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1.
Chemosphere ; 364: 143154, 2024 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-39173835

RESUMEN

As climate change induces changes in water quality and available water quantity of drinking water supply sources, the final product water quality changes in terms of trace organics including disinfection byproducts (DBPs) formed during water treatment. In this study, the seasonal variability and speciation of DBPs across nine sample sites within a drinking water distribution system serving ∼400k people over a one-year period was investigated considering the governing parameters of water quality and treatment/transport/storage of finished water. The system considered treats surface water from a river and practices aquifer storage and recovery to address seasons water availability changes. Eighty-eight (88) sample sets were collected and held for 6-months in the laboratory to simulate extended storage scenarios associated with ASR operations, and each was analyzed at 9 different timesteps for concentration and speciation of chlorinated DBPs. Samples from groundwater influenced sites exhibited significantly lower total organic carbon (TOC) compared to other sites from the river source, and also were observed to have the lowest DBP formation. Three sites exceeded the Maximum Contaminant Level (MCL) for four total trihalomethanes (THM4) within 30-60 days of storage. Chloroform was the predominant THM4 species, even in groundwater-influenced locations, whereas di- and tri-chloroacetic acid (DCA and TCA) were the most prevalent haloacetic acids (HAA5). Extended water age at one site, coupled with low initial chlorine concentrations exhibited higher initial THM4 concentrations and flat DBP formation curves. The study results provide new insights into DBP occurrence and fate in drinking water distribution systems which consider water storage such as in ASR.

2.
Environ Sci Pollut Res Int ; 31(36): 49413-49426, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-39075183

RESUMEN

The evaluation of the photocatalytic properties of electrospun TiO2 nanofibres (TiO2-NFs) synthesised in the same experimental conditions using two distinct precursors, tetraisopropyl orthotitanate (TTIP) and tetrabutyl orthotitanate (TNBT), with morphology and crystalline structure controlled by annealing at 460 °C for 3 h is presented. The presence of circular-shaped TiO2-NFs was corroborated by scanning electron microscopy (SEM). By using X-ray photoelectron spectroscopy (XPS), the chemical binding energies and their interactions of the TiO2 with the different incorporated impurities were determined; the most intense photoelectronic transitions of Ti 2p3/2 (458.39 eV), O 1 s (529.65 eV) and C 1 s (284.51 eV) were detected for TTIP and slightly blue-shifted for TNBT. By using energy-dispersive X-ray spectroscopy (EDS), the chemical element percentages in TiO2 were determined. Using X-ray diffraction, it was found that the annealed electrospun TiO2-NFs presented the anatase crystalline phase and confirmed by Raman scattering. Bandgap energies were determined by diffuse reflectance spectroscopy at room temperature. The photocatalytic degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide under exposure to ultraviolet light was studied using the TiO2-NFs obtained with the two molecular precursors. The results showed that the catalyst, prepared with the TTIP precursor, turned out to be the one that presented the highest photocatalytic activity with a half-life time (t1/2) of 28 min and a degradation percentage of 93%. The total organic carbon (TOC) in the solutions resulting from the 2,4-D degradation by the TiO2-NFs was measured, which showed a TOC removal of 50.67% for the TTIP sample and 36.14% for the TNBT sample. Finally, by using FTIR spectroscopy, the final chemical compounds of the degradation were identified as H2O and CO2.


