生态水泥中重金属测定方法研究

生态水泥中的重金属问题已经成为制约水泥回转窑混烧废物技术发展的重要因素。文章从总量及浸出性质两个方面分析了现有的重金属测定方法,并通过试验分析了各方法的特点与适用性。试验结果表明:(1)荧光光谱法是最优的总量测定方法;(2)目前我国常用的浸出毒性测定方法不适用于水泥体系;(3)长期浸泡方法可用于测定特定条件下重金属的长期浸出性。这些结论为制定水泥窑混烧危险废物技术的标准与规范提供理论依据。     

Hazardous waste solidification as a multiple barrier concept

The GFS process of waste solidification using pozzolanic material is described. This process is most successful for hazardous particulates. Final products have better landfilling properties in terms of fixing the hazardous contents of wastes, reducing leachates and improving the geo‐physical strength of particulates than the starting waste materials. Furthermore, recycling of metals from sludges of industrial processes as well as of biomass from municipal sewage sludges for agricultural purposes are improved.     

Untersuchung von Abfällen mit biologischen Testverfahren zur Bewertung der Wassergefährdung

Wastes from three different types of waste treatment facilities were examined with bioassays to determine their hazard potential to waters (→Part I). All examined wastes showed toxic effects and have to be classified as hazardous to waters according to section 19g of the German Federal Water Management Act. The toxicity is probably caused by heavy metals in the leachates, especially copper. An evaluation pattern to classify wastes in the German system of Water Hazard Classes is presented. According to this proposal, a classification of the examined wastes into Water Hazard Class 1 seems to be appropriate. This classification does not describe the hazards resulting from the regular disposal on a landfill or from the utilisation of the treated wastes.     

有机肥中重金属特征及其控制技术研究进展

随着工业的快速发展,农药、肥料及地膜等系列农用化学物质的广泛使用,农田土壤重金属污染越来越严重。重金属进入土壤后,其难移动性导致大量积累,造成土壤环境污染,影响植物生长,危及人类的健康。有机肥是我国农业生产中非常重要的肥料,其来源也十分广泛。施用有机肥是提高作物产量的必要措施,同时也是土壤重金属的主要输入途径之一,研究有机肥的重金属特征及其有关控制技术对农产品安全和有机废弃物的再利用具有重要意义。文章就畜禽排泄物堆肥、污泥堆肥、生活垃圾堆肥和沼肥等主要有机肥料的重金属来源、含量以及不同溯源有机肥料对土壤中重金属有效性的影响进行综述,重点介绍了畜禽排泄物堆肥中重金属含量和饲料添加剂之间的关系,为农田土壤重金属污染防治和农产品安全提供科学依据。除从有机肥的源头控制重金属外,文章主要介绍了化学法、生物吸附法、生物淋滤法和电化学法等重金属控制技术,针对各种控制方法,阐述了其原理、应用实例、优缺点及研究进展情况,提出了解决有机肥重金属污染问题的思路和方法,为有机肥料的资源化利用提供了参考。最后指出,为了实现养殖业与种植业的安全链接,除选用重金属含量低的有机肥,通过相关技术有效控制有机肥中的重金属外,还要注重肥料用量、施肥时间、施肥技术的合理选择,从最大程度上避免有机肥料给作物和人类带来的副作用。     

镍钴采选行业废石和尾矿中重金属淋溶释放规律研究

镍钴采选废石和尾矿中重金属的溶出释放规律对矿区的重金属污染防治具有重要意义。但目前,国内还没有对镍钴行业采选产生的尾矿和废石中重金属的溶出规律开展研究。本文以镍钴采选企业的尾矿和废石作为样本,开展了毒性浸出实验。研究了不同pH值、离子强度、温度等实验条件对重金属溶出的影响,探讨了镍钴采选过程中所产生的尾矿和废石中重金属的溶出特性和释放规律。实验结果表明,尾矿样品中Ni的浸出浓度为42.28 mg·L^-1,是最大允许排放浓度的8.86倍,为具有浸出毒性特征的危险废物;废石样品中重金属Ni和Cu的溶出浓度分别为4.72 mg·L^-1和26.2 mg·L^-1,超过最大允许排放浓度,属于第Ⅱ类一般工业固体废物。pH对样品中Ni、Cr、Pb、Co和As的溶出量影响较大,其中尾矿中Ni和Cu在pH较低的条件下,可达到44.28 mg·L^-1和53 mg·L^-1,远高于最大允许排放浓度,而Hg、Cd和Cu的溶出量随pH值的变化不大。除As以外,样品中大多数重金属的溶出质量浓度在酸性条件下比在中性条件下高,这表明在酸性环境条件下,这些重金属对周围生态环境的潜在风险更大。离子强度的变化对Cd和Co的溶出量的变化并不明显,而当离子强度变化时,Ni、Cr、Pb、Hg、Cu和As的溶出量可能达到最大,使周围环境的潜在生态风险增大。当温度达到35~40℃时,部分重金属如Co、Pb、Cd 等,溶出量将达到最大;当温度低于25℃时,除 Ni 以外,大部分重金属溶出量很低。而温度变化对重金属Cu、As、Cr和Hg的溶出量的影响不明显,波动范围较小,对周围生态环境产生的潜在生态风险较小。     

