Effects of Heavy Metals on Activated Sludge Microorganism

The efforts of heavy metals on activated sludge microorganisms are reviewed. Although some heavy metals play an important role in the life of microorganism, heavy metals concentrations above toxic levels inhibit biological processes. Copper, zinc, nickel, cadmium and chromium were mostly studied because of their toxicity and widely used, regardless of single or combination. The microorganism response to these heavy metals varied with species and concentrations of metals, factors such as pH, sludge age, MLSS etc. also affect toxicity on the microorganism. The acclimation could extend the microorganism tolerance of heavy metals. The effects of heavy metals on sludge microorganisms could be described with different models, such as Sigmoidal and Monod equation. The kinetic constants are the useful indexes to estimate the heavy metals inhibition on activated sludge system. Methods to measure the toxicity and effects on microorganism community were also reviewed.     

Toughening mechanisms of a high-strength acicular ferrite steel heavy plate

An ultra-low carbon acicular ferrite steel heavy plate was obtained with an advanced thermo-mechanical control process-relaxed precipitation controlled transformation (TMCP-RPC) at Xiangtan Steel, Valin Group. The heavy plate has a tensile strength of approximately 600 MPa with a lower yield ratio. The impact toughness of the heavy plate achieves 280 J at -40℃. The fine-grained mixed microstructures of the heavy plate mainly consist of acicular ferrite, granular bainite, and polygonal ferrite. The high strength and excellent toughness of the heavy plate are attributed to the formation of acicular ferrite microstructure. The prevention of blocks of martensite/retained austenite (M/A) and the higher cleanness are also responsible for the superior toughness.     

Composition of sandstone and heavy minerals implies the provenance of Kuqa Depression in Jurassic, Tarim basin, China

The petrological characteristics and heavy mineral assembly of the Jurassic System in Kuqa Basin are consistent with the tectonic evolution, which is the major factor controlling the filling process of Kuqa Basin. Controlled by the source areas at the both sides of the Basin, the matrixes are dominated by sedimentary rock, high-grade metamorphic rock, acid magmatic rock, and the highest heavy mineral assemblage of zircon-garnet-magnetite in the content. According to heavy mineral indexes, the Jurassic strata can be classified into three rhythmic units of heavy mineral. The lower sequence contains abundant heavy minerals and relatively high content of detritus and its matrixes primarily came form the recycling orogen. The assemblage of “zircon-garnet-magnetite” indicates that the sedimentary area in the early evolution period of the basin is relatively near the provenance. The middle sequence is different from the lower sequence in the heavy mineral assemblage and has the different characteristics from that of source rock. The heavy mineral assemblage is “garnet-zircon” with the highest content of garnet and its main matrices are the high-grade metamorphic rock, acid magmatic rock and hydrothermal vein at the northeastern edge of the basin. The middle and upper sequences are characterized by the clast provenance, which is primarily from the recycling orogen at the northern edge of the basin and secondarily from the southern uplift. As a result of the two provenances, the strata with apparent changes of heavy mineral assemblage and index better coincides with the interfaces of the secondary strata sequences, which reflects the denudation history and the filling process of the orogen at the northern edge of the basin.     

梯度温度轧制对Q500厚板裂纹愈合的促进作用

To ensure the quality of heavy plate products as determined by ultrasonic inspection, it is necessary to effectively control defects such as cracks and shrinkage cavities in heavy plates. Generally, some defects such as large size cracks exist due to insufficient deformation in the center of traditionally rolled plates. Compared with the traditional rolling process, gradient temperature rolling (GTR) process can effectively increase deformation inside heavy plates. In this study, the effect of GTR on crack healing was analyzed through a comparison experiment with the uniform temperature rolling (UTR). The results show that the GTR process could increase the plastic strain inside the heavy plate and effectively promote the healing process of the preset cracks. The degrees of crack healing at the center and quarter thickness position of the steel plate via GTR were greater than twice those of the plate via UTR. The GTR process can significantly reduce the internal defects of heavy plates and improve the defect detection level of heavy plate products. Also, The GTR process results in the formation of new crystal grains in the crack region, which is crucial to crack healing.     

