Pollution hazards of heavy metals in sewage sludge from four wastewater treatment plants in Nanchang,China

The pollution hazards of heavy metals were investigated in sewage sludge collected from four wastewater treatment plants in Nanchang City, China, including Honggutan (HGT), Chaoyang (CY), Qingshanhu (QSH) and Xianghu (XH). Contamination/risk characteristics of heavy metals (Cu, Pb, Zn, Cd, Cr and Ni) were evaluated based on their leachable content, total content and chemical speciation. The sewage sludge from QSH contained higher total contents of heavy metals (except Pb) than those from HGT, XH and CY. The total contents of Cd and Ni were mostly beyond standard. Cu, Cr and Pb were predominantly present in potential effect and stable fractions. Zn and Ni showed higher bioavailability. Cd presented roughly uniform distribution into four fractions. The leaching contents of heavy metals almost exceeded the threshold values, especially for Zn and Ni. The potential ecological risk indexes of heavy metals in sewage sludge were 4263.34–7480.26, indicating very high risks. Cd contamination is the major concern.     

Evaluation of ecological risk and primary empirical research on heavy metals in polluted soil over Xiaoqinling gold mining region,Shaanxi,China

Soil, crop and residents' hair over Xiaoqinling gold mining region, China, which was selected as a case study, were sampled and analyzed for Hg, Cd, Pb, Cu, Cr, As and Zn concentrations. The concentrations of heavy metals in soil or crop and hair samples were used to assess their potential ecological risks, or to find the responses to these metals as evidences to prove the potential risk was coming down to observed harm, respectively. The results showed that, these metals in soil were ranked by severity of ecological risk as Hg＞Cd＞Pb＞Cu＞Cr＞As＞Zn, based on their single-element indexes. In the view of the potential ecological risk indexes, of all soil samples, about half had significantly high or high potential ecological risk, which covered more than 74% of the studied region. Most of the risks were 97.41% from Hg, Pb and Cd, especially, 84.37% from Hg. Both the single-element and potential ecological risk indexes indicated that, the ecological risk grades had a special spatial characteristic, and increased from northwest to southeast generally. This was agreed with the spatial distribution of the strength in gold mining activities over the studied region. The concentrations of Hg and Pb were higher than their relative backgrounds in the corps, and were even 9.48 and 25.09 times higher than their relative backgrounds in residents' hair, respectively. All these showed that the heavy metals in the soil had a high potential ecological risk, especially, had been affecting these crops' growing and yield, and even the residents' health through food strains. Obviously, these metals' potential ecological harm had been coming down to observed harm to the ecology.     

某铅锌矿区土壤重金属形态分布及污染风险评价

对某铅锌矿区土壤的铅、镉、锌、铜和镍的污染特征进行了研究。结果表明,5种重金属的污染程度依次为：镉〉铅〉锌〉镍〉铜,其中铅、镉和锌的浓度超过了国家土壤环境质量标准Ⅲ的浓度限值。土壤受镉污染极大,受锌污染中度至严重,受铅污染严重至极严重。BCR顺序提取形态分析结果表明,活性镉、铅和锌的含量较高,可能对土壤中的植物生长产生不利影响,而铜和镍以相对稳定的形式存在。潜在生态危害结果表明,镉污染导致土壤潜在着极大的生态风险,应当引起重视。     

Heavy metals contamination characteristics in soil of different mining activity zones

Depending upon the polluted features of various mining activities in a typical nonferrous metal mine, the contaminated soil area was divided into four zones which were polluted by tailings, mine drainage, dust deposition in wind and spreading minerals during vehicle transportation, respectively. In each zone, soil samples were collected. Total 28 soil samples were dug and analyzed by ICP-AES and other relevant methods. The results indicate that the average contents of Zn, Pb, Cd, Cu and As in soils are 508.6, 384.8, 7.53, 356 and 44.6 mg/kg, respectively. But the contents of heavy metals in different zone have distinct differences. The proportion of oxidizing association with organic substance is small. Difference of the association of heavy metals is small in different polluted zones.     