大沽排污河河口地区沉积物中重金属污染及其潜在生物毒性风险评价

本文以大沽排污河口表层沉积物为研究对象,分别运用ERL/ERM和生态危害指数两种评价方法对沉积物中6种重金属的潜在生物毒性风险进行评价,并对两种方法的评价结果进行对比。经均一化处理,重金属的含量均值由大到小的顺序排列为铬（168 mg/kg）〉锌（157 mg/kg）〉镍（60.7 mg/kg）〉铜（45.3 mg/kg）〉铅（7.31 mg/kg）〉镉（0.215 mg/kg）。经计算20个采样断面的沉积物中重金属毒性单位总和均在3~4之间,有80%的采样断面沉积物中重金属毒性单位总和大于3.5,毒性单位总和最大值为3.789。说明大沽排污河口沉积物中重金属的潜在生物毒性水平较低,可视为无生物毒性。     

环草隆与重金属复合污染对黄瓜及小麦的毒性效应评估

为探究草坪除草剂与重金属复合污染对高等植物的生态毒性效应,以小麦与黄瓜为敏感受试植物,采用滤纸发芽试验法,研究了典型草坪除草剂环草隆与4种重金属(Cu/Zn/Pb/Cd)单一及复合污染条件下,对2种植物种子萌发与幼苗生长的毒性效应并进行评估。在此基础上采用评估因子法外推环草隆在土壤中的预测无效应浓度(PNECsoil)。结果表明,2种植物的根长及小麦的芽长对环草隆与重金属非常敏感(P<0.01),且存在明显的剂量-效应关系。黄瓜根长对环草隆最敏感,根长半抑制浓度(RI50)为0.281 mg·L-1。小麦根长对Cu、Pb、Cd比黄瓜根长更敏感。环草隆与重金属复合污染时,黄瓜根长表现得最为敏感,可作为敏感生物标记物。环草隆与重金属复合污染对小麦及黄瓜根长抑制具有协同作用,并且随着重金属浓度的增大,黄瓜和小麦根生长对环草隆的敏感性增加。环草隆与重金属复合污染对小麦芽长的联合效应主要与重金属种类及其暴露浓度有关。以黄瓜的根伸长抑制率为急性毒性终点,利用外推法计算得环草隆在土壤中的PNECsoil为1.90μg·kg~(-1),远远低于环草隆田间推荐使用量1.5~9 mg·kg~(-1)。与重金属复合污染时,环草隆的PNECsoil明显降低,导致其生态风险提高。上述研究结果能够为草坪除草剂环草隆与重金属复合污染的生态风险评价提供数据支持。     

利用藻红外测试技术研究多种重金属溶液对滇池铜绿微囊藻的毒性作用

为考察多种重金属同时存在的混合溶液对藻类的生物毒性,选择Cr(Ⅲ)、Pb(Ⅱ)、Hg(Ⅱ)、Cd(Ⅱ)、Mn(Ⅱ)5种重金属,以按照国家饮用水卫生标准限值浓度配制的单一重金属溶液和多种重金属混合溶液为受试样品,并利用本实验室开发的藻红外测试技术,评价了低浓度下单一重金属溶液和多种重金属共存溶液对藻的生物毒性。实验结果显示:按照饮用水标准限值配制的5种单一重金属溶液均未观察到对藻有生物毒性,但在多种重金属共存的27个不同组合的混合溶液中,有73.1%的样品表现出明显的生物毒性;藻响应出现率与混合溶液中重金属的总浓度呈正相关关系(r=0.8942)。当多种重金属以二元至五元混合时,藻响应出现率分别为50%、80%、100%、100%,表明随着重金属组分的增加,混合溶液的毒性作用越来越显著。当不同混合溶液的重金属总浓度大于0.11 mg·L-1时,平均累积藻响应占比显著上升到93%,表明重金属混合溶液中藻的毒性与总浓度之间存在剂量响应关系。采用平均藻响应出现率分析,结果显示混合溶液中不同重金属的相对影响顺序为:Cr(Ⅲ)87.5%>Pb(Ⅱ)和Hg(Ⅱ)58.3%>Cd(Ⅱ)和Mn(Ⅱ)54.3%,表明Cr(Ⅲ)表现出的藻毒性远高出其他重金属。现行的水质标准通常采用单一指标和限值,本研究结果表明采用单一指标不能有效规避多种污染物共存体系的环境风险。     

