电化学辅助微电解法处理焦化废水

制备了锰粉改进的规整化微电解填料,采用电化学辅助改进微电解填料处理初始COD为6 153.6 mg/L、ρ(NH_3-N)为182.6 mg/L的焦化废水,优化了工艺条件。实验结果表明,电化学辅助微电解法处理焦化废水的最佳工艺条件为电压8 V,填料投加量20 g/L,初始废水pH 6,反应时间30 min。在此条件下废水COD去除率为75.3%,NH_3-N去除率为65.4%;在其他工艺条件相同的情况下,未通过电化学辅助的填料微电解反应的COD去除率为33.0%,NH_3-N去除率为16.2%,电化学辅助后的COD去除率和NH_3-N去除率均明显提高。     

免烧结粉煤灰陶粒BAF对乙烯化工废水的深度处理效果

以粉煤灰为主要原料制备了免烧结粉煤灰陶粒，并将其作为曝气生物滤池(BAF)的填料用于深度处理乙烯化工厂二级生化出水。实验结果表明，在平均进水COD为54.62mg/L、平均SS为33.93mg/L、平均ρ(NH3-N)为1.33mg/L的条件下，自制免烧结粉煤灰陶粒BAF平均COD去除率为57.14%，平均SS去除率为68.64%，平均NH3-N去除率为74.89%，均略高于普通商业陶粒BAF。自制免烧结粉煤灰陶粒BAF最佳反冲洗周期为2d，并具有反冲洗耗水量小、反冲洗效果好的优势。     

用含固定化微生物的曝气生物滤池处理炼油厂高浓度废水

采用含固定化微生物的曝气生物滤池(G-BAF)处理炼油厂高浓度废水。当G-BAF池进水COD为298～11 278 mg/L时,出水COD为33.0～94.3 mg/L,COD平均去除率为97%;当G-BAF池进水ρ(NH_3-N)为12.1～188.0 mg/L时,出水ρ(NH_3-N)为0.9～49.4 mg/L,NH_3-N平均去除率为83%。经G-BAF处理后出水水质完全达到GB8978—1996《污水综合排放标准》第二类污染物的二级排放标准。     

水解酸化-好氧生物滤池处理炼油废水

以高炉水渣为填料,采用水解酸化-好氧生物滤池处理炼油废水。考察了好氧区气水比、水力停留时间对炼油废水处理效果的影响。实验结果表明：在水力停留时间为6h、温度为20～35℃、废水pH为6～9、好氧区气水比为10：1的条件下,该生物滤池对NH3-N,Ar-OH,COD的总去除率分别为100％,97％,85％,处理后出水水质达到国家《污水综合排放标准》一级标准。     

炼油废水回用流程改造

在原炼油废水处理流程的基础上增加了接触氧化和斜板沉淀等处理工艺,提高了生物处理效果,并在接触氧化池中投加专性菌种,提高了COD和NH_3-N的去除效果,出水中COD和NH_3-N质量浓度平均为64.1 mg/L和3.9 mg/L,基本达到了中水的水质要求。     

焦化废水的厌氧—好氧生物处理

焦化废水含有许多难以生物降解的有机物,采用好氧生物法进行处理,虽然出水中的酚、氰等基本上可达到国家排放标准,但COD、NH_3-N等指标远不能达标;采用厌氧生物法进行处理,虽然COD去除率较高,但出水C0D、NH_3-N等指标仍不能达标;采用厌氧-好氧生物法进行处理,可取得较为令人满意的处理效果。     

SMBBR-AF-SMBBR组合工艺处理高氨氮农药废水

采用特异性移动床生物膜反应器(SMBBR)和厌氧生物滤池(AF)组合工艺处理高氨氮农药废水。考察了HRT、pH和DO等工艺条件对SMBBR-AF-SMBBR组合工艺运行稳定期COD和氨氮去除率的影响。试验结果表明,在进水COD为2 408~7 440 mg/L、ρ(NH_4~+-N)为160.21~433.84 mg/L、TN为208.27~537.65 mg/L、HRT为8d、pH为8.0、DO为4 mg/L的条件下,处理后出水平均COD为342 mg/L,COD去除率达92.3%;ρ(NH_4~+-N)小于4.0mg/L,氨氮平均去除率为89.2%;TN小于50 mg/L,平均TN去除达83.0%。出水各指标均优于原A2O工艺出水。     

膜法A／O生物脱氮技术处理化肥厂含氮工艺废水

大型化肥厂工艺废水含有高浓度的氨氮和尿素氮,并含有镍、氰化物等毒物。在采用软性填料三段好氧硝化试验和应用碎红砖填料升流式滤池的反硝化试验均获得成功的基础上,分别采用了AO_2回流工艺和O_sA无回流工艺的膜法生物脱氮技术,对COD、TKN、TN都具有明显的去除效果。其中AO_2回流工艺的COD、TKN、TN去除率分别为93.5％、94.8％、17.9％,相应的容积去除负荷为1.115、0.3770.310公斤/米~3·日。同时,对尿素在好氧硝化和反硝化过程的生物水解规律,在生物脱氮过程中镍和氰化物的影响及去除情况作了探讨。为国内同类型高浓度含氮废水的治理提供了有益的经验。     

煤气化废水的生物除氮

对于经活性碳生物流化床处理去除有机物后的煤气化废水,采用硝化-反硝化处理系统和反硝化-硝化处理系统,进行了生物除氮试验研究。试验结果表明,必须添加甲醇作为反硝化处理过程的外来碳源,甲醇与NO_3~--N的最小投加比应为2.7:1。在适当的处理条件下,当进水NH_3-N为500毫克/升时,NH_3-N去除率可达98％,出水NH_3-N、NO_2~--N和NO_3~--N分别小于10、1和5毫克/升。     

硝化与反硝化在焦化厂酚氰废水生化处理中的地位

本文提出了焦化厂酚氰废水处理过程中一个不容忽视的新问题——NH_3-N与NH_4~+-N大量排放造成严重污染的后果。同时,对目前生化处理过程中硝化的产生和抑制进行了论述,并针对焦化废水进一步脱氮问题提出了硝化与反硝化法生物脱氮新工艺,该处理工艺可同时解决BOD_5、COD、NH_3等的脱除问题。     

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.