Leachability and fractionation of heavy metals in stainless steelmaking plant dusts

The leachability and fractionation of the selected heavy metals (Cr, Cd, Pb and Zn) in the stainless steelmaking plant dusts were studied by the modified HJ/T299-2007 method, the modified TCLP test and a seven-step sequential extraction procedure. The results show that the stainless steelmaking plant dusts are considered as hazardous materials since at least one of the leachable heavy metals exceeds the corresponding limit levels of State Environmental Protection Administration of China. Pb is the most extractable heavy metals by the sequential extraction procedure, while Cr, Cd and Zn mainly presents in the residual fraction bound to spinel phase and silicates. The mobile heavy metals in the dusts, which present as the species of water soluble, exchangeable species and the species bounded to carbonates and hydroxides, can be estimated as 0.08-1.2% of Cr, 7.6%-31.8% of Cd, 34.1% of Pb, 0.052-0.4% of Zn, respectively.     

有机酸对污染土壤中重金属释放或固定的影响

为了探明土壤中不同有机酸对土壤中重金属环境活性的影响,通过采用分批次实验分别研究高分子有机酸(HMWOA)(腐殖酸和富里酸)和低分子有机酸(LMWOA)(苏氨酸和草酸)对土壤中Pb、Cu和Cd释放或固定化效果的影响.结果表明,LMWOA特别是苏氨酸促进土壤中Pb、Cu和Cd的释放,并减少土壤中HOAc可提取态、可还原态...     

基于TIN模型和直接暴露方法的长沙土壤中重金属来源识别及人类健康风险评价(英文)

通过采集153个样品分析长沙市土壤中As、Cd、Cr、Cu、Hg、Mn、Ni、Pb和Zn的含量,利用多元统计、地学统计、直接暴露以及不规则三角网模型(TIN模型)等方法分析土壤中重金属的来源、空间分布以及对儿童的健康风险。结果表明:长沙地区部分区域需经过污染治理后才适合人类生活;约9.0%的区域风险值超过了临界值1.0,1.9%的区域风险值大于2.0,其中高风险主要集中在南部和西部地区;元素As和口腔摄入途径是儿童的主要健康风险来源;土壤重金属的直接暴露对儿童所产生的健康风险应该受到研究者的重视。     

微电解絮凝耦合技术处理含重金属铅锌冶炼废水

采用"石灰中和曝气微电解絮凝沉淀法"技术处理含重金属铅锌冶炼废水,考察微电解进水pH值、水力停留时间、铁炭质量比、絮凝pH值和助凝剂用量等反应条件对废水中铅、锌、镉、铜和砷离子去除率的影响。采用扫描电镜(SEM)和能谱(EDS)等测试手段,研究微电解反应前后铁屑和活性炭的表面形貌及物质组成的变化,分析铁炭微电解原理及铁炭床失效原因。结果表明:在微电解铁炭质量比为1:1.5、进水初始pH值为2.5、水力停留时间为40 min、絮凝pH值为11、助凝剂PAM用量为4×10 6(质量分数)的条件下,微电解絮凝耦合技术对废水中各离子的去除效果最佳,Cd2+出水浓度达到了《污水综合排放标准》(GB8978—1996)中的一级标准,Pb2+、Cu2+、Zn2+和总砷的出水浓度满足《地表水环境质量标准》(GB 3838—2002)中Ⅲ类水标准。     

广州市不同来源污泥中重金属的含量和形态分布特征

采集了广州市4个不同来源污水处理厂及1个工业废水处理厂的脱水污泥,分析污泥的理化性质参数和重金属(Zn、Cu、Pb、Cr、Ni、Mn、Cd)的含量,重点利用BCR法研究不同污泥中重金属的赋存形态。结果表明,脱水污泥中有机质含量较高,并且富含N和P营养成分。污泥中重金属含量差别较大,其中Mn、Zn、Cu含量高,其次是Ni、Pb、Cr,Cd含量最低,但5个不同来源污泥中重金属的含量都高出广州市农田背景值。除了S1污水污泥中的Cu、Cd及S1、S2、S5污水污泥中的Ni外,其他污泥中重金属的含量都低于国家污泥农用控制标准(GB 18918-2002)。BCR连续提取法表明,污泥中的Mn和Zn主要以酸可交换态及易还原态存在,Cu和Cr主要以可氧化态和残渣态存在,Pb大部分存在于残渣态,Ni和Cd的形态分布没有明显特征。     