绍兴平原二种典型农田系统中重金属流及其平衡分析

以浙江省绍兴平原为例,选择水稻（Orgza sativa L.）和蔬菜[大白菜（Brassica campestris L.ssp.pekinensis）]等2种典型农田系统,进行为期1年的观察分析,研究了农田系统中主要重金属元素流及平衡状况。结果表明,研究区农田系统中重金属来源物和农产品及排水中重金属含量有较大的空间变异性。有机肥和生活垃圾中重金属含量明显高于化肥,不同化肥品种中重金属含量：磷肥、复合肥钾肥氮肥。农田系统中重金属的输入量：有机肥施用（60.40%～99.36%）大气沉降（0.46%～39.26%）化肥施用（0.17%～1.45%）灌溉水（0.0016%～1.62%）。农田系统中Pb、Cd、Zn和Hg的输出量：农产品地表排水;重金属总积累量和输入强度：ZnCuPbCdHg。总体上,蔬菜生产系统中重金属的输入和累积量水稻生产系统。     

农田土壤重金属污染状况及修复技术研究

重金属污染因具有毒性、易通过食物链在植物,动物和人体内累积,对生态环境和人体健康构成严重威胁。随着工业快速发展、农药及化肥的广泛使用,农田土壤重金属污染越来越严重,研究农田土壤重金属污染现状及修复技术对农产品安全具有重要意义。综合国内外农田土壤重金属污染状况,农田土壤重金属污染主要来源于固体废弃物堆放及处置、工业废物大气沉降、污水农灌和农用物质的不合理施用。该文综述了国内外有关农田重金属污染土壤修复技术（物理修复、化学修复、生物修复、农业生态和联合修复）的研究进展,并针对各种修复方法,阐述了其原理、修复条件、应用实例及其优缺点,重点论述了植物修复的机理和应用,提出了草本与木本联合修复可有效提高农田土壤重金属复合污染的修复效率,为农田土壤土壤重金属复合污染修复提出了新的途径。最后在对已有研究分析的基础上,提出了联合修复技术（如生物联合技术、物理化学联合技术和物理化学-生物联合技术）可以在一定程度上克服使用单一修复手段存在的缺点,可提高复合污染的修复效率、降低修复成本,未来应深入探索联合修复技术间的相互作用机理,以期为农田土壤重金属综合治理与污染修复提供科学依据。     

化学品急性毒性藻红外测试技术的方法改进研究

在以往藻红外测试技术的急性毒性测试中,每次每个测试杯测试1个藻温,共2个测试组,并用藻最大响应温差1个指标进行毒性评价,测试结果的可行性和稳定性不理想,针对这个问题提出了改进方法:1)每次每个测试杯连测3个藻温;2)改为3个测试组;3)将单指标法改为三指标法;4)增加测试结果的重现性分析。通过蒸馏水毒性测试实验和重金属毒性测试实验,分析改进方法的效果。结果显示,不同指标方法中,三指标法控制假结果出现率为20%,控制效果最好;在测试4元重金属共存(总浓度0.066~0.156 mg·L~(-1))的毒性时,测试3个藻温的所有指标法的平均重现率(%)/重现性(%)均为100%/100%,测试1个藻温的三指标法的平均重现率(%)/重现性(%)为67%/100%,表明测试高浓度的重金属毒性时,不同指标法都有很好的评价效果;在测试一元重金属(0.001~0.1 mg·L~(-1))毒性时,只有三指标法的平均重现率(%)/重现性(%)是100%/100%,远高于其他指标法,表明只有三指标法才可准确测试低浓度重金属的毒性。在测试5种不同重金属共存的毒性时,三指标法的平均重现率(%)/重现性(%)平均为86.8%/100%。研究表明,改进后的技术用于化学品急性毒性测试,灵敏度高和稳定性好,结果可靠。     

