Refine search
Results 1411-1420 of 1,546
Application of molecularly imprinted and non-imprinted polymers for removal of emerging contaminants in water and wastewater treatment: a review Full text
2012
Murray, Audrey | Örmeci, Banu
Over the past decade, several studies have reported trace levels of endocrine disrupting compounds, pharmaceuticals, and personal care products in surface waters, drinking water, and wastewater effluents. There has also been an increased concern about the ecological and human health impact of these contaminants, and their removal from water and wastewater has become a priority. Traditional treatment processes are limited in their ability to remove emerging contaminants from water, and there is a need for new technologies that are effective and feasible. This paper presents a review on recent research results on molecularly imprinted (MIP) and non-imprinted (NIP) polymers and evaluates their potential as a treatment method for the removal of emerging contaminants from water and wastewater. It also discusses the relative benefits and limitations of using MIP or NIP for water and wastewater treatment. MIP, and in particular NIP, offer promising applications for wastewater treatment, but their toxicity and possible health effects should be carefully studied before they are considered for drinking water treatment. More research is also required to determine how best to incorporate MIP and NIP in treatment plants.
Show more [+] Less [-]Characterizations of particle-bound trace metals and polycyclic aromatic hydrocarbons (PAHs) within Tibetan tents of south Tibetan Plateau, China Full text
2012
Li, Yizhong | Kang, Shichang | Chen, Pengfei | Zhang, Qianggong | Fang, Guor Cheng
INTRODUCTION: Exposure to trace metals and polycyclic aromatic hydrocarbons (PAHs) adsorbed on particulates is of a serious health concern. Levels of some trace metals in total suspended particulate and 13 PAHs of fine particulate matter were measured from nomadic tents in the southern Tibetan Plateau in summer 2010. RESULTS AND DISCUSSION: The indoor air within the tents was seriously polluted, mainly due to yak dung combustion. Average trace metal concentrations were much higher (range of indoor/outdoor ratio 61–291) than those of the outdoor air. Additionally, enrichment factors of most trace metals of indoor air were similar to those of outdoor air, indicating outdoor air quality of the studied area was possibly influenced by pollutants emitted from local tents. Mean concentrations of total PAHs and BaP within tents was 5372.45 and 364.79 ng/m3, hundred times higher than that of outdoor air of the Tibetan Plateau. Three- and four-ring PAHs were the predominant components. The diagnostic ratio of BaA/(BaA + Chr) was 0.33. Since Tibetan women typically spend longer time within the tents, they were exposed to PAHs (BaP exposure = 1.81 μg/m3) about two times of other family members. Among all the PAHs, Bap contributed the most (82.6%) of the total carcinogenicity. Similarly, the excess lifetime cancer risk for women and other family members were 2.75 × 10−4 and 1.27 × 10−4, respectively, indicating Tibetan herdsmen, especially women who are in charge of most house chores were at risk for adverse health effects.
Show more [+] Less [-]Degradation of 1,4-dioxane using advanced oxidation processes Full text
2012
Chitra, Sengadir | Paramasivan, Kanapathy | Cheralathan, Mayilsamy | Sinha, Pradeep Kumar
INTRODUCTION: In the nuclear industry 1,4-dioxane is used as a solvent in liquid scintillation technique for measuring low-energy beta-emitters such as 3H or C14 in aqueous media. Improper disposal of 1,4-dioxane can contaminate the ground and surface waters. Conventional wastewater treatment processes like chemical treatment, air stripping, carbon adsorption, and biological treatment are ineffective for the degradation of 1,4-dioxane. METHODS: In the present study, the kinetics of degradation of 1,4-dioxane using advanced oxidation processes viz., H2O2 alone, Fe(II) + H2O2, UV (15 W) + H2O2, UV (15 W) + Fe(II) + H2O2, US (130 KHz) + Fe(II) + H2O2, and sunlight + Fe(II) + H2O2 at pH 3.0 was investigated. The optimization of Fe (II) for the processes using Fe (II) + H2O2 was carried out. CONCLUSIONS: The kinetics of degradation using sunlight + Fe (II) + H2O2 was found to be fastest when compared to the other processes. The degradation was found to follow first-order kinetics. Formation of acidic intermediates was suspected from the observed pH changes during the degradation processes.
