大块液膜法处理模拟含Cr(Ⅵ)废水

以三辛胺为载体,煤油为膜溶剂,NaOH为反萃剂,采用大块液膜法处理模拟含Cr(Ⅵ)废水.考察了Cr(Ⅵ)迁移的影响因素,实验结果表明:在料液相进水Cr(Ⅵ)质量浓度为1043.6 mg/L、料液相进水pH为1.1、反萃相中NaOH质量分数为20％、液膜相体积为100 mL、液膜相中三辛胺体积分数为15％、反应时间为50 min的条件下,料液相出水Cr(Ⅵ)质量浓度为0.5 mg/L;萃取36批废水后Cr(Ⅵ)浓缩比可达94.2％.     

流动注射在线富集分光光度法测定水样中痕量Cr(Ⅵ)

采用流动注射在线富集分光光度法测定水样中痕量Cr（Ⅵ），考察了流路条件、显色条件和共存离子的影响。在H：SO。浓度为1．2mol/L、2-（5-溴-2-吡啶偶氮）-5-二乙氨基酚溶液质量浓度为1．75g／L的条件下，试样富集4min，测定Cr（Ⅵ）的线性范围为0．01～0．60mg／L，检出限为3μg/L。连续10次测定质量浓度为0．20mg／L的Cr（Ⅵ）标准溶液相对标准偏差为0．4％。方法可应用于河水和工业废水中痕量Cr（Ⅵ）的测定，加标回收率为93．3％～106．4％。     

炉渣去除废水中六价铬

采用炉渣处理模拟含Cr（Ⅵ）废水，确定了炉渣去除Cr（Ⅵ）的适宜条件，并对去除机理及动力学规律进行了探讨。实验结果表明，对于初始质量浓度为10mg／L的含Cr（Ⅵ）废水，在室温、废水初始pH=1．00、炉渣加入量为8g/L、反应时间为240min的条件下，Cr（Ⅵ）去除率达99．2％。对于初始质量浓度低于50mg／L的含Cr（Ⅵ）废水，投加适量的炉渣，可使处理后出水中的Cr（Ⅵ）质量浓度降至排放标准以下。炉渣对Cr（Ⅵ）的去除机理主要是炉渣中溶出的Fe^2＋对Cr（Ⅵ）的还原作用，炉渣对Cr（Ⅵ）的吸附作用很小。炉渣对Cr（Ⅵ）的还原反应符合一级反应动力学规律，在pH分别为0．55，1．00，2．00的条件下，反应速率常数分别为6．0×10^-3，3．3×10^-3，4．0×10^-4min^-1．     

改性木屑吸附处理含Cr(Ⅵ)废水

对改性木屑处理含Cr(Ⅵ)废水进行了研究,考察了溶液Cr(Ⅵ)初始质量浓度、溶液pH、木屑加入量、吸附时间对吸附效果的影响.实验结果表明:在溶液初始Cr(Ⅵ)质量浓度15 mg / L 、溶液pH 2.0、木屑加入量7.5 g / L、吸附时间60 min 的优化实验条件下,硝酸改性木屑比磷酸改性木屑吸附效果好,硝酸改...     

天然膨润土还原吸附Cr（Ⅵ）

以天然膨润土为吸附剂，还原吸附处理含Cr（Ⅵ）模拟废水。实验结果表明：以（NH₄）₂FeSO₄为还原剂吸附效果最佳；在还原剂加入量为理论值的0.8倍、膨润土加入量为6 g/L、吸附时间为30 min、吸附温度为30 ℃、初始Cr（Ⅵ）质量浓度为1 mg/L的条件下，Cr（Ⅵ）去除率可达99.6%，处理后模拟废水中总铬质量浓度低至0.003 mg/L。天然膨润土对Cr（Ⅵ）的还原吸附符合准二级动力学模型及Freundlich等温吸附模型。     

