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1.
J Hazard Mater ; : 121871, 2019 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-31879098

RESUMO

This study aimed to assess the distribution of spent pesticides in an agro-farming area and to evaluate their impact on the ecological risk for an endangered species combing the health risk assessment concept with the modelling algorithm proposed by European Food Safety Authority (EFSA). An agricultural area in western Taiwan was chosen to investigate the ecological risk on Prionailurus bengalensis. Their ecological stability was evaluated in the context of the residuals' distribution of the spent pesticides in the investigated area. The pesticide residues accumulated and correlated highly to the adverse health impact on the leopard cat. In the present study, 67 pesticides were detected from 79 collected soil samples. The hazard index (HI) was found related to land use patterns and the HI values in Yuanli and Zhuolan were significantly higher than those in the other areas, increasing poisoning probability of the leopard cat. The locations of agro-chemical utilization were highly overlapped with leopard cats' activity zone, supporting the hypothesis that pesticide residues posed a potential threat to the leopard cats' health. The proposed risk assessment framework was capable of estimating the risk caused by pesticide residues and no similar study has been reported before.

2.
Artigo em Inglês | MEDLINE | ID: mdl-30871135

RESUMO

The water⁻energy⁻food (WEF) nexus attracts much attention due to the elevated public concern regarding environmental conservation and sustainability. As we head into a new era of civilization, population increase and modernized lifestyles have led to an increasing need for water, energy, and food. However, severe hydrological precipitation significantly impacts agricultural harvest, and such influence becomes more apparent under the influence of climate change. Meanwhile, the major method of electricity generation (i.e., fossil fuel burning) has a negative impact on the environment. These inevitable threats are crucial and have to be dealt with for a society on the road towards sustainability. In the present study, an integrated evaluation of the WEF nexus was conducted for two areas with different levels of urbanization using empirical multiple linear regression in a simultaneous equation model (SEM). By incorporating the collected data into the SEM, the weighting coefficient of each identified variable was obtained, and the nexus implication was assessed in model simulation at different scenarios considering the population growth, agro-technology advancement, energy structure improvement, and available water resources. In the simulated results, three observations were found: (1) the rural area is more sustainable than the urban one; (2) the sustainability for both the investigated areas is significantly subject to their water supply and demand; and (3) food production was found to have a less important effect on the sustainable development of the urban area. This study identified the key factors in the WEF nexus exploration, which are economically and environmentally important for resource allocation. An empirical model was developed to correlate sustainable achievement with WEF management, as well as strategic policies that should be implemented under the pressure of urbanization.


Assuntos
Abastecimento de Alimentos , Urbanização , Abastecimento de Água , Agricultura , Mudança Climática , Conservação dos Recursos Naturais , Crescimento Demográfico
3.
Mar Pollut Bull ; 136: 84-91, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30509845

RESUMO

Many shipwreck events occur in the neighboring areas of Taiwan due to the volume of maritime traffic and geographical conditions around Taiwan. The oil spills from such events can be devastating for the surrounding sea and coastal areas. The government realized the importance of marine pollution prevention and enforced the Marine Pollution Control Act and the Major Marine Oil Pollution Emergency Response Plan to mitigate the impact of oil spill pollution. The T.S. Taipei shipwreck highlighted the effectiveness of the national marine pollution prevention system. Inter-departmental cooperation and collaboration with private sectors are the keys for effective response. This article is the first detailed documentation of an oil spill response for a maritime incident from the beginning to the final termination of shipwreck removal. It shows the people in Taiwan intend to collaborate with other states to make a significant contribution to marine environment conservation and sustainability.


