化学沉淀法去除焦化废水中的氨氮

采用化学沉淀剂MgCl2 ·6H2 O和Na2 HPO4·12H2 O(或MgHPO4·3H2 O)与焦化废水中的NH+ 4 反应 ,生成磷酸铵镁沉淀。探讨了不同操作条件对氨氮去除率的影响。在pH为 8 5～ 9 5的条件下 ,投加的药剂Mg2 + ∶NH+ 4 ∶PO3 -4(摩尔比 )为 1 4∶1∶0 8时 ,废水氨氮的去除率达 99%以上 ,出水氨氮的质量浓度由 2 0 0 0mg/L降至 15mg/L。     

化学沉淀法预处理稀土精矿分解废水

采用化学沉淀法对稀土精矿分解废水进行预处理,实验结果表明,当pH9.0、n(M g2 )∶n(NH 4)∶n(PO34-)=3.5∶1∶1.5时,废水中NH3-N的质量浓度由8 370m g/L降为1 420m g/L,去除率为83%。为了不增加出水中PO34-污染物的浓度,向上层清液中加入相应量的CaC l2.2H2O。当n(Ca2 )∶n(PO34-)=9∶1时,完成沉淀反应,再调整上层清液的pH为10,搅拌后,上层清液中PO34-的质量浓度降为0.18m g/L。     

化学沉淀法去除煤气废水中氨氮的研究

采用化学沉淀法去除煤气废水中的氨氮。研究了不同pH、沉淀剂种类及投药比对氨氮去除效果的影响。试验表明,沉淀剂MgCl2·6H2O+Na2HPO4·12H2O明显优于MgO+H3PO4。当投药摩尔比n(Mg2+):n(NH4+):n(PO43-)为1.2:1:1、pH为9.5时,废水中氨氮的去除率为87.4％,COD的去除率为45.6％,同时得到的MgNH4PO4·6H2O可作为复合肥料使用。     

不不同金属离子存在下双氧水对难降解有机物的催化氧化

H2O2具有较高氧化电位,较强的氧化能力.后来人们发现,当H2O2与金属离子反应产生*OH自由基后,氧化能力更强.Fe2++H2O2混合液(即Fenton试剂)在催化氧化处理难降解有机物时,有很好的效果.但该试剂需要在pH≈3的酸性环境中才能发挥作用,因而在实际废水处理中往往要消耗大量的酸.若能在接近中性的条件下使H2O2发挥氧化作用,则有更重要的应用价值.     

硫酸生产中废钒催化剂回收工艺研究

采用H2SO4浸取、NH4HSO3还原、NH4NO3氧化、KOH精制的方法回收废钒催化剂中的V2O5。实验结果表明，还原反应的最佳条件为：n（NH4HSO3）／n（V2O5）=1．10，还原反应温度90℃，还原反应时间2．0h。氧化反应的最佳条件为：n（KOH）／n（VO^＋）=1．10，氧化反应温度60℃，液固比8，氧化反应时间60min。该方法V2O5回收率达90．3％以上，V2O5纯度达82％以上。     

淀粉废水水解酸化处理中的酶比活变化特性

以淀粉废水水解酸化处理系统中的蛋白酶、淀粉酶、脱氢酶为研究对象,考察了在无机离子、营养元素、pH等条件作用下的酶比活变化规律.实验结果表明:Mg2+和Co2+对酶比活有显著影响,MgCl2·6H2O加入量为30 mg/L时蛋白酶、淀粉酶、脱氖酶的比活分别是空白的5.6倍、1.6倍、1.5倍,COD去除率提高17.6%;而CoCl2·6H2O加入量为10 mg/L时,蛋白酶和淀粉酶的比活较单独投加30 mg/L的MgCl2·6H2O时分别下降了80.6%和42.5%,脱氢酶比活却提高了13.2%;以NH4Cl与CO(NH2)2作为混合N源(m(NH4Cl):m(CO(NH2)2)=1:2)时蛋白酶、淀粉酶、脱氢酶的比活分别是单独以CO(NH2)2为N源时的3.0倍、1.4倍、1.8倍,COD去除率提高了11.8%;中性偏碱性条件较利于酶促反应的进行.     

分散染料生产中废酸的利用

采用加压浸取工艺,使明矾渣与废酸反应以制取工业级的硫酸铝。其最佳工艺条件为:反应压力0.3-0.4MPa,反应时间3-4b,液固比2.7∶1(L/kg)。制得的粗品用活性炭吸附脱色,BaS法去除其中的杂质铁,再经蒸发结晶,即可得工业级的Al_2(SO_4)_3·18H_2O。废酸的利用率达到90%,废酸中COD的去除率达到60%。     

赖氨酸废水的处理和氨回收

对赖氨酸浓废水调 p H沉淀处理后的澄清水进行预处理 :先加入石灰乳 ,搅拌、沉淀 ,SO42 -从 2 0 0 0 0 m g/ L 左右降至 130 0 mg/ L 左右 ,去除率为 94%左右 ,然后进行空气吹脱 ,NH3- N从 5 0 0 0 mg/ L左右降至 80 m g/ L左右 ,去除率 >98%。吹脱出水经厌氧生化处理后 ,再进行空气吹脱 ,NH3- N从 70 0 mg/ L 左右降至 85 mg/ L 左右 ,去除率 >86 %。再吹脱出水与稀废水混合后进行好氧生化和 A/ O、O系统处理 ,出水的 COD<10 0 m g/ L,BOD5<2 0 mg/ L,SS<70 mg/ L,NH3- N<2 5 m g/ L。对浓废水与石灰乳混合后搅拌过程中及两次空气吹脱过程中挥发的 NH3进行回收 ,将其与 H2 SO4反应 ,生成的 (NH4) 2 SO4回用于生产     

三元微电解—Fenton试剂氧化法深度处理石化废水

采用三元微电解-Fenton试剂氧化法处理COD为60 ～ 90 mg/L的石化废水.三元微电解工艺最优条件为:m(铝屑)∶m(铁屑)∶m(活性碳)=1∶2∶2,废水初始pH 4 ～5,微电解时间45 min.Fenton试剂氧化工艺最优条件为:H2O2加入量0.6mL/L,废水pH 4,氧化时间30 min.在此条件...     

固定化优势菌种处理NH3和H2S恶臭气体

用海藻酸钠作包埋剂固定优势菌种(枯草芽孢杆菌、白曲霉菌、葡萄球菌)处理NH3和H2S。考察了气体流量、NH3和H2S气体浓度、循环液喷淋量对NH3和H2S去除效果的影响。固定化生物滴滤反应器最佳运行条件为:气体流量1.0m3/h、循环液喷淋量8.88L/h、进气H2S质量浓度低于51.85mg/m3、进气NH3质量浓度低于57.21mg/m3。处理NH3和H2S的最大容积负荷分别为634.1g/(m3·d)和699.6g/(m3·d)。处理后出气中的NH3和H2S的质量浓度分别达到GB14554—93《恶臭污染物排放标准》中的一级排放标准和二级排放标准。     

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.     

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.     

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.     

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.