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1.
Surface waters were collected in the River Adour estuary (south-western France) during different sampling periods from 1998 to 2001 in order to investigate the phase distribution and speciation of methylmercury (MeHg +). Although a high variability is observed, significant higher average concentrations of total MeHg + (dissolved and particulate) are measured during the warm seasons, at 4.40±8.18 pM and 3.90±1.87 pM for July 1998 and September 1999, compared with the winter seasons, with concentrations at 0.99±2.85 pM and 1.00±1.75 pM for February 1998 and February 2001, respectively (one-tailed t-test, P=0.01). The seasonal variations are explained with enhanced bacterial activity during summer and sedimentation/resuspension phenomena. Additionally, signi-ficant longitudinal variations of the MeHg + concentrations are observed. The highest levels in both dissolved and particulate fractions are found within the downstream urban estuarine area. This can be explained by the high methylation potential of the sediments, but direct anthropogenic inputs of MeHg + from specific discharge points cannot be neglected. Biogeochemical factors like phytoplankton biomass and salinity also show a relationship with MeHg + partitioning in the surface waters of the Adour estuary. 相似文献
2.
As the bioelectrochemical system, the microbial fuel cell (MFC) and the microbial electrolysis cell (MEC) were developed to selectively recover Cu 2+ and Ni 2+ ions from wastewater. The wastewater was treated in the cathode chambers of the system, in which Cu 2+ and Ni 2+ ions were removed by using the MFC and the MEC, respectively. At an initial Cu 2+ concentration of 500 mg·L -1, removal efficiencies of Cu 2+ increased from 97.0%±1.8% to 99.0%±0.3% with the initial Ni 2+ concentrations from 250 to 1000 mg·L -1, and maximum power densities increased from 3.1±0.5 to 5.4±0.6 W·m -3. The Ni 2+ removal mass in the MEC increased from 6.8±0.2 to 20.5±1.5 mg with the increase of Ni 2+ concentrations. At an initial Ni 2+ concentration of 500 mg·L -1, Cu 2+ removal efficiencies decreased from 99.1%±0.3% to 74.2%±3.8% with the initial Cu 2+ concentrations from 250 to 1000 mg·L -1, and maximum power densities increased from 3.0±0.1 to 6.3±1.2 W·m -3. Subsequently, the Ni 2+ removal efficiencies decreased from 96.9%±3.1% to 73.3%±5.4%. The results clearly demonstrated the feasibility of selective recovery of Cu 2+ and Ni 2+ from the wastewater using the bioelectrochemical system. 相似文献
3.
The effect of ion-doping on TiO 2 nanotubes were investigated to obtain the optimal TiO 2 nanotubes for the effective decomposition of humic acids (HA) through O 3/UV/ion-doped TiO 2 process. The experimental results show that changing the calcination temperature, which changed the weight fractions of the anatase phase, the average crystallite sizes, the Brunauer-Emmett-Teller surface area, and the energy band gap of the catalyst, affected the photocatalytic activity of the catalyst. The ionic radius, valence state, and configuration of the dopant also affected the photocatalytic activity. The photocatalytic activities of the catalysts on HA removal increased when Ag +, Al 3+, Cu 2+, Fe 3+, V 5+, and Zn 2+ were doped into the TiO 2 nanotubes, whereas such activities decreased as a result of Mn 2+- and Ni 2+-doping. In the presence of 1.0 at.% Fe 3+-doped TiO 2 nanotubes calcined at 550°C, the removal efficiency of HA was 80% with a pseudo-first-order rate constant of 0.158 min −1. Fe 3+ in TiO 2 could increase the generation of ·OH, which could remove HA. However, Fe 3+ in water cannot function as a shallow trapping site for electrons or holes. 相似文献
4.