洞庭湖湿地周围表层土壤重金属污染及其人体健康风险评价

为了查明洞庭湖湿地周围表层土壤重金属污染及其对人体健康的风险,选择2016~2018年洞庭湖区域周围10个土壤采样点,共采集了表层土壤(0~30 m)样品100份,分析了其中的重金属含量、分布,并采用地累积指数法(Igeo)、内梅罗指数法(NI)和土壤健康风险评价法等方法进行了风险评价。结果表明:土壤样品中Pb、Cd、Hg、As和Cu 5种重金属元素的平均浓度分别为53.33、1.62、0.27、26.8和37.72 mg/kg,高于研究区域土壤环境背景值。其中Cd、As的平均浓度,西洞庭湖、南洞庭湖和东洞庭湖Cd的浓度和南洞庭湖As的浓度均高于《土壤环境质量标准》(GB 15618—2018)中农用地土壤污染风险筛选值的标准。Cd、Hg、As和Cu的最大污染值在南洞庭湖,Pb的最大污染值在东洞庭湖。地累积指数法(Igeo)研究表明,三年时间里,Cd处于重度污染水平,Pb、Hg、As处于无污染到中度污染水平。内梅罗指数法(NI)研究表明,三年时间里,西洞庭湖、南洞庭湖和东洞庭湖都处于轻度污染水平。运用土壤健康风险评价体系中的无意吸食、皮肤接触、呼吸接触3种暴露因素对人体健康风险的评估表明:每百万人口中,平均有13个成年人和8个儿童具有癌症风险。研究结果为洞庭湖湿地土壤污染的来源和特征提供参考和建议。     

Spatial distribution of chromium in soils contaminated by chromium-containing slag

To evaluate the metal chromium (Cr) contamination of soil at a chromium-containing slag site by ferrochromium production, the contaminated sites, under slag heap, in the vicinity of slag heap and arable soils near the outlet of sewer channel, and unpolluted site 5 km away from one ferroalloy plant in Hunan Province, China, were selected. The concentrations of total Cr and water soluble Cr in bulk soil samples and profile depth samples were determined. The results show that the soils in the vicinity of slag heap have the highest total Cr content followed by the soils under the slag heap and near the outlet of sewer channel of the factory. The mean concentrations of total Cr in the top soils at above three contaminated locations exceed the critical level of Secondary Environmental Quality Standard for Soil in China by 3.5, 5.4 and 1.8 times. In most Cr polluted soils, total Cr has a relative accumulation in soil depth of 40-60 cm, but this trend is not found in unpolluted soils. The average concentrations of water soluble Cr (Ⅵ) in top soils under slag heap and in the vicinity of slag heap are 176.9 times and 52.7 times higher than that in the uncontaminated soils, respectively. However, water soluble Cr (Ⅵ) contents in soils near sewer channel are all low and the values are close to that in the uncontaminated soils. Although water soluble Cr (Ⅵ) content in soil profiles decreases with soil depths, it in soils under slag heap maintains a high level even at a depth of 100-150 cm. The results imply that the transportation of Cr (Ⅵ) can result in a potential risk of groundwater system in this area.     

