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23441. 题目: KMnO4-mediated reactions for hexachlorophene in aqueous solutions: Direct oxidation, self-coupling, and cross-coupling Hexachlorophene (HCP) is used in a range of general cleaning and disinfecting products and has received increased attention due to its damaging effect to the central nervous system in animals and its toxicity in humans. The chemical oxidation of HCP by KMnO4 was performed to systematically evaluate the effects of oxidant dose, pH, temperature, typical anions, humic acid (HA), and various matrices on HCP removal. The second-order rate constant for HCP was determined to be 4.83 × 104 M−1 s−1 at pH 7.0 and 25 °C. The presence of HA can inhibit the removal of HCP by KMnO4, while Cl−, NO3−, SO42−, PO43−, and CO32− have negligible effects. Degradation products analysis of the reaction, as well as theoretical calculations of HCP molecule and its phenoxy radical species, indicated that KMnO4 oxidation for HCP included a C–C bridge bond cleavage, hydroxylation, direct oxidation and self-coupling, and cross-coupling reactions. This study revealed that KMnO4 oxidation is an effective technique for eliminating HCP in real water and wastewater. | |||||
23442. 题目: The Rock-Eval® signature of soil organic carbon in arenosols of the Senegalese groundnut basin. How do agricultural practices matter? Soil organic carbon (SOC) ensures soil quality and productivity of cultivated systems in the Sahelian region. This study uses Rock-Eval® pyrolysis to examine how cultural practices impact the quantity of SOC and quality of SOM in cultivated sandy soils in the Senegal groundnut basin. This cost-effective method provides information on SOC thermal stability, which has been shown to be related qualitatively to biogeochemical stability of SOC. We sampled soils within two villages in agricultural plots representative of local agricultural systems, and in two local preserved areas (tree plantation and shrubby savanna). SOC concentrations ranged from 1.8–18.5 g.kg−1 soil in the surface layer (0−10 cm) and from 1.5–11.3 g.kg−1 soil in the 10−30 cm layer. SOC contents of cultivated soils decreased significantly (p-value < 0.0001) according to field amendment, in the following order: addition of organic wastes> addition of manure > millet residues left after harvest > no organic input. We found that the quantity and the quality of SOC are linked, and that both depend on land-use and agricultural practices, especially upon the type of organic inputs. Quantity of SOC and quality of SOM are correlated strongly in the tree plantation (R² = 0.98) and in the protected shrubby savanna (R² = 0.97). They are also correlated significantly in cultivated soils receiving organic wastes (R² = 0.82), manure (R² from 0.74 and 0.91), or millet residues (R2 = 0.91) but not in soils that receive no organic inputs. Indexes based upon Rock-Eval® pyrolysis were represented in an I/R diagram that illustrates the level of SOC stabilization. The indexes of the studied soils were plotted against comparable results from literature. Thermal signatures of the Senegalese Arenosols show an inversion of I and the R indexes compared to data from the literature. This result highlights SOC stabilization as a function of soil depth. Indeed, the refractory pool in the studied soils (where refractory pool ranged from 7.7–21.3 % in the 0−10 cm layer, and from 12.5–24.3 % in the 10−30 cm) was more abundant than in Ferralsols in natural conditions, where refractory pool ranged from 2 to 9%. The soil organic matter in these Arenosols while positively affected by organic inputs, is dominated by more or less labile forms that mineralize quickly: a quality that is excellent for productivity of these agrosystems, but not for mitigation of climate change in the long term. | |||||
