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Characterisation of Prolonged Deposits of Organic Matter in Infiltration System Inlets and Their Binding with Heavy Metals: a PARAFAC Approach
2015
Aryal, Rupak | Furumai, Hiroaki | Nakajima, Fumiyuki | Beecham, Simon | Kandasamy, Jaya
This study investigated and characterised organic matter present in sediment particles deposited in infiltration facilities using an excitation-emission matrix method combined with parallel factor analysis (EEM-PARAFAC). The organic fluorophore identified was correlated with sediment bound metals. The PARAFAC analysis identified three major components. The fluorophore in each of the three components appeared in different locations with different spectral shapes. The maximum fluorescence intensity (F ₘₐₓ) observed for each fluorescent component was correlated with seven heavy metals (Cr, Mn, Co, Ni, Cu, Zn and Pb). F ₘₐₓ of component 1 displayed a negative relationship with all the metals (correlation coefficient = −0.28 to −0.72), and F ₘₐₓ of component 3 showed a positive relationship (0.20 to 0.62), and among them, Cu, Ni and Zn had higher correlation. Our results demonstrate that a PARAFAC approach can help to further elucidate organic matter species, thereby allowing a better understanding of the mobility of elemental species in the deposited sediment.
显示更多 [+] 显示较少 [-]Removal of Phosphate from Aqueous Solutions by Chemical- and Thermal-Modified Bentonite Clay
2015
Tanyol, Mehtap | Yonten, Vahap | Demir, Veysel
The study investigated phosphate adsorption from aqueous solutions using chemical- and thermal-modified bentonite in batch system. The adsorbent was characterized by SEM, BET, and FTIR spectroscopy. Contact time, beginning phosphate concentration, pH of the solution, and the effects of the temperature on phosphate adsorption capacity were determined by a series of experimental studies. In a wide pH range (3–10), high phosphate removal yields were obtained (between 94.23 and 92.26 %), and with the increase in temperature (from 25 to 45 °C), phosphate removal increased. Langmuir and Freundlich isotherms were used to determine the sorption equilibrium, and the results demonstrated that equilibrium data displayed better adjustment to Langmuir isotherm than the Freundlich isotherm. Phosphate sorption capacity, calculated using Langmuir equation, is 20.37 mg g⁻¹ at 45 °C temperature and pH 3. Mass transfer and kinetic models were applied to empirical findings to determine the mechanism of adsorption and the potential steps that control the reaction rate. Both external mass transfer and intra-particle diffusion played a significant role on the adsorption mechanism of phosphate, and adsorption kinetics followed the pseudo-second-order-type kinetic. Furthermore, thermodynamic parameters (ΔH°, ΔG°, ΔS°) which reveal that phosphate adsorption occur spontaneously and in endothermic nature were determined. The results of this study support that bentonite, which is found abundant in nature and modified as an inexpensive and effective adsorbent, could be used for phosphate removal from aqueous solutions.
显示更多 [+] 显示较少 [-]Efficiency of Microfiltration Systems for the Removal of Bacterial and Viral Contaminants from Surface and Rainwater
2015
Dobrowsky, P. H. | Lombard, M. | Cloete, W. J. | Saayman, M. | Cloete, T. E. | Carstens, M. | Khan, S. | Khan, W.
The aim of this study was to evaluate the efficiency of a passive point-of-use treatment system, namely, a polyvinyl (alcohol) (PVA) nanofiber membrane/activated carbon column, for the treatment of harvested rainwater. The efficiency of SMI-Q10 [quaternized poly (styrene-co-maleimide)] nanofiber membrane disks placed in a filtration assembly for the treatment of surface water (Plankenburg River, Western Cape, South Africa) and harvested rainwater was also assessed. Two rainwater harvesting tanks were installed at the Welgevallen Experimental farm, Stellenbosch, South Africa, with the filtration system intermittently attached to the tanks for collection of rainwater samples throughout the study period. Parameters used to monitor the filtration systems included heterotrophic bacteria, Escherichia coli, and total coliform enumeration and the presence/absence of adenovirus. When compared to drinking water guidelines, the results indicated that 3 L of potable water could be produced by the synthesized PVA nanofiber membrane/activated carbon column. However, PCR assays indicated that adenovirus and numerous bacteria such as Klebsiella spp., Legionella spp., Pseudomonas spp., and Yersinia spp. were not effectively removed by the filtration system utilized. Additionally, the SMI-Q10 nanofiber membrane disks did not remove viruses from the river or tank water samples as bovine adenovirus 3 strain, simian adenovirus, and human adenovirus A strain were detected in all water samples analyzed. Thus, while the microfiltration system was efficient in reducing the level of indicator organisms to within drinking water standards, further optimization of the electrospun filtration membranes is required as molecular analysis revealed that numerous opportunistic bacterial pathogens and viruses persisted after filtration.