Asunto(s)
Ácido 2,4-Diclorofenoxiacético , Nanofibras , Titanio , Titanio/química , Nanofibras/química , Ácido 2,4-Diclorofenoxiacético/química , Catálisis
3.
Ecotoxicol Environ Saf ; 281: 116669, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38954908

RESUMEN

In most of advanced oxidation processes (AOPs) used to destroy harmful organic chemicals in water/wastewater hydroxyl radical (•OH) reactions oxidize (increasing the oxygen/carbon ratio in the molecules) and mineralize (transforming them to inorganic molecules, H2O, CO2, etc.) these contaminants. In this paper, we used the radiolysis of water to produce •OH and characterised the rate of oxidation and mineralization by the dose dependences of the Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) content values. Analysis of the dose dependences for 34 harmful organic compounds showed large differences in the oxidation and mineralization rates and these parameters are characteristic to the given group of chemicals. E.g., the rate of oxidation is relatively low for fluoroquinolone antibiotics; it is high for ß-blocker medicines. Mineralization rates are low for both fluoroquinolones and ß-blockers. The one-electron-oxidant •OH in most cases induces two - four-electron-oxidations. Most of the degradation takes place gradually, through several stable molecule intermediates. However, based on the results it is likely, that some part of the oxidation and mineralization takes place parallel. The organic radicals formed in •OH reactions react with several O2 molecules and release several inorganic fragments during the radical life cycle.


Asunto(s)
Radical Hidroxilo , Compuestos Orgánicos , Oxidación-Reducción , Contaminantes Químicos del Agua , Radical Hidroxilo/química , Contaminantes Químicos del Agua/química , Compuestos Orgánicos/química , Análisis de la Demanda Biológica de Oxígeno , Aguas Residuales/química , Carbono/química
4.
Sci Total Environ ; 943: 173743, 2024 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-38848906

RESUMEN

This study utilizes machine learning (ML) algorithms to develop a robust total organic carbon (TOC) prediction model for river waters in the Geumho River sub-basins, South Korea, considering both non-rain and rain events. The model incorporates geospatial parameters such as land use, slope, flow rate, and basic water quality metrics including biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), and suspended solids (SS). A key aspect of this research is examining how land use information enhances the model's predictive accuracy. We compared two ML algorithms-extreme gradient boosting (XGBoost) and deep neural networks (DNN)-with a traditional multiple linear regression (MLR) approach. XGBoost outperformed the others, achieving an R2 value between 0.61 and 0.68 in the test dataset and demonstrating significant improvement during rain events with an R2 of 0.77 when including land use data. In contrast, this enhancement was not observed with the MLR model. Feature importance analysis using Shapley values highlighted COD as the primary predictor for non-rain events, while during rain events, COD, TP, TN, SS and agricultural land collectively influenced TOC levels. This study significantly advances understanding of TOC variability across different land use scenarios in river systems and underscores the importance of integrating geospatial and water quality parameters to enhance TOC prediction, particularly during rain events. This methodology provides a valuable framework for developing river management strategies and monitoring long-term TOC trends, especially in scenarios with gaps in essential monitoring data.

5.
Insects ; 15(5)2024 Apr 25.
Artículo en Inglés | MEDLINE | ID: mdl-38786863

RESUMEN

This work attempts to find the reasons for the rather limited range of occurrence of Cheilotoma musciformis in Poland, based on soil properties, which affects both the plant cover and the entomofauna. The aim of the study was to assess the influence of soil enzyme activity on the occurrence of Ch. musciformis in xerothermic grasslands in Southern Poland. The sites inhabited by the beetle were most often extensively grazed by farm animals or had recently been cleared of bushes. The control plots were in wasteland. The soils of most sites with Ch. musciformis were characterized by significantly higher activity of the tested enzymes and higher content of total organic carbon and total nitrogen, as well as lower pHKCl compared to the control sites. The higher enzymatic activity of soils in sites with the beetle than in the control sites may indicate the dependence of the occurrence of this beetle on the presence of patches of extensively grazed xerothermic grasslands. Grazing influences the behavior of preferred host plant species. Therefore, when planning active protection of xerothermic grasslands inhabited by Ch. musciformis, changes in the biochemical properties of the soil and vegetation structure should be taken into account.