23443. 题目: Removal of legacy PFAS and other fluorotelomers: Optimized regeneration strategies in DOM-rich waters We present the first study investigating optimized regeneration strategies for anionic ion exchange (IX) resins during the removal of persistent per- and poly-fluoroalkyl substances (PFAS, including GenX) from surface and treated wastewater effluents. IX regeneration studies are of critical importance from environmental perspectives. Specifically, the knowledge is essential for water utilities who presently operate IX (for PFAS removal) in a single use-and-dispose mode. In this study, legacy PFAS such as PFOA/PFOS were tested along with other harmful short-chained PFAS (PFBA/PFBS) and other toxic perfluorinated substitutes (GenX). Studies were performed on synthetic water (spiked with Suwannee River Natural Organic Matter (SRNOM), Fulvic Acid (SRFA) and Humic Acid (SRHA)), surface water, and wastewater effluents, and the regeneration was performed in batch stirred reactors. The resin service life with and without regeneration was investigated in the presence of background organic matter. In ultra-pure waters, all PFAS (C0 ∼10 μg/L, concentrations similar to that of natural waters) were effectively removed for >100,000 Bed Volume (BV) of operation. This was reduced to ∼23,500 BV in the presence of SRNOM (C0 = 5 mg C/L), 20,500 BV in SRFA and 8500 BV in SRHA, after which the saturated resins required regeneration. More importantly, all resin breakthrough (PFAS> 70 ng/L) corresponded to > 90% resin site saturation (in meqs), an essential information for optimizing IX loading. The competitive dissolved organic matter (DOM) fractions were estimated to be approximately 5–9% of the initial DOC, as estimated by the IAST-EBC model. Finally, it was identified that IX regeneration efficiency improved with increasing brine contact time but effectiveness plateaued for brine concentrations above 10% (W/V). Nonetheless, a regeneration with 10% NaCl solution with a contact time of 2 h was found to be optimal for IX operations in synthetic and natural waters. Therefore, this study provides key knowledge essential for the scientific community and the water industry on optimizing IX operational parameters for DOM and PFAS removal and would be highly valuable for systems which presently operate IX in a use-and-dispose mode. | |||||
23444. 题目: Combined application of modified corn-core powder and sludge-based biochar for sewage sludge pretreatment: Dewatering performance and dissipative particle dynamics simulation Sludge is an inevitable by-product of municipal wastewater treatment processes, and its high moisture content poses a major challenge for its subsequent treatment and disposal. Previous studies have explored the effects of applying modified corn-core powder (MCCP) on dewatering sludge. Here, we characterized the effects of applying both MCCP and sludge-based biochar (SBB) on dewatering sludge. Analysis of the anti-shear ability of SBB revealed that SBB was a skeleton builder with high compressive strength, demonstrating that SBB could maintain the permeability of sludge under high-pressure filtration processes and facilitate the flow of bound water. Dissipative particle dynamics (DPD) was used to simulated the sludge flocculating process and verify the feasibility of the experiment. As the simulation progressed, the reaction in the sludge network reached equilibrium and the simulated structure of the sludge became loose. The dewatering performance and physicochemical properties of the treated sludge were studied to further characterize the effect of this combined technology. Compared with MCCP-sludge, MCCP&SBB-sludge, which was treated by 20% DS (mass of dry solids in sludge) of SBB and 20% DS of MCCP, achieved superior dewaterability. This combined method reduced the specific resistance of filtration by 76% and enlarged the net sludge solids yield by 138%. Further study of the properties of MCCP&SBB-sludge revealed a loose structure that resembled the structure recovered by the simulation, suggesting that the DPD simulation method simulated the sludge flocculating process successfully. Therefore, the combined application of MCCP and SBB was superior for sludge dewatering because of the synergistic effects of MCCP and SBB. | |||||
