超临界水氧化法处理造纸黑液

采用自制的超临界水氧化反应装置,对造纸工业排放的黑液进行处理。考察了反应温度、反应压力、反应时间、过氧量(初始反应时所加氧气的量与废水完全氧化所需氧气的理论量的比,%)等对黑液中COD去除率的影响。实验结果表明,处理黑液的最佳反应条件为:反应温度500℃,压力26M Pa,过氧量500%,反应时间120s。在此最佳条件下处理COD为85 000m g/L的造纸黑液,COD去除率可达99.9%。     

湿式氧化法预处理四氢呋喃生产废水

采用湿式氧化法预处理四氢呋喃(THF)生产废水,考察了不同反应条件对废水处理效果的影响。实验结果表明:废水COD去除率随着反应温度和压力的升高而增大,而有机物初始浓度对COD去除率的影响较小;当反应温度为250℃、反应压力为5.0 MPa时,出水COD为353 mg/L、BOD_5为233 mg/L,BOD_5/COD从0.18提高到0.67,废水的可生化性显著提高,处理后废水的水质达到GB8978—1996《污水综合排放标准》中的三级标准。     

低温湿式空气氧化法处理废碱液的研究

对采用低温湿式空气氧化法处理炼油和乙烯废碱液进行了研究。考察了停留时间对废碱液中硫化物的氧化、氧化产物的形态、COD和酚去除率的影响，反应温度对废碱液中污染物氧化反应的影响。试验结果表明，废碱液的脱臭效果很好，S^2-的氧化产物以S2O3^2-和SO4^2-2种形式共存；酚、COD的去除率及S^2-的氧化反应停留时间影响小，受反应温度影响明显；废碱液的S^2-的酚浓度相当时，COD去除率一 般低于40％， 废碱液的S^2-浓度远大于酚浓度时，废碱液的COD去除率为40％－70％；废碱液中酚的质量浓度大于20000mg/L时才有回收价值。     

NaOH强化催化湿式氧化处理制药污泥

采用NaOH强化催化湿式氧化的方法处理制药污泥,考察了各工艺条件对污泥VSS去除率和COD去除率的影响。实验结果表明,在NaOH加入量10 g/L、反应温度260 ℃、初始氧气压力1.0 MPa、反应时间60 min的最佳工艺条件下,污泥VSS去除率和 COD去除率分别达到95%和60%,VSS去除率较高,污泥减量化效果显著。NaOH强化催化湿式氧化反应处理制药污泥的机理是氢氧根在高温条件下促进了微生物细胞的水解,促使污泥固体组分分解转移到液相中,最终有机物被降解为小分子有机物、CO₂和水。     

多相催化湿式氧化法处理高浓度难降解有机废水的研究

在高压反应釜内，采用自制颗粒贵金属催化剂催化湿式氧化法处理高浓度饲料抗氧化剂合成废水，探讨了温度、压力、进水pH等反应条件对废水处理效果的影响。在温度为220℃、总压为8MPa条件下，COD，TOC，TN和色度的去除率分别达到77．0％，66．1％，70．2％，91％；处理后的废水pH很低，催化剂显示出较好的耐酸性；随进水pH的增加，COD的去除率逐渐降低，出水pH增加。     

国外动态

芬顿氧化法,即用 Fe~(2 )和过氧化氢对废水进行处理的方法。将此法与生物处理法结合使用,可处理难分解的有机合成废水。研究结果表明,对几乎不含 BOD 的 P-甲苯胺废水,投加 Fe~(2 )200ppm,过氧化氢9000ppm,反应20分钟,其 TOC(770ppm)和 COD(1400ppm)可分别除去64%和92%,若再接着用间歇活性污泥法处理,其TOC 和 COD 的总去除率分别可达93%和94%。该方法用于处理 m-甲苯胺废水同样取得良好效果,该废水经芬顿氧化法处理后,TOC 和 COD 的去除率分别为61%,93%,再经生物处理,其 TOC 和COD 的总去除率分别可达94%,98%。用芬顿氧化法处理尿素高缩合树脂和三羟密胺树脂的废水时,其 TOC 的去除率分别为84%和89%,但再进行生物处理,无明显效果。对抛光研磨废水,采用酸化处理,芬顿氧化处理及生物处理相结合的形式,COD 总去除率为98%。     