6.
Membranes (Basel) ; 14(5)2024 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-38786946

RESUMEN

This study highlights the effectiveness of photocatalytically modified ceramic ultrafiltration (UF) membranes in alleviating two major drawbacks of membrane filtration technologies. These are the generation of a highly concentrated retentate effluent as a waste stream and the gradual degradation of the water flux through the membrane due to the accumulation of organic pollutants on its surface. The development of two types of novel tubular membranes, featuring photocatalytic Mo-BiVO4 inverse opal coatings, demonstrated a negligible impact on water permeance, ensuring consistent filtration and photocatalytic efficiency and suggesting the potential for maintaining membrane integrity and avoiding the formation of highly concentrated retentate effluents. Morphological analysis revealed well-defined coatings with ordered domains and interconnected macropores, confirming successful synthesis of Mo-BiVO4. Raman spectroscopy and optical studies further elucidated the composition and light absorption properties of the coatings, particularly within the visible region, which is vital for photocatalysis driven by vis-light. Evaluation of the tetracycline removal efficiency presented efficient adsorption onto membrane surfaces with enhanced photocatalytic activity observed under both UV and vis-light. Additionally, vis-light irradiation facilitated significant degradation, showcasing the versatility of the membranes. Total Organic Carbon (TOC) analysis corroborated complete solute elimination or photocatalytic degradation without the production of intermediates, highlighting the potential for complete pollutant removal. Overall, these findings emphasize the promising applications of Mo-BiVO4 photocatalytic membranes in sustainable water treatment and wastewater remediation processes, laying the groundwork for further optimization and scalability in practical water treatment systems.

7.
Environ Sci Pollut Res Int ; 31(23): 33515-33529, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38683429

RESUMEN

Airborne particles (dust pollution) pose a significant threat to both human and plant populations. Plant leaves act as crucial biofilters, capturing significant amounts of air pollution; this characteristic offers a valuable tool to measure local pollution levels and assess individual plant species' ability to intercept and mitigate harmful dust particles. The present study was carried out to asses the effect of responses of various plant species to dust pollution near and around the marble mining site comprising residential site, highway area, and Central University of Rajasthan as control. The anticipated pollution index, air pollution tolerance index (APTI), dust absorption capacity, metal accumulation index (MAI), and biochemical factors were used to evaluate plant responses. Azadirachta indica A. Juss. demonstrated the highest (29.0) and Vachellia nilotica L. showed lowest (5.6) APTI, respectively. A. indica showed maximum MAI values in comparison to other plant species situated at residential site. Additionally, monitoring of particulate matter (PM10) observed to highest at highway, followed by mining, residential, and control sites. Overall A. indica representing highest APTI and effective dust capturing capacity at all sites could serve as potential pollution sinks. V. nilotica, with its very low APTI, can be marked as biomonitoring tool for detecting dust pollution.


Asunto(s)
Contaminantes Atmosféricos , Polvo , Monitoreo del Ambiente , Minería , Plantas , India , Polvo/análisis , Monitoreo del Ambiente/métodos , Contaminantes Atmosféricos/análisis , Plantas/efectos de los fármacos , Contaminación del Aire , Material Particulado/análisis
8.
Environ Sci Pollut Res Int ; 31(21): 30716-30734, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38613753

