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1.
The oxidation of organic matter from wastewater using ozone, ultraviolet radiation and ozone/UV oxidation was evaluated in a pilot plant, applying a continuous effluent arising from the Autonomous Metropolitan University wastewater treatment plant. The oxidation was measured as the efficiency to remove organic load, measured as chemical oxygen demand. The use of ozone and UV was evaluated separately and in combination through a continuous process. Three different ozone doses (0.6–1.2 mg O3/L) and three different UV radiation fluencies (6.7–20.12 mJ/cm2) were assessed. A synergistic effect of the combined process ozone/UV was demonstrated, and a maximal chemical oxygen demand reduction was achieved both processes. Due to residence times used (less than 1 min), 36% of chemical oxygen demand reduction was obtained when ozone treatment was evaluate separately and only 9% using ultraviolet radiation. 相似文献
2.
The catalytic activity of horseradish (Armoracia lapathifolia) peroxidase in the oxidation reactions of benzo(a)pyrene (BP) and phenols, separately and in admixture, has been studied. Experiments were carried out with model phenols from industrial sewage (phenol, m-, p-cresols, catechol, hydroquinone, resorcinol, orcinol), keeping to the real concentration ratio of reagents, 0.5 mM for phenols, 0.1 nM for benzo(a)pyrene. The total oxidation process for all reagents tested is described by the second-order formal kinetic equation up to 60 … 90% of their conversion. Addition of peroxidase increases the rate of oxidation of benzo(a)pyrene and phenols 2 … 6 times as compared with the control test (with hydrogen peroxide), whereas a linear dependence of the rate of benzo(a)pyrene oxidation on the enzyme concentration is observed. By cooxidation a mutual inhibition of benzo(a)pyrene and phenols is established whose degree depends on the phenol-chemical structure and varies in the range of 23 … 58% for BP under the influence of phenols and 35 … 80% for phenols under the influence of benzo(a)pyrene. The results obtained permit a supposition that peroxidase containing plants are capable of simultaneously transforming carcinogenic benzo(a)pyrene and toxic phenols in water reservoirs and in the soil, thus promoting the detoxication of environment. 相似文献
3.
Studies are performed on the toxicity for 24, 48, 72 and 96 hours in the static test with dilutions of 10 … 32 vol.% of wastewaters from the pulp and paper production as well as of the mixed wastewater. The pulp waste shows the highest toxic effect, the LC50 of the three types of wastewater being between 15 and 27% in dependence on the test conditions. A general increase of the toxic effect is caused by a rise in temperature from 26 °C to 36 °C and an increase of the pH value from 7.5 to 8.2. The increase of the oxygen concentration from 5.2 to 7.2 mg/1 results in a reduction of the toxicity of the pulp and mixed wastes, the size of fishes having a significant effect only for the pulp waste. Concentrations of wastes of 6 … 9% may be regarded to be harmless for long periods of time. 相似文献
4.
Débora V. Franco Wilson F. Jardim Julien F. C. Boodts Leonardo M. Da Silva 《洁净——土壤、空气、水》2008,36(1):34-44
Perspectives, advances and environmental aspects concerning electrochemical ozone production applied to water purification are presented and discussed in relation to the conventional corona process (silent electric discharge). Ozone generated using a laboratory‐made electrochemical reactor was applied for the discoloration/degradation of dyes used in the Brazilian textile industry and for degradation of endocrine disruptors. A constant ozone load of 0.35 ± 0.02 g/h was used throughout. The study, concerning color removal from dye solutions, revealed that total discoloration is rapidly achieved. The degradation rate of the textile dyes evaluated by TOC is little affected by the dye composition and considerably influenced by the pH and ozonation time. Analysis of the COD/TOC‐ratio indicates that ozonation increases oxidation feasibility of the organic matter (dye by‐products) when compared to the original compounds. Ozonation of mixed aqueous solutions containing different endocrine disruptors revealed these compounds are totally degraded with a very high removal rate. 相似文献
5.