Show more [+] Less [-]Assessing the effects of tertiary treated wastewater reuse on a Mediterranean river (Llobregat, NE Spain), part III: pathogens and indicators Full text
2012
Rubiano, María-Eugenia | Agulló-Barceló, Míriam | Casas-Mangas, Raquel | Jofre, Juan | Lucena, Francisco
PURPOSE: Need, coupled with advances in water treatment technology, is motivating a growing interest in augmenting drinking water supplies with reclaimed water. Using reclaimed water to increase the flow of the Llobregat River upstream the water catchment site of the complex multi-step drinking water treatment plant of Sant Joan Despí has been considered. The impact of reclaimed water discharges on the load of E. coli, spores of sulphite-reducing clostridia, somatic coliphages, cytopathogenic enteroviruses, and total and infectious Cryptosporidium oocysts in the Llobregat River water was assessed to gain information for funded decisions in potential future emergencies. METHODS: Enterovirus and Cryptosporidium oocysts were concentrated from great water volumes prior to enumeration, whereas indicators were enumerated directly from the samples. Both indicators and pathogens were enumerated by cultural techniques that determine infectious microbes. RESULTS AND DISCUSSION: Densities of both indicators and pathogens in reclaimed water, despite that it was disinfected by UV irradiation alone or by UV irradiation plus chlorination, were significantly lower than their densities in the river water, both upstream and downstream the reclaimed water release site in the river. CONCLUSION: Results gathered indicate that discharging reclaimed water into the river does not increment the load of indicators and pathogens of the river water. Then, in emergency situations due to severe water shortages after prolonged droughts, at least from the infectious diseases point of view, the risks of augmenting drinking water supplies with reclaimed water can be satisfactorily and safely managed.
Show more [+] Less [-]Heterogeneous photocatalytic degradation of methyl orange in schwertmannite/oxalate suspension under UV irradiation Full text
2012
Wu, Yong | Guo, Jing | Jiang, Danjun | Zhou, Pei | Lan, Yeqing | Zhou, Lixiang
INTRODUCTION: Schwertmannite was synthesized through an oxidation of FeSO4 by Acidithiobacillus ferrooxidans LX5 cell suspension at an initial pH 2.5 and 28°C for 3 days and characterized using X-ray diffraction spectroscopy and scanning electron microscope. The schwertmannite photocatalytic degradation of methyl orange (MO) by oxalate was investigated at different initial pH values, concentrations of schwertmannite, oxalate, and MO. RESULTS: The results demonstrated that photodegradation of MO in the presence of schwertmannite or oxalate alone was very weak. However, the removal of MO was significantly enhanced when schwertmannite and oxalate coexisted in the reaction system. Low pH (4 or less) was beneficial to the degradation of MO. The optimal doses of schwertmannite and oxalate were 0.2 g L−1 and 2 mM, respectively. Hydroxyl radicals (·OH) and Fe(II), the intermediate products, were also examined during the reaction to explore their correlation with the degradation of MO. CONCLUSION: A possible mechanism for the photocatalytic decomposition of MO in the study was proposed. The formation of Fe(III)-oxalate complexes on the surface of schwertmannite was a precursor of H2O2 and Fe(II) production, further leading to the yield of ·OH responsible for the decomposition of MO.
Show more [+] Less [-]Long-term automated sampling of PCDD/PCDF flue gas: current status and critical issues Full text
2012
Vicaretti, M. | Mosca, S. | Guerriero, E. | Rotatori, M.