23445. 题目: Activation of percarbonate by water treatment sludge–derived biochar for the remediation of PAH-contaminated sediments Sludge from a groundwater treatment plant was used to prepare biochar by pyrolysis. The Fe–Mn rich biochar was used to activate percarbonate for the remediation of polycyclic aromatic hydrocarbons (PAHs) contaminated aquatic sediments. Results showed that the sludge–derived biochar (SBC) produced at a pyrolysis temperature of 700 °C was the most effective in activating percarbonate, which exhibited significant oxidative removal of PAHs. PAHs degradation took place via a Fenton-like oxidation manners, contributed from the Fe3+/Fe2+ and Mn3+/Mn2+ redox pairs, and achieved the highest degradation efficiency of 87% at pH0 6.0. Reactions between oxygenated functional groups of biochar and H2O2 generated of O2•– and HO• radicals in abundance under neutral and alkaline pH was responsible for the catalytic degradation of PAHs. Our results provided new insights into the environmental applications of SBC for the green sustainable remediation of organics-contaminated sediments and aided in reduction of associated environmental and health risk. | |||||
23446. 题目: Co-pyrolysis of sewage sludge and biomass in carbon dioxide as a carrier gas affects the total and leachable metals in biochars The total and available (water extracted) content of selected metal were determined in co-pyrolyzed SSL with willow (8:2, 6:2 w/w) at 500, 600, and 700 °C using two different carrier gases (N2 or CO2). The study investigated the relationship of metal content and bioavailability to toxicity of biochars towards bacteria (Vibrio fischeri), plants (Lepidium sativum), and arthropods (Folsomia candida). For the biochar produced at a ratio of 6:4 (SSL:willow), the content of most metals significant decrease (P ≤ 0.05) from 5.9% to 28.9%. Co-pyrolysis of SSL with willow decreased water extractable metal concentrations (Ba, Cd, Cu, Fe, Mn, Ni, and Zn) from 8.0% to 100%. The CO2 resulted from 6 to 200 % increase (P ≤ 0.05) of metal content relative to the biochar pyrolyzed in N2. An increase in pyrolysis temperature caused a higher concentration of the metals in the biochars. The available content of most metals decreased from 9 to 100 %. The adverse effect of these biochars on living organisms was reduced due to a stronger binding of the metals (especially Cu and Cd) with the biochar matrix. The negative impact of Cd, Cr, and Cu on living organisms was also confirmed by principal component analysis (PCA). | |||||
23447. 题目: Soil properties rather than climate and ecosystem type control the vertical variations of soil organic carbon, microbial carbon, and microbial quotient Small changes in soil organic carbon (SOC) may have great influences on the climate-carbon (C) cycling feedback. However, there are large uncertainties in predicting the dynamics of SOC in soil profiles at the global scale, especially on the role of soil microbial biomass in regulating the vertical distribution of SOC. Here, we developed a database of soil microbial biomass carbon (SMBC), SOC, and soil microbial quotient (SMQ = SMBC/SOC) from 289 soil profiles across five continents, as well as climate, ecosystem types, and edaphic factors associated with these soil profiles. We assessed the vertical distribution patterns of SMBC and SMQ and the contributions of climate, ecosystem type, and edaphic condition to their vertical patterns. Our results showed that SMBC and SMQ decreased exponentially with soil depth, especially within the 0–40 cm soil depth. SOC also decreased exponentially with depth but in different magnitudes compared to SMBC and SMQ. Edaphic factors (e.g., soil clay content and C/N ratio) had the strongest control on the vertical distributions of SMBC and SMQ, probably by mediating substrate and nutrient supplies for microbial growth in soils. Mean annual temperature and ecosystem types (i.e., forests, grasslands, and croplands) had weak influences on SMBC and SMQ. In contrast, the vertical distribution of SOC was significantly affected by climate and edaphic factors. Climate and ecosystem types likely simultaneously affected multiple factors that control SMBC, such as the distribution of soil clay and nutrients along soil profiles. Overall, our data synthesis provides quantitative information of how SMBC, SMQ, and SOC changed along soil profiles at large spatial scales and identifies important factors that influence their vertical distributions. The findings can help improve the prediction of C cycling in terrestrial ecosystems by incorporating the contribution of soil microbes in Earth system models. | |||||