L. Küchler 《洁净——土壤、空气、水》1986,14(1):47-57
The meliorated Oberes Rhinluch fen is used by agriculture as grassland with maize-cultivation on about 30 % of its area. In the ditch system of this area with water levels of 30 to 150 there were observed 67 taxa of aquatic plants and marsh plants, of which about 15 achieve covering degrees of more than 3 % and form 80 … 90 % of the biomass. Biomasses of between 20 … 184 g/m2 dry weight (Lemna) and 504 … 1612 g/m2 (Phragmites) are obtained in pure populations. In mixed populations the biomasses amount to between 304 and 916 g/m2 dry weight. According to their density and orientation, riparian copses and trees cause a more or less intense overshadowing of ditches, resulting in a considerable reduction of the biomass of macrophytes. By copses and trees on the south side of the waters the light available may be reduced to 30 %, from which a reduction of the biomass to 10 … 30 % results. By means of such planting it is possible to control the growth of plants in order to reduce the necessary and very expensive weed-removal and bottom-clearing actions. 相似文献
6.
This study attempts to explore the possibility of treating dye solutions containing Disperse Yellow 119 and Disperse Red 167 by Fenton and Fenton under solar‐light oxidation processes. Experiments were conducted to examine the effects of various operating conditions on the performance of the treatment systems. The Fenton results showed that 98.6% spectral absorption coefficient (SAC) and 90.8% chemical oxygen demand (COD) removals were proved at pH 3, 50 mg/L Fe2+, and 75 mg/L H2O2, 15 min oxidation time for Disperse Yellow 119. After 40 min solar irradiation time during Fenton process the SAC removal was 99.1%. COD reduction of about 98.3% was observed at the same time. It was also obtained as 97.8% SAC and 97.7% COD removal with pH 3, 75 mg/L Fe2+, 100 mg/L H2O2, and 25 min oxidation time for Disperse Red 167 at this optimum conditions. For Disperse Red 167 during Fenton under solar light process, after 40 min of solar irradiation time the SAC and COD reduction were obtained 99.3 and 98.4%, respectively. 相似文献
7.
In an attempt to reduce the threat of global warming, it has been proposed that the rise of atmospheric carbon dioxide concentrations be reduced by the ocean disposal of CO2 from the flue gases of fossil fuel-fired power plants. The release of large amounts of CO2 into mid or deep ocean waters will result in large plumes of acidified seawater with pH values ranging from 6 to 8. In an effort to determine whether these CO2-induced pH changes have any effect on marine nitrification processes, surficial (euphotic zone) and deep (aphotic zone) seawater samples were sparged with CO2 for varying time durations to achieve a specified pH reduction, and the rate of microbial ammonia oxidation was measured spectrophotometrically as a function of pH using an inhibitor technique. For both seawater samples taken from either the euphotic or aphotic zone, the nitrification rates dropped drastically with decreasing pH. Relative to nitrification rates in the original seawater at pH 8, nitrification rates were reduced by ca. 50% at pH 7 and more than 90% at pH 6.5. Nitrification was essentially completely inhibited at pH 6. These findings suggest that the disposal of CO2 into mid or deep oceans will most likely result in a drastic reduction of ammonia oxidation rates within the pH plume and the concomitant accumulation of ammonia instead of nitrate. It is unlikely that ammonia will reach the high concentration levels at which marine aquatic organisms are known to be negatively affected. However, if the ammonia-rich seawater from inside the pH plume is upwelled into the euphotic zone, it is likely that changes in phytoplankton abundance and community structure will occur. Finally, the large-scale inhibition of nitrification and the subsequent reduction of nitrite and nitrate concentrations could also result in a decrease of denitrification rates which, in turn, could lead to the buildup of nitrogen and unpredictable eutrophication phenomena. Clearly, more research on the environmental effects of ocean disposal of CO2 is needed to determine whether the potential costs related to marine ecosystem disturbance and disruption can be justified in terms of the perceived benefits that may be achieved by temporarily delaying global warming. 相似文献
8.
In bioassays in aquaria, the dying of Escherichia coli was accelerated by Glyceria maxima, Schoenoplectus lacustris, Alisma plantago-aquatica as well as Mentha aquatia as compared with check tanks without any plants (initial concentration 15 × 103 colony-forming units per ml). As expected, by this the antibacterial effect of the limnic macrophytes attains its maximum effectivity within the first days of the period of investigation. The decimal time of reduction is shortened by one third to half, the centimal reduction time is shortened by one fourth to one third. Mean contact times of 7… 11 h are required for the decimation of bacteria by 90 %, and mean contact times of 16… 19 h are necessary for a 99 % reduction of the population. Possibly, the antibacterial effect in mixed stands of different plant species is increased additively or superadditively. 相似文献
9.
