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901.
Zhijian Liu Haiyang Liu Hang Yin Rui Rong Guoqing Cao Qihong Deng 《Frontiers of Environmental Science & Engineering》2021,15(3):36
902.
A new contact oxidation filtration separation integrated bioreactor (CFBR) was used to treat municipal wastewater. The CFBR was made up of a biofilm reactor (the upper part of the CFBR) and a gravitational filtration bed (the lower part of the CFBR). Polyacrylonitrile balls (50 mm diameter, 237 m2/m3 specific surface, 90% porosity, and 50.2% packing rate) were filled into the biofilm reactor as biofilm attaching materials and anthracite coal (particle size 1–2 mm, packing density 0.947 g/cm3, non-uniform coefficient (K80 = d80/d10) < 2.0) was placed into the gravitational filtration bed as filter media. At an organic volumetric loading rate of 2.4 kg COD/(m3 d) and an initial filtration velocity of 5 m/h in the CFBR, the average removal efficiencies of COD, ammonia nitrogen, total nitrogen and turbidity were 90.6%, 81.4%, 64.6% and 96.7% respectively, but the treatment process seemed not to be effective in phosphorus removal. The average removal efficiency of total phosphorus was 60.1%. Additionally, the power consumption of the CFBR was less than 0.15 kWh/m3 of wastewater treated, and less than 1.5 kWh/kg BOD5 removal. 相似文献
903.
A series of processes by biofilter and Fenton oxidation to treat mature landfill leachate has been devised. At a hydraulic loading rate of 20 l m?3 d?1, a biofilter packed with aged refuse is found to remove 80% of chemical oxygen demand (COD), 89% of ammonia nitrogen and 96% of total phosphorus (TP). Particularly, TP levels dropped below 1 mg l?1. The optimal condition for Fenton oxidation was selected to be an initial pH of 5, a dosage of 0.01 and 0.02 mol l?1 of FeSO4 and H2O2, respectively, and a duration of 3 h, where COD removal efficiency reaches 58.6%, and BOD5/COD ratio is raised from 0.05 to 0.20. Subsequent treatment by a biofilter packed with slag reduces COD, ammonia nitrogen levels to less than 100, 25 mg l?1, respectively. A pilot scale experiment conducted in situ demonstrates that this series of processes exhibits a high efficiency in removing pollutants from mature landfill leachate and it is viable for application. 相似文献
904.
Bing Liu X.J. Liu Hong Zhang 《Journal of Loss Prevention in the Process Industries》2009,22(6):884-888
Traditional pipeline design analysis methods presented in various codes are usually based on limit stress criteria. However, these methods may be inapposite to modern steels, especially for displacement controlled loads such as ground displacement load. Strain limits, including ovalization limit, tensile strain limit and compression strain limit, are compared in this paper based upon various codes and recommendations. In addition, most factors of strain limits are also reviewed respectively. 相似文献
905.
L. W. Cooper T. M. Beasley X.-L. Zhao C. Soto K. L. Vinogradova K. H. Dunton 《Marine Biology》1998,131(3):391-399
Iodine-129:iodine-127 ratios were determined using accelerator mass spectrometry in 34 Arctic marine algae collected between
1930 and 1993. A smaller set (5) of marine algae were also analyzed mass spectrometrically to determine plutonium-isotope
ratios. The 129I:127I ratio increased as much as three orders of magnitude from a mean of <1×10−11 (atom/atom) in the pre-nuclear era (before 1945) to nearly 1000×10−11 in 1993 for marine algae collected from the Novaya Zemlya archipelago separating the Barents and Kara Seas. The predominant
basis for the higher ratios in the Novaya Zemlya kelps appears to be upcurrent sources of 129I from nuclear fuel-reprocessing facilities at Sellafield (UK) and La Hague (France). Relatively high 241Pu:239Pu ratios (compared to observed bomb fallout at boreal latitudes, decay corrected to the date of collection) also corroborate
the influence of non-fallout sources. The small size of the data set precludes determining if there are significant contributions
of 129I and other radionuclides from Russian sources. In contrast, marine algae collected between 1969 and 1993 in the Bering, Beaufort
and East Siberian Seas had much lower 129I:127I ratios (mean=14.04×10−11±3.15 SD) than those observed in the European Arctic. The narrow range of ratios in Ameriasian Arctic kelps, and the modest
change over that time period, indicate that there were no major contributions of non-fallout 129I to North American Arctic surface waters at the time that the algae were collected. The potential for timing the transport
of fuel-reprocessed 129I through analysis of additional archived samples is outlined.