Calculation methodology of marine environmental capacity for heavy metal: A case study in Jiaozhou Bay, China

Results from past pollution control practices show that environmental quality can be ensured by controlling the actual amount of pollutants formed in the environment.Therefore,the marine environmental capacity for heavy metals was introduced.Marine environmental capacity for heavy metals is defined as the maximum amount of heavy metals permitted in the marine environment system to preserve the benign cycle of materials in the oceansphere,and to limit the adverse effects of heavy metals on the biosphere,hydrosphere,atmosphere,and lithosphere.Based on the box or three-dimensional model in the target coastal region,including the self-purification and output of heavy metals,the marine environmental capacity for heavy metals can be calculated within a given criterion and time.In this study,a method was proposed to calculate the marine environmental capacity for heavy metals which includes four steps:(1) gathering the basis information of target coastal ecosystem,(2) selection of water control points and water quality criteria for these points,(3) development of numerical models for the biogeochemical cycling of heavy metals in target coastal region,and(4) calculation of environmental capacity using the developed model.According to the proposed method,the marine environmental capacity for lead is approximately 60 tons per year if Grade I seawater quality is set as the control criterion in Jiaozhou Bay.An effective seawater quality management plan can also be framed based on the environmental capacity for metals.     

Research progress of heavy metal pollution in China: Sources, analytical methods, status, and toxicity

Heavy metal pollution is one of the most serious environmental problems in China and a large number of people are threatened by heavy metal pollution.Extensive damage to human organs,such as liver,kidney,digestion system,and nervous system can be caused by uptake of excess heavy metals.Heavy metals in the environment can originate from both natural and anthropogenic sources.Although contamination of heavy metals has been known to be a severe environmental problem for decades,it is still getting worse in recent years and there are few feasible approaches to resolve this problem.Due to their high toxicity,prevalent existence and persistence in the environment,lead(Pb),mercury(Hg),cadmium(Cd),chromium(Cr) and arsenic(As) are commonly considered as the priority heavy metals which should be concerned and their emission should be controlled in China.This paper reviewed the pollution of heavy metals in China,focusing on the following four aspects:current status of heavy metal pollution in China,sources of heavy metals in China,toxicity and potential risk,and possible reduction strategies.     

Practice and design of the self-purification system for heavy metals-bearing contaminants

Many minerals in nature have self-purification capacity to hold and stabilize deleterious contaminants into their lattice structures, which can be used for treatment of heavy metals-bearing contaminants. Hydrotalcite Layer Double Hydroxide （LDH）, tobermorite Calcium Silicate Hydrate （CSH） and apatite are ubiquitous minerals in nature, having higher geochemical stability and potential for binding and stabilizing heavy metals. Based on the elucidation of crystal structure property and self-purification principles of the three minerals above, this article discussed how to design the self-purification system of heavy metal-bearing contaminants.     

Leaching behavior of V,Pb,Cd,Cr,and As from stone coal waste rock with different particle sizes

