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目前 ,城市固体废物主要采用地质填埋处理 ,淋滤液循环可以使填埋场的稳定化进程加快。但使用淋滤液循环方法的填埋场中仍有大量需要进一步处理的淋滤液。粉煤灰具有优良的吸附净化功能 ,介绍了粉煤灰在垃圾淋滤液循环处理中的作用。通过分析粉煤灰与垃圾混合处理 ,及在此基础上进一步采用粉煤灰做过滤层的不同效果 ,表明粉煤灰可以在填埋场淋滤液循环处理方法中起到一个较好的作用。这种方法在实际应用中还需做进一步的研究工作。 相似文献
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高钙粉煤灰是燃煤电厂排出的固体废物,其堆放不仅需占用大量土地,而且对周围环境存在严重威胁。通过系统的室内试验,着重研究了高钙粉煤灰固化铅与锌污染土的工程性质,揭示了其作用机制,探讨了利用高钙粉煤灰固化重金属污染土的可行性。试验结果表明,土体受到重金属离子污染后其无侧限抗压强度降低,掺入高钙粉煤灰可提高土体强度,并能抑制重金属离子的滤出;污染物浓度较低时,固化污染土中的Pb2+和Zn2+均能得到有效固化,污染物浓度较高时,Zn2+的固化效果优于Pb2+。干湿循环试验结果表明,高钙粉煤灰固化污染土的强度随干湿循环次数的增加,先增大后减小;固化土体中重金属离子浓度较低时,滤出液中金属离子浓度随干湿循环次数增加而增大;重金属离子浓度较高时,滤出液中金属离子浓度基本保持不变。 相似文献
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利用粉煤灰处理含铜废水的实验研究 总被引：8，自引：0，他引：8
研究了粉煤灰去除废水中铜离子的速率、粉煤灰投加量对粉煤灰去除废水中铜离子的影响和粉煤灰对质量浓度不同的含铜离子废水的去除效果,进一步探讨了粉煤灰去除铜离子的机理,实验结果显示粉煤灰在去除废水中铜离子的过程中反应3 h后就达到了平衡,粉煤灰对Cu2 的去除率随粉煤灰投加量的增加而增加,但是就充分利用吸附剂粉煤灰的角度而言,并非其投加量越多去除量越大,粉煤灰吸附废水中的铜离子更符合Langmuir模型,而不是Freundlich模型;粉煤灰去除废水中的Cu2 主要是静电吸附、阳离子交换吸附和表面络合吸附作用,但是,当用碱性粉煤灰处理质量浓度较低的含Cu2 废水时,生成Cu(OH)2的沉淀作用可能占主要的地位. 相似文献
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运用柱子淋洗法，通过分析淋出液中六价铬的浓度，测定淋出六价铬质量与滇充铬渣质量百分比，并计算六价铬淋也速率；研究了在铬渣与粉煤灰主混合体系中加入不同配料对铬渣中六价铬阻留效果的影响，研究结果表明，各种混合填充体系均对六价铬有一定程度的阻留作用并降低六价铬的淋出速率，其中,铬渣：辅料C：粉煤灰为1：3：5（填充高度比）的配合填充体系中，淋出六价铬质量只占滇充铬渣质量的0．060％，相对阻留效果达94．53％，其机理可能是辅料C对粉煤灰的活化作用。 相似文献
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《地下水》2016,(6)
释氧化合物应用于地下水有机污染原位修复技术具有广阔的应用前景,然而地下水中各离子组分对释氧化合物性能的影响却鲜有文献提及。本研究建立了一套地下水流模拟装置,以含有热解改性含油污泥残渣的新型释氧材料(Modified Oxygen Releasing Compound,简称MORC)作为研究对象,采用Na Cl溶液和去离子水作为对照组,探讨Na Cl对MORC释氧性能的影响,并采用扫描电镜对MORC表面矿物结构进行表征。研究结果表明:Na Cl对MORC释氧具有显著的促进作用,当Na Cl溶液浓度为1 000 mg/L、3 000 mg/L时,其促进释氧率分别为12.91%和14.13%。MORC释氧过程中产生的矿物沉淀逐渐在MORC表面沉积,导致材料表面释氧孔道堵塞是影响MORC释氧的重要限制因素。 相似文献
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中国是煤炭资源非常丰富的国家,大多数火力发电厂均以煤炭为其电力生产的基本燃料,而其副产品粉煤灰则露天 露天堆放。粉煤灰中含有的大量重金属和放射性元素是潜在的污染源,尤其是对水环境的污染。文中选取一位于安徽淮北 的火力发电厂的储灰场,对其周边地表及地下水进行野外采样和分析,并取该灰场粉煤灰进行元素含量、矿物成分的分析 及室内淋滤实验。结果表明粉煤灰堆放场周边 12 个取样点的地下水水样中 NO3-,Cr6+,Se 含量超标,其中超标最严重的 Se 的超标率占检测水样的 58.3%,最大浓度值达到III类标准的 6.6 倍。进一步应用主成分分析和聚类分析方法对研究区地下水 离子进行水源分析,发现地下水化学成分主要有 3 个来源:天然背景下,很少受人为影响的水源,其贡献率为 53.32%;第 二个来源反映了处于径流区或排泄区的地下水源并受到一定程度人为因素的影响,其贡献率为 17.37%;第三个来源反映了 粉煤灰对地下水的污染,其贡献率为 14.96%。聚类分析的结果进一步验证了粉煤灰场污染地下水中的空间分布特征:即离 灰场越近,埋深越浅受污染的风险就越大。主成分分析和聚类分析法的应用为今后开展灰场对周围地下水影响的研究,确 定地下水是否受到污染及污染来源 , 提供了一条有效途径。 相似文献
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郭莹 《水文地质工程地质》2001,28(2):63-65
本文结合福州电厂粉煤灰室内试验结果分析，探讨粉煤灰扰动样现场取样及试验控制干密度的等问题，该电厂粉煤灰的沉积规律与其它电厂有所不同，灰料颗粒组细分布和距排灰口远近基本无关，取样也不能按以往经验进行。 相似文献
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粉煤灰土壤主所产蔬菜的有害元素含量变化的环境意义 总被引：1，自引：0，他引：1
利用南京第二热电厂湿排的粉煤灰,进行了改良蔬菜土壤的试验,并对试验用的粉煤灰,不同施灰量的土壤及所产蔬菜的３８个样品的有害元素和放射性元素含量进行了系统的测定。结果表明：这些元素在土壤中的含量与粉煤灰施用量无明显相关性;在本次试验范围内施用粉煤灰没有造成土壤的污染,其所产蔬菜的这些元素含量也均低于国家卫生标准限值,食用是安全的。 相似文献
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水热条件下利用微波加热从粉煤灰合成沸石研究 总被引：14，自引：0，他引：14
着重选用NaOH水溶液为反应前驱物, 通过改变反应温度、NaOH浓度与合成时间等参数, 在水热条件下利用微波加热直接对粉煤灰进行晶化, 合成得到了浊沸石、菱沸石、NaP1沸石3种沸石.粉煤灰转化为沸石率约15%~40%.研究表明: (1) 反应体系在15min左右即有合成沸石产生, 30min左右合成沸石转化率达到最佳; (2) 为保证沸石晶核生成和晶体的生长, 反应体系的溶液/粉煤灰比不应低于2.5; (3) 在溶液/粉煤灰比为2.5时, 应控制加热时间在30min左右. 相似文献
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P.V. Sivapullaiah J.P. Prashanth A. Sridharan B.V. Narayana 《Geotechnical and Geological Engineering》1998,16(3):239-250