Selected by-products which are produced upon chlorination or ozonization of seawater were examined for their effect on eastern oyster (Crassostrea virginica) larvae. The compounds, bromate, bromoform, and chloroform, were studied at 0.05, 0.1, 1.0, and 10.0 mg/l. Repeated bioassays indicated that even at these low levels, all three substances produced some larval mortality. This preliminary study suggests that oxidation by-products formed during chlorination or ozonization of power plant cooling waters may have adverse effects upon the growth of marine invertebrates, such as C. virginica, during their delicate larval stages. 相似文献
10.
11.
Using a modified Brewer bubbler ozone sensor, continuous measurements of the ozone concentration near the ground were made at Poona (18°N, 73°E) for one year 1969–1970. The surface ozone concentration shows a pronounced seasonal variation, with a minimum during the monsoon months and a maximum during the pre-monsoon summer months. There is also a marked diurnal variation in surface ozone concentration which clearly follows the diurnal variation of temperature and is again a maximum during the summer months and a minimum during the monsoon. A secondary maximum in ozone concentration occurs in the forenoon during the winter months, associated with the temperature inversions that occur near the ground in this season.Both ozone and radioactive tracers, such as Cs-137 both in air and in precipitation show variations indicating that they have identical source regions and sinks. The latitudinal anomaly of surface ozone and Cs-137 observed in the low latitudes over India is explained as arising from the reduction in the rate of transfer of these tracers from the stratosphere to the troposphere, as a result of the reversed circulation at the upper levels in this season.From continuous measurements of surface ozone made with three electrochemical sensors exposed at three levels, 0, 15 and 35 m above the ground, the ozone flux has been directly calculated for the first time in the tropics. The ozone flux was calculated using both the rate of decay method used by Kroening and Ney and Regener's profile method. The profile method gives values of the order of 1.71 to 7.04×1011 mol/cm2/sec and that obtained by the rate of decay method is found to be 4.2 to 5.6×1011 mol/cm2/sec and are in good agreement with the flux values reported by other investigators. 相似文献
12.
B. S. Khangarot 《洁净——土壤、空气、水》1981,9(5):505-509
The acute toxicity of copper and copper plus complexing agents to common guppy Lebistes reticulatus was studied for 96 h by a static bioassay technique. The addition of complexing agents viz. disodium salt of EDTA, citric acid, sodium thiosulphate and glycine in Cu2+ solutions caused a great decrease in the per-cent mortality as compared to that of Cu2+ test solutions alone. 10 mg/l of complexing agent was added in each copper concentration in all the test series. The 96 h LC50 values and 95% confidence limits in mg/l of Cu2+ plus were 1.23 (0.95…1.65) for Cu2+ alone; 4.30 (4.04 … 4.55) for Cu2+ plus EDTA; 1.94 (1.69 … 2.18) for Cu2+ plus citric acid; 3.44 (2.96 … 3.74) for Cu2+ sodium thiosulphate and 2.29 (2.22 … 3.02) for Cu2+ plus glycine. 相似文献
13.
The small eutrophic man-made lake in Wadi el Majanin, Libya has a well-buffered hydrogen-carbonate (98 … 160 mg/l CaCO3) system (pH = 7 … 7.8) and a poor Secchi visibility (21 … 35 cm). Conductivity data (272 … 480 μS/cm) fit the water-body in class 2 (‘freshwater’ range) of Beadle. The annual surface water temperature cycle (before noon readings) showed strong seasonal variations from 12 °C in Jan. and Feb. 1986 to 28.5 °C in June, 1987. The lake sustains a good crop of plankton populations. The main phytoplankton were species of Pediastrum, Scenedesmus, Navicula, Amphora, Synedra, Gomphonema, Oscillatoria, Gomphosphaeria and from zooplankton these were Keratella, Polyarthra, Brachionus, Moina, Acanthocyclops and nauplii of copepods. The presence of euglenoids supports the enriched water status of the ecosystem. Planktonic algal flora appeared closer to the eutrophic chlorococcales-diatom type (Hutchinson). Rotifers dominated the zooplankton community. A well established macrophytic vegetation was lacking. 相似文献
14.