This paper investigates the leaching behavior of heavy metals(V,Pb,Cd,Cr,and As) from stone coal waste rocks with various particle sizes using dynamic leaching experiments.The results show that the dissolved concentrations of V and As initially increased and then slightly decreased as time progressed and that the dissolved concentrations of Pb,Cd,and Cr were high in the early stage before decreasing.The particle size of the stone coal waste rocks strongly influenced the heavy metal concentration in the leaching solutions.The effects of the particle size of the stone coal waste rocks on the dissolved concentrations of V,Pb,and As decreased in the order fine fraction medium fraction coarse fraction,and the effects of particle size on the dissolved concentrations of Cr and Cd decreased in the order medium fraction coarse fraction fine fraction and coarse fraction medium fraction fine fraction,respectively.The quantities of heavy metals dissolved from the stone coal waste rock with fine particle sizes were observed to decrease in the order V(17104.36 μg/kg) As(609.41 μg/kg) Pb(469.24 μg/kg) Cr(56.35 μg/kg) Cd(27.52 μg/kg),and the dissolution rates decreased in the order As(2.96%) Pb(0.93%) V(0.35%) Cd(0.25%) Cr(0.01%).The specific surface area,pore size of the stone coal waste rocks,and chemical forms of heavy metals also influenced the release of heavy metals from the stone coal waste rocks.Kinetic analysis showed that the dissolution of heavy metals fundamentally agreed with the rate equation controlled by the shrinking core model.The results of this study are expected to serve as a reference for the evaluation of heavy metals contamination from stone coal waste rocks.     

Review of source identification methodologies for heavy metals in solid waste

Source characterization of heavy metals is prerequisite to assessing their potential contamination pathways and environmental risks,based on which pollution control and environmental remediation measures can be properly targeted.In the present study,recent progress in methodologies of source identification of heavy metals in solid waste are summarized.The key scientific concerns related to these methodologies based on the total contents,chemical speciation,isotopic composition,and single-particle signature are also discussed.Finally,prospective research with regard to source identification of heavy metals in solid waste is discussed according to current research conditions and progress.     

Desorption characteristics of total phosphorus and heavy metals from impervious urban surface sediments

Dry sediments were collected from one roof and two roads in the central area of Beijing. The sediments were dry and wet sieved. The concentrations of total phosphorus (TP) and heavy metals were analyzed. The highest mass proportion of the dry sediments from the roads were between 125 and 300 μm in diameter, while the roof sediments were much smaller, with 75% of the total sediment mass between 40 and 74 μm in diameter. The concentrations of TP and heavy metals in the roof sediments were much higher than in the road sediments. The concentrations of the six heavy metals investigated had a similar order for all three sampling sites, with the Zn concentration always being the highest, followed by the Mn concentration, and the Ni concentration was always the lowest. After wet sieving, 76.9% to 91% of the TP in the sediments from the three sites remained in undesorbable particulate form, and 68.9% to 97% of the heavy metals were present in undesorbable particulate form. The concentrations of undesorbed heavy metals in the roof sediments tended to increase with increasing sediment size, but a similar trend was not found in the road sediments. This study shows that more attention should be given to the particulate matter in stormwater runoff, as reducing the amount of particulates will improve the efficiency of pollution control measures.     

Leaching behavior of V,Pb, Cd,Cr, and As from stone coal waste rock with different particle sizes

This paper investigates the leaching behavior of heavy metals (V, Pb, Cd, Cr, and As) from stone coal waste rocks with various particle sizes using dynamic leaching experiments. The results show that the dissolved concentrations of V and As initially increased and then slightly decreased as time progressed and that the dissolved concentrations of Pb, Cd, and Cr were high in the early stage before decreasing. The particle size of the stone coal waste rocks strongly influenced the heavy metal concentration in the leaching solutions. The effects of the particle size of the stone coal waste rocks on the dissolved concentrations of V, Pb, and As decreased in the order fine fraction > medium fraction > coarse fraction, and the effects of particle size on the dissolved concentrations of Cr and Cd decreased in the order medium fraction > coarse fraction > fine fraction and coarse fraction > medium fraction > fine fraction, respectively. The quantities of heavy metals dissolved from the stone coal waste rock with fine particle sizes were observed to decrease in the order V (17104.36 μg/kg) > As (609.41 μg/kg) > Pb (469.24 μg/kg) > Cr (56.35 μg/kg) > Cd (27.52 μg/kg), and the dissolution rates decreased in the order As (2.96%) > Pb (0.93%) > V (0.35%) > Cd (0.25%) > Cr (0.01%). The specific surface area, pore size of the stone coal waste rocks, and chemical forms of heavy metals also influenced the release of heavy metals from the stone coal waste rocks. Kinetic analysis showed that the dissolution of heavy metals fundamentally agreed with the rate equation controlled by the shrinking core model. The results of this study are expected to serve as a reference for the evaluation of heavy metals contamination from stone coal waste rocks.     