After entry into force of the Stockholm Convention and Aarhus Protocol and in order to implement the upcoming European legal background, the European countries are asked to apply control measures to reduce the release of persistent organic pollutants (POPs) such as dioxins and furans (PCDD/PCDF) and polychlorinated biphenyls as well as to establish POPs release inventories. In this perspective, development of measuring techniques of emissions is a focal issue in acquiring useful information. In this paper, results of various measurement campaigns at different municipal waste incineration (MWI) plants using long-term automated sampling of PCDD/PCDF are presented. The samples collected from both manual and automated campaigns were analyzed following the European Standard EN-1948:2006 by high-resolution gas chromatograph/high-resolution mass spectrometer. Performances of two different commercial systems have been investigated. Anomalous values occurred during one long-term campaign (22.16 pg I-toxic equivalent (TEQ)/Nm3), compared to average values (4–5 pg I-TEQ/Nm3) of the MWI. At this maximum value, a main occurrence of abnormal and instable operating conditions has been found. Sampling based on long-term basis was found to be more reliable to monitor PCDD/PCDF emissions than occasional short-term sampling. Nevertheless, the results of long-term campaigns demonstrate that emission levels detected in 15–30 days campaigns, when unsteady operating conditions can occur, as start-up and shut down, are not immediately comparable to the typical levels in a 6–8 h, when operating conditions are generally stable. Moreover, there are often differences observed in the congener profiles between short- and long-term campaigns.
Show more [+] Less [-]Size distribution and seasonal variation of airborne particulate matter in five areas in Istanbul, Turkey Full text
2012
Şahin, Ülkü Alver | Scherbakova, Kristina | Onat, Burcu
GOAL, SCOPE, AND BACKGROUND: Many studies have focused on measuring fine and course particulate matter (PM) in urban and rural sites around the world. The aim of this research is to gain information on the size distribution of particles. The physical characteristics of PM in the urban air of Istanbul were determined. METHODS: PM sampling was carried out at five stations (Avcılar, Beşiktaş, Kilyos, Rasathane, and Göztepe) over a period of 2 years. PM filter samples were collected for eight different size ranges (<0.43, 0.43–1, 1–1.7, 1.7–2.6, 2.6–3.5, 3.5–5.2, 5.2–6.5, 6.5–8, and >8 μm) using a Cascade Impactor. The size distributions of the PM samples were determined. RESULTS AND DISCUSSION: The mean total PM concentrations were 48.6 ± 34.0, 34.8 ± 11.6, 28.6 ± 13.6, 21.5 ± 9.1, and 16.8 ± 5.1 μg/m3 for the Göztepe, Beşiktaş, Avcılar, Rasathane, and Kilyos stations, respectively. The total PM concentrations were found to be 1.2–1.5 times higher in the fall and winter than in the spring and summer, except for at the station in Avcılar. The PM concentrations in Avcılar did not exhibit seasonal variations. This is thought to result from the intense industrial activity in the area. PM2.6 (below 2.6 μm particles) comprised up to 62% of the total amount of PM in samples collected at the Göztepe, Beşiktaş, and Rasathane stations during the fall and winter. PM1 was determined to be approximately 45% of the total, corresponding to 57% of the amount of PM2.5. A multi-modal PM size distribution was observed. The lowest Mass Median Aerodynamic Diameter (MMAD) values observed in Avcılar, Beşiktaş, Rasathane, and Göztepe were 4.2, 3.9, 2.9, and 3.5 μm, respectively, and were observed during the season of active household heating. No difference was measured in the MMAD values (5.2 μm) between the seasons of heating and non-heating in Kilyos.