RESUMEN

Textile effluent discharge can negatively impact the environment and living organisms due to its potential toxicity, higher percentages of total organic carbon (TOC) contents, and so on. The study investigates the extraordinary performance of the electrocoagulation process (ECP) combined with powdered activated carbon (PAC) as a highly effective and environmental friendly method of treating textile effluents. This scientific work mainly includes the focus on removing toxic components in textile effluents, such as high concentrations of colour and TOC using synthesized PAC derived from coconut shells coupled with the ECP (ECP-PAC). Initially, PAC was characterized by using XRD, Raman, BET, FTIR, and TGA studies. Subsequently, the pilot-scale ECP-PAC batch reactor was constructed with iron (Fe) as an anode and copper (Cu) as a cathode. The pilot-scale ECP-PAC batch reactor has achieved higher treatment efficiency in a shorter reaction time with low energy consumption compared to a stand-alone ECP. Further, the optimum conditions for effective ECP-PAC have been optimized, such as pH 7.5, applied current density (0-50 mA/cm2), reaction time (0-30 min), electrode combinations (Fe-Cu) with electrode distances of 5 cm apart, and an optimum dose of 5 g/L of PAC. Specifically, 98% of the colour and 96% of the TOC contents present in the industrial textile effluent were treated in 15 and 30 min, respectively. In quantitative perspectives, the developed batch reactor has sharply decreased TOC (324.1 mg/L), IC (1410 mg/L) and TC (1019 mg/L) to 13.55 mg/L (96%), 31.49 mg/L (97%), and 48.05 mg/L (95%), respectively, in 30 min demonstrating its sensitivity and selectivity with the utmost care. Moreover, the physicochemical properties of the treated water were convincingly assessed. That is, it remains suitable for the seed germination of mung bean and chlorophyll content study. Thus, the developed methodology could effectively reduce freshwater consumption in the agricultural sector, increase freshwater availability in water-scarce regions, and facilitate the increase of the recharging capacity of groundwater tables.


Asunto(s)
Carbono , Germinación , Textiles , Eliminación de Residuos Líquidos , Contaminantes Químicos del Agua , Carbono/química , Eliminación de Residuos Líquidos/métodos , Adsorción , Color , Electrocoagulación , Semillas/química , Aguas Residuales/química
9.
Mar Pollut Bull ; 202: 116307, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38564820

RESUMEN

This study utilizes ultraviolet and fluorescence spectroscopic indices of dissolved organic matter (DOM) from sediments, combined with machine learning (ML) models, to develop an optimized predictive model for estimating sediment total organic carbon (TOC) and identifying adjacent land-use types in coastal sediments from the Yellow and Bohai Seas. Our results indicate that ML models surpass traditional regression techniques in estimating TOC and classifying land-use types. Penalized Least Squares Regression (PLR) and Cubist models show exceptional TOC estimation capabilities, with PLR exhibiting the lowest training error and Cubist achieving a correlation coefficient 0.79. In land-use classification, Support Vector Machines achieved 85.6 % accuracy in training and 92.2 % in testing. Maximum fluorescence intensity and ultraviolet absorbance at 254 nm were crucial factors influencing TOC variations in coastal sediments. This study underscores the efficacy of ML models utilizing DOM optical indices for near real-time estimation of marine sediment TOC and land-use classification.


Asunto(s)
Carbono , Monitoreo del Ambiente , Sedimentos Geológicos , Aprendizaje Automático , Sedimentos Geológicos/química , Carbono/análisis , Monitoreo del Ambiente/métodos
10.
Water Res ; 256: 121610, 2024 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-38663212

RESUMEN

Lacking of available water quality data causes the limited understanding of the coupled dynamics of hydrologic and nutrient cycles in lakes and reservoirs and along river streams. This study conducts the rotated Principal Component Analysis (rPCA) of water volume and total organic carbon (TOC) concentration data from ∼2200 agricultural reservoirs in South Korea to extract the major modes of their spatiotemporal variability. Over 2020-2022, the total TOC load in the reservoirs ranges between 1,165 and 1,492 tons (289 and 360 Mtons of water storage volume; 3.54 and 4.60 mg/L of TOC concentration). The first rPCA mode is assoicated with a decreasing trend of water level (38 % of the explained variance) and increasing trend of TOC concentration (27 %) over the southern Korea region, where the TOC concentration increased during the 2022 drought. The second rPCA mode is associated with interannual variability of water level (25 %) and TOC concentration (18 %) over the central Korea region. This study found a marginal relationship between paddy field area and TOC concentration and their regime shift to high TOC concentration during the 2022 drought, which was a potential cause of the increased TOC concentration in 2022. This study provided observational evidence of interactions between water volume and TOC concentration during a severe drought, suggesting a possible shift of the role of agricultural reservoirs to carbon source.