硝酸改性活性炭的制备及其对Cr（Ⅵ）

利用硝酸对颗粒活性炭进行改性，处理含铬废水，并考察了吸附时间、溶液pH、吸附剂加入量对改性活性炭吸附Cr（Ⅵ）效果的影响。实验结果表明：经过硝酸氧化改性的活性炭比表面积有所增加，官能团总量增加明显；吸附剂对Cr（Ⅵ）的去除率随振荡时间的增加而增加；对于质量浓度为10mg/L的100mLCr（Ⅵ）溶液，当溶液pH为中性，30%（体积分数）硝酸改性的颗粒活性炭的加入量为0.4g，其对Cr（Ⅵ）的最大去除率为98%。     

微生物处理含Cr废水工艺研究

利用从Cr污染土壤中分离筛选出的高效还原Cr(Ⅵ)的土著微生物Pannonibacter phragmitetus,通过摇瓶单因素实验对所筛选的土著微生物处理含Cr废水效果及影响因素进行研究。实验结果表明:最优的处理条件为废水Cr(Ⅵ)质量浓度为301.4mg/L,细菌接种量为20%,反应温度为30℃,废水pH为10.0,震荡速率为100r/min。模拟连续化工废水处理实验表明,在最佳优化条件下,处理后废水的色度、悬浮物以及细菌浓度分别为48倍、65mg/L和60个/L,达到GB8978—1996《污水综合排放标准》。     

铁矿石烧结烟气脱硫灰处理含铬废水

在分析铁矿石烧结烟气脱硫灰成分的基础上,利用脱硫灰中的亚硫酸盐还原废水中的Cr(Ⅵ),再加碱中和,通过沉淀去除铬。在初始废水pH 1.0、脱硫灰加入量0.06 g/mg(以Cr(Ⅵ)计)、振荡转速160 r/min、振荡时间25 min、中和pH 7.5的最佳工艺条件下处理模拟含铬废水,Cr(Ⅵ)质量浓度由10.00 mg/L降至0.18 mg/L,去除率达98.2%。最佳工艺条件下处理3种实际含铬废水,处理后出水的Cr(Ⅵ)和总铬的质量浓度及pH均满足GB 8978—1996《污水综合排放标准》。实现了对脱硫灰的综合利用、化害为利和以废治废的目标。     

氟苯生产废水处理及资源化技术

采用酸化、萃取、反萃、除氟、电催化氧化技术处理氟苯生产废水（简称废水）。工艺条件为：以硫酸为酸化剂，pH小于等于1；萃取温度10～25℃，搅拌时间大于4min，油水比（萃取剂与废水的体积比）1：4．0；反萃碱油比（NaOH溶液体积与油相体积比）1：3，NaOH质量分数10％；除氟时先加入2倍理论计算量的氯化钙、后加入氧化钙调pH至7～8；电催化氧化时粒子群电催化反应器槽电流2．0～2．5A，停留时间40～60min。处理后废水的COD、苯酚、F^-、石油类去除率分别高于99．3％，99．9％，99．8％，99．9％，苯酚回收率高于93．5％；出水COD、苯酚、F^-、石油类的浓度低于GB8978—1996《污水综合排放标准》中的一级排放标准。     

Alamine336对低浓度模拟含硝酸废水的萃取分离

以模拟低浓度含硝酸废水为研究对象,以煤油为稀释剂,考察了工艺条件对硝酸萃取和反萃效果的影响,并对萃取机理进行了探讨。实验结果表明：以10.0%（φ）Alamine336为萃取剂,在有机相与水相的体积比为1∶2、萃取温度为298 K的条件下,对初始硝酸质量浓度为2.00 g/L的含硝酸废水进行两级逆流萃取操作后,理论上水相硝酸质量浓度低于15 mg/L,达到GB 8987—1996中的一级标准;以0.05 mol/L氢氧化钠溶液为反萃剂,在有机相与水相的体积比为1∶2、反萃温度为298 K的条件下,对硝酸负载量为1.50 g/L的有机相进行两级反萃后,理论上有机相硝酸残余量小于0.005 g/L。机理研究表明Alamine336通过与硝酸形成离子对络合物来萃取硝酸。     