Recent progress in molecule modification with heavy ion beam irradiation

The research into heavy ion beam biology started in the 1960s, and so far it has become an important interdisciplinary study. Heavy ion beam is more suitable for molecule modification than other sorts of radiation, for it has many superiorities such as the energy transfer effect and the mass deposition effect. Molecule modification with heavy ion beam irradiation can be applied to developing new medicines and their precursors, genetic engineering, protein engi neering, outer space radiobiology, etc. Retrospect and prospect of the research and development of molecule modifica tion with heavy ion beam irradiation are given.     

Effects of heavy metal on dielectric properties of E. coli revealed by dielectric spectroscopy

Dielectric spectroscopy of E. coli cell before and after exposure to heavy metals Cd^2＋ , Cu^2＋ , Zn^2＋ and Ca^2＋ was investigated. The results indicate that changes in dielectric spectra reflect effects of heavy metal on the structure and function of E. coli cells. Heavy metal can change membrane capacitance as well as pennittivity and conductivity of the cytoplasm. Changes in volume fraction suggested that dielectric measurement could monitor the growth of E. coli cells. These results demonstrated that dielectric spectroscopy was a potential effective technique for studying electric properties of biological cells.     

Contamination trends of polybrominated diphenyl ethers, organochlorine pesticides and heavy metals in sediments from Dagu Drainage River estuary, Tianjin

Concentrations of polybrominated diphenyl ethers （PBDEs）, organochlorine pesticides （OCPs） and heavy metals in two sediment cores, taken from the Dagu Drainage River, were determined. The contamination trends of these three kinds of compounds were obtained. The results showed that concentrations of PBDEs increased in recent years; there were new contamination sources for OCPs in this area; contamination levels of heavy metals had no significant change in the last several years. Comparing the results of these two cores, erosion and dilution of seawater had different effects on the transportation of these compounds.     

Adsorption Mechanisms of Heavy Metal Ions from Drinking Water by Weakly Basic Anion Exchange Resins

IntroductionWastewater of mineral processing industriesnormally contains a variety of hazardous heavymetals and sometimes may be discharged withoutadequate treatment. These heavy metalcontaminants may be transported into drinkingwater sources,such as rivers,lakes,even theground water by natural circulation.Most waterworks can not remove these heavy metals due tothe lack of suitable treatment processes. In China,along the Yangzi River and the Huaihe River,some water sources have micro- pollut…     

Gray Synthetic Evaluation on Moisture Comfort of Sportswear Fabrics under the Condition of Heavy Sweating

Moisture and water transfer under the condition of heavy sweating are analyzed. Four different experiments are made to test moisture resistance, water-keep, wicking effect and drying ability of samples. Then gray analysis method is introduced to evaluate the comprehensive comfort of these fabrics. Result shows chemical fiber with high moisture transfer performance has advantage in water transfer and diffusion, which is suitable for human under the condition of heavy sweating. Though natural fiber can absorb moisture well, it cannot transfer fluid sweat. Therefore natural fiber fabrics such as cotton, wool are unsuitable to make functional sportswear.     