Assuntos
Conservação dos Recursos Hídricos/métodos , Planejamento em Desastres/legislação & jurisprudência , Poluição por Petróleo/prevenção & controle , Navios , Poluição da Água/prevenção & controle , Conservação dos Recursos Hídricos/legislação & jurisprudência , Planejamento em Desastres/organização & administração , Regulamentação Governamental , Cooperação Internacional , Oceanos e Mares , Poluição por Petróleo/análise , Poluição por Petróleo/legislação & jurisprudência , Taiwan , Poluição da Água/análise , Poluição da Água/legislação & jurisprudência
4.
Artigo em Inglês | MEDLINE | ID: mdl-29414884

RESUMO

Taste- and odor-causing (T&O) compounds are a major concern in drinking water treatment plants due to their negative impacts on the safety and palatability of water supply. This study explored the degradation kinetics and radical chemistry of four often-detected T&O compounds, geosmin (GSM), 2-methylisoborneol (MIB), benzothiazole (BT), and 2-isobutyl-3-methoxypyrazine (IBMP), in the ultraviolet/chlorine (UV/chlorine) advanced oxidation process. All experiments were carried out in a 700 mL photoreactor and the process effectively degraded the investigated T&O compounds in a slightly acidic environment. The degradation of T&O decreased with increasing pH but slightly with decreasing chlorine dosage. When the pH increased from 6 to 8, the pseudo-first-order rate constants of GSM, MIB, BT, and IBMP dropped from 2.84 × 10-3, 2.29 × 10-3, 3.64 × 10-3, and 2.76 × 10-3 s-1 to 3.77 × 10-4, 2.64 × 10-4, 6.48 × 10-4, and 6.40 × 10-4 s-1, respectively. Increasing the chlorine dosage slightly accelerated the degradation of the investigated T&O compounds, but excessive hypochlorous acid and hypochlorite scavenged the HO• radicals and reactive chlorine species (RCS). Generally, HO• primarily contributed to the degradation of all of the investigated T&O compounds as compared to RCS. The degradation by RCS was found to be structurally selective. RCS could not degrade GSM, but contributed to the degradation of MIB, BT, and IBMP. The results confirmed that the proposed oxidation process effectively degraded typical T&O compounds in aqueous phase.


Assuntos
Cloro/química , Odorantes , Oxirredução , Paladar , Raios Ultravioleta , Poluentes Químicos da Água , Purificação da Água/métodos , Cinética , Poluentes Químicos da Água/análise
5.
Sci Total Environ ; 610-611: 845-853, 2018 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-28826122

RESUMO

Paddy rice (Oryza sativa L.) is a major staple crop in Asia. However, heavy metal accumulation in paddy soil poses a health risk for rice consumption. Although plant uptake of Pb is usually low, Pb concentrations in rice plants have been increasing with Pb contamination in paddy fields. It is known that iron oxide deposits in the rhizosphere influence the absorption of soil Pb by rice plants. In this study, 14 rice cultivars bred in Taiwan, including ten japonica cultivars (HL21, KH145, TC192, TK9, TK14, TK16, TN11, TNG71, TNG84, and TY3) and four indica cultivars (TCS10, TCS17, TCSW2, and TNGS22), were used in a field experiment. We investigated the genotypic variation in rice plant Pb in relation to iron oxides deposited in the rhizosphere, as seen in a suspiciously contaminated site in central Taiwan. The results showed that the cultivars TCSW2, TN11, TNG71, and TNG84 accumulated brown rice Pb exceeding the tolerable level of 0.2mgkg-1. In contrast, the cultivars TNGS22, TK9, TK14, and TY3 accumulated much lower brown rice Pb (<0.1mgkg-1); therefore, they should be prioritized as safe cultivars for sites with potential contamination. Moreover, the iron oxides deposited on the rhizosphere soil show stronger affinity to soil-available Pb than those on the root surface to form iron plaque. The relative tendency of Pb sequestration toward rhizosphere soil was negatively correlated with the Pb concentrations in brown rice. The iron oxides deposited on the rhizosphere soil but not on the root surface to form iron plaque dominate Pb sequestration in the rhizosphere. Therefore, the enhancement of iron oxide deposits on the rhizosphere soil could serve as a barrier preventing soil Pb on the root surface and result in reduced Pb accumulation in brown rice.


