要原因,其中硫化氢是造成电化学腐蚀的重要杂质。针对产生腐蚀的原因给出了防腐措施。     

城市小区天然气钢质埋地管道防腐层检测与修复

对埋地天然气钢质管道防腐层定期进行检测和修复,是管道安全运行的重要保证措施.本文介绍了克拉玛依市南泉小区庭院天然气钢质埋地管道的检测方法、管道外防腐层修复等技术的应用,旨在交流管道腐蚀状况检测与修复技术的实践经验,并对检测仪器的正确使用及庭院埋地管道防腐层的修复提出建议.     

埋地钢质燃气管道腐蚀漏气维修经验

论述了在城市埋地钢质燃气管道发生腐蚀漏气后,应用检测技术对管道防腐系统进行检测,然后维修与改造管道防腐系统,防止管道继续发生腐蚀的经验.     

混凝土排水管道内部腐蚀研究

排水管道是城市的基础设施,也是城市经济健康发展的强大保障。混凝土管道因具有良好的抗腐蚀性能和承载性能,以及适用于大口径等特点,是排水管道中应用最为广泛的一种。然而随着使用年限的增长,污水中微生物诱导产生的硫化氢被污水液面以上的管壁吸收,并被硫化物氧化菌氧化成硫酸,对混凝土管道形成腐蚀,影响管道的使用性以及安全性。从污水管道的腐蚀机理和腐蚀模型方面展开研究,采用不同的腐蚀模型进行了实际管道腐蚀深度的预测,通过预测结果与实测结果的比对,确定了具有普适性的预测模型。并进一步采用COMSOL MULTIPHYSICS软件对管道的腐蚀现象进行了数值模拟,模拟结果可在一定程度上预测混凝土污水管道的腐蚀程度。     

建筑水暖管道腐蚀成因及解决办法

文章首先说明了建筑水暖管道腐蚀的原因,其次提出了水暖管道的防腐处理措施,包括环境腐蚀性检测技术、使用化学防腐缓蚀剂、应用不同类型的涂层技术、涂抹防腐蚀涂层、预防管道外部的腐蚀。     

Assessment of hydrogen sulphide corrosion of cementitious sewer pipes: a case study

A study was conducted to assess hydrogen sulphide corrosion in cementitious sewer pipes and concrete culverts existing in the four largest coastal cities and their environs in Lebanon. Significant factors and parameters affecting H₂S corrosion were measured both in the field and in the laboratory. All collected samples were obtained from existing sewer networks that are more than 30 years old. Pipe samples obtained from these locations did not exhibit any corrosion indicators. Alkalinity measurements indicated the occurrence of mild corrosion leading to neutralization of concrete (calcareous aggregates) particularly at the pipe crown. Testing for the sulphate content of the samples did not reveal a clear trend as to the distribution of sulphates along the pipe circumference. Parameters of the existing sewer networks upstream of sample sites, along with survey data obtained from the field were introduced into commercial software for the evaluation of sulphide generation and annual corrosion rates. The results indicated that hydrogen sulphide will only be generated in negligible quantities under the prevailing environmental conditions, and hence H₂S corrosion could proceed, but at very slow rates.     

Integrated Monitoring and Modelling of Odours in Sewerage Systems

The parameters of sewage that affect the production and resulting concentration of hydrogen sulphide in both liquid and gas phases have been monitored in a sewerage system. The data have been used to develop a model of the chemical and physical processes leading to sulphide production in sewers, so that the sources and causes of the problem can be identified. This model has been adapted to predict the concentrations of hydrogen sulphide that can be expected in the sewage and sewer atmosphere, following the construction of a major interceptor tunnel.     