We have studied the effects on the ozone concentration and surface temperature, of perturbations in the atmospheric content of nitrous oxide, methane, carbon dioxide and chlorofluorocarbons (CFC). The sensitivity study has been carried out with a radiative-convective-photochemical model. The doubling of carbon dioxide concentration has the effect of warming the troposphere and cooling the stratosphere. As a result of this cooling, the change of ozone columnar density produced by 10 ppb of chlorine amount to 9.3% as compared to –10.9% obtained without temperature feedback. Perturbation in nitrous oxide correspond to an increase in NO
x
of the stratosphere with consequent ozone reduction while doubling the methane concentration correspond to a slight increase in columnar density. The effect of the increased methane concentration in the stratosphere contributes to reduce the effect of CFC due to the enhanced formation of HCl. The perturbation of these two minor constituents appreciably increase the greenhouse effect to 2.30 from 1.67°, obtained when carbon dioxide alone is considered. 相似文献
15.
Elimination of Swimming Pool Water Disinfection By‐products with Advanced Oxidation Processes (AOPs)
Ozonation is a treatment step which was first applied in the 1960s in pool water treatment for disinfection as well as for oxidation of pool water contaminants. Contact time between ozone and pool water was identified to be of significance with an increased elimination efficiency regarding chloramines, trihalogenmethane formation potential and the permanganate index for longer reaction times. Oxidation via OH radicals might be the dominating pathway. In this study ozonation was compared with the ozone based advanced oxidation processes ozone/UV and ozone/hydrogen peroxide regarding the elimination efficiency of both disinfection by‐products (DBPs) and DBP precursors. It was observed that AOPs in comparison to ozonation showed an increased elimination efficiency regarding total organic carbon (TOC), the organically bound halogens adsorbable on activated carbon (AOX) and AOX formation potential. A contact time of 3 minutes between pool water and oxidant turned out to be practically sufficient. Just for the trihalomethane (THM) formation potential ozonation showed a slight advantage compared to the AOPs because ozonation is a highly selective oxidant and OH radical reactions are known to produce small reactive molecules which are easier transformed to THMs. Combination of membrane filtration and AOPs resulted in an elimination of 10 to 90 % of the DBPs and their precursors. The ozone/hydrogen peroxide process is suggested for pool water treatment because of the higher elimination rates compared to ozonation and of economic reasons compared to the ozone/UV process. 相似文献
16.
Water samples of 100 ml are salted out with 35 g NaCl and extracted with 3 × 10 ml chloroform, the extract is dried and taken up with 0.2 ml ethanol. The ethanol extract is incubated with 7.857 mmol/l acetylcholinhydrochloride and an enzymatic activity of 88.8 U/l cholinesterase from horse-serum. An inhibition of cholinesterase and, therefore, of the formation of acetic acid from acetylcholin is caused by P-organic insecticides present in the investigated extract. Since the reaction proceeds in a buffer at pH 8.2 … 8.3, the pH-difference occurring between sample and control constitutes a measure of the cholinesterase inhibition. Prior to reaction, an oxidation is required for thio-compounds, which is carried out with bromine water for parathion and with potassium permanganate for dimethoat. The detection limits of the method are in the nanogram-range. Extractives from plants as well as substances from faecal matter may have a disturbing effect. 相似文献
17.
In this study, results of source identification and apportionment for ambient volatile organic compounds (VOCs) from a previous work were used to estimate ozone‐forming potentials (OFPs) of effective sources for developing proper strategies for reduction of tropospheric ozone pollution. The source identification and apportionment of ambient VOC pollution within Yildiz Technical University's Davutpasa Campus (Istanbul, Turkey) was done by positive matrix factorization (PMF). The results suggested five effective source groups with the emissions related with paint use and solvent use having the highest contributions (36.8 and 28.2%). The results from PMF were used along with maximum incremental reactivities to estimate potentials of individual sources for ozone formation. It was found that biogenic emissions (3.78) and traffic related emissions (gasoline and diesel vehicle exhaust) (3.83 and 3.15, respectively) have the highest potential for ozone formation in terms of grams O3/g VOC emitted. The results were used to suggest proper source‐based reduction strategies for OFP. 相似文献
18.