Assuntos
Compostos Férricos/química , Chumbo/farmacocinética , Oryza/química , Poluentes do Solo/farmacocinética , Solo/química , Genótipo , Oryza/genética , Raízes de Plantas , Rizosfera , Taiwan
6.
Artigo em Inglês | MEDLINE | ID: mdl-30598034

RESUMO

Urban metabolism analyzes the supply and consumption of nutrition, material, energy, and other resources within cities. Food, water, and energy are critical resources for the human society and have complicated cooperative/competitive influences on each other. The management of interactive resources is essential for supply chain analysis. This research analyzes the food-water-energy system of urban metabolism for sustainable resources management. A system dynamics model is established to investigate the urban metabolism of food, water, and energy resources. This study conducts a case study of Shihmen Reservoir system, hydropower generation, paddy rice irrigation of Taoyuan and Shihmen Irrigation Associations, and water consumption in Taoyuan, New Taipei, and Hsinchu cities. The interactive influence of the food-water-energy nexus is quantified in this study; the uncertainty analysis of food, water, and energy nexus is presented.


Assuntos
Conservação dos Recursos Naturais/métodos , Conservação dos Recursos Naturais/estatística & dados numéricos , Ingestão de Líquidos , Abastecimento de Alimentos/estatística & dados numéricos , Abastecimento de Água/estatística & dados numéricos , Cidades/estatística & dados numéricos , Humanos , Modelos Teóricos , Taiwan
7.
Water Res ; 124: 446-453, 2017 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-28783498

RESUMO

A novel Fe(II)/citrate/UV/PMS process for degrading a model micropollutant, carbamazepine (CBZ), at a low Fe(II)/PMS ratio and neutral pH has been proposed in this study, and the mechanisms of radical generation in the system was explored. With a UV dose of 302.4 mJ/cm2, an initial pH of 7, and CBZ, PMS, Fe(II) and citrate at initial concentrations of 10, 100, 12 and 26 µM, respectively, the CBZ degradation efficiency reached 71% in 20 min in the Fe(II)/citrate/UV/PMS process, which was 4.7 times higher than that in either the citrate/UV/PMS or Fe(II)/citrate/PMS process. The enhanced CBZ degradation in the Fe(II)/citrate/UV/PMS process was mainly attributed to the continuous activation of PMS by the UV-catalyzed regenerated Fe(II) from a Fe(III)-citrate complex, [Fe3O(cit)3H3]2-, which not only maintained Fe(III) soluble at neutral pH, but also increased 6.6 and 2.6 times of its molar absorbance and quantum yield as compared to those of ionic Fe(III), respectively. In the Fe(II)/citrate/UV/PMS process, the SO4•- produced from the fast reaction between PMS and the initially-added Fe(II) contributed 11% of CBZ degradation. The PMS activation by the UV radiation and regenerated Fe(II) contributed additional 14% and 46% of CBZ removal, respectively. The low iron and citrate doses and the fast radical generation at neutral pH make the Fe(II)/citrate/UV/PMS process suitable for degrading recalcitrant organic compounds in potable water.


Assuntos
Carbamazepina/química , Compostos Ferrosos , Poluentes Químicos da Água/química , Citratos , Ácido Cítrico , Compostos Férricos , Concentração de Íons de Hidrogênio
8.
Water Res ; 121: 329-337, 2017 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-28570872