Methane formation in sewer systems

Methane formation and emission in sewer systems has not received as much attention as hydrogen sulphide formation. Through field measurements from two rising mains, with an average sewage temperature of 28.4 and 26.6 degrees C, respectively, at the time of sampling, this study shows that a significant amount of methane can be produced in sewer systems, and that this production is positively correlated with the hydraulic retention time of wastewater in these systems. The experimental results from a laboratory-scale sewer system fed with real sewage with a temperature of approximately 21 degrees C confirmed these field observations and further revealed that methanogenesis and sulphate reduction occur simultaneously in sewers, with methane production contributing considerably more to the loss of soluble COD in sewers than sulphate reduction. The production of methane in sewers at levels revealed by this study is a serious environmental concern as it potentially results in greenhouse emissions that is comparable to that caused by the energy consumption for the treatment of the same wastewater. Further, methane production in sewers influences sulphide production and its management due to the competition between methanogens and sulphate-reducing bacteria for potentially the same electron donors. The potential interactions between sulphate-reducing and methanogenic bacteria in sewer networks are discussed.     

Influence of pipe material and surfaces on sulfide related odor and corrosion in sewers

Hydrogen sulfide oxidation on sewer pipe surfaces was investigated in a pilot scale experimental setup. The experiments were aimed at replicating conditions in a gravity sewer located immediately downstream of a force main where sulfide related concrete corrosion and odor is often observed. During the experiments, hydrogen sulfide gas was injected intermittently into the headspace of partially filled concrete and plastic (PVC and HDPE) sewer pipes in concentrations of approximately 1000 ppm_v. Between each injection, the hydrogen sulfide concentration was monitored while it decreased because of adsorption and subsequent oxidation on the pipe surfaces. The experiments showed that the rate of hydrogen sulfide oxidation was approximately two orders of magnitude faster on the concrete pipe surfaces than on the plastic pipe surfaces. Removal of the layer of reaction (corrosion) products from the concrete pipes was found to reduce the rate of hydrogen sulfide oxidation significantly. However, the rate of sulfide oxidation was restored to its background level within 10-20 days. A similar treatment had no observable effect on hydrogen sulfide removal in the plastic pipe reactors. The experimental results were used to model hydrogen sulfide oxidation under field conditions. This showed that the gas-phase hydrogen sulfide concentration in concrete sewers would typically amount to a few percent of the equilibrium concentration calculated from Henry's law. In the plastic pipe sewers, significantly higher concentrations were predicted because of the slower adsorption and oxidation kinetics on such surfaces.     

Beneficial impact of coatings on biological generation of sulfide in concrete sewer pipes

Hydrogen sulfide is a serious problem for many municipalities across North America and worldwide. Odor, safety, and corrosion are the major problems associated with the presence of hydrogen sulfide in sewerage systems. This paper investigates the effect on sulfide generation of using innovative coatings in concrete sewer pipes. A pilot-scale model, consisting of three concrete pipes (each 75 cm in length and 30 cm in internal diameter), was used to simulate the process of sulfide generation in a sewer system. Two of the pipes were internally coated with either cuprous oxide (C.O) or silver oxide (S.O), while the third one served as a control. Each of the oxides was mixed with a commercial epoxy, used for repairing concrete sewer pipes, prior to spraying on the internal surface of the concrete pipe specimens to form a coating film. Test data showed that the sulfide generation by sulfate-reducing bacteria (SRB) in the C.O and S.O coated pipes was reduced by 92% and 100%, respectively, compared with that of the control pipe. The coating films effectively decreased the bacterial count in the nutrient solution. Results also suggested that the slime layer formed in the C.O coated pipe was significantly smaller and thinner compared with that of the control pipe. No slime layer was observed on the internal surface of the S.O coated pipe at the conclusion of the test.     

Assessment of reinforced concrete sewer after long service: a case study

Assessment of the reinforced concrete shells of a sewer after two decades of service is presented. The methods used to investigate the sewer structure are described and the criteria for evaluating its safety are given. As part of the assessment and analysis laboratory tests of the concrete were carried on core samples taken from the shells. Concrete strength, carbonation, water permeability and leaching depth were checked. The degree of corrosion of the reinforcing steel and loss of reinforcement cover were also examined. The material tests’ results were then used in a numerical analysis of the stress in the shells that checked level of the structural safety. Based on the experimental and numerical results the approximate life cycle was estimated at another 55 years.     

