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。     

污水环境中混凝土的微生物腐蚀与防腐措施

概述了污水环境中混凝土微生物腐蚀的研究现状和侵蚀机理,介绍了评定混凝土微生物侵蚀程度的试验方法,并论述了防腐措施的有效性和可行性,可为后续混凝土微生物腐蚀机制和防腐技术的深入研究以及相关规范和标准的建立提供参考。     

城市污水管道的混凝土腐蚀机理与耐久性设计

城市污水管道是重要的基础设施,对城市生态安全、社会生产发展等都起着至关重要的作用。对某市污水管道的混凝土腐蚀情况进行调查分析,在此基础上开展了室内模拟腐蚀试验研究,提出了污水管道混凝土的耐久性设计方法。研究表明:该城市污水管道混凝土腐蚀破坏的主要因素为硫酸盐侵蚀;采用矿物掺合料、聚丙烯纤维对管道混凝土进行改性,能够有效提高管道混凝土在污水腐蚀环境中的耐久性,双掺粉煤灰和矿渣并添加适量聚丙烯纤维(CX组)的效果最佳,与原配比混凝土相比,CX组混凝土的立方体抗压强度和劈裂抗拉强度分别提高了20. 7%和16. 9%。在试验条件下,水泥基结晶型防水涂料对于管道混凝土耐久性的改善尚不明显。     

BCCP混凝土管道腐蚀机理及防护措施

文中从BCCP管道的腐蚀机理和防护措施两方面,分析了延长管道寿命的主要因素,探讨了各因素的影响机理,提出了一些防护措施,为对BCCP管道工程腐蚀防护提供借鉴。     

脱苯塔腐蚀机理及其影响因素探讨

探讨回收工艺操作对脱苯塔腐蚀的影响。研究脱苯塔的腐蚀机理，并提出了相应的防腐措施。     

预应力钢筒混凝土管在海水输送工程中的应用

介绍了PCCP在海水输送工程中的应用情况,同时对输送过程中管壁内外不介质对管壁的腐蚀机理作了分析,并提出了相应的防腐措施.     

混凝土排污管的微生物腐蚀

本文叙述了混凝土管在排放过程中受微生物侵蚀的原因和机理,讨论了污水和废水中存在的各种侵蚀因素,硫杆菌属的各类细菌的生存条件,生物化学腐蚀过程。指出最终由食砼菌在混凝土表面与氢硫酸产生生化反应,生成硫酸,导致混凝土破坏。提出了各种防护措施。     

海工混凝土结构的腐蚀机理与防腐措施

海工混凝土结构的腐蚀破坏是因海水环境中的氯离子渗透聚集于混凝土内钢筋表面并致其钝化膜失去保护作用而造成的,这是一个复杂的电化学腐蚀过程。为了避免或减少因海水腐蚀作用对混凝土力学性能及耐久性能的影响,就必须采取切实可行的防腐措施。论文在总结国内外混凝土腐蚀现状的基础上,从结构的腐蚀破坏机理出发,归纳了包括采用结构措施、改善混凝土性能措施、增加混凝土保护层厚度、预留钢结构材料腐蚀厚度、改善施工工艺与提高施工技术水平及其它特别辅助防腐措施与方法的应用特点及要求。     

浅议井下油管的腐蚀机理及防腐措施

腐蚀已成为影响油气田安全生产的重大不利因素。文章阐述了井下油管的腐蚀现状、特点,对造成腐蚀的影响因素进行了系统的分析,并结合腐蚀发生的条件和危害,简要地提出了有效控制井下油管腐蚀的措施,如主要有正确选材与合理设计、缓蚀剂保护、涂镀层保护、阴极保护、改善油田水介质状况、加强和完善管理体制等。     

H_2S引起的污水管道腐蚀及其控制

世行贷款淮河流域城市污水处理工程中污水管网的管材,世行要求具备防腐性能,由于过去在这方面的讨论不多,因此请合肥市市政设计院高文乔同志就污水管道主要由 H2S引起腐蚀的基本原理、腐蚀速度计算与防腐措施作简要介绍,希望有更多排水工程科技工作者讨论这一问题,还希望广大排水工程人员提高对污水管道防腐重要性的认识,使我省污水管道工程的质量上一个新台阶。     