Study of ozone “weekend effect” in Shanghai 总被引：6，自引：0，他引：6
WenYuan Tang ChunSheng Zhao FuHai Geng Li Peng GuangQiang Zhou Wei Gao JianMing Xu XueXi Tie 《中国科学D辑(英文版)》2008,51(9):1354-1360
Analysis of observed ozone data in 2006 from five monitoring sites (Xujiahui, Chongming, Baoshan, Pudong, Jinshan) in Shanghai reveals that ozone (O_3) concentrations in Xujiahui are higher at week-ends than those on weekdays, despite the fact that emissions of ozone precursor substances, such as oxides of nitrogen (NOx), carbon monoxide (CO) and volatile organic compounds (VOCs) are lower at weekends than those on weekdays. The possible chemical cause of ozone "weekend effect" is that NO_2/NO ratio increases at weekends by 25.61% compared with those on weekdays. In addition, because of an average 12.13% reduction in NOx (NO NO_2) in the early morning (05:00-09:00) at weekends compared with that on weekdays, the ozone inhibition period ends 0.5 h earlier at weekends resulting in the longer duration of ozone accumulation and the higher ozone production rate. The rate of ozone production is a function of VOCs and NOx in the atmosphere. VOCs/NOx ratio in Xujiahui is 4.55 at weekends, and 4.37 on weekdays, belonging to the "NOx-limited". The increasing VOCs/NOx ratio at weekends leads to ozone enhancement from 73 ppbv to 80 ppbv, which are consistent with ozone "weekend effect" in Xujiahui. Furthermore, combining with MICAPS cloud amount data, the fact that ozone "weekend effect" in Xujiahui weakens gradually along with the increasing of cloud amount indicates that ozone photochemical production leads to ozone "weekend effect" in Xujiahui of Shanghai. 相似文献
19.
A. Nishri 《Earth and Planetary Science Letters》1984,71(2):415-426
The most important source of dissolved manganese, Mn(II), to the Dead Sea is by upward diffusion from bottom sediments. This source contributes about 80 tons of Mn(II) each year. The concentration of dissolved manganese in the Dead Sea is extraordinarily high (7.03 mg 1?1). It appears that the content (some 1.026 × 106 tons) of dissolved manganese in the sea has remained constant during 1977–1979, although oxygen was introduced into deeper layers during the deepening of the pycnocline (1977–1978) and during the overturn of its water masses in the winter of 1978/79. The rate of oxidation of Mn(II) in Dead Sea water is extremely slow hence Mn(II) may practically be considered as the stable form of Mn in Dead Sea waters. Dilution by fresh water causes a pH rise and may facilitate faster oxidation of the dissolved divalent manganese. It is shown here that the shape of the Mn(II) profile, observed in the lake during 1963, may have developed by oxidation of Mn(II) in the more diluted upper layers and subsequent reduction of the oxidation products in the anoxic and more saline deeper layers during 260 years of continuous meromixis. 相似文献
20.
In the chlorination of drinking water about 90% of chlorine show an oxidizing effect, 10% result in halogenated reaction products, ca. 1% of them consisting of trihalomethanes. When chlorine dioxide is applied, in most the trihalomethanes remain below the detection limit, but increasingly polar organic reaction products originate, on the other hand. Chloramine is rarely applied, mostly for securing transport with storage reservoir waters. Only little information about reaction products is available. By the application of ozone one obtains a wide spectrum of reaction products, the aldehyde contents can be influenced by activated carbon. Especially critical is the formation of persistent epoxides, above all from pesticides. Due to antimon burners, the ultraviolet irradiation is gaining in interest, and in many cases its biocidal effect is superior to that produced by chlorination and ozonization, except for the problem of re-germination in the water supply network. The costs of ultraviolet irradiation, however, are much higher than those of the other techniques, of which chlorination causes only about one quarter of the costs of the other chemical disinfection techniques. 相似文献