RESUMO

The present study aimed to derive an analytical formula to quantify the diffusion of organic contaminant in a biofilm. The experiments were conducted to investigate the BOD degradation under the conditions of influent COD concentration from 50 to 300 mg/L, COD:N:P ratios of 100:5:1 and 100:15:3, with and without auxiliary aeration. The BOD removal rate was around 73% for non-aerated influent COD of 50 mg/L with 1-h hydraulic retention time. The BOD removal rate increased as the influent loading and hydraulic retention time increased while the influent COD was no more than 150 mg/L. Without aeration, the removal rate dropped significantly when influent COD increased to the range no less than 200 mg/L, due to the fact that the BOD diffusive flux driven by the biomass uptake was not further enhanced by higher ambient organic loading. The diffusion coefficient was calculated to be 1.12 × 10-6 m2/d with influent COD of 50 mg/L at COD:N:P ratio of 100:5:1 and 1 h hydraulic retention time and aeration, and the coefficient increased to 3.35 × 10-6 m2/d as the influent COD concentration increased to 300 mg/L. The diffusion coefficient decreased to 4.09 × 10-7 m2/d as the retention time increased to 3 h. The overall diffusion coefficients showed an increasing trend as the influent organic loading increased. The difference in diffusion coefficients between 1 and 2 h was apparently greater than that between 2 and 3 h, indicating a smaller overall diffusive flux due to a longer retention time. Further analysis revealed that BOD diffusion activity exhibited a declining trend as the wastewater travelled through the system. An analytical diffusion-reaction model was developed to characterize the diffusion behaviour, and applied to estimating the treatment efficiency for real domestic sewage. The result showed that the estimated effluent BOD concentrations were quite comparable to those from experimental measurements.


Assuntos
Reatores Biológicos , Águas Residuárias , Biomassa , Difusão , Esgotos , Eliminação de Resíduos Líquidos
9.
Chemosphere ; 183: 582-588, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28570902

RESUMO

When a bromide-containing water is treated by the ultraviolet (UV)/chlorine process, hydroxyl radicals (HO) and halogen radicals such as Cl or Br are formed due to the UV photolysis of free halogens. These reactive species may induce the formation of bromate, which is a probable human carcinogen. Bromate formation in the UV/chlorine process using low pressure (LP) and medium pressure (MP) lamps in the presence of bromide was investigated in the present study. The UV/chlorine process significantly enhanced bromate formation as compared to dark chlorination. The bromate formation was elevated with increasing UV fluence, bromide concentration, and pH values under both LP and MP UV irradiations. It was significantly enhanced at pH 9 compared to those at pH 6 and 7 with MP UV irradiation, while it was slightly enhanced at pH 9 with LP UV. The formation by UV/chlorine process started with the formation of free bromine (HOBr/OBr-) through the reaction of chlorine and bromide, followed by a subsequent oxidation of free bromine and formation of BrO and bromate by reacting with radicals.


Assuntos
Bromatos/análise , Brometos/análise , Cloro/química , Raios Ultravioleta , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Brometos/efeitos da radiação , Halogenação , Concentração de Íons de Hidrogênio , Radical Hidroxila , Oxirredução , Fotólise , Poluentes Químicos da Água/efeitos da radiação
10.
Chemosphere ; 184: 417-428, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28614745

RESUMO

This paper applied the response surface methodology (RSM) to optimizing a novel Fe(II)/citrate/UV/PMS process in the degradation of a model micropollutant, carbamazepine (CBZ), a persistent emerging contaminant frequently detected in surface water and groundwater. The experimental conditions in terms of two responses, CBZ removal efficiency (Y1) and cost per unit CBZ removal (Y2), were optimized by the central composite design (CCD) in RSM. Modeling data exhibited that the optimum condition resulting in the lowest Y2 while achieving >70% of Y1 was at a UV dose of 265.5 mJ/cm2 and Fe(II), PMS and citrate concentrations of 12.2 µM, 100 µM and 26.4 µM, respectively. Increasing Fe(II) concentration led to the decrease in CBZ degradation and cost-effectiveness of the process. On the other hand, increasing the UV dose, PMS concentration and citrate/Fe(II) ratio over 265.5 mJ/cm2, 100 µM and 2.16:1, respectively, slightly increased the CBZ degradation, but significantly increased the cost. Under the optimized condition, the experimentally obtained values for Y1 and Y2 were 70.44% and 0.0104 H K$/%/m3, respectively. The predicted Y1 and Y2 were 71.07% and 0.0098 H K$/%/m3, respectively, suggesting that RSM can be readily used to determine the optimum condition of the Fe(II)/citrate/UV/PMS process for CBZ degradation. Other aqueous constituents which impacted the CBZ removal in the Fe(II)/citrate/UV/PMS process are in the following order: NOM > alkalinity > bromide > ammonia ≈ chloride (both negligible).


