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31.
Brenda Borbón Mercedes Teresita Oropeza-Guzman Enric Brillas Ignasi Sirés 《Environmental science and pollution research international》2014,21(14):8573-8584
Dairy wastewater is characterized by a high content of hardly biodegradable dissolved, colloidal, and suspended organic matter. This work firstly investigates the performance of two individual electrochemical treatments, namely electrocoagulation (EC) and electro-oxidation (EO), in order to finally assess the mineralization ability of a sequential EC/EO process. EC with an Al anode was employed as a primary pretreatment for the conditioning of 800 mL of wastewater. A complete reduction of turbidity, as well as 90 and 81 % of chemical oxygen demand (COD) and total organic carbon (TOC) removal, respectively, were achieved after 120 min of EC at 9.09 mA cm?2. For EO, two kinds of dimensionally stable anodes (DSA) electrodes (Ti/IrO2-Ta2O5 and Ti/IrO2-SnO2–Sb2O5) were prepared by the Pechini method, obtaining homogeneous coatings with uniform composition and high roughness. The ·OH formed at the DSA surface from H2O oxidation were not detected by electron spin resonance. However, their indirect determination by means of H2O2 measurements revealed that Ti/IrO2-SnO2–Sb2O5 is able to produce partially physisorbed radicals. Since the characterization of the wastewater revealed the presence of indole derivatives, preliminary bulk electrolyses were done in ultrapure water containing 1 mM indole in sulfate and/or chloride media. The performance of EO with the Ti/IrO2-Ta2O5 anode was evaluated from the TOC removal and the UV/Vis absorbance decay. The mineralization was very poor in 0.05 M Na2SO4, whereas it increased considerably at a greater Cl? content, meaning that the oxidation mediated by electrogenerated species such as Cl2, HClO, and/or ClO? competes and even predominates over the ·OH-mediated oxidation. The EO treatment of EC-pretreated dairy wastewater allowed obtaining a global 98 % TOC removal, decreasing from 1,062 to <30 mg L?1. 相似文献
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Xavier Flores-Alsina Alejandro Gallego Gumersindo Feijoo Ignasi Rodriguez-Roda 《Journal of environmental management》2010,91(5):1193-1201
Besides the evaluation of the environmental issues, the correct assessment of wastewater treatment plants (WWTP) should take into account several objectives such as: economic e.g. operation costs; technical e.g. risk of suffering microbiology-related TSS separation problems; or legal e.g. accomplishment with the effluent standards in terms of the different pollution loads. For this reason, the main objective of this paper is to show the benefits of complementing the environmental assessment carried out by life cycle assessment with economical, technical and legal criteria. Using a preliminary version of the BSM2 as a case study, different combinations of controllers are implemented, simulated and evaluated. In the following step, the resulting multi-criteria matrix is mined using multivariate statistical techniques. The results showed that the presence of an external carbon source addition, the type of aeration system and the TSS controller are the key elements creating the differences amongst the alternatives. Also, it was possible to characterize the different control strategies according to a set of aggregated criteria. Additionally, the existing synergies amongst different objectives and their consequent trade-offs were identified. Finally, it was discovered that from the initial extensive list of evaluation criteria, only a small set of five are really discriminant, being useful to differentiate within the generated alternatives. 相似文献
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Since the beginning of the 1960s, mass tourism has been the most important menace to the environmental stability of fragile
and vulnerable Mediterranean microinsular systems. The socioeconomic changes introduced by tourism have produced important
variations in the use of resources, including land. The result usually has been an increase in the level of artificiality
of the territory, particularly in coastal areas. The intensity and frequency of change in the use of resources and the induced
changes in the level of artificiality may be used as an estimation of environmental stability. The northern area of Formentera,
Balearic islands, Spain, being the most environmentally important area of the island and simultaneously the most threatened
by mass tourism development, has been chosen as a study case. Forty types of vegetation and land use have been estimated and
mapped in the area. The stability level of each land use type has been estimated, before and after the development of tourism,
and the main environmental processes have been identified. An attempt is made to predict some future trends and their variations. 相似文献
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Pedro P. Olea Fabián Casas Steve Redpath Javier Viñuela 《Behavioral ecology and sociobiology》2010,64(6):927-937
Visual displays are signals that may be selected to increase visibility. Light is a crucial component in the transmission
of visual signals, and white colour is very conspicuous when illuminated by sun and exhibited against darker backgrounds.