掺管沟污泥水泥混凝土的物理力学性能研究

研究了以管沟污泥等量替代天然细集料制备水泥混凝土的技术。结果表明，在混凝土中掺加一定量的管沟污泥可以配制出强度为40MPa以上的混凝土，同时其28d强度可高于同配合比的基准混凝土。此外，随污泥掺量的增加，混凝土坍落度会降低，凝结时间会延长。测试掺污泥的水泥混凝土固结体中重金属溶出量表明其可满足国家标准的要求，无二次污染。     

掺管沟污泥水泥混凝土的性能研究

采用管沟污泥等量替代天然细集料,制备了掺管沟污泥的水泥混凝土.研究结果表明:在混凝土中掺加一定量的管沟污泥,可以配制出强度等级为40 MPa以上的混凝土,其28 d抗压强度高于同配合比的基准混凝土;随着管沟污泥掺量的增加,混凝土坍落度降低;掺管沟污泥水泥混凝土固结体的重金属溶出量满足国家标准,无二次污染.     

Microbial community structures and in situ sulfate-reducing and sulfur-oxidizing activities in biofilms developed on mortar specimens in a corroded sewer system

Microbially induced concrete corrosion (MICC) caused by sulfuric acid attack in sewer systems has been a serious problem for a long time. A better understanding of microbial community structures of sulfate-reducing bacteria (SRB) and sulfur-oxidizing bacteria (SOB) and their in situ activities is essential for the efficient control of MICC. In this study, the microbial community structures and the in situ hydrogen sulfide production and consumption rates within biofilms and corroded materials developed on mortar specimens placed in a corroded manhole was investigated by culture-independent 16S rRNA gene-based molecular techniques and microsensors for hydrogen sulfide, oxygen, pH and the oxidation-reduction potential. The dark-gray gel-like biofilm was developed in the bottom (from the bottom to 4 cm) and the middle (4–20 cm from the bottom of the manhole) parts of the mortar specimens. White filamentous biofilms covered the gel-like biofilm in the middle part. The mortar specimens placed in the upper part (30 cm above the bottom of the manhole) were corroded. The 16S rRNA gene-cloning analysis revealed that one clone retrieved from the bottom biofilm sample was related to an SRB, 12 clones and 6 clones retrieved from the middle biofilm and the corroded material samples, respectively, were related to SOB. In situ hybridization results showed that the SRB were detected throughout the bottom biofilm and filamentous SOB cells were mainly detected in the upper oxic layer of the middle biofilm. Microsensor measurements demonstrated that hydrogen sulfide was produced in and diffused out of the bottom biofilms. In contrast, in the middle biofilm the hydrogen sulfide produced in the deeper parts of the biofilm was oxidized in the upper filamentous biofilm. pH was around 3 in the corroded materials developed in the upper part of the mortar specimens. Therefore, it can be concluded that hydrogen sulfide provided from the bottom biofilms and the sludge settling tank was emitted to the sewer atmosphere, then oxidized to corrosive compounds in the upper and middle parts of the manhole, and only the upper part of the mortar specimens were corroded, because in the middle part of the manhole the generated corrosive compounds (e.g., sulfuric acid) was reduced in the deeper parts of the biofilm.     

内衬HDPE片材大口径钢筋混凝土排水管检测试验初探

基于工程实际要求,对内衬高密度聚乙烯(HDPE)片材化学物理性能及内衬HDPE片材钢筋混凝土管节进行了试验研究,包括内衬HDPE单键和多键的抗拉拔试验、管节接头抗内水压和外水压试验、HDPE片材覆贴接头抗外水压试验、外压荷载试验,可为HDPE片材在钢筋混凝土排水管中的应用和推广提供参考。