The use of fly ash in geotechnical engineering depends greatly on its pozzolanic reactivity. Though many factors influence the reactivity of fly ash it is well recognized that reactive silica and lime content play a major role. A new, accurate and reliable method for the determination of reactive silica content of fly ash has been established. The reactive silica content, obtained as acid soluble silica in about 2 to 3 N hydrochloric acid, is found to correlate well with unconfined compressive strength of fly ashes. The reactive silica content of fly ash is also important in the stabilization of soils using fly ash. © Rapid Science Ltd. 1998 相似文献
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垃圾焚烧飞灰水泥固化体强度稳定性研究 总被引：1，自引：0，他引：1
针对垃圾焚烧飞灰安全处置技术要求,采用水泥对其进行固化、稳定化处理,研究了不同水泥添加量、不同养护时间和渗沥液浸泡时间对固化体无侧限抗压强度及破坏特性的影响,并对垃圾渗沥液的侵蚀机制进行了分析。结果表明：当水泥添加量小于5%,养护时间小于3 d时,飞灰固化体在渗沥液浸泡下迅速解体,垃圾渗沥液的侵蚀对飞灰固化体的强度有较大的影响,浸泡后的固化体呈现出明显的应变软化特征,而未经浸泡的固化体的强度增长符合y=a[1-exp(-bt)]模式。随着水泥添加量及养护时间的增加,飞灰固化体无侧限抗压强度增加,破坏应变减小,而随着浸泡时间的增加,飞灰固化体的无侧限抗压强度先增大后减小,转折点大约在5～7 d,破坏应变近似呈线性增大。渗沥液对飞灰固化体的侵蚀主要是其成分抑制了固化体水化反应和破坏了水化产物。研究成果可为垃圾焚烧飞灰的安全处置技术提供理论依据和参数支持。 相似文献
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Pozzolanic fly ash as a hydraulic barrier in land fills 总被引：2，自引：0，他引：2
The liner plays an important role in controlling migration of contaminants present in the leachate in waste containment systems such as land fills and impoundments. Although questions have been raised about the performance of clay liners, they are increasingly used singly or as double liners in disposal sites. Though the clay liners possess many advantages such as low permeability and large attenuative capacity, they also possess high shrinkage potential and hence can crack under unsaturated conditions causing instability and increase in leakage rates. Further, the permeability of the clay linear can increase due to clay–pollutant interaction. This study examines the potential of pozzolanic fly ash as a hydraulic barrier in land fill. The behaviour of three different types of fly ashes, showing a range of physical properties and chemical composition from three different sources are reported in the study. Geotechnical properties, needed to evaluate the use of fly ashes as barriers, such as shrinkage, compaction, permeability, consolidation and strength characteristics are reported. The results show that fly ashes possess low shrinkage and hence do not crack. Compacted fly ashes undergo very little volume changes. They also show that pozzolanic fly ashes develop good strength properties with time. Pozzolanic fly ashes containing sufficient lime develop strength even without addition of lime. Non-pozzolanic fly ashes do not develop strength even on addition of lime. Fly ashes generally consist of silt size particles and consequently possess high permeability. However, pozzolanic fly ashes with lime exhibit low permeability on curing because of the formation of gelatinous compounds which block the pores. Thus, pozzolanic fly ashes appear to be promising for construction of liners to contain alkaline leachate. 相似文献
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Leaching characteristics of fly ash 总被引：6，自引：0，他引：6
Aysenur Ugurlu 《Environmental Geology》2004,46(6-7):890-895