Elimination of hydrogen sulphide from odorous air by a wood bark biofilter

Wood bark, used as biofilter material, gives less back pressure than fibre peat or household compost and is therefore cheaper in variable costs than the other materials. With a filter bed height of 0.9 m and with a surface load of 65 m³ m⁻² h⁻¹, 10 ppm hydrogen sulphide is efficiently eliminated from odorous air by a wood bark biofilter. The most important parameter for a good functioning of the filter is the water content of the filter material. The optimum for wood bark is about 65%. Unnecessarily high back pressures are recorded during sprinkling water on top of the filter. Therefore, it seems preferable to condition the relative humidity of air entering the filter. If absorption and adsorption were the only factors in the biofilter mechanism, hydrogen sulphide would, in the given circumstances, break through after about 7 h. It is shown that hydrogen sulphide is oxidized to sulphate. According to literature data, chemical oxidation is too slow and therefore hydrogen sulphide oxidation in the biofilter is attributed to microbiological action.     

DNA damage induced by wastewater from cocoa industry in two prokaryotic systems

In this study, the potential genotoxic and mutagenic effects of cocoa industry wastewater was assessed using SOS Chromo and Ames fluctuation tests, respectively. The physico-chemical analyses of the wastewater were also carried out. The SOS Chromo and Ames fluctuation tests results showed that cocoa industry wastewater can induce different levels of DNA damage and mutagenic potential at the different concentrations used in this study. Salmonella typhimurium TA98 was more sensitive than TA100 strain, indicating frameshift mutation as a possible mechanism of DNA damage. High concentrations of Pb, Cd, Cr, Ni and Cu in the tested sample were possibly responsible for the observed mutagenicity and genotoxicity.     

A survey of heavy metals in municipal wastewater in combined sewer systems during wet and dry weather periods

During wet weather, combined sewer system overflows affect the quality of water in watercourses. For planning overflows, the lowest possible load of priority substances according to Directive 2008/105/EC is crucial and the knowledge of variability in concentrations of elements in the sewer system is necessary. The behaviour of heavy metals in a sewer system was observed in the course of dry weather flow (DWF) and wet weather flow (WWF). We found, from the comparison of concentration medians for the WWF and DWF that during wet weather periods, an increase in the concentrations of As, Cr, Cd, Pb, Mn and Fe occurs in the sewer system and the effect of nonpoint sources manifests itself. Zn, Cu and Ni concentrations decreased during wet weather periods, and Hg concentrations did not significantly change. During the WWF period, a considerable nonhomogeneity of the sewage system was demonstrated.     

Mathematical modelling of hydrogen sulphide emission and removal in aerobic biofilters comprising chemical oxidation

Four different empirical expressions have been compared for estimating the removal of hydrogen sulphide (H₂S) from wastewater by chemical oxidation during its treatment in an aerated biofilter. The relative importance of this removal process is considered in a mass balance proposed by an emission model. Two of the four models investigated were able to predict the mean H₂S removed fraction within a confidence interval of 95% and they demonstrated good agreement with experimental data. Biodegradation and oxidation were the two main removal mechanisms in the biofilter whereas stripping and volatilization made only minor contributions. However they can be of significance when the emission rates are calculated.     

Contributions of wastewater, runoff and sewer deposit erosion to wet weather pollutant loads in combined sewer systems

An observatory of urban pollutants was created in Paris for the purpose of assessing the dynamics of wastewater and wet weather flow (WW and WWF) pollutant loads within combined sewers. This observatory is composed of six urban catchments, covering land areas ranging in size from 42 ha to 2581 ha. For a wide array of parameters including total suspended solids (TSS), chemical and biochemical oxygen demand (COD and BOD₅), total organic carbon (TOC), total Kjeldahl nitrogen (TKN), heavy metals (Cu and Zn) and polycyclic aromatic hydrocarbons (PAHs), this article is intended to evaluate the contributions of wastewater, runoff and in-sewer processes to WWF pollutant loads through the use of an entry–exit mass balance approach. To achieve this objective, a total of 16 rain events were sampled on these sites between May 2003 and February 2006. This study has confirmed that at the considered catchment scale (i.e. from 42 ha to 2581 ha) the production and transfer processes associated with WWF pollutant loads do not vary with basin scale. Entry–exit chemical mass balances over all catchments and for a large number of rain events indicate that wastewater constitutes the main source of organic and nitrogenous pollution, while runoff is the predominant source of Zn. For Cu, PAHs and TSS, the calculation underscores the major role played by in-sewer processes, specifically by sediment erosion, as a source of WWF pollution. A significant loss of dissolved metals was also observed during their transfer within the sewer network, likely as a consequence of the adsorption of dissolved metals on TSS and/or on sewer deposits. Moreover, the nature of eroded particles was examined and compared to the various sewer deposits. This comparison has highlighted that such particles exhibit similar organic and PAH contents to those measured in the organic layer, thus suggesting that the deposit eroded during a wet weather period is organic and of a nature comparable to the organic layer. Despite the extent of initial field investigations, no organic deposit was observed to be present on sewer lines within the catchments, which implies that this organic deposit is probably present in another form or to be found elsewhere in the main trunks.     