23448. 题目: High dissolved organic radiocarbon in precipitation during winter and its implication on the carbon cycle Radiocarbon (14C) analysis is a powerful tool for tracing carbon in the global carbon cycle. Precipitation is a component of the global carbon cycle through which dissolved organic carbon (DOC) enters terrestrial and aquatic ecosystems from the atmosphere. In previous studies, the Δ14C of DOC in rain or snow was negative indicating an input of relatively old organic carbon including fossil fuels, with only a few positive values up to +108‰ showing the signal of recent photosynthesis. However, here we report surprisingly high Δ14C-DOC in bulk precipitation, more than 1000‰ in Seoul, South Korea, especially when the Northwesterly wind blows during winter. In contrast, Δ14C of particulate organic carbon (POC) in bulk precipitation was negative, indicating that the sources of POC and DOC were different. Although the sources of the high Δ14C-DOC are not clear and future studies on them are required, the relatively high Δ14C-DOC in a nearby headwater stream suggests that precipitation DOC has the potential to affect the local carbon cycle, and that stream DOC derived from terrestrial ecosystems could be older than previously thought. The analysis of Δ14C-DOC of precipitation in many other locations is necessary to understand how long carbon stays in terrestrial ecosystems. | |||||
23449. 题目: Insight into the mechanism of low molecular weight organic acids-mediated release of phosphorus and potassium from biochars A crucial mechanism for the application of biochar in soil improvement is the direct release of nutrients from biochar. Low molecular weight organic acids (LMWOAs) ubiquitously exist in soil. However, the mechanism of LMWOAs-mediated release of nutrients from biochars remains little known. Ten biochars with different mineral element stoichiometric ratio were produced, and four LMWOAs [acetic (HAc), glycolic (GA), tartaric (TA), and citric acids (CA)] were employed, to enunciate the influence mechanism of LMWOAs on the release of phosphorus and potassium from biochar. The results showed that HAc suppressed the release of P from biochars, while TA and CA facilitated the release of P from biochars with high ratios of polyvalent metals to P. A new mechanism was proposed that the deprotonated HAc combined with the dissolved HPO42− or H2PO4− to form a complex through hydrogen bond and cation bridging. The hydrophobic methyl group of HAc was exposed outside of the complex, which decreased the water-solubility of phosphate. Meanwhile, a high ratio of polyvalent metals to P benefited more P to combine with polyvalent metals, which decreased the water-solubility of P, but the deprotonated TA and CA are polyvalent anions that could substitute this part of P by anion exchange. Also, LMWOAs promoted the release of K from biochars with low K/(P + S) ratios, possibly due to unionized carboxyl of LMWOAs served as a hydrogen bond donor to displace K out of biochars. This study gives a deep understanding of the fate of biochar originated nutrients response to LMWOAs. | |||||
23450. 题目: Comprehensive evaluation of dissolved organic matter molecular transformation in municipal solid waste incineration leachate Transformations of the molecular compositions of dissolved organic matter (DOM) in incineration leachate (IL) were investigated. Results revealed that DOM in IL had a lower oxidation degree than that in mature MSW landfill leachate (LL). Moreover, aliphatic compounds (2.0 ≥ H/C ≥ 1.5) having the highest bioavailability were the most abundant type of DOM in IL, making IL significantly more biodegradable than LL. Under microbial actions, etc., DOM composed of phenolic compounds (aromaticity index (AI) ≤ 0.50 and H/C < 1.5), polyphenols (0.66 ≥ AI > 0.50) and polycyclic aromatics (AI > 0.66) in MBR-treated effluents were enriched and more diverse than in the untreated leachates. Nanofiltration (NF) dramatically lowered the relative abundances of phenolic compounds, polyphenols and polycyclic aromatics in effluent generated by treatment of IL in a MBR. Although the concentration of DOM in NF effluent was comparatively low, the DOM compositions in the resulting NF concentrate were nearly identical to those in MBR effluent, but were more complex than those in an international standard DOM due to a higher content of CHOS and CHONS heteroatomic compounds. Particularly, coagulation in conjunction with ozone/hydrogen peroxide oxidation process were dramatically reduced most polyphenols and polycyclic aromatics from the NF concentrate. | |||||