Assuntos
Recuperação e Remediação Ambiental/métodos , Poluentes Químicos da Água/química , Purificação da Água/métodos , Carbamazepina/química , Ácido Cítrico/química , Compostos Ferrosos/química , Peróxidos/química , Raios Ultravioleta
11.
Chemosphere ; 179: 306-315, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28376394

RESUMO

The enhanced removal of organic material from municipal waste water containing 50 mg/L of chemical oxygen demand and a given amount of alkyl paraben using a biofilm system was investigated. The parabens used were methyl, ethyl, and propyl paraben. The experiments were conducted at influent paraben concentrations of 10 and 50 mg/L. The influent pH was measured around 4.6 because of paraben hydrolysis. The effluent pH increased due to hydrogen consumption and small molecular acid generation. The higher removal rates were observed for the paraben with longer alkyl chains, which were more hydrophobic and capable of penetrating into microbial cells. The co-existing organic constituents in municipal waste water were found to be competitive with paraben molecules for microbial degradation at low paraben loading (i.e., 10 mg/L). Instead, the co-metabolic effect was observed at a higher paraben loading (i.e., 50 mg/L) due to more active enzymatic catalysis, implying the possible enhancement or organic removal in the presence of high levels of parabens. The difference in BOD and TOC removing ratios for parabens decreased with increasing HRT, implying their better mineralization than that of municipal organic constituents. This was because the microbial organism became more adapted to the reacting system with longer HRT, and more oxygenase was produced to facilitate the catechol formation and ring-opening reactions, causing apparent enhancement in mineralization.


Assuntos
Cosméticos/química , Parabenos/química , Águas Residuárias/química , Purificação da Água/métodos , Bactérias/efeitos dos fármacos , Bactérias/metabolismo , Análise da Demanda Biológica de Oxigênio , Conservantes Farmacêuticos/química , Relação Estrutura-Atividade , Águas Residuárias/microbiologia
12.
Water Environ Res ; 88(12): 2285-2291, 2016 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-26961282

RESUMO

This study aims to assess the upstream rainfall thresholds corresponding to the maximum allowable turbidity of source water, using monitoring data and artificial neural network computation. The Taipei Water Source Domain was selected as the study area, and the upstream rainfall records were collected for statistical analysis. Using analysis of variance (ANOVA), the cumulative rainfall records of one-day Ping-lin, two-day Ping-lin, two-day Tong-hou, one-day Guie-shan, and one-day Tai-ping (rainfall in the previous 24 or 48 hours at the named weather stations) were found to be the five most significant parameters for downstream turbidity development. An artificial neural network model was constructed to predict the downstream turbidity in the area investigated. The observed and model-calculated turbidity data were applied to assess the rainfall thresholds in the studied area. By setting preselected turbidity criteria, the upstream rainfall thresholds for these statistically determined rain gauge stations were calculated.


Assuntos
Chuva , Movimentos da Água , Abastecimento de Água , Modelos Teóricos , Nefelometria e Turbidimetria , Rios
13.
Chemosphere ; 150: 731-739, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26733013

