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341.
Xinyan ZHANG Binbin WANG Qingqing HAN Hongmei ZHAO Dangcong PENG 《Frontiers of Environmental Science & Engineering》2013,7(6):896-905
This paper reports the effects of shear force on anoxic granular sludge in sequencing batch reactors (SBR). The study was carried out in two SBRs (SBR1 and SBR2) in which sodium acetate (200mg COD·L^-1) was used as the sole substrate and sodium nitrate (40 mgNO3-N·L^-1) was employed as the electron acceptor. The preliminary objective of this study was to cultivate anoxic granules in the SBR in order to investigate the effects of shear force on the formation of anoxic granular sludge and to compare the properties of anoxic sludge in the SBR. This study reports new results for the values of average velocity gradient, a measure of the applied shear force, which was varied in the two SBRs (3.79 s^-1 and 9.76 s^-1 for SBR1 and SBR2 respectively). The important findings of this research highlight the dual effects of shear force on anoxic granules. A low shear force can produce large anoxic granules with high activity and poor settling ability, whereas higher shear forces produce smaller granules with better settling ability and lower activity. The results of this study show that the anoxic granulation is closely related to the strength of the shear force. For high shear force, this research demonstrated that: 1) granules with smaller diameters, high density and good settling ability were formed in the reactor, and 2) granular sludge formed faster than it did in the low shear force reactor (41days versus 76 days). Once a steady-state has been achieved, the nitrate and COD removal rates were found to be 98% and 80%, respectively. For low shear force, such as was applied in SBR1, this research demonstrated that: 1) the activity of anoxic granular sludge in low shear force was higher than that in high shear force, 2) higher amount of soluble microbial products (SMPs) were produced, and 3) large pores were observed inside the larger granules,which are beneficial for nitrogen gas diffusion. Electron microscopic examination of the anoxic granules in both reactors showed that the morphology of the granules was ellipsoidal with a clear outline. Coccus and rod-shaped bacteria were wrapped by filamentous bacteria on the surface of granule. 相似文献
342.
Junjun TAN ;Guohua YANG ;Jingqiao MAO ;Huichao DAI 《Frontiers of Environmental Science & Engineering》2014,8(6):863-870