• Nano zero-valent manganese (nZVMn, Mn0) is synthesized via borohydrides reduction. • Mn0 combined with persulfate/hypochlorite is effective for Tl removal at pH 6-12. • Mn0 can activate persulfate to form hydroxyl and sulfate radicals. • Oxidation-induced precipitation and surface complexation contribute to Tl removal. • Combined Mn0-oxidants process is promising in the environmental field. ![]() Nano zero-valent manganese (nZVMn, Mn 0) was prepared through a borohydride reduction method and coupled with different oxidants (persulfate (S 2O 82−), hypochlorite (ClO −), or hydrogen peroxide (H 2O 2)) to remove thallium (Tl) from wastewater. The surface of Mn 0 was readily oxidized to form a core-shell composite (MnO x@Mn 0), which consists of Mn 0 as the inner core and MnO x (MnO, Mn 2O 3, and Mn 3O 4) as the outer layer. When Mn 0 was added alone, effective Tl(I) removal was achieved at high pH levels (>12). The Mn 0-H 2O 2 system was only effective in Tl(I) removal at high pH (>12), while the Mn 0-S 2O 82− or Mn 0-ClO − system had excellent Tl(I) removal (>96%) over a broad pH range (4–12). The Mn 0-S 2O 82− oxidation system provided the best resistance to interference from an external organic matrix. The isotherm of Tl(I) removal through the Mn 0-S 2O 82− system followed the Freundlich model. The Mn 0 nanomaterials can activate persulfate to produce sulfate radicals and hydroxyl radicals. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggested that oxidation-induced precipitation, surface adsorption, and electrostatic attraction are the main mechanisms for Tl(I) removal resulting from the combination of Mn 0 and oxidants. Mn 0 coupled with S 2O 82−/ClO − is a novel and effective technique for Tl(I) removal, and its application in other fields is worthy of further investigation. 相似文献
5.
Dielectrophoresis (DEP) process could enhance the removal the Cd2+ and Pb2+ with less absorbent. The removal rates of both Cd2+ and Pb2+ increased with the increase of voltage. The overall removal rate of Cd2+ and Pb2+ in the binary system is higher than that of Cd2+ or Pb2+ in the single system. DEP could cause considerable changes of the bentonite particles in both surface morphology and microstructure. ![]() Dielectrophoresis (DEP) was combined with adsorption (ADS) to simultaneously and effectively remove Cd 2+ and Pb 2+ species from aqueous solution. To implement the process, bentonite particles of submicro-meter size were used to first adsorb the heavy metal ions. These particles were subsequently trapped and removed by DEP. The effects of the adsorbent dosage, DEP cell voltage and the capture pool numbers on the removal rate were investigated in batch processes, which allowed us to determine the optimal experimental conditions. The high removal efficiency, 97.3% and 99.9% for Cd 2+ and Pb 2+, respectively, were achieved when the ions are coexisting in the system. The microstructure of bentonite particles before and after ADS/DEP was examined by scanning electron microscopy. Our results suggest that the dielectrophoresis-assisted adsorption method has a high capability to remove the heavy metals from wastewater. 相似文献
6.
The highest removal efficiencies of COD and TN were achieved under 10 mg/L of Al3+. The highest TP removal efficiency occurred under 30 mg/L of Al3+. EPS, PS and PN concentrations increased with the addition of Al3+. Sludge properties significantly changed with the addition of Al3+. ![]() Aluminum ions produced by aluminum mining, electrolytic industry and aluminum-based coagulants can enter wastewater treatment plants and interact with activated sludge. They can subsequently contribute to the removal of suspended solids and affect activated sludge flocculation, as well as nitrogen and phosphorus removal. In this study, the effects of Al 3+ on pollutant removal, sludge flocculation and the composition and structure of extracellular polymeric substances (EPS) were investigated under anaerobic, anoxic and oxic conditions. Results demonstrated that the highest chemical oxygen demand (COD) and total nitrogen (TN) removal efficiencies were detected for an Al 3+ concentration of 10 mg/L. In addition, the maximal dehydrogenase activity and sludge flocculation were also observed at this level of Al 3+. The highest removal efficiency of total phosphorus (TP) was achieved at an Al 3+ concentration of 30 mg/L. The flocculability of sludge in the anoxic zone was consistently higher than that in the anaerobic and oxic zones. The addition of Al 3+ promoted the secretion of EPS. Tryptophan-like fluorescence peaks were detected in each EPS layer in the absence of Al 3+. At the Al 3+ concentration of 10 mg/L, fulvic acid and tryptophan fluorescence peaks began to appear, while the majority of protein species and the highest microbial activity were also detected. Low Al 3+ concentrations (<10 mg/L) could promote the removal efficiencies of COD and TN, yet excessive Al 3+ levels (>10 mg/L) weakened microbial activity. Higher Al 3+ concentrations (>30 mg/L) also inhibited the release of phosphorus in the anaerobic zone by reacting with PO 43-. 相似文献
7.