RESUMO

N-Nitrosopyrrolidine (NPYR) is an emerging contaminant in drinking water and wastewater. The degradation kinetics and mechanisms of NPYR degradation by the O3/UV process were investigated and compared with those of UV direct photolysis and ozonation. A synergistic effect of ozone and UV was observed in the degradation of NPYR due to the accelerated production of OH• by ozone photolysis. This effect was more pronounced at higher ozone dosages. The second-order rate constants of NPYR reacting with OH• and ozone was determined to be 1.38 (± 0.05) × 10(9) M(-1) s(-1) and 0.31 (± 0.02) M(-1) s(-1), respectively. The quantum yield by direct UV photolysis was 0.3 (± 0.01). An empirical model using Rct (the ratio of the exposure of OH• to that of ozone) was established for NPYR degradation in treated drinking water and showed that the contributions of direct UV photolysis and OH• oxidation on NPYR degradation were both significant. As the reaction proceeded, the contribution by OH• became less important due to the exhausting of ozone. Nitrate was the major product in the O3/UV process by two possible pathways. One is through the cleavage of nitroso group to form NO• followed by hydrolysis, and the other is the oxidation of the intermediates of amines by ozonation.


Assuntos
N-Nitrosopirrolidina/química , Ozônio/química , Poluentes Químicos da Água/química , Cinética , Oxirredução , Fotólise , Raios Ultravioleta , Purificação da Água
14.
Environ Monit Assess ; 186(8): 4925-34, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24691737

RESUMO

The purpose of this study is to establish a turbidity forecasting model as well as an early-warning system for turbidity management using rainfall records as the input variables. The Taipei Water Source Domain was employed as the study area, and ANOVA analysis showed that the accumulative rainfall records of 1-day Ping-lin, 2-day Ping-lin, 2-day Fei-tsui, 2-day Shi-san-gu, 2-day Tai-pin and 2-day Tong-hou were the six most significant parameters for downstream turbidity development. The artificial neural network model was developed and proven capable of predicting the turbidity concentration in the investigated catchment downstream area. The observed and model-calculated turbidity data were applied to developing the turbidity early-warning system. Using a previously determined turbidity as the threshold, the rainfall criterion, above which the downstream turbidity would possibly exceed this respective threshold turbidity, for the investigated rain gauge stations was determined. An exemplary illustration demonstrated the effectiveness of the proposed turbidity early-warning system as a precautionary alarm of possible significant increase of downstream turbidity. This study is the first report of the establishment of the turbidity early-warning system. Hopefully, this system can be applied to source water turbidity forecasting during storm events and provide a useful reference for subsequent adjustment of drinking water treatment operation.


Assuntos
Algoritmos , Poluentes da Água/análise , Abastecimento de Água/estatística & dados numéricos , Monitoramento Ambiental , Previsões , Modelos Estatísticos , Probabilidade , Chuva
15.
Chemosphere ; 105: 95-9, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24530166

RESUMO

This study aimed to explore the structure variation of bagasse-derived composts during their maturation process. The surface tension and dissolved carbon content of their extract (compost tea) were measured, and the compost structure was analyzed using FTIR and (13)C NMR. The FTIR and (13)C NMR analyses showed that the alkyl and aromatic contents of the investigated composts increased as the composting time increased from 0 to 6 months. The aqueous solubility enhancements of tetrachloroethene (PCE) and toluene by bagasse-derived compost tea with different maturities were investigated. The PCE and toluene solubility enhancement experiments were conducted at various compost concentrations. The most PCE and toluene solubility were enhanced by 3 and 6-month bagasse-derived composts, respectively. This observation was due to the structural transformation from alkyl to aromatic functional groups in the composting process.


Assuntos
Celulose/química , Tetracloroetileno/química , Tolueno/química , Poluentes Químicos da Água/química , Carbono/análise , Recuperação e Remediação Ambiental , Espectroscopia de Ressonância Magnética , Saccharum , Solo/química , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier
16.
Chemosphere ; 93(1): 178-83, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23786814