根际环境的调节与重金属污染土壤的修复

根际环境的pH和Eh会产生影响土壤中重金属的化学过程。pH的变化影响到重金属的固定和活化，根际的酸化能够活化大多数重金属，使其毒性增强；反之，则固定大多数重金属，减轻其毒性。Eh的变化可改变重金属的价态和存在形态，使其毒性减弱或增强。根分泌物可从多方面影响金属的毒性和有效性，如改变根际环境的pH值和Eh来改变金属的存在形态和活度；与金属络合或者吸附、包埋金属污染物；通过影响根际微生物特征来改变金属的毒性。根际环境中微生物能改变金属离子存在形态，其代谢产物能对金属离子产生沉淀、螯合等作用。土壤脲酶对重金属污染最敏感，可以用于监测土壤重金属污染。调控根际环境，可以有效地调节土壤中重金属污染物的活度、毒性及其转移，对重金属污染土壤起到修复作用。     

植物耐受和解除重金属毒性研究进展

总结了植物细胞及分子水平对重金属耐性和解除其毒性的途径.植物通过避免增加细胞内敏感位点毒物浓度来解除重金属毒性.其途径主要有:一方面通过菌根化、细胞壁吸收及根系分泌物的螯合作用减少根系吸收重金属进入细胞质;另一方面通过体内调节机制解除重金属毒性和提高耐性,主要通过一系列膜蛋白对进入细胞质内的重金属排出细胞质外、隔离于液泡中,或将重金属转变为无毒性形态挥发入大气,或通过细胞质内的植物螯合素、金属硫蛋白、有机酸、氨基酸、多胺等对重金属螯合,解除重金属毒性;同时植物还可以在重金属胁迫下产生热休克蛋白修复胁迫伤害的蛋白质.本文提供了涉及植物重金属解毒和耐性广泛的观点和证据.     

酸阻滞技术的研究与应用

本文提出酸阻滞法从废液中分离，回收重金属和酸的新技术工艺，从十多种国产树脂中成功地筛选出两种可作为酸阻滞剂，有较好的分离效果。但洗脱时酸脱尾严重，当选择穿透比在０．６左右时，可以解决酸脱尾现象，使脱尾酸损失由３０％降到７％，而酸的回收率由６０％提高到９０％，采用该工艺对几种废液进行处理，重金属回收液中酸去除率大于９５％，而回用酸中金属去除率大于７０％，该工艺既可回收重金属，同时也可回收酸。     

应用斜生栅藻生长抑制实验对重金属污染土壤的毒性进行诊断

应用斜生栅藻（Scenedesmus Obliquus）对重金属污染土壤的毒性进行诊断.结果表明,斜生栅藻的生长率与土壤中的重金属含量明显相关,并且随重金属投加量的增加而逐渐降低.对两种测试参数进行比较,发现采用细胞数生长率作为土壤毒性的检测指标要比采用光密度D(λ)增长率更为敏感.当采用细胞数生长率作为检测指标时,4种重金属的EC50顺序为Pb>Cu>Zn>Cd;采用光密度生长率作为检测指标时,4种重金属的EC     

A critical review on the recycling of copper and precious metals from waste printed circuit boards using hydrometallurgy

Currently, increasing amounts of end-of-life (EoL) electronic products are being generated due to their reduced life spans and the unavailability of suitable recycling technologies. In particular, waste printed circuit boards (PCBs) have become of global concern with regard to environmental issues because of their high metal and toxic material contents, which are pollutants. There are many environmental threats owed to the disposal of electronic waste; off-gasses, such as dioxins, furans, polybrominated organic pollutants, and polycyclic aromatic hydrocarbons, can be generated during thermal treatments, which can cause serious health problems if effective off-gas cleaning systems are not developed and improved. Moreover, heavy metals will dissolve, and release into the ground water from the landfill sites. Such waste PCBs contain precious metals which are of monetary value. Therefore, it is beneficial to recover the metal content and protect the environment from pollution. Hydrometallurgy is a successful technique used worldwide for the recovery of precious metals (especially gold and silver) from ores, concentrates, and waste materials. It is generally preferred over other methods because it can offer high recovery rates at a relatively low cost. This article reviews the recent trends and developments with regard to the recycling of precious metals from waste PCBs through hydrometallurgical techniques, such as leaching and recovery.

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Comparative toxicity of nine metals to two Malaysian aquatic dipterian larvae with reference to sediment composition

A study was conducted on the effects of sediment type in modifying the toxicity of heavy metals to chironomus and culicoides larvae. Three types of sediment were obtained from three locations within the University Malaysia Terengganu compound and analyzed for sediment type. Based on the analysis, the sediment samples were classified as silt loam, silty–clay loam, and loam. Sediment toxicity tests were conducted following the standard methods of ASTM (2005). Toxicity studies using the three sediment samples were conducted to determine if sediment type affected the toxicity of heavy metals to the two dipterian larvae. The LC₅₀ of the different heavy metals was observed to vary between the three sediment types. In the case of zinc, the LC₅₀ value was observed to be 38.53 mg L^?1 for silt loam, 42.22 mg L^?1 for silty-clay loam and 70.99 mg L^?1 for loam, in the case of Chironomus plumosus. This trend was observed for all nine heavy metals tested, as well as for both dipterian larvae. The data indicate that sediment type plays a role in the manner in which these organisms react to pollutants entering their habitat.     