Fenton氧化法处理石化含油废水生化出水

采用Fenton氧化法处理石化含油废水生化出水,通过正交实验和单因素实验优化了反应工艺条件。正交实验得到各因素对COD去除率的影响大小顺序为:溶液初始pHH_2O_2投加量n(H_2O_2)∶n(Fe~(2+))反应温度。实验最佳工艺条件为:初始溶液pH 4.0,H_2O_2投加量3.00 mL/L,n(H_2O_2)∶n(Fe~(2+))=10,反应温度35℃,反应时间60 min。在此最佳工艺条件下COD可降至60.33 mg/L,COD去除率达61.33%。在最佳工艺条件下,分别采用超声(US)-Fenton氧化和紫外光(UV)-Fenton氧化技术处理含油废水生化出水,COD去除率分别达76.77%和80.23%。但单一Fenton氧化、US-Fenton氧化和UV-Fenton氧化工艺对NH_3-N的去除效果均并不明显。     

Fenton混凝沉淀法处理高浓度焦化废水的研究

对以H2O2为氧化剂,FeSO4.7H2O为催化剂的Fenton氧化法处理高浓度复杂焦化废水进行了系统研究,氧化处理后用氯化铁作为混凝剂,对COD、NH3-N、色度及浊度的去除率进行了考查。确定了氧化试验的影响因素和最佳混凝试验条件。结果表明:当pH值控制在3左右,反应时间为30 min,反应温度为80℃时,焦化废水COD,NH3-N,浊度和色度去除率分别达到了93.1%、96.2%、90.8%和90.2%。     

高压脉冲放电-臭氧氧化处理活性艳红K-2BP废水

自制电压为10kV的高压脉冲放电反应器，对质量浓度为200mg／L的模拟活性艳红K-2BP废水进行脱色和去除COD实验。实验结果表明：通氧气高压脉冲放电与高压脉冲放电相比，废水脱色率提高了1．3％，约为6％，COD去除率提高了3％，达14％；高压脉冲放电协同臭氧氧化与臭氧氧化相比，反应初期废水脱色率提高了约10％，反应30min后废水脱色率均达99％以上，COD去除率提高了15．2％，达80％。向废水中加入Na2CO3可使COD去除率明显下降；加入NaCl，在臭氧氧化条件下，COD去除率由66．86％降至58．86％；而加入Na2SO4后COD去除率升至81．70％。     

臭氧氧化处理页岩气钻井废水的机理与动力学

采用臭氧氧化法处理页岩气钻井废水经混凝沉淀后的出水(COD=759.63 mg/L),重点研究了废水中有机污染物的去除机理与反应动力学。实验结果表明:在废水pH为11.2、臭氧通入量为8 mg/min、反应时间为50 min的最佳工艺条件下,废水的COD去除率为42.51%;羟基自由基抑制剂CO_3~(2-)、HCO_3~-和叔丁醇的引入抑制了废水COD的臭氧氧化去除,尤其是叔丁醇的加入使COD去除率显著下降,说明废水中有机物的臭氧氧化去除过程遵循羟基自由基机理;臭氧氧化法对钻井废水中有机物的氧化去除过程符合表观二级反应动力学规律。     

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.     

High Immobilization of NH4+ in Danish Heath Soil Related to Succession,Soil and Nutrients: Implications for Critical Loads of N

During recent decades heathlands havechanged into grasslands in regions with high atmosphericnitrogen deposition. In regions with intermediatedeposition level (e.g., Denmark) changes have been lesspronounced which may be due to delay or decrease inresponse of the ecosystem. The mor layer (O horizon) mayplay an important role for this delay due to high sinkstrength for N. In this study, the capacity for netNH₄ ⁺ immobilization and mineralization wasstudied during short- and long-term incubations (2–36 days)of mor samples from Danish dry inland heaths. High short-term capacity for net NH₄ ⁺ immobilization wasfound to be a general characteristic of Danish heath morlayers both under heather (Calluna vulgaris) andcrowberry (Empetrum nigrum ssp nigrum), the latterdominating late stages in heathland succession. The netNH₄ ⁺ immobilization was higher under youngcompared to old or dead vegetation, and higher on lessnutrient poor soils than on extremely nutrient poor soils.The addition of N, P and C stimulated CO₂ productionand net NH₄ ⁺ immobilization, but not net Nmineralization. The immobilization of ¹⁵NH₄ ⁺caused release of dissolved organic N, increased N anddecreased C/N ratio in the microbial biomass, and indicatedgrowth of microorganisms with other metabolic abilitiesthan the indigenous population. No evidence was obtained ofstabilization of immobilized ¹⁵NH₄ ⁺ intosoil organic matter during the experiment. On background ofthe results and current knowledge it was concluded that therecognition of the high capacity for net NH₄ ⁺immobilization in mor layers does not allow for a raiseof critical loads for N for northern dry inland heaths.     

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.