• Challenges in sampling of NH3 sources for d15N analysis are highlighted. • Uncertainties in the isotope-based source apportionment of NH3 and NH4+ are outlined. • Characterizing dynamic isotopic fractionation may reduce uncertainties of NHx science. Agricultural sources and non-agricultural emissions contribute to gaseous ammonia (NH 3) that plays a vital role in severe haze formation. Qualitative and quantitative contributions of these sources to ambient PM 2.5 (particulate matter with an aerodynamic equivalent diameter below 2.5 µm) concentrations remains uncertain. Stable nitrogen isotopic composition (δ 15N) of NH 3 and NH 4+ (δ 15N(NH 3) and δ 15N(NH 4+), respectively) can yield valuable information about its sources and associated processes. This review provides an overview of the recent progress in analytical techniques for δ 15N(NH 3) and δ 15N(NH 4+) measurement, sampling of atmospheric NH 3 and NH 4+ in the ambient air and their sources signature (e.g., agricultural vs. fossil fuel), and isotope-based source apportionment of NH 3 in urban atmosphere. This study highlights that collecting sample that are fully representative of emission sources remains a challenge in fingerprinting δ 15N(NH 3) values of NH 3 emission sources. Furthermore, isotopic fractionation during NH 3 gas-to-particle conversion under varying ambient field conditions (e.g., relative humidity, particle pH, temperature) remains unclear, which indicates more field and laboratory studies to validate theoretically predicted isotopic fractionation are required. Thus, this study concludes that lack of refined δ 15N(NH 3) fingerprints and full understanding of isotopic fractionation during aerosol formation in a laboratory and field conditions is a limitation for isotope-based source apportionment of NH 3. More experimental work (in chamber studies) and theoretical estimations in combinations of field verification are necessary in characterizing isotopic fractionation under various environmental and atmospheric neutralization conditions, which would help to better interpret isotopic data and our understanding on NH x (NH 3 + NH 4+) dynamics in the atmosphere. 相似文献
8.
为研究乌鲁木齐市米东区大气降水中的化学组分特征及来源,对2017-2019年降水中主要离子浓度及来源进行了分析.研究结果显示,米东区2017-2019年降水的雨量加权pH年均值为7.95,雨量加权平均电导率年均值为16.15 mS·m-1,雨量加权平均总离子浓度为72.75-95.89 μeq·L-1,年均浓度为81.... 相似文献
9.
• Mechanisms of redox reactions of Fe- and Mn-oxides were discussed. • Oxidative reactions of Mn- and Fe-oxides in complex systems were reviewed. • Reductive reaction of Fe(II)/iron oxides in complex systems was examined. • Future research on examining the redox reactivity in complex systems was suggested. ![]() Conspectus Redox reactions of Fe- and Mn-oxides play important roles in the fate and transformation of many contaminants in natural environments. Due to experimental and analytical challenges associated with complex environments, there has been a limited understanding of the reaction kinetics and mechanisms in actual environmental systems, and most of the studies so far have only focused on simple model systems. To bridge the gap between simple model systems and complex environmental systems, it is necessary to increase the complexity of model systems and examine both the involved interaction mechanisms and how the interactions affected contaminant transformation. In this Account, we primarily focused on (1) the oxidative reactivity of Mn- and Fe-oxides and (2) the reductive reactivity of Fe(II)/iron oxides in complex model systems toward contaminant degradation. The effects of common metal ions such as Mn 2+ , Ca 2+, Ni 2+, Cr 3+ and Cu 2+, ligands such as small anionic ligands and natural organic matter (NOM), and second metal oxides such as Al, Si and Ti oxides on the redox reactivity of the systems are briefly summarized. 相似文献
10.