Here we tested the hypothesis that orientation of sexual displays in male great bustard (Otis tarda) depends upon position of the sun, i.e., males direct their uplifted white tails towards the sun in order to maximise signal
detectability to distant females. We recorded the orientation of 405 male displays in relation to the sun and to females at
seven leks. Great bustard males signalled towards the sun more often than expected by chance in early morning, although this
pattern was not obvious at other times of day, when males displayed more towards females. Our hypothesis was further supported
by the fact that displays were more directed towards the sun when the sun was most visible. Males were more likely to direct
their displays towards females during the most elaborate components of their courtship display and when there were fewer males
on the lek. Pointing white plumage to the sun may be a behaviour selected in species living in steppe-like open landscapes
if individuals obtain net fitness benefit by increasing the likelihood of mating. 相似文献
37.
V. Alzaga J. Vicente D. Villanua P. Acevedo F. Casas C. Gortazar 《Behavioral ecology and sociobiology》2008,62(5):769-775
Preys require effective anti-predator traits to escape from predator attacks, whereas predators focus on individuals that
have lower fitness. This fitness reduction is due to the effects of many regulatory forces such as parasites. We directly
observed in the field the escape performance of the Iberian hare (Lepus granatensis) against coursing predators (measured as the time to be taken by greyhounds) and examined the relationships between parasite
loads and duration of escape behaviours to test the hypothesis that predators would more easily catch substandard individuals.
We found a negative relationship between the hare’s escape duration and parasite burdens in various taxa (Taenia pisiformis cisticercus, intestinal Coccidia) as well as with parasite diversity. Moreover, the escape duration of the hares is related
positively to their condition. In the particular case of T. pisiformis cisticercus, we found a negative relationship with body condition, suggesting that its effect on anti-predation ability could
be mediated by direct spoliation of host resources and/or by increasing requirements for anti-parasite defence. As parasite
loads were not directly manipulated, experimental studies are needed to elucidate any causal links between parasite and anti-predatory
capacity in Iberian hares. 相似文献
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Fortuny M Baeza JA Gamisans X Casas C Lafuente J Deshusses MA Gabriel D 《Chemosphere》2008,71(1):10-17
Removal of hydrogen sulfide from waste and energy-rich gases is required, not only because of environmental health and safety reasons, but also because of operational reasons if such gases have to be used for energy generation. A biotrickling filter for the removal of ultra-high concentrations of H2S from oxygen-poor gases is proposed and studied in this work. Two laboratory-scale biotrickling filters were used to study the startup period and to determine the long-term performance of the gas sweetening process. The inlet H2S concentration ranged from 900 to 12000ppmv and two different packing materials were investigated. There was no toxicity effect observed even at a the highest H2S concentration, and maximum elimination capacities of 280 and 250g H2Sm(-3)h(-1) were obtained at gas contact times of 167 and 180s, respectively. Elemental sulfur and sulfate were found to be the most abundant end-products of the biological oxidation of sulfide when operated under microaerophilic conditions. The biotrickling filter was able to quickly recover its nominal performance after different load increases and system shutdowns simulating field operation. The results reported here show that biotreatment can be an interesting alternative to conventional gas sweetening systems normally used for such applications. 相似文献
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Romanyà J Arco N Solà-Morales I Armengot L Sans FX 《Journal of environmental quality》2012,41(4):1337-1347
The use of composted manures and of legumes in crop rotations may control the quality and quantity of soil organic matter and may affect nutrient retention and recycling. We studied soil organic C and N stocks and N mineralization in organically and conventionally managed dryland arable soils. We selected 13 extensive organic fields managed organically for 10 yr or more as well as adjacent fields managed conventionally. Organic farmers applied composted manures ranging from 0 to 1380 kg C ha yr and incorporated legumes in crop rotations. In contrast, conventional farmers applied fresh manures combined with slurries and/or mineral fertilizers ranging from 200 to 1900 kg C ha yr and practiced a cereal monoculture. Despite the fact that the application of organic C was similar in both farming systems, organically managed soils showed higher C and similar N content and lower bulk density than conventionally managed soils. Moreover, organic C stocks responded to the inputs of organic C in manures and to the presence of legumes only in organically managed soils. In contrast, stocks of organic N increased with the inputs of N or C in both farming systems. In organically managed soils, organic N stocks were less mineralizable than in conventional soils. However, N mineralization in organic soils was sensitive to the N fixation rates of legumes and to application rate and C/N ratio of the organic fertilizers. 相似文献