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1.
Daniel Scott Taira Hidaka Pablo Campo Eric Kleiner Makram T. Suidan Albert D. Venosa 《Chemosphere》2013,90(4):1412-1418
A novel membrane system, the Biomass Concentrator Reactor (BCR), was evaluated as an alternative technology for the treatment of municipal wastewater. Because the BCR is equipped with a membrane whose average poresize is 20 μm (18–28 μm), the reactor requires low-pressure differential to operate (gravity). The effectiveness of this system was evaluated for the removal of carbon and nitrogen using two identical BCRs, identified as conventional and hybrid, that were operated in parallel. The conventional reactor was operated under full aerobic conditions (i.e., organic carbon and ammonia oxidation), while the hybrid reactor incorporated an anoxic zone for nitrate reduction as well as an aerobic zone for organic carbon and ammonia oxidation. Both reactors were fed synthetic wastewater at a flow rate of 71 L d?1, which resulted in a hydraulic retention time of 9 h. In the case of the hybrid reactor, the recycle flow from the aerobic zone to the anoxic zone was twice the feed flow rate. Reactor performance was evaluated under two solids retention times (6 and 15 d). Under these conditions, the BCRs achieved nearly 100% mixed liquor solids separation with a hydraulic head differential of less than 2.5 cm. The COD removal efficiency was over 90%. Essentially complete nitrification was achieved in both systems, and nitrogen removal in the hybrid reactor was close to the expected value (67%). 相似文献
2.
Nobuhisa Watanabe Saburo Inoue Hisao Ito 《Journal of Material Cycles and Waste Management》1999,1(1):38-47
The arsenic and antimony balance in two municipal waste incinerators was investigated. Initially, the production rates of
ash and wet scrubber effluent were estimated. Then the arsenic and antimony in the ash and wet scrubber effluent were determined,
which gave an estimate of the elemental balance. The total amounts of arsenic and antimony in the municipal waste were 0.9 g/t
and 30–44 g/t, respectively. The distributions to fly ash were 45–47% and 33–74% for arsenic and antimony, respectively. The
distribution mechanisms of arsenic and antimony are discussed from the viewpoints of their thermodynamics as well as their
initial valencies, which greatly affect their behaviour.
Received: July 2, 1998 / Accepted: February 27, 1999 相似文献
3.
The photocatalytic oxidation of oxalyldihydrazide, N,N'-bis(hydrazocarbonyl)hydrazide, N,N'-bis(ethoxycarbonyl)hydrazide, malonyldihydrazide, N-malonyl-bis[(N'-ethoxycarbonyl)hydrazide] was examined in aqueous TiO2 dispersions under UV illumination. The photomineralization of nitrogen and carbon atoms in the substrates into N2 gas, NH4+ (and/or NO3-) ions, and CO2 gas was determined by HPLC and GC analysis. The formation of carboxylic acid intermediates also occurred in the photooxidation process. The photocatalytic mechanism is discussed on the basis of the experimental results, and with molecular orbital (MO) simulation of frontier electron density and point charge. Substrate carbonyl groups readily adsorb on the TiO2 surface, and the bonds between carbonyl group carbon atoms and adjacent hydrazo group nitrogen atoms are cleaved predominantly in the initial photooxidation process. The hydrazo groups were photoconverted mainly into N2 gas (in mineralization yields above 70%) and partially to NH4 ions (below 10%). The formation of NO3- ions was scarcely recognized. 相似文献
4.
Subramanian AN Tanabe S Tanaka H Hidaka H Tatsukawa R 《Environmental pollution (Barking, Essex : 1987)》1987,43(1):39-46
The gain and loss rates and the biological half-life of polychlorinated biphenyls (PCBs) and p,p'-DDE in wild birds were calculated using the values on burdens of these compounds in the bodies of adelie penguins in a previous report (Subramanian et al., 1986). The daily loss rate of PCBs (0.26%) was found to be higher than DDT compounds (0.12%) resulting in the longer biological half-life of the latter compounds (580 days) than PCBs (270 days). Hence, once DDT compounds are absorbed they are more persistent in the organisms' bodies due to their high lipophilicity and comparatively less metabolisable nature than PCBs. 相似文献
5.