Asunto(s)
Agricultura , Carbono , República de Corea , Carbono/análisis , Monitoreo del Ambiente , Análisis Espacio-Temporal , Ríos/química , Agua
11.
Sci Total Environ ; 926: 171964, 2024 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-38537810

RESUMEN

Short (SCCPs) and medium (MCCPs) chain chlorinated paraffins being the emerging organic pollutants have raised serious concerns due to their widespread use and related human health risks. However, their occurrence in aquatic bodies like rivers and associated damage to ecological integrity is yet unknown in some regions of the world. The current study is the first ever assessment of SCCPs and MCCPs in sediment and water of river Ravi, Pakistan. Spatial occurrence and associated ecological risks were investigated from sediments (n = 16) and composite water samples (n = 8) collected at eight locations along the stretch of river Ravi. The concentrations of SCCPs and MCCPs varied from below limit of detection (

Asunto(s)
Cloro , Hidrocarburos Clorados , Humanos , Animales , Hidrocarburos Clorados/análisis , Parafina/análisis , Ríos , Pakistán , Monitoreo del Ambiente , Medición de Riesgo , Carbono , China
12.
J Hazard Mater ; 466: 133504, 2024 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-38310848

RESUMEN

This study aims to evaluate the role of indigenous microorganisms in the mobilization of potentially toxic elements (PTE) and rare-earth elements (REE), the influence of the bioavailability of carbon sources that might boost microbial leaching, and the generation of neutral/alkaline mine drainage from alkaline tailings. These tailings, with significant concentrations of total organic carbon (TOC), were mainly colonized by bacteria belonging to the genera Sphingomonas, Novosphingobium and Solirubrobacter, and fungi of the genera Alternaria, Sarocladium and Aspergillus. Functionality analysis suggests the capability of these microorganisms to leach PTE and REE. Bio-/leaching tests confirmed the generation of neutral mine drainage, the influence of organic substrate, and the leaching of higher concentrations of PTE and REE due to the production of organic acids and siderophores by indigenous microorganisms. In addition, this study offers some insights into a sustainable alternative for reprocessing PMC alkaline tailings to recover REE.


Asunto(s)
Metales de Tierras Raras , Metales de Tierras Raras/metabolismo , Bacterias/metabolismo , Carbono/metabolismo
13.
Chemosphere ; 352: 141458, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38364920

RESUMEN

Accurate analyses of total organic carbon (TOC) encompassing particulate organic carbon in wastewater are key for evaluating the behavior of particulate organic contaminants and maintaining the carbon mass balance throughout the wastewater treatment process. This study was conducted to develop candidate reference materials of environmental origin from excess sludge collected from wastewater treatment facilities, primarily receiving industrial wastewater and livestock manure as the main sources. Homogeneity and stability assessments for total carbon (TC) and TOC were conducted in the particle samples following the standardized procedures of ISO Guide 35 and ISO 13258. The results showed that high inorganic carbon (IC) content in particles, such as YJ(500) (IC: 29%), rendered them unsuitable for TOC quality control (QC), as they increased uncertainty in both homogeneity and stability assessments. Additionally, a13C NMR analysis revealed that samples with a high (O-alkyl)/(C-H-alkyl) ratio in their carbon structures exhibited relatively low stability. Through the homogeneity and stability assessments, a particle sample, YJ(100), was selected as the reference material (RM); the assigned values were as follows: 30.78% for TC and 27.94% for TOC, with uncertainties of 0.01% and 1.1%, respectively. Furthermore, considering sample transportation conditions, the safe storage period for the RM particles was determined to be 2 weeks under harsh conditions (at 40 °C). In our inter-laboratory test (n = 8) using the particle samples, we confirmed that the particle samples can effectively enhance particle processing QC and validate a proposed suspended solids pretreatment method. This study showcases valuable environmental particle sample production and evaluation, offering potential advancements in the QC of TOC analysis for wastewater samples.