Chromium accumulation, microorganism population and enzyme activities in soils around chromium-containing slag heap of steel alloy factory

The environmental risk of chromium pollution is pronounced in soils adjacent to chromate industry. It is important to investigate the functioning of soil microorganisms in ecosystems exposed to long-term contamination by chromium. 45 soil samples obtained from different places of the slag heap in a steel alloy factory were analyzed for chromium contamination level and its effect on soil microorganisms and enzyme activities. The results show that the average concentrations of total Cr in the soil under the slag heap, adjacent to the slag heap and outside the factory exceed the threshold of Secondary Environmental Quality Standard for Soil in China by 354%, 540% and 184%, respectively, and are 15, 21 and 9 times higher than the local background value, respectively. Elevated chromium loadings result in changes in the activity of the soil microbe, as indicated by the negative correlations between soil microbial population and chromium contents. Dehydrogenase activity is greatly depressed by chromium in the soil. The results imply that dehydrogenase activity can be used as an indicator for the chromium pollution level in the area of the steel alloy factory.     

EFFECTS OF TEMPERATURE ON DISTRIBUTION BEHAVIORS OF MINOR ELEMENTS IN COPPER FLASH SMELTING──COMPUTER SIMULATION

ＥＦＦＥＣＴＳＯＦＴＥＭＰＥＲＡＴＵＲＥＯＮＤＩＳＴＲＩＢＵＴＩＯＮＢＥＨＡＶＩＯＲＳＯＦＭＩＮＯＲＥＬＥＭＥＮＴＳＩＮＣＯＰＰＥＲＦＬＡＳＨＳＭＥＬＴＩＮＧ──ＣＯＭＰＵＴＥＲＳＩＭＵＬＡＴＩＯＮ￥ＴａｎＰｅｎｇｆｕ；ＺｈａｎｇＣｈｕａｎｆｕ（Ｄｅ...     

锌浸出渣中重金属的环境活性和生态风险评价

采用矿物学分析、BCR三步连续浸提、动态淋洗实验以及Hakanson潜在生态风险评价4种方法对锌浸出渣重金属的环境活性以及生态风险进行评价.结果表明,锌浸出渣中重金属的环境活性大小依次为Cd＞Zn＞Cu＞As＞Pb.废渣中主要重金属的潜在生态风险评价表明,该种废渣对环境具有很高的生态风险,单个重金属的生态危害顺序为Cd＞Zn＞Cu＞As＞Pb.Cd有很严重的生态风险,是对生态环境造成毒性的主要原因.     

Immobilization of Cd and Pb in soils by polymeric hydroxyl ferric phosphate

A polymeric hydroxyl ferric phosphate (PHFP) was prepared by using a byproduct of titanium dioxide containing ferrous sulfate and phosphates under alkaline condition. The PHFP was used to immobilize lead (Pb) and cadmium (Cd) in soils. Fourier transform infrared spectra, X-ray diffraction were applied to revealing the characteristics of PHFP, and the modified Tessier sequential extraction and column leaching experiment with simulated acid rain were used to assess the effectiveness of immobilization of Cd and Pb in soils by PHFP. The results showed that PHFP was indeed a polymer with complicated OH—Fe—P structure and consisted of Fe₆(OH)₅(H₂O)₄(PO₄)₄(H₂O)₂ and Fe₂₅(PO₄)₁₄(OH)₂₄. Moreover, the removal rates of DTPA-extractable Cd and Pb in soils reached up to 33% and 45%, and the water-soluble Cd and Pb decreased by 56% and 58%, respectively, when PHFP was added in soils at 4% dosage. In addition, the immobilization of Cd and Pb contributed to transforming water soluble, exchangeable and carbonate-bonded fractions to Fe and Mn oxides-bonded, organic-bonded and residual fractions. Under leaching with simulated acid rain, Cd and Pb release amount in PHFP amended soil declined by 53% and 52%, respectively, as compared with non-treated soil. The result implied that PHFP had a potential application for the remediation of Cd- and Pb-contaminated soils.     