显示更多 [+] 显示较少 [-]Antibiotic Degradation During Thermophilic Composting
2015
Mitchell, S. M. | Ullman, J. L. (Jane L.) | Bary, A. | Cogger, C. G. | Teel, A. L. | Watts, R. J.
Residual antibiotics in land-applied manure and biosolids present a potential threat to public and ecological health. It remains important to determine antibiotic degradation efficiencies for manure and biosolids waste management practices and to identify conditions that enhance antibiotic degradation. The fates of the antibiotics florfenicol, sulfadimethoxine, sulfamethazine, and tylosin were studied during pilot-scale static pile thermophilic composting, and the effects of temperature and feedstock particles on antibiotic degradation rates were tested. The antibiotics were spiked into dairy manure solids and wastewater biosolids, and treatments included aerated and non-aerated manure and biosolids/wood-product (1:3 v/v) composting. Results showed no significant differences between aerated and non-aerated treatments; on average, ≥85, ≥93, and ≥95 % antibiotic degradation was observed after 7, 14, and 21 days of composting. Greater antibiotic degradation was observed in manure compost compared to biosolids compost for florfenicol (7, 14, 21, 28 days) and tylosin (14, 28 days); however, there was no significant difference for sulfadimethoxine and sulfamethazine. Peak temperatures were 66–73, and ≥55 °C was maintained for 6–7 days in the biosolids compost and 17–20 days in the manure compost. Bench-scale experiments conducted at 25, 55, and 60 °C showed that lower temperature decreased degradation of the sulfonamides and tylosin in both feedstocks and florfenicol in the biosolids. The presence of compost particles increased antibiotic degradation, with time to 50 % degradation ≤2 days in the presence of solids (60 °C) compared to no degradation in their absence. These results indicate that thermophilic composting effectively degrades parent antibiotic compounds in manure and biosolids.
显示更多 [+] 显示较少 [-]Dissipation and Degradation Dynamics of Thifluzamide in Rice Field
2015
Wei, Li Na | Wu, Ping | Wang, Fu Rong | Yang, Hong
Thifluzamide fungicide is widely used to protect rice (Oryza sativa) against the sheath blight fungus (Rhizoctonia solani). The continuous application of thifluzamide may lead to accumulation in soil and contaminate rice crop. To sustain the environment, it is necessary to assess its accumulation and degradation in field. The method limit of detection (LOD) was 0.022 ng. The limits of quantitation detection (LOQ) were 5.0 μg L⁻¹in water and 4.0 μg kg⁻¹in paddy soil and rice crop. In this study, a 2-year (2011–2012) field study was performed to monitor thifluzamide degradation in the rice production areas of Nanjing, Xiaoxian, and Changsha. The degradation dynamics of thifluzamide in paddy water, paddy soil, and rice crop were well described by the first-order kinetics equation. The 2-year average half-lives of thifluzamide in paddy water, paddy soil, and rice crop were 26.19, 17.92, 14.61 days (Nanjing), 15.63, 20.71, 9.10 days (Xiaoxian), and 9.47, 13.92, 10.08 days (Changsha), respectively. Thifluzamide degraded more rapidly in rice crop than in soil and paddy water. The variation in thifluzamide degradation was attributed to the difference in rainfall during the period of rice cultivation. The maximum residue of thifluzamide in brown rice was 0.0303 mg kg⁻¹in Nanjing and the residue of thifluzamide in brown rice was not detected in other two sites before thifluzamide was applied at pre-harvest. The experimental data demonstrated that thifluzamide recommended dosage of 72 g a.i.ha⁻¹can be used in rice fields with less than three times within a 30-day time interval.