Asunto(s)
Aguas del Alcantarillado , Aguas Residuales , Aguas del Alcantarillado/química , Carbono/análisis , Polvo
14.
Sci Total Environ ; 919: 170704, 2024 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-38346654

RESUMEN

South Korea recently shifted its assessment indicator for organic matter in terrestrial environments from chemical oxygen demand (COD) to total organic carbon (TOC) due to the increase in refractory organic carbon levels. However, in the marine environment, where the inflow of refractory organic matter is also on the rise, COD is still used in some instances to assess organic pollution in contaminated areas. Our findings reveal that the main source of dissolved organic carbon (DOC) is terrestrial-derived refractory organic carbon, which enters through nearby wastewater treatment plant (WWPT) outlets. The low oxidation efficiency of COD to TOC (approximately 4 %) prevents it from being an accurate measure of terrestrial-derived refractory DOC. Contrasting results were observed when comparing the organic pollution index (OPI), which we calculated using TOC, with the currently employed water quality index (WQI) for ocean water quality evaluation, particularly in areas influenced by WWPTs. This discrepancy arises because the WQI primarily evaluates autochthonous organic carbon through chlorophyll measurements, whereas the OPI incorporates both autochthonous and allochthonous organic carbon through TOC measurements. Our findings demonstrate that TOC can effectively replace COD as an organic pollution indicator in marine environments.

15.
Ecol Appl ; 34(2): e2945, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38286682

RESUMEN

Eutrophication and brownification are ongoing environmental problems affecting aquatic ecosystems. Due to anthropogenic changes, increasing amounts of organic and inorganic compounds are entering aquatic systems from surrounding catchment areas, increasing both nutrients, total organic carbon (TOC), and water color with societal, as well as ecological consequences. Several studies have focused on the ability of wetlands to reduce nutrients, whereas data on their potential to reduce TOC and water color are scarce. Here we evaluate wetlands as a potential multifunctional tool for mitigating both eutrophication and brownification. Therefore, we performed a study for 18 months in nine wetlands allowing us to estimate the reduction in concentrations of total nitrogen (TN), total phosphorus (TP), TOC and water color. We show that wetland reduction efficiency with respect to these variables was generally higher during summer, but many of the wetlands were also efficient during winter. We also show that some, but not all, wetlands have the potential to reduce TOC, water color and nutrients simultaneously. However, the generalist wetlands that reduced all four parameters were less efficient in reducing each of them than the specialist wetlands that only reduced one or two parameters. In a broader context, generalist wetlands have the potential to function as multifunctional tools to mitigate both eutrophication and brownification of aquatic systems. However, further research is needed to assess the design of the generalist wetlands and to investigate the potential of using several specialist wetlands in the same catchment.


Asunto(s)
Ecosistema , Humedales , Eutrofización , Nitrógeno , Agua
16.
Atmos Environ (1994) ; 3192024 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-38250566

RESUMEN

In this study, we developed two online monitors for total organic carbon (TOC) and water-soluble organic carbon (WSOC) measurements in fine (dp < 2.5µm) and coarse (2.5µm < dp < 10µm) particulate matter (PM), respectively. Their performance has been evaluated in laboratory and field tests to demonstrate the feasibility of using these monitors to measure near real-time concentrations, with consideration of their potential for being employed in long-term measurements. The fine PM collection setup was equipped with a versatile aerosol concentration enrichment system (VACES) connected to an aerosol-into-liquid-sampler (AILS), whereas two virtual impactors (VIs) in tandem with a modified BioSampler were used to collect coarse PM. These particle collection setups were in tandem with a Sievers M9 TOC analyzer to read TOC and WSOC concentrations in aqueous samples hourly. The average hourly TOC concentration measured by our developed monitors in fine and coarse PM were 5.17 ± 2.41 and 0.92 ± 0.29 µg/m3, respectively. In addition, our TOC readings showed good agreement and were comparable with those quantified using Sunset Lab EC/OC analyzer operating in parallel as a reference. Furthermore, we conducted field tests to produce diurnal profiles of fine PM-bound WSOC, which can show the effects of ambient temperature on maximum values in the nighttime chemistry of the winter, as well as on increased photochemical activities in afternoon peaks during the summer. According to our experimental campaign, WSOC mean values during the study period (3.07 µg/m3 for the winter and 2.7 µg/m3 for the summer) were in a comparable range with those of earlier studies in Los Angeles. Overall, our results corroborate the performance of our developed monitors in near real-time measurements of TOC and WSOC, which can be employed for future source apportionment studies in Los Angeles and other areas, aiding in understanding the health impacts of different pollution sources.