Combustion-generated hydrogen chloride (HCl) is considered to be a very hazardous acid gaseous pollutant. This paper presents a laboratory study on the dry adsorption of HCl. The experiments were conducted in a dual-layer granular bed filter, at gas temperatures of 500℃-700℃ and n(Ca)/n(Cl)molar ratios of 1.0-5.0 using the silver nitrate titration method by dry adsorbent powders Ca(OH)2. Mainly, the adsorption efficiency of HCI and utilization efficiency of Calcium were studied, by varying relevant factors including n(Ca)/n(Cl), tempera- ture, feeding method, water vapor and CO2. With a relatively higher HCl concentration of 1000ppm, the experimental results revealed that 600℃ may be the optimum temperature for HCl adsorption when optimum n (Ca)/n(Cl) was 2.5 in our tests. The results also demonstrated that the feeding at a constant pressure was more effective, and the HCl adsorption efficiency could rapidly reach over 90% with n(Ca)/n(Cl) = 2.5 at 600℃. Furthermore, the HCl adsorption efficiency was found to be slightly promoted by water vapor, while could be impeded by CO2, and the utilization efficiency of calcium could be up to 74.4% without CO2, while was only 36.8% with CO2 when n(Ca)/n(Cl) was 2.5 at 600℃. 相似文献
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以苯甲酸(BA)、邻苯二甲酸(PA)、连苯三甲酸(HA)、1-萘甲酸(1NA)为研究对象,探究了不同结构芳香酸对厌氧颗粒污泥理化特性与微生物群落的影响.结果表明,在40 d的接触实验中,1NA实验组对溶解性化学需氧量(SCOD)的去除率为86.09%,与空白对照组相比降低了7%.4个实验组污泥疏松胞外聚合物(LB-EPS)和紧密胞外聚合物(TB-EPS)中多糖含量分别比对照组高0.30~1.28、0.19~1.03 mg·g-1,蛋白含量分别提高了0.025~0.326、0.007~0.171 mg·g-1.在LB-EPS三维荧光(EEM)光谱中,HA和1NA实验组中出现了类腐殖酸物质荧光峰,且辅酶F420峰强度有所降低.对于酶活性而言,HA、1NA实验组乙酸激酶相对活性比对照组减少了65.26%、6.93%.通过高通量测序发现,对照组与实验组中的优势菌群均为Proteobacteria、Chloroflexi和Firmicutes.HA与1NA的加入降低了Actinobacteria的相对丰度,提高了Bacteroidetes和Synergistetes的相对丰度.对于古细菌而言,Methanothrix在对照组与实验组中为优势种属,其相对丰度达到49.95%~80.40%;但实验组Methanothrix的相对丰度减少了10.69%~30.45%,且1NA实验组尤为明显;而1NA的加入提高了Methanospirillum的相对丰度,达到34.08%.同时,细菌和古细菌代谢通路预测表明,其主要功能组为代谢、遗传信息处理、环境信息处理和细胞过程,芳香酸使得厌氧颗粒污泥中氨基酸的代谢功能有所增强. 相似文献
345.
本文研究UASB反应器处理石灰法制浆的草浆蒸煮黑液,在较短时间内培养出首育良好沉淀性能和较高活性的厌氧颗粒污泥。并对其形态、结构和化学组份及不同生理类群的厌氧微生物特性等进行了观察和测试,结果表明厌氧颗粒污泥高活性的原因。为进一步探索厌氧颗粒污泥的形成机理提供了依据。 相似文献
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结合国内外的研究成果,对好氧颗粒污泥的影响因素及形成机理进行了探讨,认为接种污泥、进水基质和有机负荷、运行方式、水力剪切力、沉淀时间等对好氧颗粒污泥的培养具有重大影响,是好氧颗粒污泥形成的主要影响因素;并提出了好氧颗粒污泥形成机理的"凝结核猜想",认为好氧颗粒污泥的最终形成分为出现凝结核、形成胚胎颗粒污泥及形成好氧颗粒污泥三个阶级。 相似文献
348.
铁渗透反应格栅是铬污染地下水的有效去除技术,但地下水中SO42-对铁格栅长期运行性能影响还不清楚。文章采用批实验和柱实验的方法,分别研究了硫酸根离子浓度对颗粒铁从液相去除常量C(rVI)(20mg/L)的动力学影响及这种影响随时间的变化。批试验表明,随SO42-浓度的增加,C(rVI)的面积标准化速率系数kSA增加。柱试验采用三个平行柱实验系统连续输入含20mg/LC(rVI)的模拟地下水(含或不含SO42(-1000mg/L))。柱实验表明,运行100PV以前,SO42-显著增大颗粒铁对C(rVI)的面积标准化速率常数kSA,随后SO42-增强作用逐渐减弱,运行337PV时,SO42-没有明显的影响。硫酸根离子通过在铁表面形成配合物而加速铁的溶解,增加颗粒铁的表面活性,从而增强颗粒铁对C(rVI)的去除,生物作用不强时可以不考虑硫酸根对铁格栅长期运行性能的影响。 相似文献
349.
文章利用取自厌氧折流板反应器中的硫酸盐还原菌(SRB)颗粒污泥,通过间歇试验,研究了不同质量浓度的SO42-对SRB颗粒污泥性能的影响。结果表明,当SO42-质量浓度为2000mg/L,COD与SO42-质量浓度的比值ω(COD)/ω(SO42-)=2时,SRB颗粒污泥的活性最高,此时系统比产甲烷活性(SMA)为406.2mL/g·d,SO42-的去除率达93.4%,Cu2+的去除效率高达97.1%,且Cu2+的去除率与SO42-的还原率呈正相关关系;而ω(COD)/ω(SO42-)=2~4时,COD去除率稳定在88.8%以上,最大去除率在ω(COD)/ω(SO42-)=2.7处。 相似文献
350.