23451. 题目: [ASAP] Novel Humo-Pectic Hydrogels for Controlled Release of Agroproducts | |||||
23452. 题目: Effects of rehabilitation through afforestation on soil aggregate stability and aggregate-associated carbon after forest fires in subtropical China The recovery of carbon stocks through the afforestation of degraded lands is a management practice that can be applied to mitigate rising concentrations of atmospheric carbon dioxide; however, due to economic pressure, most plantations are cut down in the growth stage, and the effect of forest stand age on soil carbon accumulation is unknown. We evaluated the effects of forest stand age on soil organic carbon (SOC), soil aggregate stability, and aggregate-associated SOC during afforestation. We collected soils along a chronosequence of 10, 20, 40, 60, and 100 years following restoration with P. massoniana after forest fires in the subtropical region of China. The results showed that the soil aggregates were primarily macroaggregates (>10 mm, 2–5 mm), and the stability of the soil aggregates first increased and then decreased as time progressed. The stability of the soil aggregates was at its maximum at 20 years post-planting. The mean weight diameter (MWD), geometric mean diameter (GMD) and fractal dimension (D) were 5.90 ± 0.17 mm, 4.25 ± 0.21 mm and 2.10 ± 0.04 mm, respectively, for the soil aggregates in the 0–20 cm layer. SOC content continuously increased with time since restoration, and SOC storage was mainly concentrated in the soil aggregates with sizes of >10 mm and 2–5 mm. Compared with the forests with restoration times of 10 years, the SOC storage in the 0–20 cm layer in the 20-, 40-, 60-, and 100-year-old forests increased by 10.10%, 9.57%, 31.39% and 69.40%, respectively. Compared with the forests with restoration times of 10 years, the SOC storage in the 80–100 cm layer of 20- and 40-year-old forests did not differ significantly, but those in the 60- and 100-year-old forests increased by 83.76% and 116.85%, respectively. For the forests between 10 and 100 years of age, the soil carbon sequestration rates were 0.33 ± 0.02 (0–20 cm), 0.42 ± 0.07 (20–40 cm), 0.39 ± 0.09 (40–60 cm), 0.33 ± 0.05 (60–80 cm) and 0.28 ± 0.03 (80–100 cm) Mg·C·ha−1·a−1. We concluded that SOC accumulation during afforestation occurs mainly in macroaggregates, which have faster turnover than microaggregates. The soils of mature and over-mature forests still have high carbon storage and sequestration rate, especially in the deeper soil layers (60–80 cm, 80–100 cm). | |||||
23453. 题目: Interaction effects of the main drivers of global climate change on spatiotemporal dynamics of high altitude ecosystem behaviors: process-based modeling | |||||
23454. 题目: Flexible Superhydrophobic Metal-Based Carbon Nanotube Membrane for Electrochemically Enhanced Water Treatment | |||||
23455. 题目: Different responses of root exudates to biochar application under elevated CO2 Biochar application and rising carbon dioxide (CO2) concentrations are likely to influence both aboveground and belowground plant processes. However, little is known about the influence of biochar and CO2 enrichment on root exudation, as well as their interactive effects. The aim of this study was to reveal whether rice paddy root exudates responded to biochar and CO2 enrichment and whether this effect varied at different plant growth stages. Rice was grown in growth chambers with different biochar addition rates (1%, 2%, 3%, 4%, and 5% by weight) under both ambient (aCO2, 400 ppm) and elevated (eCO2, 700 ppm) CO2 levels. Root exudation variables were measured at the tillering and stem elongation stages. Electrical conductivity (EC), amino acid (AA), indole acetic acid (IAA), and abscisic acid (ABA) levels were significantly increased but cytokinin (CYT) concentrations decreased in response to biochar addition rates. In addition, eCO2 increased root and shoot biomass but decreased the root-to-shoot ratio. eCO2 significantly decreased EC, potassium (K+), ABA, and CYT concentrations, while the opposite pattern was found for AA and IAA. Significant interactive effects between biochar addition and eCO2 were only found on CYT and AA concentrations, while no significant interactive effects of plant growth stage, biochar addition, and eCO2 were found on root exudation. These results indicate that the additive effects of biochar and eCO2 should be integrated into assessments of carbon storage ability in the future. Understanding the different responses of these variables within the rhizosphere is crucial for predicting changes in the carbon balance in response to biochar application and climate change. | |||||