Peter Leinweber Ulrich Bathmann Uwe Buczko Caroline Douhaire Bettina Eichler-Löbermann Emmanuel Frossard Felix Ekardt Helen Jarvie Inga Krämer Christian Kabbe Bernd Lennartz Per-Erik Mellander Günther Nausch Hisao Ohtake Jens Tränckner 《Ambio》2018,47(1):3-19
This special issue of Ambio compiles a series of contributions made at the 8th International Phosphorus Workshop (IPW8), held in September 2016 in Rostock, Germany. The introducing overview article summarizes major published scientific findings in the time period from IPW7 (2015) until recently, including presentations from IPW8. The P issue was subdivided into four themes along the logical sequence of P utilization in production, environmental, and societal systems: (1) Sufficiency and efficiency of P utilization, especially in animal husbandry and crop production; (2) P recycling: technologies and product applications; (3) P fluxes and cycling in the environment; and (4) P governance. The latter two themes had separate sessions for the first time in the International Phosphorus Workshops series; thus, this overview presents a scene-setting rather than an overview of the latest research for these themes. In summary, this paper details new findings in agricultural and environmental P research, which indicate reduced P inputs, improved management options, and provide translations into governance options for a more sustainable P use. 相似文献
6.
The photochemical decomposition of short-chain (C(3)-C(5)) perfluorocarboxylic acids (PFCAs) was investigated. Direct photolysis in water proceeded slowly with the 220- to 460-nm light emission from a xenon-mercury lamp to form F(-), CO(2), and shorter-chain PFCAs. Addition of a small amount of Fe(3+) to the aqueous solutions of the PFCAs dramatically enhanced their photochemical decomposition under an oxygen atmosphere: when the (initial PFCA)/(initial Fe(3+)) molar ratio was 13.5 (initial PFCA concentration=67.3mM), the pseudo-first-order rate constants for the PFCA decomposition were 3.6-5.3 times those with photolysis alone, and the turnover number for the catalytic PFCA decomposition [i.e., (moles of decomposed PFCA)/(moles of initial Fe(3+))] reached 6.71-8.68 after 24h of irradiation. The catalysis can be explained by photoredox reactions between PFCA, Fe(3+)/Fe(2+) and oxygen via photo-induced complexation of Fe(3+) with the PFCAs. 相似文献
7.
Chen Zongliang Zhang Yang Wang Yubao Zhuang Yahui KazuhikoSakamoto Katsunori Kimijim Tadao Suzuki Masahiro Uchiyam Yoshikazu Hashimoto Hisao oht Yasuaki mae NobutoshiHoriuchi Shin Suzuki 《环境科学学报(英文版)》1990,2(1):41-48
The conversion rates of SO2 to SO2-4 and NO2 to HNO3+NO3- are estimated from the field-data obtained in Beijing in summer, 1988. The results show that the conversion rate of NO2 is about four times as much as that of SO2; The conversion rates have a diurnal variation in a day. On the average, the rate of SO2 is estimated to be 4.7% h-1 during the daytime and 3.4% h-1 during the nighttime. Similarly, the rate of NO2 is estimated to be 17.2% h-1 and 12% h-1 respectively. 相似文献
8.