NaOH分解含铟铁矾渣新工艺

提出NaOH分解含铟铁矾渣新工艺,考察NaOH用量、液固比、温度和时间对铁矾渣分解率的影响,并讨论铁矾渣中杂质金属,如Zn、In、Cu、Cd、Pb、As、Sb、Sn和Ag等在NaOH分解过程中的行为.结果表明:在m(NaOH)-m(铁矾渣)=0.381 4-1、温度60 ℃、液固比2-1、反应时间2 h的最优条件下,铁矾渣的分解率达到98.03%,而原料中的杂质金属,如Sn、Sb、Zn、In、Cu、Cd、Pb和Ag等绝大部分留在分解渣中,As则以AsO43-的形态大部分进入溶液,浸出率达到83.36%.DSC-TGA热分析和X射线衍射分析结果表明:在NaOH分解过程中,铁矾渣中的铁主要以Fe3O4形式沉淀入渣;分解渣中Fe、In和Zn的含量分别为38.81%、0.23%和12.89%;经稀盐酸选择性浸出铟和锌后,进一步磁选富集可作为炼铁原料.     

Der interkristalline Angriff von Metallschmelzen auf Stahl

The intercrystalline attack of steel by molten metals Specimens of steel and low alloy steels under tensile stress have been tested in pure molten metals (Sn, Bi, Cd, Pb, Al) and low alloy metals (SnCu, CdZn, CdAl, CdNi, PbBi, PbZn, PbAs, PbSb, PbCu). From among the pure metals only molten cadmium gives rise to intercrystalline corrosion which becomes apparent as a diminution of the rupture strength. Additions of Zn, Cu, Sb and Cd in the mineral molten metals, however, produce very strong corrosion even when the addition elements are present in low concentration only; the attack becomes visible even at temperatures below the melting point of the particular addition element. Lead and bismut additions (with or without Mn, Al, As or Ni) have no negative effect. As to the inert behaviour of pure molten tin investigations are still required in a wider temperature range.     

Stabilization of heavy metals in biochar pyrolyzed from phytoremediated giant reed (Arundo donax) biomass

The pyrolysis of phytoremediated giant reed (Arundo donax) biomass could cause secondary pollution of heavy metals. The stabilization of heavy metals in the pyrolysis process with external materials such as Al₂O₃, CaCO₃, FeCl₃ and NaOH, was studied. The results showed that 37% As and 97% Cd in biochar were stabilized when giant reed powder was pyrolyzed at 250 °C with 5% Al₂O₃ for 2 h. Furthermore, 59% Pb in biochar was stabilized at 400 °C with 5% CaCO₃ for 1 h. Under biochar produced in optimized pyrolysis conditions, Cd mainly existed in a residual fraction, while Pb and As mainly existed in oxidizable fraction in BCR analysis. In XRD analysis, As was only found in Ca₂As₂O₇; Cd in biochar mainly existed in Cd (AlCl₄)₂, CdPbO₃ or CdSO₃; and Pb mainly existed as Pb₃O₂SO₄.     

Recycling of valuable metals from spent zinc-manganese batteries by vacuum metallurgy

1　INTRODUCTIONThe yieldofzinc manganesebatteriesisthelargestinbatteryindustryintheworldbecauseoftheirlowcost .Chinaisthelargestcountryforpro ducingandconsumingdry batteries ,produced 1.7×10 10 piecesofprimarybatteriesandconsumed 7.0×10 9piecesin 2 0 0 0 ,about 70 %ofthosewerezinc manganesebatteries[1,2 ] .ItwasreportedthattheconsumptionofZn ,MnO2 ,CuandHgusedinbat teryindustrywas 2 .5× 10 5,2 .3× 10 5,4 .5× 10 3and 6 0t ,respectively[2 ] .However ,dry batteriesareusuallydiscardeda…     

Ida~(2-)-H_2O体系浸出低品位氧化锌矿(英文)

采用Ida2--H2O体系(亚氨二乙酸盐水溶液)处理高碱性脉石型低品位氧化锌矿,考察浸出时间、液固比、配体总浓度、温度及pH值对矿物中主金属Zn及杂质元素Ca、Mg、Cu、Ni、Fe、Pb、Cd的溶出影响。结果表明:在弱碱性Ida2--H2O体系中,Ca、Mg、Fe不会被大量溶出,有价金属Cu、Ni、Pb、Cd可部分随主金属Zn溶出而进入浸出液;在浸出时间4h、液固比5:1、配体总浓度0.9mol/L、温度70℃、pH8的优化条件下,锌浸出率为76.6%。