● Simultaneous NH4+/NO3– removal was achieved in the FeS denitrification system ● Anammox coupled FeS denitrification was responsible for NH4+/NO3– removal ● Sulfammox, Feammox and Anammox occurred for NH4+ removal ● Thiobacillus, Nitrospira , and Ca. Kuenenia were key functional microorganisms An autotrophic denitrifying bioreactor with iron sulfide (FeS) as the electron donor was operated to remove ammonium (NH 4+) and nitrate (NO 3−) synergistically from wastewater for more than 298 d. The concentration of FeS greatly affected the removal of NH 4+/NO 3−. Additionally, a low hydraulic retention time worsened the removal efficiency of NH 4+/NO 3−. When the hydraulic retention time was 12 h, the optimal removal was achieved with NH 4+ and NO 3− removal percentages both above 88%, and the corresponding nitrogen removal loading rates of NH 4+ and NO 3− were 49.1 and 44.0 mg/(L·d), respectively. The removal of NH 4+ mainly occurred in the bottom section of the bioreactor through sulfate/ferric reducing anaerobic ammonium oxidation (Sulfammox/Feammox), nitrification, and anaerobic ammonium oxidation (Anammox) by functional microbes such as Nitrospira, Nitrosomonas, and Candidatus Kuenenia. Meanwhile, NO 3− was mainly removed in the middle and upper sections of the bioreactor through autotrophic denitrification by Ferritrophicum, Thiobacillus, Rhodanobacter, and Pseudomonas, which possessed complete denitrification-related genes with high relative abundances. 相似文献
11.
The methanogenesis was severely inhibited with 0.46 mM ASA addition.PO43− didn’t attenuate the methanogenesis inhibition in the existence of ASA.ASA was transformed to As(III), As(V), MMA and DMA in anaerobic digestion.Cu2+ mitigated the methanogenesis inhibition via impeding the degradation of ASA. ![]() Arsanilic acid (ASA), copper ion (Cu 2+) and phosphate (PO 43−) are widely used as feed additives for pigs. Most of these three supplemented feed additives were excreted in feces and urine. Anaerobic digestion is often used for the management of pig manure. However, the interaction of ASA with Cu 2+ or PO 43− on anaerobic digestion is still not clear. In this study, the influence of ASA, Cu 2+, PO 43− and their interaction on anaerobic digestion of pig manure and the possible mechanisms were investigated. The initial concentrations of ASA, Cu 2+ and PO 43− were 0.46 mM, 2 mM and 2 mM in the anaerobic digester, respectively. The methanogenesis was severely inhibited in the assays with only ASA addition, only Cu 2+ addition and ASA+ PO 43− addition with the inhibition index of 97.8%, 46.6% and 82.6%, respectively, but the methanogenesis inhibition in the assay with ASA+ Cu 2+ addition was mitigated with the inhibition index of 39.4%. PO 43− had no obvious impacts on the degradation of ASA. However, Cu 2+ addition inhibited the degradation of ASA, mitigating the methanogenesis inhibition. The existence of ASA would inhibit methanogenesis and generate more toxic inorganic arsenic compounds during anaerobic digestion, implying the limitation of anaerobic digestion for ASA- contaminated animal manure. However, the co-existence of ASA and Cu 2+ could mitigate the inhibition. These results could provide useful information for the management of anaerobic digestion of pig manure containing ASA with Cu 2+. 相似文献
12.
本研究于2018年12月3日-2019年1月1日在辽宁省西南典型城市葫芦岛市和朝阳市分别布设3个城区采样点,在区域传输点龙屯水库布设1个采样点,采集大气细颗粒物PM2.5样品(n=201).使用离子色谱检测样品中的Na+、Mg2+、Ca2+、K+、NH4+、SO42-、F-、Cl-和NO3-的质量浓度.观测期间PM2.... 相似文献
13.