Treatment of wastewater in sewer by Spirogyra sp. green algae: effects of light and carbon sources

The aim of this study is to evaluate the use of Spirogyra sp. green algae for wastewater treatment process in sewer. The effects of light and carbon sources were investigated on growth of the algae Spirogyra sp, removal of nitrate, nitrite, phosphate, chemical oxygen demand (COD) and pH changes. Samples 1 & 4 were grown in autotroph form, while samples 2 & 5 and 3 & 6 were grown in media containing 100 and 200 mg/L of glucose, respectively. Samples 1 up to 3 were grown in cycling light but samples 4 up to 6 were grown in continuous light. Results indicated that algal growth, levels of nitrites and pH and removal of nitrate and phosphate were increased in continuous illumination and carbon sources availability (100 and 200 mg/L of glucose). It can be recommended to apply Spirogyra sp. for wastewater treatment proces s in sewer collection system.     

双氧水的发泡及其在制造轻混凝土中的应用

主要研究了双氧水发泡剂在制备超轻混凝土过程中的效果,同时通过对制得混凝土的容重、气孔和强度等方面对其检测来对发泡剂进行评价。     

Quantitative detection of previously characterized syntrophic bacteria in anaerobic wastewater treatment systems by sequence-specific rRNA cleavage method

Quantitative monitoring method of two important trophic groups of bacteria in methanogenic communities was established and applied to six different anaerobic processes. The method we employed was based upon our previous sequence-specific rRNA cleavage method that allows quantification of rRNA of target groups so that the populations reflecting in situ activity could be determined. We constructed a set of scissor probes targeting the Chloroflexi group known as ‘semi-syntrophic’ heterotrophic bacteria and fatty acid-oxidizing syntrophs to determine their relative abundance in the processes. By using the method, we found that several reactors harbored a large amount of organisms belonging to the phylum Chloroflexi accounting for up to 20% of the total prokaryotic populations. Propionate-oxidizing syntrophs, Syntrophobacter, Smithella and Pelotomaculum were also found to be significant comprising up to 3.9% of the total populations, but their distribution is highly dependent on the process examined. This is the first clear, non-PCR based quantitative evidence that those organisms play active roles under in situ methanogenic conditions.     

活性污泥在天津港污水处理中常见问题的分析

论述了活性污泥的主要指标、水质管理监测项目等,归纳了活性污泥在天津港污水处理运行中常见的问题,并分析了其产生的原因,提出相应的解决措施,最后指明污水处理日常管理运行的关键。     

Assessment of plausible bioindicators for plant performance in advanced wastewater treatment systems

Three full-scale advanced biological systems for nitrogen removal showing different efficiencies were assessed during one year, to investigate the protist communities supported in these wastewater treatment plants (WWTP). The main goal of this research was to explore the differences of these communities from those observed in conventional activated sludge systems. The final objective was to provide background support for the proposal of bioindicators in this type of biological systems, where scarce information was available until now, since only conventional systems had been previously studied from this point of view.Results obtained indicate that, in fact, protist population density and diversity in advanced systems for N-elimination are quite different from other wastewater systems studied before. A statistical approach through multivariate analysis was developed to search for association between protist species and physical-chemical system performance, and specifically N-removal efficiencies. The original hypothesis proposing that previous indicators from conventional systems are not adequate in advanced N-removal mechanisms was proved to be correct. Efficient processes on N-removal, despite what it had been usually found in conventional systems, show important flagellate and amoeba populations and these populations tend to reduce their abundances as nitrogen removal performance decreases (moderate to low). Ciliates are however less abundant in these N-removal efficient systems. Certain groups and genera of protist such as flagellates and small amoebae are thus proposed as indicative of high performance N-removal, while in this case the appearance of certain ciliates were indicative of low performance on N- or high organic matter removal (as COD) efficiencies.