Distribution of Cd,Ck, Pb and Zn in Soil and Vegetation Compartments in Stands of Five Boreal Tree Species in N.E. Sweden

Concentrations and total quantity of cadmium (Cd), cupper (Cu),lead (Pb) and zink (Zn) were determined in biomass and soil compartments in a replicated tree species experiment with 27-yr-old stands growing on former farmland in N.E. Sweden. Sequentialextractions of soil samples were performed in order to estimate the exchangeable and an organically bound fraction of each element. The tree species included were Picea abies (L.)H. Karst., Pinus sylvestris L., Pinus contorta Dougl., Larix sibirica Ledeb., and Betula pendula Roth.Tree species influenced the rate of removal of Cu, Pb and Zn incase of stemwood harvesting, and of Cd, Cu and Zn in the case ofwhole-tree harvesting. B. pendula and P. abies had higher quantities and average concentrations of Zn in the biomass. For all species, >50% of the Zn in the stems was found in the bark. P. abies and L. sibirica had higher quantities of Cu in the biomass than the other species.P. abies and P. contorta had high quantities of Cd inthe biomass in relation to the other species. Branches and stembark contained high concentrations of Cd and Pb in relation to foliage and stemwood. Dead branches had especially high concentrations of Pb. The high accumulation rate of Zn in thebiomass of B. pendula was related to a low exchangeable amount of Zn in the A horizon. In the superficial centimeters ofthe A horizon, a depletion similar to that found for Zn was detected for Cu, whereas for Cd and Pb, no correlations were found between quantities of elements in the trees and element pools in the soil.     

Programs assessing implementation and effectiveness of state forest practice rules and BMPs in the West

The major forest nonpoint source control programs in the West are largely regulatory, either under forest practices acts (California, Idaho, New Mexico, Nevada, Oregon, and Washington) or a streamside management act (Montana). These programs and the specific rules they enforce continue to undergo intensive scrutiny. Still, the questions are the same for these regulatory programs as for states that base nonpoint source control on voluntary BMPs (Arizona, Colorado, Utah, Wyoming). Are the rules or BMPs being applied, and are they effective in reducing nonpoint source pollution to levels that protect beneficial uses of water? The level of debate about forestry in the West has resulted in detailed monitoring and research to answer these questions. In the past, state agencies have assumed levels of BMP compliance based on the percent of operations without enforcement actions. These estimates are being replaced by statistically valid and reproducible monitoring of forest practices rules and BMP compliance levels. BMP effectiveness is being assessed using both qualitative and quantitative methods. This can involve field assessments, process-based research, and control watershed studies. Some trend monitoring is also beginning. With the regional implementation rate for forestry BMPs at about 94% and rising, it is likely that effectiveness testing will continue to be a priority and consume the majority of assessment resources for this region.     

Starch-plastic materials—Preparation,physical properties,and biodegradability (a review of recent USDA research)

Recent starch-plastic research at the National Center for Agricultural Utilization Research is reviewed and related worldwide efforts are noted. Properties of starch that influence its formulation and performance in plastics are discussed. Methods are given for preparation of starch-poly(methyl acrylate) graft copolymer, starch-poly(ethylene-co-acrylic acid), and starch-poly(ethylene-co-acrylic acid)-polyethylene plastics. Their physical properties are discussed, as is degradability by enzymes or amylolytic organisms from soil, ponds, and streams.The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

四氮唑废水处理工艺设计

高浓度、高盐分的四氮唑生产废水通过三效蒸发浓缩，馏出液经铁炭氧微电解和混凝预处理，再采用水解酸化一接触氧化一反应二沉主体组合工艺进行处理。研究了该工艺所需构筑物和设备的设计与选型。该工艺在正常运行条件下，处理后出水pH6～9，COD 302mg／L，BOD5 108mg／L，SS30mg／L，色度36倍，水质达到GB8978--1996（污水综合排放标准》三级标准。     