Full-scale experiments have been carried out to adapt the activated sludge model ASM2d to include the influence of metal dosage (Fe 3+ and Al 3+) for phosphorus removal. Phosphorus removal rates, nitrification rates, as well as pH and sludge settling performance, were evaluated as functions of the metal dosages. Furthermore, models relating certain parameters to the dosage of chemicals have been derived. Corresponding parameters in the ASM2d and the secondary settler models, included in the Benchmark Simulation Model No 1 (BSM1), have been modified to take the metal influence into consideration. Based on the effluent limits and penalty policy of China, an equivalent evaluation method was derived for the total cost assessment. A large number of 300-day steady-state and 14-day open-loop dynamic simulations were performed to demonstrate the difference in behavior between the original and the modified BSM1. The results show that 1) both in low and high mole concentrations, Fe 3+ addition results in a higher phosphorus removal rate than Al 3+; 2) the sludge settling velocity will increase due to the metal addition; 3) the respiration rate of the activated sludge is decreased more by the dosage of Al 3+ than Fe 3+; 4) the inhibition of Al 3+ on the nitrification rate is stronger than that of Fe 3+; 5) the total operating cost will reach the minimum point for smaller dosages of Fe 3+, but always increase with Al 3+ addition. 相似文献
14.
• Unmodified-AuNP based, colorimetric nanosensor was constructed for Pb2+ detection. • 5-nucleotide truncation in DNAzyme made complete substrate detachment upon Pb2+. • Ultrasensitive and selective detection of Lead (II) was achieved with 0.2×10-9 mol/L LOD. ![]() Water pollution accidents, such as the Flint water crisis in the United States, caused by lead contamination have raised concern on the safety of drinking water distribution systems. Thus, the routine monitoring of lead in water is highly required and demands efficient, sensitive, cost-effective, and reliable lead detection methods. This study reports a label-free colorimetric nanosensor that uses unmodified gold nanoparticles (AuNPs) as indicators to enable rapid and ultra-sensitive detection of lead in environmental water. The 8–17 DNAzyme was truncated in this study to facilitate the detachment of single-stranded DNA fragments after substrate cleavage in the presence of Pb 2+. The detached fragments were adsorbed over AuNPs and protected against salt concentration-induced aggregation. Accordingly, high Pb 2+ would result in rapid color change from blue to pink. The established sensing principle achieved a sensitive limit of detection of 0.2×10 -9 mol/L Pb 2+, with a linear working range of two orders of magnitude from 0.5×10 -9 mol/L to 5×10 -9 mol/L. The selectivity of the nanosensor was demonstrated by evaluating the interfering metal ions. The developed nanosensor can serve as a substitute for the rapid analysis and monitoring of trace lead levels under the drinking water distribution system and even other environmental water samples. 相似文献
15.
微生物诱导碳酸盐沉淀(MICP)可将游离的重金属离子转化为稳定的矿化物,在修复土壤重金属污染方面具有广阔的应用前景.本研究从铜陵矿区周边土壤中筛选得到1株产脲酶且耐镉矿化菌株CZW-1,16S rDNA鉴定为芽孢杆菌(Bacillus sp.),并将其利用于添加外源Ca 2+的矿化固结Cd 2+实验中.通过扫描电镜(SEM)、傅立叶红外光谱(FT-IR)以及X射线衍射(XRD)对矿化产物进行表征和分析.结果表明,添加一定浓度的Ca 2+可促进细菌的生长,其最佳浓度为20 mmol·L -1.且Ca 2+的添加可提高细菌的最小抑制浓度和促进脲酶活性,提高对Cd 2+的矿化率,加钙前后的矿化率由68.93%提高到75.95%.通过对矿化物的定性分析,可知加钙前后的矿物沉淀由单一CdCO 3变为CdCO 3和CaCO 3的复合沉淀,其表面也由严密紧实变成填满了小颗粒CdCO 3的多孔状. 相似文献
16.