23456. 题目: Change in composition and function of microbial communities in an acid bamboo (Phyllostachys praecox) plantation soil with the addition of three different biochars Biochar has been known as means to increase soil carbon (C) storage, and at the same time to ameliorate soil acidity and enhance plant growth. However, how biochar addition affects microbial community composition and metabolic function in subtropical plantation soils and their linkage with soil quality change is still poorly understood. We selected bamboo stick, corn straw and peel of Carya cathayensis as feedstocks to produce three biochars at 350 °C by slow pyrolysis, and added them to an acid bamboo (Phyllostachys praecox) plantation soil. Changes in soil nutrient and C availability, soil acidity, plant biomass, and microbial function in terms of C source utilization and soil enzyme activities were investigated after a three-month greenhouse trial. The results showed that the biochars from corn straw and peel significantly increased plant biomass, soil pH, organic C, total nitrogen (N) and dissolved organic N contents, while decreased exchangeable H+ and exchangeable Al3+ concentrations. The concentration of total phospholipid fatty acids (PLFAs) was increased significantly under biochars from corn straw and peel. The activities of β-D-cellobiosidase, N-acetylglucosaminidase and acid phosphatase were significantly increased by peel biochar. Soil basal respiration and microbial utilization rate of carbohydrates, carboxylic acids and amino acids compounds were significantly increased under the three biochars, suggesting a higher capacity of biochar-treated soil to catabolize C sources. Increased plant biomass was related to the increased N availability and decreased acidity. Our study suggests that biochar–induced changes in soil acidity and soil nutrient availability are key drivers shaping the composition of microbial communities and enhancing their catabolic capacity, but the effects on soil microbial function vary depending on feedstock origins. | |||||
23457. 题目: Age matters: Fate of soil organic matter during ageing of earthworm casts produced by the anecic earthworm Amynthas khami The fate of organic matter (OM) occluded in earthworm casts during the casts' lifetime is poorly known. We collected casts produced by the anecic earthworm Amynthas khami in tropical woodland in Northern Vietnam at different times after their production. The aim of this study was to assess the (1) the effect of earthworms on biogeochemical OM properties compared to control aggregates, separated from the surrounding soil and (2) the fate of OM during cast ageing. We analyzed five cast ageing stages for elemental content, OM chemical composition by analytical pyrolysis and stability by Rock-Eval thermal analysis. Moreover, we assessed the distribution of organic carbon (OC) in density fractions. Compared to control aggregates, fresh casts had higher OC values (5.3 vs. 2.6%) and increased OC in all density fractions. Cast OM had more lignin (1.1 vs.<0.1%), similar polysaccharide and N-compound contribution and was more thermally labile than those of control aggregates. Changes in OM composition and content during cast ageing appeared at the end of the casts' lifetime, when they were broken into small sized aggregates (10–13 mm). At these latest stages, OC content decreased (1.5-fold); along with OM in macro-aggregates (2.2-fold) and microaggregates (6.8-fold). Reduced mineral-associated OC was also recorded (1.3-fold). During ageing, the percentage of lignin decreased (5.5-fold) while the thermal stability of OM increased. Most properties were still significantly different between the oldest ageing stage and control aggregates. This study highlights that the impact of earthworms on OM storage goes beyond cast disintegration and that there is a need to better understand their influence on soil organic matter stabilization processes and in particular the formation and stability of organo-mineral associations. | |||||
