厌氧折流板反应器处理石化剩余污泥

研究了厌氧折流板反应器(ABR)在厌氧消化处理石化剩余污泥启动过程中的性能及相关参数。实验结果表明:污泥挥发性固体含量的去除率达43.7%;反应器内pH维持在6.4~7.4;从启动到稳定运行,第一隔室最大比产甲烷活性变化不大,在0.14 L/(g·d)以下,第二、第三、第四隔室的最大比产甲烷活性在0.29 L/(g·d)以上,污泥在反应器内部实现了分级分相处理。     

气浮-水解-序批式活性污泥法处理高浓度特种丙烯酸废水

采用气浮—水解—序批式活性污泥法(SBR)处理高浓度特种丙烯酸废水,研究了投加生活污水对处理效果的影响及厌氧水解时间、SBR曝气时间、污泥负荷等因素对COD去除率的影响,结果表明,按1∶1体积比投加生活污水,厌氧水解时间2d,序批式活性污泥法曝气时间10h(进水后期曝气1h,共曝气11h),污泥负荷小于或等于0.08kg/(kg.d)时,出水COD小于85m g/L,满足处理要求。     

起声波法减少污泥量

德国Fraunhofer陶瓷技术研究院与两个工业合作伙伴共同开发出一种超声波污泥处理法,可减少污泥量约20%,增加沼气产量20%～25%,并在德国的Detmold建成一套示范装置。污泥连续进入有7个声极的超声波反应器。每个声极在12kW产生20kHz的超声波。这种超声波将细菌团粒及其他固体打破,使污泥易于脱水,使分解有机物的酶放出,增加沼气的产量,并使脱水用的絮凝剂用量减少约25%。可用这种超声波反应器改造现有的污泥处理装置,1～2年就可收回投资起声波法减少污泥量     

纤维素与稻草厌氧消化产气性能对比实验研究

以纤维素和稻草为原料,猪粪消化液为接种物,进行厌氧消化对比实验。研究结果表明:纤维素单位TS产甲烷量分别比预处理后稻草和未预处理稻草高出18.4%和46.0%,纤维素厌氧消化VS去除率分别比预处理后的稻草和未预处理的稻草高出22.7个百分点和27.0个百分点。说明纤维素的厌氧消化较稻草的厌氧消化进行得更充分,而用NH_3·H_2O预处理稻草,能够提高稻草的厌氧消化效率;纤维素对微生物的可接触程度直接影响了厌氧消化产气性能。     

污泥热水解技术研究进展

热水解可以改善污泥的生物降解性能和脱水性能,提高后续厌氧消化系统中有机物的去除率。本文阐述了热水解对污泥物理特性主要包括流变特性和脱水行为的影响;分析了热水解对污泥中氨氮浓度及对厌氧消化的作用;同时介绍了热水解技术对整个污泥处理系统能量需求的影响。指出：热水解改善了污泥的厌氧消化性能,提高了沼气等再生资源的产量,且厌氧消化产生的沼气量与热水解技术所需的能量基本平衡。     

国外动态

改进污泥处理过程减少污泥量JWPCF,57[2],116(1985).污水处理厂污泥的处理一般采用重力增稠和厌氧消化,以稳定污泥和除臭.消化后的污泥就地堆放后倾入海中.在纽约,为了减少污泥体积,研究了多种技术,包括消化污泥的循环、倾析、淘洗-再增稠和     

低压直流电电解剩余活性污泥

采用低压直流电电解剩余活性污泥，优化了支持电解质的种类、加入量及电压梯度等工艺条件，并考察了在最佳工艺条件下SS去除率、污泥中有机物的质量分数（以VSS/SS计）、污泥pH及污泥沉降性能随电解时间的变化情况。实验结果表明，低压直流电电解污泥的最佳工艺条件为：电压梯度7 V/cm;支持电解质Na₂SO₄加入量0.4.0 mmol/g（以每克干污泥计）。在最佳工艺条件下电解pH为5.8、SS=（7 850 ±200）mg/L、VSS=（6 150±150）mg/L、溶解性化学需氧量（SCOD）为（61.2 ±20）mg/L的污泥，电解60 min时污泥的SCOD最大，达393.3 mg/L，SS去除率达14.4%，VSS/SS为58.5%，污泥pH为3.1。电解后污泥中微生物的细胞结构已不完整，污泥絮体被严重破坏。电解时间越长，污泥的沉降速率越快。     

厌氧消化法处理石油化工废水剩余活性污泥的研究

辽阳石油化纤公司采用两段厌氧消化工艺处理石油化工废水剩余活性污泥,引进鞍山市城市污水处理厂的厌氧污泥作为种泥,中温驯化约110天,投配率为4.7％,消化达到平衡时的有机物去除率为31％、产气量为0.22米~3/公斤有机物(产气中的甲烷含量为68％)、有机物负荷为1.1公斤/米~3日。污泥两段消化与传统消化处理的对比试验结果表明,前者的处理效果优于后者。     

用高效优势菌强化升流式厌氧污泥床的废水处理性能

针对酒精废水中难生物降解的有机物,从氧化塘污泥中筛选分离出高适应能力和降解能力的高效优势菌群,将其投加到升流式厌氧污泥床反应器中进行中试。运行结果表明:利用高效优势菌群培养高活性的颗粒污泥,可大大强化UASB反应器的废水处理性能,35d即可完成系统的启动;反应器容积负荷从2.0kg/(m3.d)提高到39.0kg/(m3.d),COD去除率保持在90%左右,最高达到96%。     

膜生物反应器中污泥自消化技术进展

介绍了国内外膜生物反应器(MBR)中污泥的消化技术,分析了控制运行条件法、物理法、化学法污泥消化技术及生物法污泥自消化技术的优缺点,指出了在MBR中没置局部厌氧区域法污泥自消化技术的重要意义.     

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.     

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.     

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.