Show more [+] Less [-]Personal monitoring of exposure to particulate matter with a high temporal resolution Full text
2012
Broich, Anna V. | Gerharz, Lydia E. | Klemm, Otto
BACKGROUND: Continuous monitoring of air quality is implemented by government institutions at fixed ambient sites. However, the correlation between fixed site measurements and exposure of individual persons to air contaminants is likely to be weak. MATERIALS AND METHODS: We measured particulate matter both outdoors and indoors by following the spatial movement of individuals. Sixteen test persons took part and carried a measurement backpack for a 24-h period. The backpack was comprised of a Grimm Aerosol Spectrometer model 1.109, a GPS device, and a video camera for tracking of human behavior. The spectrometer provided information about particle numbers and mass in 32-size classes with a high temporal resolution of 6 s. RESULTS: The personal exposure of individuals during 24 h could significantly exceed the outdoor particulate matter (PM)₁₀ concentrations measured at the fixed sites. The average 24-h exposure of all test persons for PM₁₀ varied from 27 to 322 μg m⁻³. Environmental tobacco smoke and cooking emissions were among the main indoor sources for PM. The amount of particulate matter a test person was exposed to was highly dependent on the spatial behavior and the surrounding microenvironment conditions. DISCUSSION: Large-scale experiments including personal measurements might help to improve modeling approaches to approximate the actual exposure on a statistically sound basis.
Show more [+] Less [-]Sampling and analytical methods for assessing the levels of organic pollutants in the atmosphere: PAH, phthalates and psychotropic substances: a short review Full text
2012
Cecinato, Angelo | Balducci, Catia | Mastroianni, Daniele | Perilli, Mattia
This short review presents the procedures used to monitor PAHs, phthalates and psychotropic substances in the air, and the results of some measurements made in Italy and abroad. Organic contaminants are characterized by a variety of physical and chemical properties, including aggregation phase, concentration level, and life time. This variety widens the spectrum of procedures developed to assess their occurrence in the environment and biota, but prevents the complete speciation of the “organic fraction” of air, waters and particulates, and attention is paid to a few substances. The progress in health sciences stimulates the concern on contaminants and the development of new instrumental apparatuses and methods; new chemicals are continuously identified or recognized as capable of injuring the environment and organisms. Persistent organic pollutants and persistent biologically active toxicants are subject to regulation and extensively measured by means of standard procedures. For instance, polycyclic aromatic hydrocarbons, polychlorobiphenyls and polychlorodibenzodioxins are recovered from air through phase partition, thermal desorption or solvent extraction, then separated and detected through GC–MS or HPLC–MS procedures. By contrast, dedicated methods must be still optimized to monitor candidates or possible candidates as emerging organic pollutants, e.g. phthalates, flame retardants and perfluoroalkanes. Also, psychotropic substances appear of potential concern. Legal and illicit substances are commonly detected in the urban air besides waste and surface waters. If nicotine, caffeine and cocaine will result to enough persistence in the air, their monitoring will become an important issue of global chemical watching in the next future.
Show more [+] Less [-]Thermophilic desulfurization of dibenzothiophene and different petroleum oils by Klebsiella sp. 13T Full text
2012
Bhatia, Sumedha | Sharma, Durlubh K.
PURPOSE: Biodesulfurization (BDS) has the potential to desulfurize dibenzothiophene (DBT) and its alkylated derivatives, the compounds that are otherwise refractory to hydrodesulfurization (HDS). Thermophilic microorganisms are more appropriate to be used for BDS applications following HDS. The aim of the present study was to isolate a thermophilic microorganism and to explore its commercial relevance for BDS process. METHODS: The desulfurizing thermophilic strain was isolated and enriched from various soil and water samples using sulfur free medium (SFM) supplemented with DBT. Microbiological and genomic approach was used to characterize the strain. Desulfurization reactions were carried out using DBT and petroleum oils at 45°C followed by different analytical procedures. RESULTS: We report the isolation of a thermophilic bacterium Klebsiella sp. 13T from contaminated soils collected from petroleum refinery. HPLC analysis revealed that Klebsiella sp. 13T could desulfurize DBT to 2-hydroxybiphenyl (2-HBP) at 45°C through 4S pathway. In addition, adapted cells of Klebsiella sp. 13T were found to remove 22–53% of sulfur from different petroleum oils with highest sulfur removal from light crude oil. CONCLUSION: Klebsiella sp. 13T is a potential candidate for BDS because of its thermophilic nature and capability to desulfurize petroleum oils.
Show more [+] Less [-]