The chromium(VI) biosorption onto guava seeds, as an alternative method for Cr 6+ removal from aqueous solutions, was investigated. The parameters affecting kinetics and equilibrium of Cr 6+ adsorption onto guava seeds were studied. An external mass-transfer diffusion coefficient k and intra-particle diffusion coefficient ki were determined to measure the rate-limiting step of adsorption. A single external mass-transfer diffusion model and intra-particle diffusion models were used. The effects of initial pH, sorbent mass, and initial Cr 6+ concentrations on mass-transfer coefficients were investigated. The external mass-transfer coefficient has an average value of 7.2×10 -3 cm s -1, while the intra-particle mass-transfer diffusion coefficient was 0.34 mg g -1 min -0.5. This indicates that external diffusion to the guava seeds surface and intra-particle diffusion are both involved in the sorption process. The isotherm equilibrium data were well fitted by the Langmuir and Freundlich models with an average correlation coefficient R2=0.98. The maximum removal of Cr 6+ was obtained at pH 1 (about 100% for adsorbent dose of 15 g l -1 and 25 mg l -1 initial concentration of Cr 6+). The results indicated that the guava seeds exhibit acceptable sorption capacity. 相似文献
17.
● A series of mixed-LOFs and portable LOF-fibers were synthesized. ● LOF-S3 was selected as a luminescent sensor for antibiotics. ● Mixed-LOF was capable of decoding antibiotics by emission intensity ratios. ● Linear relationship between antibiotic concentration and I545nm/I618nm was observed. Due to the potential risk of antibiotics to the environment, the development of inexpensive, simple, and reliable antibiotic detection methods is significant but also faces challenges. In this work, several lanthanide-organic frameworks (LOFs), constructed from lanthanide ions (Eu 3+ and/or Tb 3+) and 1,3,5-benzene-tricarboxylic acid (BTC), were synthesized by solvothermal method. LOF-S3 with comparable emission peaks of 5D 4 → 7F 5 (Tb 3+, 545 nm) and 5D 0 → 7F 2 (Eu 3+, 618 nm) was selected as a luminescent sensor. In this system, the highly efficient energy transferred from the organic linker to lanthanide ions and from Tb 3+ to Eu 3+ occurs. LOF-S3 sensor was capable of decoding antibiotics by distinguishable emission intensity ratios. Therefore, a two-dimensional decoded map of antibiotics was established. The linear relationship between antibiotic concentration and emission intensity ratio indicated the quantitative determination of antibiotics was feasible. As a typical analyte, the response mechanism of nalidixic acid (NA) was investigated in detail. The competition of NA and BTC for UV light absorption, as well as the binding propensity of NA and Tb, affected the organic linkers-to-lanthanide ions and Tb-to-Eu energy transfer, resulting in the change of fluorescence intensity ratio. The self-calibrating mixed-LOF sensor overcame the uncontrollable errors of the traditional absolute emission intensity method and generated stable luminescent signals in multiple cycles. Furthermore, the integration of LOF-S3 with polymer fibers enabled the formation of a LOF-polymer fibrous composite with fluorescence detection capability, which is a promising portable sensor for practical applications. 相似文献
18.
● A composite aerogel was simply obtained to remove various fluoroquinolones (FQs). ● The structural and textural properties of this composite aerogel are improved. ● Its adsorption capacity was improved at a low content of coexisting Cu2+ or Fe3+ ion. ● Two substructural analogs of FQs are compared to explore the adsorption mechanisms. ● This aerogel after saturated adsorption can be reused directly for Cu2+ adsorption. 3D composite aerogels (CMC-CG) composed of carboxymethyl cellulose and κ-carrageenan were designed and fabricated using the one-pot synthesis technique. The optimized CMC-CG showed a good mechanical property and a high swelling ratio due to its superior textural properties with a proper chemically cross-linked interpenetrating network structure. CMC-CG was utilized for the removal of various fluoroquinolones (FQs) from water and exhibited high adsorption performance because of effective electrostatic attraction and hydrogen bonding interactions. Ciprofloxacin (CIP), a popular FQ, was used as the representative. The optimized CMC-CG had a theoretically maximal CIP uptake of approximately 1.271 mmol/g at the pH of 5.0. The adsorption capacity of CMC-CG was improved in the presence of some cations, Cu 2+ and Fe 3+ ions, at a low concentration through the bridging effect but was reduced at a high concentration. The investigation of adsorption mechanisms, based on the adsorption kinetics, isotherms and thermodynamic study, Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy analyses before and after adsorption, and changes in the adsorption performance of CMC-CG toward two molecular probes, further indicated that electrostatic attraction was the dominant interaction rather than hydrogen bonding in this adsorption. CMC-CG after saturated adsorption of CIP could be easily regenerated using a dilute NaCl aqueous solution and reused efficiently. Moreover, the disused aerogel could still be reused as a new adsorbent for effective adsorption of Cu 2+ ion. Overall, this study suggested the promising applications of this composite aerogel as an eco-friendly, cost-effective, and recyclable adsorbent for the efficient removal of FQs from water. 相似文献
19.