Application of Cellulose Microfibrils in Polymer Nanocomposites

Cellulose microfibrils obtained by the acid hydrolysis of cellulose fibers were added at low concentrations (2–10% w/w) to polymer gels and films as reinforcing agents. Significant changes in mechanical properties, especially maximum load and tensile strength, were obtained for fibrils derived from several cellulosic sources, including cotton, softwood, and bacterial cellulose. For extruded starch plastics, the addition of cotton-derived microfibrils at 10.3% (w/w) concentration increased Young’s modulus by 5-fold relative to a control sample with no cellulose reinforcement. Preliminary data suggests that shear alignment significantly improves tensile strength. Addition of microfibrils does not always change mechanical properties in a predictable direction. Whereas tensile strength and modulus were shown to increase during addition of microfibrils to an extruded starch thermoplastic and a cast latex film, these parameters decreased when microfibrils were added to a starch–pectin blend, implying that complex interactions are involved in the application of these reinforcing agents.     

Hysteresis in Reversal of Central European Mountain Lakes from Atmospheric Acidification

Extremely high emissions of S and N compounds in Central Europe (both 280 mmol m^-2 yr^-1) declined by 70and 35%, respectively, during the last decade. Decreaseddeposition rates of SO₄ ^-2, NO₃ ^-, and NH₄ ⁺ in the region paralleled emission declines. The reduction in atmospheric inputs of S and N to mountain ecosystemshas resulted in a pronounced reversal of acidification in the Tatra Mountains and Bohemian Forest lakes. Between the 1987–1990and 1997–1999 periods, concentrations of SO₄ ^-2 and NO₃ ^- decreased (average ± standard deviation) by 22±7 and 12±7 mol L^-1, respectively, in theTatra Mountains, and by 19±7 and 15±10 mol L^-1, respectively, in the Bohemian Forest. Their decrease was compensated in part (1) by a decrease in Ca²⁺ + Mg²⁺ (17±7 mol L^-1) and H⁺ (4±6 mol L^-1), and an increase in HCO₃ ^-(10±10 mol L^-1) in the Tatra Mountains lakes, and (2) by a decrease in Al (7±4 mol L^-1), Ca²⁺ + Mg²⁺ (9±6 mol L^-1), and H⁺ (6±5 mol L^-1), in Bohemian Forest lakes. Despite the rapid decline in lake water concentrations of SO₄ ^-2 and NO₃ ^- in response to reduced S and N emissions, their present concentrations in some lakes are higher than predictionsbased on observed concentrations at comparable emission rates during development of acidification. This hysteresis in chemical reversal from acidification has delayed biological recovery of the lakes. The only unequivocal sign of biological recovery hasbeen observed in erné Lake (Bohemian Forest) where a cladoceran species Ceriodaphnia quadrangular has recentlyreached its pre-acidification abundance.     

Reconstruction of Long-Term Changes in Lake water Chemistry,Zooplankton and Benthos of a Small,Acidified High-Mountain Lake: Magic Modelling and Palaeolimnogical Analysis

Starolesnianske pleso is a small and shallow acid lake in the High Tatra Mountains, situated at 2000 m above sea level, on granitic bedrock, with sparse and thin soil cover. When detailed measurements began in the 1980s Starolesnianske pleso had pH below 5 and only one species of cladoceran zooplankton, the ubiquitous Chydorus sphaericusPalaeolimnological investigations show changes in cladoceran zooplankton and chironomid zoobenthic assemblages since about 1920 and a major change in 1970–1980. The dynamic acidification model MAGIC was used to reconstruct changes in water chemistry over the past 150 years. The results from MAGIC agree well with the sediment record; pH levels gradually decreased from 6.5 in the mid-1800s to about 5.6 in 1920 (first response in biota) to below 5.0 by 1970, and concentrations of inorganic aluminium rose dramatically beginning about 1960. In the 1990s the lake water chemistry showed clear signs of reversal in acidification brought about by a major decline in S deposition.     