RESUMO

This study aimed to characterize the NOM structural variation during Fenton process, in which the methomyl and humic acid were selected as the investigated compounds. The preliminary degradation experiments were conducted at various H2O2 and Fe(2+) concentrations without the presence of NOM to determine the applied Fenton reagent dosages for subsequent NOM impact on Fenton degradation. The methomyl removal at 80% was observed at the Fenton reagent ratio ([H2O2]/[Fe(2+)]) of 1 while Fe(2+) concentration was no less than 2mM. In the presence of NOM, the methomyl removal by Fenton process was further enhanced apparently. The NOM used in this study was found to be a macromolecule with tryptophan-like and tyrosine-like functional groups through fluorescence spectrometry analysis. The addition of ferrous ions in the NOM solution initiated the reactions between Fe(2+)/Fe(3+) redox couples and NOM molecules, breaking the NOM into smaller organic fractions. These organic fractions were further oxidized into even smaller molecules by hydroxyl radicals after H2O2 addition. The NOM might compete with methomyl for hydroxyl radicals, and enhance the catalytical generation of hydroxyl radicals by reducing Fe(3+) to Fe(2+) at the same time. Apparently, the increase in OH generation was more than the OH consumption by NOM presence, resulting in the observed enhancement of methomyl removal.


Assuntos
Produtos Biológicos/química , Poluentes Ambientais/química , Peróxido de Hidrogênio/química , Ferro/química , Metomil/química , Substâncias Húmicas
17.
Biodegradation ; 24(2): 227-43, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22842856

RESUMO

This study aimed to explore the microbial community variation and treatment ability of a full-scale anoxic-aerobic-anoxic-aerobic (AOAO) process used for optoelectronic wastewater treatment. The sludge samples in the biological treatment units were collected and subsequently subjected to polymerase chain reaction (PCR) amplification and denaturing gradient gel electrophoresis identification and the wastewater components such as BOD5 and NH3-N were evaluated during the processes. The group specific primers selected were targeting at the kingdom Bacteria, the Acidobacterium, the α-proteobacteria, the ß-proteobacteria ammonia oxidizers, Actinobacteria and methyllotrophs, and the 16S rDNA clone libraries were established. Ten different clones were obtained using the Bacteria primers and eight different clones were obtained using the ß-proteobacteria ammonia oxidizer primers. Over 95 % of BOD5 and 90 % of NH3-N were removed from the system. The microbial community analysis showed that the Janthinobacterium sp. An8 and Nitrosospira sp. were the dominant species throughout the AOAO process. Across the whole clone library, six clones showed closely related to Janthinobacterium sp. and these species seemed to be the dominant species with more than 50 % occupancy of the total population. Nitrosospira sp. was the predominant species within the ß-proteobacteria and occupied more than 30 % of the total population in the system. These two strains were the novel species specific to the AOAO process for optoelectronic treatment, and they were found strongly related to the system capability of removing aquatic contaminants by inspecting the wastewater concentration variation across the system.


Assuntos
Biotecnologia/métodos , Eletroforese em Gel de Gradiente Desnaturante/métodos , Reação em Cadeia da Polimerase/métodos , Eliminação de Resíduos Líquidos/métodos
18.
Bioresour Technol ; 102(22): 10498-504, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21924893

RESUMO

This study sets up microcosms using two types of compost samples, bagasse/manure compost, and yard-trimming compost with different maturity, to evaluate their capacity for reductive dechlorination of tetrachloroethene (PCE). The experimental results show that less matured compost samples could reduce 300 µM of PCE to ethene within 180 days of incubation. Decreasing initial PCE concentration and removing dissolved oxygen from the solution could enhance reducing efficiency. The solution remains near neutral pH throughout the experiment, and ethene emerged when the redox potential dropped to below -150 mV. Different microbial inhibition agents, such as 2-bromoethanesulfonic acid and sodium molybdate 2-hydrate, exhibit different effects on the dechlorination efficiency. The potential advantages of using compost to remove PCE are discussed. Overall, due to their high carbon content, diverse microbial activity, high buffer capacity, and complex physical structure, compost samples could serve as suitable media for dechlorinating PCE.