17.
Molecules ; 29(2)2024 Jan 14.
Artículo en Inglés | MEDLINE | ID: mdl-38257318

RESUMEN

The long time (2 h) required for measurement, expensive chemicals (Ag2SO4), and toxic reagents (K2Cr2O7, HgSO4) limit the application of the standard method for measuring the oxygen equivalent of organic content in wastewater (chemical oxygen demand, COD). In recent years, the COD has increasingly been replaced by the total organic carbon (TOC) parameter. Since the limit values of the pollution levels are usually given in terms of the COD, efforts are being made to find the correlation between these parameters. Several papers have published correlation analyses of COD and TOC for industrial and municipal wastewater, but the relationship has not been discussed for individual chemicals. Here, this relationship was investigated using 70 contaminants (laboratory chemicals, pharmaceuticals, and pesticides). The calculated COD values, in most cases, agreed, within ~10%, with the experimental ones; for tetracyclines and some chloroaromatic molecules, the measured values were 20-50% lower than the calculated values. The COD/TOC ratios were between 2 and 3: for macrolides, they were ~3; for fluoroquinolones and tetracyclines, they were ~2. The molecular structure dependence of the ratio necessitates the establishing of the correlation on an individual basis. In advanced oxidation processes (AOPs), the ratio changes during degradation, limiting the application of TOC instead of COD.

18.
Waste Manag Res ; 42(3): 206-217, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-37486123

RESUMEN

Wet oxidation can be an effective process for the pretreatment of complex biomass such as lignocellulose. However, studies on the use of wet oxidation for treating solid waste such as dairy manure are limited. The use of partial wet oxidation to convert dairy manure into low molecular weight carboxylic acids as final products were investigated. This work focuses on the performance of the sub-critical wet oxidation treatment of dairy cattle manure as a conversion/pretreatment process to release matter from the lignocellulosic fraction rather than a destructive process. The operating conditions were controlled at the short residence time and optimal temperature in the presence of oxygen under a pressure of 120 psi. The thermal hydrolysis under wet oxidation significantly affected conversion manure slurry into organic acids. The concentration of acetic acid reached 1778 mg L-1, achieved at 190°C (60 minutes reaction time) as the reaction temperature increased within the range of 150°C-200°C, total organic carbon was reduced and monomers in the process liquids decreased. On the other hand, soluble COD in process liquids increased with an increment in reaction temperature. The results provide insights into technical options to pretreat dairy manure to improve biochemical conversion yield.