The disposal of fly ash as a byproduct of thermic power stations, results in significant environmental problems. The leaching of coal fly ash during disposal is of concern for possible contamination, especially for the aquatic environment when ash is in contact with water. The aim of this study was to investigate the leaching behaviour of fly ashes currently disposed in Kemerkoy Power Plant (Turkey) fly-ash-holding pond. The studies were conducted with fly ashes from the electrostatic precipitators (fresh fly ash) and from the fly ash pond (pre-leached fly ash). The fly ashes has alkaline in nature and pH ranges between 11.9 to 12.2. The pre-leached fly ash exhibited lower EC values (7,400 µS) than the fresh fly ash (10,300 µS). In contrast to Fe and Pb, the elements such as Cr, Cd, Cu and Co did not leach from the fly ash. The Ca and Mn concentrations decreased with increasing temperature whereas, Na and K concentrations increased. The results showed that the most important effects of fly ash leaching were pH, Na, Ca, K, Fe, Mg, Mn and Pb. 相似文献
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In this paper, an experimental study was conducted in order to test the feasibility of sintering mullite directly from the high-alumina fly ash, without adding any extra material. The results show that the mullite contents in most sintered samples are over 70%. The samples sintered from the beneficiated fly ash have a higher content of mullite than those from the as-received fly ash under the same synthetic conditions. To obtain an equal amount of mullite, a higher sintering temperature is needed for the beneficiated fly ash than for the as-received fly ash. Considering the physical properties of sintered mullite, the favorable sintering temperature is 1400℃ for the as-received fly ash and 1500℃ for the beneficiated fly ash. A higher sintering temperature and a shorter holding time are profitable to sintering mullite. The orthogonal test confirmed that the dominant factor affecting mullite synthesis is sintering temperature, and that the most profitable matching conditions are 200 MPa-1500℃-3 h for the as-received fly ash and 200 MPa-1500 ℃-4 h for the beneficiated fly ash. 相似文献
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Using a modified extraction procedure, the effect of pH on the leaching of selected elements from Ca-rich (Type C) power plant fly ash was studied. Continuous additions of acetic acid were used to maintain pH values of fly ash slurries at 4.0, 6.0 and 8.0 for 24 h and an additional set was leached at its natural pH (average 11.8) value. Analyses for Se, As, Ca, Cd, Cr, Fe, Na and Pb showed that the highest concentrations occur in the leachate at pH 4.0 and decline with increasing pH. Concentrations of Cr and Fe increased slightly between neutral and high pH. Arsenic, Cd, Cr, Pb and Se concentrations exceeded the Environmental Protection Agency's toxicity criteria at pH 4.0. Selenium was above its toxicity level at pH values near 7 but the other elements were below their respective toxicity levels near neutral pH. Because recent studies show adverse effects of Se on aquatic life at far lower concentrations than the current Environmental Protection Agency's standard, high-Ca, power plant fly ashes represent a potentially hazardous pollutant to surface and subsurface waters. 相似文献