Saki Harii Naoko Yasuda Mauricio Rodriguez-Lanetty Takahiro Irie Michio Hidaka 《Marine Biology》2009,156(6):1203-1212
The establishment of symbiosis in early developmental stages is important for reef-building corals because of the need for
photosynthetically derived nutrition. Corals spawn eggs and sperm, or brood planula larvae and shed them into the water. Some
coral eggs or planulae directly inherit symbiotic dinoflagellates (Symbiodinium spp.) from their parents, while others acquire them at each generation. In most species examined to date, the larvae without
dinoflagellates (aposymbiotic larvae) can acquire symbionts during the larval stage, but little is known regarding the timing
and detailed process of the onset of symbiosis. We examined larval uptake of symbiotic dinoflagellates in nine species of
scleractinian corals, the onset of symbiosis through the early larval stages, and the distribution pattern of symbionts within
the larval host, while living and with histology, of two acroporid corals under laboratory conditions. The larvae acquired
symbiotic dinoflagellates during the planktonic phase in all corals examined which included Acropora digitifera, A. florida, A. intermedia, A. tenuis, Isopora
palifera, Favia pallida, F. lizardensis, Pseudosiderastrea tayamai, and Ctenactis echinata. The larvae of A. digitifera and A. tenuis first acquired symbionts 6 and 5 days after fertilization, respectively. In A. digitifera larvae, this coincided with the formation of an oral pore and coelenteron. The number of symbiotic dinoflagellates increased
over the experimental periods in both species. To test the hypothesis that nutrients promotes symbiotic uptake, the number
of incorporated dinoflagellates was compared in the presence and absence of homogenized Artemia sp. A likelihood ratio test assuming a log-linear model indicated that Artemia sp. had a significantly positive effect on symbiont acquisition. These results suggest that the acquisition of symbiotic
dinoflagellates during larval stages is in common with many coral species, and that the development of both a mouth and coelenteron
play important roles in symbiont acquisition. 相似文献
9.
The existence of “free-living” Symbiodinium that can form symbioses with hosts is implied by the presence of hosts that produce Symbiodinium-free gametes and expulsion and/or expelled symbiotic algae from host. However, it is still unclear if potentially symbiotic
Symbiodinium are found “free-living” in the coral reef environment. Sixteen Symbiodinium strains were established from samples taken from three sampling locations of coral reef sand in Okinawa, Japan. Phylogenetic
analyses of the partial large subunit ribosomal DNA (28S-rDNA) and the internal transcribed spacer of ribosomal DNA (ITS-rDNA)
conclusively showed that all 16 isolates belonged to Symbiodinium clade A sensu Rowan and Powers (1991). The lack of other Symbiodinium clades besides clade A in this study may be due to other clades not being readily culturable under culture conditions used
here. The new isolates could be phylogenetically divided into four groups, though no sequences were identical to previously
reported Symbiodinium. Two of the four groups were closely related to symbiotic Symbiodinium clade A isolated from a variety of host species. One isolate group formed a highly supported monophyly with Symbiodinium types that have previously been characterized as “free-living”. The remaining isolate group, although within clade A, was
quite divergent from other clade A Symbiodinium. These results indicate that novel diversity of free-living Symbiodinium exists in coral sand. 相似文献
10.
The decomposition of hydroperfluorocarboxylic acids [H-PFCAs; HCnF2nCOOH (n = 4 and 6)] induced by heteropolyacid photocatalyst H4SiW12O40 in water was investigated, and the results are compared with the results for the corresponding perfluorocarboxylic acids (PFCAs; CnF2n+1COOH). This is the first report on the photochemical decomposition of H-PFCAs, which are being developed as alternative surfactants to environmentally persistent and bioaccumulative PFCAs. H-PFCAs were not decomposed by irradiation with UV-Visible light (>290 nm) in the absence of H4SiW12O40. In contrast, UV-Visible light irradiation of H-PFCAs in the presence of H4SiW12O40 efficiently decomposed H-PFCAs to F− and CO2. The decomposition reactions showed pseudo-first-order kinetics, and the decomposition rate constants were 1.8-2.5 times higher than those for the corresponding PFCAs. The reaction mechanism can be explained by elimination of H+ from the ω-H atom of the H-PFCAs by the excited catalyst, followed by formation of perfluorodicarboxylic acids. 相似文献