硫酸生产废水中砷去除方法的研究

对硫酸生产中水洗净化工序排放的废水分别采用灰灰石和鼓风氧化法,铁屑法和铁盐法进行处理试验,结果表明,采用铁盐法级处理工艺处理废废水是可行的,控制组处理的ＰＨ分别为８－１０和８－９,Ｆｅ／Ａｓ摩尔比分别为１和５,当进水Ａｓ含量为１１５ｍｇ／Ｌ时,经两组处理后,出水Ａｓ含量〈０．５ｍｇ／Ｌ,重金属离子,ＰＨ,ＳＳ等指标均符合国家排放标准。     

制革铬鞣废水中Cr（Ⅲ）的处理和回收

制革铬鞣废水中Ｃｒ（Ⅲ）的处理和回收制革工业铬鞣废水是工业废水中较难处理的一种。废水中含有大量Ｃｒ（Ⅲ）,Ｃｒ２Ｏ３的含量高达３０００～４０００ｍｇ／Ｌ。这种高浓度Ｃｒ３＋废水的排放,不仅污染水体,危害人体健康,同时也是资源的浪费。对铬鞣废水中Ｃｒ（...     

硫酸生产中废水治理工艺的改进

采用ＮａＣｌＯ氧化共沉淀脱砷工艺处理硫酸废水，在ＮａＣｌＯ投加量１２００ｍｇ／Ｌ、铁砷比３．０、氧化终点ｐＨ３．５、聚丙烯酰胺投加量１５ｍｇ／Ｌ的条件下，处理后出水中砷含量降至１．０６ｍｇ／Ｌ，再经第二级中和沉淀后可达国家排放标准。此工艺能使砷富集于沉渣中，达到可回收的水平，此外还可大大减少含砷废渣的产生量。     

氯氰菊酯废水物化和生化处理的研究

对氯氰菊酯生产废水进行了物化预处理和生化处理试验,物化预处理工艺路线为高温高压氧化法,最佳温度为２２０℃,对庆压力为３．５４ＭＰａ,最佳时间为１ｈ。废水经预处理后,ＣＯＤ从４３１００ｍｇ／Ｌ降至１７３００ｍｇ／Ｌ,去除率为６０％;氰含量从３６４０ｍｇ／ＫＬ降至小于１ｍｇ／Ｌ,去除率高达９９．９％;出水ＢＯＤ５／ＣＯＤ上升至０．３４。     

缩合－电解法处理苯胺废水

采用缩合－电解法处理苯胺废水，缩合过程的最佳ｐＨ为５．０—６．０，甲醛的最佳投加量视废水中苯胺含量而定；电解过程中，ＮａＣｌ的最佳投加量为３％（ｗｔ），控制电解液ｐＨ为５．０—７．０、电解时间１２０—１４０ｍｉｎ、槽电压３Ｖ、电流密度０．９Ａ／ｄｍ￣２。在上述条件下，苯胺含量为１０００—１００００ｍｇ／Ｌ的废水经缩合－电解法处理后，ＣＯＤ＜２５０ｍｇ／Ｌ，苯胺＜０．１ｍｇ／Ｌ。     

聚苯乙烯三乙醇胺树脂对水中镉离子的吸附

镉是一种对人体有害的重金属元素。２０世纪６０年代初，日本曾发生镉污染而引起的“软骨病”公害事件，震惊世界。因此，各国对含镉废水相继制定了较严格的排放标准。我国国家标准规定：废水中镉的最高允许排放质量浓度为０．１ｍｇ／Ｌ，饮用水中镉含量不得高于０．０１ｍｇ／Ｌ。含镉废水常采用化学沉淀、离子交换及吸附等方法处理。一些螯合树脂对镉离子具有较强的螯合能力，适用于处理镉离子含量较低的废水。本试验研究了聚苯乙烯三乙醇胺树脂对镉离子的吸附，取得了良好的处理效果。１　试验仪器与试剂　　ＰＥ－２４００型ＣＨＮ元素…     

缩合—电解法处理苯胺废水

采用缩合－电解法处理苯胺废水，缩合过程的最佳ＰＨ为５．０－６．０，甲醛的最佳投加量视废水中苯胺含量而定；电解过程中，ＮａＣｌ的最佳投加量为３％（ｗｔ），控制电解液ＰＨ为５．０－７．０、电解时间１２０－１４０ｍｉｎ、槽电压３Ｖ、电流密度０．９Ａ／ｄｍ＾２。在上述条件下，苯胺含量为１０００－１００００ｍｇ／Ｌ的废水经缩合－电解法处理后，ＣＯＤ＜２５０ｍｇ／Ｌ，苯胺＜０．１ｍｇ／Ｌ。     

喷射溶气回流浮选工艺处理含油废水

采用喷射溶气回流浮选工艺处理含油废水，替代原来的全加压溶气浮选工艺，提高了浮选过程的处理效果，增强了系统的抗负荷冲击能力，浮选出水油含量由原来的〈４０ｍｇ／Ｌ降至〈２０ｍｇ／Ｌ，ＣＯＤ由原来的〈１５０ｍｇ／Ｌ降至〈１１０ｍｇ／Ｌ。     

蛋氨酸生产废水的处理

对蛋氨酸生产废水的处理方法进行了试验研究，采用化学氧化－生化－絮凝的处理方法，可使处理后的排水ＣＯＤ≤１２０ｍｇ／Ｌ，ＢＯＤ５≤１０ｍｇ／Ｌ，符合排放标准，另外，对其它的处理方法也进行了探讨。     

重油气化炭黑废水的处理

采用气浮－离心组合工艺处理炭黑废水，出水炭黑含量为５０ｍｇ／Ｌ，达到国家排放标准，离心后所得炭黑滤饼的含水量为９０－９２％。整个处理过程中不产生二次污染。     

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.     

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.     

Heavy Metals Removal by Biosorption and Flotation

The removal of a mixture of heavy (toxic) metal cations (copper, nickeland zinc) from liquid effluents was investigated in this study at pilotscale, using counter-current contact mode. The innovative processinvolved the abstraction of metal ions onto fungal biosorbents, followedby the application of flotation for the subsequent solid/liquid separationof biomass particles. The ability of microorganisms to remove metal ionsfrom aqueous solutions is a well-known phenomenon. Nevertheless,engineering considerations are very important in decisions, concerningthe commercial future of biosorption and practical solutions are neededfor certain problems, such as the efficient post-separation ofmetal-loaded biomass. The two processes (flotation and biosorption) caneffectively operate in combination, in what it was termed biosorptiveflotation process. The sorbents may be recycled, after appropriate elutionof metals, as well as the treated (clean) water.     

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.     

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.