Asunto(s)
Ácido Acético , Estiércol , Animales , Bovinos , Ácidos Carboxílicos , Biomasa , Oxidación-Reducción
19.
Environ Pollut ; 342: 123043, 2024 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-38036093

RESUMEN

Large quantities of organochlorine pesticides (OCPs) have been used in tropical regions. The fate processes and risks of these legacy contaminants in the tropics are poorly understood. Herein, we investigated the occurrence of three classes of widely used OCPs and their metabolites in surface and core soil from five cities across Vietnam with a prevalent tropical monsoon climate and a long history of OCP application. We aimed to elucidate migration potentials, degradation conditions, and transformation pathways and assess current health risks of these contaminants. Generally, the concentrations of OCPs and metabolites in the soil core were slightly lower than those in surface soil except for hexachlorocyclohexane (HCH) isomers. 2,2-bis(4-chlorophenyl)-1,1,1-trichloroethane (p,p'-DDT), 2,2-bis(4-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE), the sum of dicofol and 4,4'-dichlorobenzophenone (p,p'-DBP), and 2,2-bis(4-chlorophenyl)-1,1-dichloroethane (p,p'-DDD) were the most abundant compounds in both surface and core soils. A uniform distribution of HCHs (the sum of α-, ß-, γ-, and δ-HCH) at trace levels was found in almost all soils, serving as evidence of the lack of recent use of HCH pesticides. Higher concentrations of DDTs (the sum of DDT, DDD, and DDE) were observed in north-central Vietnamese soil, whereas appreciable concentrations of ENDs (the sum of α- and ß-endosulfan and endosulfan sulfate) were only found in southern Vietnamese soils. Empirical diagnostic ratios indicated residuals of DDTs were mainly from technical DDT rather than dicofol, whereas aged HCHs could be explained by the mixture of lindane and technical HCH. Both historical applications and recent input explain DDTs and ENDs in Vietnamese soil. Total organic carbon performs well in preventing vertical migration of more hydrophobic DDTs and ENDs. The dominant transformation pathway of DDT in surface soil followed p,p'-DDE→2,2-bis(4-chlorophenyl)-1-chloroethylene or p,p'-DDMU→1,1-bis(4-chlorophenyl)ethylene or p,p'-DDNU→p,p'-DBP, whereas the amount of p,p'-DDMU converted from p,p'-DDD and p,p'-DDE is similar in soil core. Non-cancer risks of OCPs and metabolites in all soils and cancer risks of those chemicals in core soils were below the safety threshold, whereas a small proportion of surface soil exhibited potential cancer risk after considering the exposure pathway of vegetable intake. This study implied that organic matter in non-rainforest tropical deep soils still could hinder the leaching of hydrophobic organic contaminants as in subtropical and temperate soils. When lands with a history of OCP application are used for agricultural purposes, dietary-related risks need to be carefully assessed.


Asunto(s)
Hidrocarburos Clorados , Plaguicidas , Contaminantes del Suelo , Plaguicidas/análisis , DDT/análisis , Diclorodifenil Dicloroetileno/análisis , Suelo/química , Vietnam , Dicofol , Ciudades , Hexaclorociclohexano/análisis , Hidrocarburos Clorados/análisis , Contaminantes del Suelo/análisis , Monitoreo del Ambiente , China
20.
Plant Direct ; 7(11): e544, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-38028650

RESUMEN

Poplar is a short-rotation woody crop frequently studied for its significance as a sustainable bioenergy source. The successful establishment of a poplar plantation partially depends on its rhizosphere-a dynamic zone governed by complex interactions between plant roots and a plethora of commensal, mutualistic, symbiotic, or pathogenic microbes that shape plant fitness. In an exploratory endeavor, we investigated the effects of a consortium consisting of ectomycorrhizal fungi and a beneficial Pseudomonas sp. strain GM41 on plant growth (including height, stem girth, leaf, and root growth) and as well as growth rate over time, across four Populus trichocarpa genotypes. Additionally, we compared the level of total organic carbon and plant exometabolite profiles across different poplar genotypes in the presence of the microbial consortium. These data revealed no significant difference in plant growth parameters between the treatments and the control across four different poplar genotypes at 7 weeks post-inoculation. However, total organic carbon and exometabolite profiles were significantly different between the genotypes and the treatments. These findings suggest that this microbial consortium has the potential to trigger early signaling responses in poplar, influencing its metabolism in ways crucial for later developmental processes and stress tolerance.

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