Received: 10 November 1997 / Accepted: 24 February 1998 相似文献
906.
针对废手机线路板碱性矿浆电解资源化过程中电解液带来的污染问题,采用氨-氯化铵碱性矿浆电解液循环回收废手机线路板中金属,以降低能耗、减少污染。研究了氨-氯化铵碱性矿浆电解体系从废手机板制备阴极铜的过程中,电解液循环对Cu的回收率、电流效率、Cu纯度以及Cu和Ni、Zn、Pb等金属迁移转化的影响。经过7次电解液循环实验,结果表明,电解液循环对Ni、Zn、Pb等金属分布及电流效率的影响十分显著,但Cu的分布、纯度及回收率基本不受影响。Cu主要分布在电解液和沉积物中,其他金属则主要在电解液与阳极渣中;8组实验获得的沉积物中Cu的纯度和回收率分别高于99.9%和90%。基于碱性矿浆电解回收废手机板中金属工艺中,完全可以实现电解液的循环利用。本研究可为碱性矿浆电解废线路板提供参考。 相似文献
907.
为了评价三峡库区香溪河流域内所堆存的磷矿废石对地表水体的磷污染风险,以香溪河支流高岚河流域内具有不同风化时间的6座磷矿废石堆体为研究对象,依据US EPA Method 1313所规定的实验方法,开展了9种不同pH(2.0~13.0)条件下磷矿废石磷素浸出特性的实验研究,探讨了液相环境pH对磷矿废石磷素浸出浓度的影响。结果表明:在酸性环境下磷矿废石的磷素浸出浓度与pH呈负相关关系;中性及碱性环境下的磷素浸出浓度总体上低于酸性条件,其大小与环境pH之间无显著关系存在,但在pH=10.5±0.5范围内存在小幅升高;自然条件下磷矿废石堆体内部的液相环境为弱碱性(pH=7.8~8.8),且不会受当地酸雨长期淋滤的影响,在此条件下6种磷矿废石的磷素平均浸出浓度为0.7 mg/L,超标率为33 %。因此,研究区内的磷矿废石堆体可以形成点源形式的磷污染。在香溪河库湾水体富氧化问题日趋严重的前提下,应考虑将流域内堆存的磷矿废石作为第II类一般工业固体废物进行妥善处置,以降低其对香溪河库湾水体环境的磷污染风险。 相似文献
908.
J. L. Fernndez-Turiel A. Lpez-Soler J. F. Llorens X. Querol P. Aceolaza F. Durand J. P. Lpez M. E. Medina J. N. Rossi A. J. Toselli J. Saavedra 《Environment international》1995,21(6)
This work discusses trace elements studied beneath the semiarid endorheic region of the Famatina Range (La Rioja, NW Argentina). The results obtained in 27 control sites allow the determination of five distinct geochemical patterns in the Famatina Range. Pattern 1 reflects the composition of underlying Paleozoic and Tertiary bedrock (background level: water pH, 7.5–9; specific conductance, 0.2–0.7 mS cm−1), which is influenced by mineralization. Pattern 2 exhibits water pH, 6; specific conductance, 0.7 mS cm−1; high contents of Cu, Cd, Rb, Zn, Sn, and Be in waters; and high contents of Cu, Cd, Zn, Pb, Cr, Sb, Ag, Be, Co, Ni, Bi, Rare Earth Elements (REE), Li, Ba, Cs, and Sr in sediments. Pattern 3 exhibits water pH, 3–4; specific conductance, 1.0 mS cm−1; high contents of Pb, Co, Be, Au, As, Cr, Hg, Th, Ba, Cs, Rb, Sb, Y, Zr, REE, and Hf in waters; high contents of Cd, Zn, Mo, and As in sediments). Pattern 3 is also modified by the input of elements from a source external to the Famatina Range. Pattern 4 exhibits water pH, 7–8; specific conductance, 1.5–2.3 mS cm−1; high contents of B, Li, Ba, Sr, and Zn in waters; high contents of Li, Cr, Sr, Ni, and Cs in sediments. Finally, Pattern 5 is developed on the red sandstones from De la Cuesta Formation (water pH, 8; specific conductance, 2.5–5.0 mS cm−1; high contents of Sr, Mo, U, B, Li, Rb, and Hf in waters; high contents of B, Ba, Cs, Li, and Rb in sediments). The mobility of above-mentioned elements is mainly related to water pH changes and evaporation processes. 相似文献
909.
910.