23458. 题目: Sulfidation of sea urchin-like zinc oxide nanospheres: Kinetics, mechanisms, and impacts on growth of Escherichia coli Nanoscale zinc oxide (n-ZnO) with different morphology and sizes has been used in personal care products due to their antibacterial properties, resulting in discharge of n-ZnO into the environment with potential toxic effect to ecological systems. Sulfidation is one of pathways of transformation of n-ZnO, but a very limited information on the conversion of n-ZnO under sulfidic environment with special morphology such as sea urchin-like zinc oxide nanospheres (ZnO-NSs) is available to know the potential environmental risks of n-ZnO. Herein, sea urchin-like ZnO-NSs with an average size of 78 nm were synthesized and adopted as the model n-ZnO of special morphology. The ZnO-NPs at average sizes of 71 nm (ZnO-NPs-71), 48 nm (ZnO-NPs-48), and 17 nm (ZnO-NPs-17) nm were used to examine possible differences in the sulfidation between the sea urchin-like ZnO-NSs and ZnO-NPs. A new analytical method selectively dissolving ZnO over ZnS in partially sulfidized n-ZnO was developed and applied to understand the kinetics of n-ZnO sulfidation. The sulfidation rate constant (ks) of sea urchin-like ZnO-NSs was 2.9 × 10−3 h−1, comparable to that of ZnO-NPs-71 (4.1 × 10−3 h−1), but much lower than those of ZnO-NPs-48 (20.1 × 10−3 h−1) and ZnO-NPs-17 (67.8 × 10−3 h−1). This might be attributed to the differences in the specific surface area; ks positively correlated with the specific surface area (R2 = 0.97). Natural organic matter (NOM) decreased dissolution and sulfidation of the sea urchin-like ZnO-NSs. Aggregate ZnS nanocrystals instead of the original sea urchin-like ZnO-NSs were observed. We proposed that sea urchin-like ZnO-NSs were transformed to ZnS through a dissolution-precipitation pathway, consistent with the sulfidation pathway of ZnO-NPs. Sulfidation drastically reduced toxicity of sea urchin-like ZnO-NSs to Escherichia coli due to negligible dissolution of ZnS nanocrystals. These results greatly improved our understanding of the transformation and potential risks of n-ZnO with special morphology. | |||||
23459. 题目: Assessing the efficacy of dissolved air and flash-pressurized flotations using low energy for the removal of organic precursors and disinfection byproducts: a pilot-scale study | |||||
23460. 题目: An enhanced coagulation using a starch-based coagulant assisted by polysilicic acid in treating simulated and real surface water In this work, a simple and environmentally-friendly enhanced coagulation, by using a cationic starch-based coagulant (starch-3-chloro-2-hydroxypropyl trimethyl ammonium chloride, St-CTA) coupled with an optimized polysilicic acid (PSA), has been tried to coagulate the kaolin suspensions and humic acid (HA) aqueous solutions, which are used as the simulated sources of inorganic colloidal particles and organic pollutant, respectively, in micro-polluted turbid surface water. Dosing of St-CTA and PSA at the same time is more efficient and more convenient than other two separated feeding methods in this enhanced coagulation process. The synergic coagulation process and mechanism were studied and discussed in detail based on the apparent coagulation performance, floc properties, and zeta potentials of supernatants. St-CTA caused an efficient charge neutralization, i.e. compression of electric double layer of kaolin particles and electrostatic adsorption of HA, followed by an effective netting-bridging effect of PSA, resulting in an improved purification performance. St-CTA with a higher charge density showed better purification performance due to enhanced charge neutralization effect. In addition to simulated water, the validation of this enhanced coagulation process was further confirmed by comparison with a conventional coagulant, polyaluminium chloride, in treating a real surface water. This work thus provides a simple and environmentally-friendly strategy to efficiently purify micro-polluted turbid surface water and further improve the water safety. | |||||