显示更多 [+] 显示较少 [-]Alkylphenols and Phthalates in Greywater from Showers and Washing Machines
2015
Deshayes, Steven | Eudes, Véronique | Droguet, Christine | Bigourie, Magali | Gasperi, Johnny | Moilleron, Régis
Paris conurbation is a heavily urbanized but weakly industrialized catchment. Recently, it has been shown at the scale of Paris that alkylphenols (AP) and phthalates (PAE) are not rejected by the industry, but they originate from domestic wastewater at more than 95 %. However, the contribution of the different types of greywater to the pollution by alkylphenols and phthalates was not addressed. This work aims at providing new insights on this particular point. Hence, the concentration of four phthalates (diethyl phthalate (DEP), di-n-butyl phthalate (DnBP), benzyl butyl phthalate (BBP), and di(2-ethylhexyl)phthalate (DEHP)) and two alkylphenols (octylphenols (OP) and isomers of nonylphenol (NP)) were followed in greywater. For each sample, analyses were carried out on both the dissolved and particulate phases. Moreover, water quality parameters were also monitored, in order to find out whether or not any correlation exists between the concentration of the investigated contaminants and the quality of water. Water quality parameters studied are pH, total suspended solids (TSS), dissolved and particular organic carbon (DOC and POC), chemical and biochemical oxygen demands (COD and BOD5), total Kjeldahl nitrogen (TKN), and anionic detergents (methylene blue active substance or MBAS). This paper presents the methodology used to monitor two greywater with the most important volumes: showers and washing machines. These greywater showed high variability with regard to water quality parameters. Moreover, AP and PAE concentrations are given for the first time for these two types of greywater. All compounds except OP were observed in almost all samples in at least one of the two monitored phases. The concentrations varied between limit of quantification for OP and 102 μg/l for DEHP. The levels measured in washing machines were higher than those for showers for all compounds. For instance, median NP concentration in washing machines was 3.59 μg/l against 1.09 μg/l in showers, DEHP was observed at 102 μg/l in washing machines against 16.6 μg/l in showers. Variability of the results was explained by habits of individuals (shower time, number of products used…) but also by differences in product composition. However, each type of water exhibited the same distribution. NP was the most abundant AP (about 85 % of the total amount) while DEHP represented the two thirds of the PAE compounds. The partition coefficients (Kd in l/kg) were evaluated. The results showed that log Kd ranged between 2.1 (DEP) and 4.8 (DEHP). Log Koc presented similar trends lying in the 2.4 (DEP)-5.0 (DEHP) range. Finally, with regard to greywater quality, the application for greywater reuse is discussed.
显示更多 [+] 显示较少 [-]Evaluation of Mutagenic and Genotoxic Activity in Vinasses Subjected to Different Treatments
2015
Oñate, José | Arenas, Armando | Ruiz, Alejandro | Rivera, Katherin | Peláez, Carlos
The mutagenic and genotoxic activity of vinasses collected from a fuel alcohol plant, located in the municipality of Frontino, Northwestern Colombia, were evaluated. Two samples obtained from an 82-L capacity hybrid reactor (UASB-anaerobic filter (AF)-UASB) were studied under laboratory conditions after being treated with biological oxidation, the first, and the second with Fenton reaction consecutively. Mutagenicity was evaluated in vitro by the Ames test using strains TA98 and TA100 with and without S9 metabolic activation. The genotoxic analysis was conducted using the Allium cepa roots assay where chromosomal aberrations were used as clastogenic or aneugenic response markers, and micronuclei as mutagenic response. The Ames test results showed a strain-dependent positive linear association with the vinasse sample concentration before treatment (dose–response effect). Unlike TA100, strain TA98 showed a mutagenic effect in both the presence and absence of metabolic enzymes. After the biological oxidation treatment, vinasse mutagenicity significantly decreased. Finally, after Fenton treatment, the sample did not induce any mutagenic event. Genotoxic activity was observed in all three samples, but there was a higher frequency in the vinasse sample before treatment. Concerning the frequency of micronuclei, no clear association was observed with either the concentration or the type of sample.