Physico-chemical characteristics of fine fraction materials from an old crystal glass dumpsite in Sweden

Physico-chemical characteristics of waste, particularly fine fraction (FF), from an old crystal glass waste dump in Sweden were studied to assess recycling or disposal alternatives. Hand-sorting of the waste indicated glass content of 44.1% while sieving established the FF as a more soil-like mix of glass and other materials constituting 33.3% of all excavated waste. The FF was around neutral pH with 24.4% moisture content, low values of Total Dissolved Solids, Dissolved Organic Carbon and fluorides, but hazardous concentrations of As, Cd, Pb and Zn according to the Swedish Environmental Protection Agency guidelines. While the FF leached metals in low concentrations at neutral pH, it leached considerably during digestion with nitric acid, implying leaching risks at low pH. Thus, the waste requires safe storage in hazardous waste class ‘bank account’ storage cells to avoid environmental contamination as metal recovery and other recycling strategies for the glass waste are being developed. The study could fill the information gap regarding preservation of potential resources in the on-going, fast-paced excavation and re-landfilling of heavy metal contaminated materials in the region.     

Effective remediation of organic-metal co-contaminated soil by enhanced electrokinetic-bioremediation process

• A new EK-BIO technology was developed to decontaminate e-waste contaminated soil. • Adding sodium citrate in electrolyte was a good choice for decontaminating the soil. • The system has good performance with low cost. This work investigates the influence of electrokinetic-bioremediation (EK-BIO) on remediating soil polluted by persistent organic pollutants (POPs) and heavy metals (mainly Cu, Pb and Ni), originated from electronic waste recycling activity. The results demonstrate that most of POPs and metals were removed from the soil. More than 60% of metals and 90% of POPs in the soil were removed after a 30-day EK-BIO remediation assisted by citrate. A citrate sodium concentration of 0.02 g/L was deemed to be suitable because higher citrate did not significantly improve treatment performance whereas increasing dosage consumption. Citrate increased soil electrical current and electroosmotic flow. After remediation, metal residues mainly existed in stable and low-toxic states, which could effectively lower the potential hazard of toxic metals to the surrounding environment and organisms. EK-BIO treatment influenced soil microbial counts, dehydrogenase activity and community structure.     

Co-pyrolysis of sludge and kaolin/zeolite in a rotary kiln: Analysis of stabilizing heavy metals

• Adding kaolin/zeolite promotes the formation of stable heavy metals. • The potential ecological risk index of co-pyrolysis biochar is extremely low. • Increasing the pyrolysis temperature reduces the leaching toxicity of heavy metals. • The toxicity of biochar reduces with the increasing content of stable heavy metals. Pyrolysis is a promising technique used for treating of sewage sludge. However, the application of pyrolysis products is limited due to the presence of heavy metals. In this study, sewage sludge mixed with kaolin/zeolite was pyrolyzed in a rotary kiln, aiming to improve the immobilization of heavy metals in pyrolytic carbon. The total concentrations, speciation distributions, leaching toxicities, and potential ecological risk indices of heavy metals in pyrolysis biochar were explored to examine the effects of kaolin/zeolite and pyrolytic temperature on immobilizing heavy metals. Further, mineral composition and surface morphology of biochar were characterized by X-ray diffraction and scanning electron microscopy to reveal the potential mechanism of immobilizing heavy metals. Increasing pyrolysis temperature facilitated the stabilization of heavy metals in pyrolysis biochar. The proportions of stable heavy metals in biochar obtained at 650℃ were 54.50% (Cu), 29.73% (Zn), 79.29% (Cd), 68.17% (Pb) and 86.70% (Cr). Compared to sewage sludge, the potential contamination risk index of pyrolysis biochar obtained at 650℃ was reduced to 17.01, indicating a low ecological risk. The addition of 7% kaolin/zeolite further reduced the risk index of co-pyrolysis biochar prepared at 650℃ to 10.86/15.28. The characterization of biochar revealed that increase in the pyrolysis temperature and incorporation of additives are conducive to the formation of stable heavy metal-inorganics. This study demonstrates that the formation of stable mineral compounds containing heavy metals is the key to stabilizing heavy metals in pyrolysis biochar.