Does Soil Acidification Affect Spruce Needle Chemical Composition and Tree Growth?

In 1994, a large survey of soil chemistry was undertaken in thecounty of Värmland in central Sweden (Lundström et al., 1998).The southern part of the county was affected by soilacidification whereas there were no such indications in thenorthern part. To investigate the influence of soil chemistryon the trees at the specific sites, the survey was continued byan analysis of needle chemistry (Norway spruce) which wasundertaken at 150 of the 180 sites, and of tree growth at 65 ofthe 180 sites. Growth was expressed as a ratio between expectedgrowth, estimated with a national, empirical growth model, andthe growth observed in the field. In statistical analyses,using rank correlation, PCA and PLS, there were only weakindications of an influence of soil chemistry on needlechemistry and on tree growth. A moderate correlation betweennitrogen and sulphur in needles was found, which wasinterpreted as an effect of deposition and of processes in thetree canopy. No obvious regional pattern of the growth ratiowas found, in contrast to the clear pattern of soilacidification. The statistical analysis could not with anycertainty point out any of the soil chemistry variables asespecially important for the tree growth ratio.     

Bioassessment of silvicultural impacts in streams and wetlands of the Eastern United States

Bioassessment is a useful tool to determine the impact of logging practices on the biological integrity of streams and wetlands. Measuring biota directly has an intuitive appeal for impact assessment, and biota can be superior indicators to physical or chemical characteristics because they can reflect cumulative impacts over time. Logging can affect stream and wetland biota by increasing sedimentation rates, altering hydrologic, thermal, and chemical regimes, and changing the base of food webs. Biotic impacts of logging on streams compared to wetlands probably differ, and in this paper we review some of those differences. In streams, invertebrates, fishes, amphibians, algae, and macrophytes have been used as indicators of logging impacts. In wetlands, bioassessment is just beginning to be used, and plants and birds are the most promising indicator taxa. Various best management practices (BMPs) have been developed to reduce the impacts of logging on stream and wetland biota, and we review quantitative studies that have evaluated the efficacy of some of these techniques in streams and wetlands in the eastern United States. Remarkably few studies that address the overall efficacy of BMPs in limiting biotic changes in streams and wetlands after BMP implementation have been published in scientific journals, although some work exists in reports or is unpublished. We review these works, and compile conclusions about BMP efficacy for biota from this body of research.     

Characterization of air emissions and residual ash from open burning of electronic wastes during simulated rudimentary recycling operations

Air emissions and residual ash samples were collected and analyzed during experiments of open, uncontrolled combustion of electronic waste (e-waste), simulating practices associated with rudimentary e-waste recycling operations. Circuit boards and insulated wires were handled separately to simulate processes associated with metal recovery. The average emissions of polychlorinated dibenzodioxins and dibenzofurans (PCDD/PCDFs) were 92 ng toxic equivalency (TEQ)/kg [n = 2, relative standard deviation (RSD) = 98%] and 11 900 ng TEQ/kg (n = 3, RSD = 50%) of the initial mass of the circuit boards and insulated wire, respectively. The value for the insulated wire is about 100 times higher than that for backyard barrel burning of domestic waste. The emission concentrations of polybrominated dibenzodioxins and dibenzofurans (PBDD/PBDFs) from the combustion of circuit boards were 100 times higher than for their polychlorinated counterparts. Particulate matter (PM) sampling of the fly ash emissions indicated PM emission factors of approximately 15 and 17 g/kg of the initial mass for the circuit boards and insulated wire, respectively. Fly ash samples from both types of e-waste contained considerable amounts of several metallic elements and halogens; lead concentrations were more than 200 times the United States regulatory limits for municipal waste combustors and 20 times those for secondary lead smelters. Leaching tests of the residual bottom ash showed that lead concentrations exceeded U.S. Environmental Protection Agency landfill limits, designating this ash as a hazardous waste.