显示更多 [+] 显示较少 [-]Immobilization of Trace Metals in Contaminated Urban Soil Amended with Compost and Biochar
2015
Kargar, Maryam | Clark, O Grant | Hendershot, William H. | Jutras, Pierre | Prasher, Shiv O.
Urban soil amendment with organic matter can increase the steady state concentration of trace metals in urban soil. Different types of organic matter have different abilities to sorb and retain trace metals. The potential of urban soil amended with compost derived from mixed green and table waste and with maple-wood-derived biochar to retain trace metals (Cu, Zn, Cd, Pb) in the presence of de-icing salt (Na) was studied in a leaching test. Soil amended with compost retained significantly higher concentrations of Zn and Pb, as compared to soil amended with biochar, possibly due to the high cation exchange capacity of compost and its positive effect on soil pH. Indicating high ability for retaining trace metals, compost can bind contaminants originating from urban runoff water percolating through urban soil and provide a healthier medium for street tree growth.
显示更多 [+] 显示较少 [-]Adsorptive Removal of Methylene Blue from Aqueous Solution by the Activated Carbon Obtained from the Fruit of Catalpa bignonioides
2015
Geçgel, Ünal | Kocabıyık, Barış | Üner, Osman
In this study, the fruit of Catalpa bignonioides was used as the raw material to obtain low-cost activated carbon. The activation process was carried out by using chemical activation method with zinc chloride. Catalpa activated carbon (CAC) was characterized using elemental analyzer, Brunauer-Emmet-Teller (BET), scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), and the point of zero charge (pHZPC). The BET surface area of CAC prepared by the impregnation ratio of 30 % ZnCl₂ (w/w) was found to be 896.02 m²/g. The efficiency in the process of the removal of methylene blue (MB) from aqueous solution by CAC was searched with different factors, such as temperature, pH, adsorbent concentration, dye concentration, and contact time. From the experimental data obtained, the studies related to adsorption isotherm, kinetics, and thermodynamics were performed. Langmuir model provided the best fit, and the adsorption capacity for the removal of methylene blue from aqueous solution by CAC was calculated to be 271.00 mg/g at 25 °C. The adsorption follows a pseudo-second-order kinetic model. Moreover, the thermodynamic parameters such as ΔG°, ΔH°, and ΔS° presented that the adsorption was spontaneous and endothermic.
显示更多 [+] 显示较少 [-]Effects of a Giant Pulp and Paper Mill on the Pollutant Accumulating Capacity of the Soil with Special Reference to its Carbon Sequestering Potential
2015
Adhikari, Gopi | Bhattacharyya, Krishna G.
Inadequately treated effluents from industry have serious environmental and public health concerns. Even low level discharges create problems through accumulation in water and soil. In the present work, the pollutant accumulating capacity and the general environmental health status of soil which is a repository of treated and untreated effluent discharges and solid waste dumping of a giant pulp and paper mill have been evaluated with respect to some selected physicochemical parameters. The pollutant accumulating capacity of the soil in seven well-defined sites in and around the mill was found with reference to a “control” site with no history of receiving effluent discharges or solid wastes. The changes in texture, bulk density, water-holding capacity, electrical conductivity, pH, organic carbon, cation exchange capacity, exchangeable sodium, etc. of the soil up to the normal tilled depth were observed in different seasons. In most sites, the soil organic carbon was poorly correlated to the bulk density, water-holding capacity, pH, and clay and sand contents, indicating an unhealthy state of the soil and, correspondingly, nearly exhausted pollutant accumulating capacity. Considerable differences in pH, electrical conductivity, bulk density, and water-holding capacity were observed between the soil receiving effluent discharge and solid waste dumping and the control soil. The soil had accumulated considerable amounts of the exchangeable cations (Ca, Mg, Na, and K). The work has found that industrial activities have worked against the normal behavior of the soil and reduced its capacity to serve as a natural repository of carbon.
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