• Forward osmosis (FO) coupled with chemical softening for CCI ROC minimization • Effective removal of scale precursor ions by lime-soda ash softening • Enhanced water recovery from 54% to 86% by mitigation of FO membrane scaling • High-purity CaCO3 was recovered from the softening sludge • Membrane cleaning efficiency of 88.5% was obtained by EDTA for softened ROC ![]() Reverse osmosis (RO) is frequently used for water reclamation from treated wastewater or desalination plants. The RO concentrate (ROC) produced from the coal chemical industry (CCI) generally contains refractory organic pollutants and extremely high-concentration inorganic salts with a dissolved solids content of more than 20 g/L contributed by inorganic ions, such as Na +, Ca 2+, Mg 2+, Cl −, and SO 42−. To address this issue, in this study, we focused on coupling forward osmosis (FO) with chemical softening (FO-CS) for the volume minimization of CCI ROC and the recovery of valuable resources in the form of CaCO 3. In the case of the real raw CCI ROC, softening treatment by lime-soda ash was shown to effectively remove Ca 2+/Ba 2+ (>98.5%) and Mg 2+/Sr 2+/Si (>80%), as well as significantly mitigate membrane scaling during FO. The softened ROC and raw ROC corresponded to a maximum water recovery of 86% and 54%, respectively. During cyclic FO tests (4 × 10 h), a 27% decline in the water flux was observed for raw ROC, whereas only 4% was observed for softened ROC. The cleaning efficiency using EDTA was also found to be considerably higher for softened ROC (88.5%) than that for raw ROC (49.0%). In addition, CaCO 3 (92.2% purity) was recovered from the softening sludge with an average yield of 5.6 kg/m 3 treated ROC. This study provides a proof-of-concept demonstration of the FO-CS coupling process for ROC volume minimization and valuable resources recovery, which makes the treatment of CCI ROC more efficient and more economical. 相似文献
20.
The concentration of 210Po, an alpha emitter from the natural uranium series was measured in the soft tissues (total), shell, and different organs - digestive glands, gills, mantle and foot - of the freshwater mussel, Parreysia favidens (Benson), collected from the river Kaveri, at Tiruchirapalli in South India. the analyses were made in three size groups based on shell length (Group 1: 2-4 cm; Group 2: 4-5 cm; Group 3: 5-6 cm). the soft tissues of the mussel accumulated higher concentrations of 210Po (74.0-125.5 Bq kg -1 fresh) than the shell (2.9-3.9 Bq kg -1 fresh). Further, younger mussels (1 group) showed higher concentrations (125.5+2.0 Bq kg -1 fresh) in total soft tissues than older ones (III Group) (74.0+1.6 Bq kg -1 fresh); concentration factors were 1.59x 10 5 in I group and 9.37 × 10 4 in III group. the 210Po was observed to be non-uniformly distributed among the internal organs, which maintained the following descending order with reference to 210Po accumulation: digestive glands, ranging from 286.2+3.5 Bq kg -1 fresh to 43+1.3 Bq kg -1 fresh. the concentration of 210Po in the mussels was distinctly higher than that in the grass, Echinochloa colonum (J. Koenig), and carp, Cirrhinus cirrhosa (Bloch), from the same river. These data indicate that younger mussels could be used as an excellent biological indicator of 210Po and among soft tissues, digestive glands are preferable to other tissues to monitor the distribution of 210Po in the riverine system. 相似文献
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