Assuntos
Halogenação , Solo/química , Tetracloroetileno/isolamento & purificação , Bactérias/efeitos dos fármacos , Bactérias/metabolismo , Biodegradação Ambiental/efeitos dos fármacos , Celulose/química , Halogenação/efeitos dos fármacos , Hidrogênio/metabolismo , Concentração de Íons de Hidrogênio/efeitos dos fármacos , Esterco , Molibdênio/farmacologia , Nitrogênio/química , Oxirredução/efeitos dos fármacos , Oxigênio/isolamento & purificação , Solubilidade/efeitos dos fármacos
19.
Chemosphere ; 82(2): 229-36, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21035166

RESUMO

The purpose of this study is to investigate parathion degradation by Fenton process in neutral environment. The initial parathion concentration for all the degradation experiments was 20 ppm. For hydrogen ion effect on Fenton degradation, the pH varied from 2 to 8 at the [H2O2] to [Fe²(+)] ratio of 2-2 mM, and the result showed pH 3 as the most effective environment for parathion degradation by Fenton process. Apparent degradation was also observed at pH 7. The subsequent analysis for parathion degradation was conducted at pH 7 because most environmental parathion exists in the neutral environment. Comparing the parathion degradation results at various Fenton dosages revealed that at Fe²(+) concentrations of 0.5, 1.0 and 1.5 mM, the Fenton reagent ratio ([H2O2]/[Fe²(+)]) for best-removing performance were found as 4, 3, and 2, resulting in the removal efficiencies of 19%, 48% and 36%, respectively. Further increase in Fe²(+) concentration did not cause any increase of the optimum Fenton reagent ratio for the best parathion removal. The result from LC-MS also indicated that hydroxyl radicals might attack the PS double bond, the single bonds connecting nitro-group, nitrophenol, or the single bond within ethyl groups of parathion molecules forming paraoxons, nitrophenols, nitrate/nitrite, thiophosphates, and other smaller molecules. Lastly, the parathion degradation by Fenton process at the presence of humic acids was investigated, and the results showed that the presence of 10 mg L⁻¹ of humic acids in the aqueous solution enhanced the parathion removal by Fenton process twice as much as that without the presence of humic acids.


Assuntos
Inseticidas/química , Paration/química , Poluentes Ambientais/química , Recuperação e Remediação Ambiental/métodos , Substâncias Húmicas , Peróxido de Hidrogênio/química , Concentração de Íons de Hidrogênio , Ferro/química , Cinética
20.
J Hazard Mater ; 181(1-3): 763-70, 2010 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-20638964

RESUMO

The purpose of this present study is to investigate the removal efficiency of chemical oxygen demand (COD) from pulp and paper wastewater using laccase-polymerized membrane filtration process. The membranes with molecular weight cut-off (MWCO) of 5000 and 10,000, 30,000 and 54,000 were used in a cross-flow module to treat the pulp and paper wastewater containing high phenolic constituents and COD. With 2.98 IU/L of activated laccase applied at room temperature for 180 min, the contaminants in raw wastewater and second effluent were polymerized to form larger molecules with average molecular weight of 1300 and 900 Da (Dalton), respectively. With laccase polymerization prior to filtration, over 60% removals of COD by the four investigated membranes were observed, compared with low COD removal without laccase polymerization. Moreover, the addition of laccase resulted in 4-14% reduction of membrane permeability during the first 180 min filtration operation due to gel layer formation by the polymerization. No further flux decline was observed afterwards indicating the steady state was reached and the membranes could be used to remove the polymerized pollutants without significant fouling. The maximum apparent resistance occurrence for raw wastewater treated with laccase also supported the effectiveness for COD removal with laccase polymerization before membrane filtration. Additionally, pretreatment by inactivated laccase only caused further flux reduction without additional removal of COD.


Assuntos
Resíduos Industriais/prevenção & controle , Oxigênio/química , Papel , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Filtração , Lacase/metabolismo , Membranas Artificiais , Fenóis
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