Accumulation process and model for the Ordovician buried hill reservoir in the western Lunnan area,the Tarim Basin

The Ordovician buried hill reservoir in the western Lunnan area, a type of dissolved fracture and cavernous reservoir, is mainly composed of heavy oil. The oil is the mixture sourcing from the Middle-Lower Cambrian and Middle-Lower Ordovician, with three stages of pool forming process: (1) the destruction and parallel migration/accumulation during the late Caledonian to early Hercynian; (2) the oil and gas accumulation during the late Hercynian characterized by adjustment upward along faults and parallel migration/accumulation; (3) the formation of heavy oil during the latest Hercynian. The Ordovician buried hill reservoir is affected by the diffusion of light oil and gas but had no hydrocarbon charging during the late Yanshan period to Himalayan period, but in this period, formed the association of heavy oil and dissolved gas cracked from crude oil with dry coefficient of 0.91-0.96. The study on accumulation process of the Ordovician buried hill reservoir has important implications for the exploration potential of early oil and gas accumulation in the cratonic area of the Tarim Basin.     

Accumulation process and model for the Ordovician buried hill reservoir in the western Lunnan area, the Tarim Basin

The Ordovician buried hill reservoir in the western Lunnan area, a type of dissolved fracture and cavernous reservoir, is mainly composed of heavy oil. The oil is the mixture sourcing from the Middle-Lower Cambrian and Middle-Lower Ordovician, with three stages of pool forming process： （1） the destruction and parallel migration/accumulation during the late Caledonian to early Hercynian; （2） the oil and gas accumulation during the late Hercynian characterized by adjustment upward along faults and parallel migration/accumulation; （3） the formation of heavy oil during the latest Hercynian. The Ordovician buried hill reservoir is affected by the diffusion of light oil and gas but had no hydrocarbon charging during the late Yanshan period to Himalayan period, but in this period, formed the association of heavy oil and dissolved gas cracked from crude oil with dry coefficient of 0.91-0.96. The study on accumulation process of the Ordovician buried hill reservoir has important implications for the exploration potential of early oil and gas accumulation in the cratonic area of the Tarim Basin.     

Change of precipitation intensity spectra at different spatial scales under warming conditions

The long-term change of the whole spectra of precipitation intensity in China is examined using observed daily data recorded at 477 surface stations for the period from 1961 to 2008. The results show a spatially coherent decrease of trace precipitation despite different reduction magnitudes among the regions. For measurable precipitation, significant regional and seasonal characteristics are observed. In autumn, the whole measurable precipitation decreased over Eastern China (east of 98°E). In summer and winter, a significant increase of heavy precipitation and decrease of light precipitation are detected south of Eastern China. In Western China, measurable precipitation is found to have increased in all four seasons. Composite analysis reveals a quasi-linear relationship between increasing surface temperature and precipitation on a global scale. The responses of precipitation at different intensities to the increased temperature are distinct, with a significant spectra-shifting from light to heavy precipitation. Compared with precipitation over the ocean, the amplification of heavy precipitation over land is relatively less, most likely constrained by the limited water supply. The response of regional precipitation to global warming shows greater uncertainties compared with those on the global scale, perhaps due to interference by more complex topography and land cover, as well as human activities, among other factors.     

矿山尾矿作为碱活化原料的研究进展

The mining industry produces billions of tons of mine tailings annually. However, because of their lack of economic value, most of the tailings are discarded near the mining sites, typically under water. The primary environmental concerns of mine tailings are related to their heavy metal and sulfidic mineral content. Oxidation of sulfidic minerals can produce acid mine drainage that leaches heavy metals into the surrounding water. The management of tailing dams requires expensive construction and careful control, and there is the need for stable, sustainable, and economically viable management technologies. Alkali activation as a solidification/stabilization technology offers an attractive way to deal with mine tailings. Alkali activated materials are hardened, concrete-like structures that can be formed from raw materials that are rich in aluminum and silicon, which fortunately, are the main elements in mining residues. Furthermore, alkali activation can immobilize harmful heavy metals within the structure. This review describes the research on alkali activated mine tailings. The reactivity and chemistry of different minerals are discussed. Since many mine tailings are poorly reactive under alkaline conditions, different pretreatment methods and their effects on the mineralogy are reviewed. Possible applications for these materials are also discussed.