JOURNAL OF MEMBRANE SCIENCE
·
2021
·
IF 8.742
Bing Zhang,Xin Mao,Xiaomin Tang,Heli Tang,Bing Zhang,Yu Shen,Wenxin Shi
Coagulation has become a hotspot for membrane fouling control; however, there is a gap in research regarding the application of modified microbial flocculants (MMFs) to mitigate membrane fouling. Herein, we prepared an MMF and compared it with conventional organic flocculants for their effects on mitigating membrane fouling in an aerobic granular sludge membrane bioreactor (AGMBR). The results showed that electrical neutralization played a dominant role in the flocculation process of polymeric aluminum chloride (PAC)/MMF, which exhibited the optimal performance for the removal of pollutants and membrane fouling control. Moreover, the characteristics of the fouled membrane and the fitting of membrane fouling models indicated that the cake layer formation was the main fouling mechanism underlying membrane fouling, and MMF could mitigate the accumulation of foulants on the membrane surface, forming a loose and porous cake layer. Based on the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, the largest energy barriers of the membrane-foulant and foulant-foulant interactions were observed in the PAC/MMF-AGMBR hybrid system. Furthermore, correlation analysis revealed that total phosphorus, polysaccharide , zeta potential , and particle size had the greatest correlation with the fouling resistance. Thus, this study shows that MMF pre-coagulation is feasible and provides a new method for membrane fouling mitigation in an AGMBR.
研究领域:
环境工程学
·
废水处理技术
✓ 已验证
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2018
·
IF 6.434
Hong-cheng Fan,Jing Yu,Rong-ping Chen,Lei Yu
A novel bioflocculant, A-GS408, produced by Klebsiella oxytoca GS-4-08 cultured in acetonitrile (ACN) as sole nitrogen source was investigated in this study. A complete degradation of 1 g l −1 of ACN was achieved in 350 h, and 4.6 g of crude A-GS408 can be obtained in one litter of synthetic medium. The as-prepared bioflocculant exhibits good flocculation efficiency (over 90%) toward Kaolin solution with the aid of Fe 3+ . Chemical analysis showed that the bioflocculant was mainly composed of polysaccharides (46.3%) and proteins (20.6%). FTIR and XPS results indicated the abundant carboxyl, amine and hydroxyl groups in A-GS408 s, which play an important role on Pd 2+ and Cu 2+ adsorption. The adsorption of heavy metals can be well stimulated by Freundlich isotherm equation, and the K f was up to 439.2 mg 1-1/n l 1/n g −1 and 112.2 mg 1-1/n l 1/n g −1 for Pb 2+ and Cu 2+ , respectively. The kinetic fitting results proved that the adsorption of heavy metals by A-GS408 was chemisorption. This study may provide a new method for preparation of bioflocculant, which can not only degrade toxic compound i . e ., acetonitrile, but also can reuse considerable nitrogen source from nitrile-containing wastewater.
研究领域:
环境生物学
·
微生物学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Yongze Li,Yazhou Tang,Yuchen Yang,Wenxiang Zhou,Chujie Qi,Kai Zhou,Bo Bian
Existing cyanobacteria thickening and dewatering processes in Taihu Lake commonly use conventional inorganic flocculants to condition the cyanobacteria, which poses certain environmental risks. In this study, three different types of typical flocculants, namely polymerized aluminum chloride (PAC), cationic polyacrylamide (CPAM) and starch-based flocculant (St-CTA), were selected to investigate their flocculant effects on cyanobacteria and the mechanism of action. The analysis showed that the dosage of St-CTA was low, the flocculation efficiency was high, and it could form flocs with large particle size and high strength. The adsorption and precipitation effect of St-CTA on protein and polysaccharide in flocculated EPS was stronger than that of CPAM and PAC, and it was able to act on the protein structure of EPS favorable for flocculation, improve the hydrophilic effect of S-EPS and LB-EPS, and reduce the content of bound water in EPS from 2.08 to 1.22 g/g DS, thus improving the efficiency of algae-water separation. The free energy and energy barrier of the EPS surface in each layer of the cyanobacterial floc after flocculation by St-CTA were significantly reduced, which resulted in the tendency of the cyanobacterial particles to aggregate and thus flocculate and settle. The pilot validation of St-CTA for cyanobacteria dewatering showed that the water content of algal residue could be reduced to 93.48 %, and the removal efficiencies of total nitrogen (TN), total phosphorus (TP), ammoniacal nitrogen (NH 3 -N), and chemical oxygen demand (COD) in the air-floated water could be up to 27.3 %, 76.6 %, 27.4 %, and 56.4 %, respectively. In conclusion, this study provides scientific knowledge and demonstration for promoting the use of St-CTA to condition cyanobacterial thickening and dewatering, which is a new idea to solve the problem of cyanobacterial resourcefulness and safe utilization.
研究领域:
环境科学
·
生物学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2024
·Vol. 14
·期 44
·32389-32397
·
IF 3.9
Shuichang Chen,Shiqian Li,Wanghua Wu,Haodong Ye,Haiqing Liu,Shibin Ma,Qinghua Chen
Water resources are vital for sustainable human life and economic activities. However, the issue of water pollution has reached alarming levels. Coking wastewater, known for its high concentrations of organic matter and toxic substances, poses significant environmental hazards. In response to this challenge, we developed a novel composite flocculant called polymeric aluminum ferric chloride (PAFC)/rice straw (PAFC/RS) from fly ash (a coal waste) and rice straw (an agricultural waste). The PAFC/RS was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and Fourier transformed infrared (FT-IR). The flocculation performance of PAFC/RS was studied utilizing humic acid simulated coking wastewater as the target by measuring the chemical oxygen demand (COD), UV254, and turbidity. A removal efficiency of 97.3% for turbidity, 79.7% for COD, and 98.2% for UV254 was reached for the PAFC/RS with an optimal composition. It demonstrated a better flocculation effect compared to the traditional aluminum–iron-based inorganic flocculant. The PAFC/RS possesses great potential for a straightforward, cost-effective, and environmentally friendly water treatment material.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL TECHNOLOGY
·
2024
·
IF 2.2
Yuejin Liu,Xiaojun Niu,Dongqing Zhang,Lingling Zhou,Chunyang Tao,Yu Lin,Siping Chen,Yawen Chen,Zhang Lin,Suying Kong
Flocculation is one of the most significant conditioning methods for sludge dewatering. In the study, a novel flocculant CS–TA, prepared through free radical-mediated conjugation of tannic acid (TA) and chitosan (CS), was proposed to improve sludge dewatering. The characterisation using Fourier transform infra-red spectroscopy and X-ray diffraction analysis shows that the CS chain was the backbone of CS–TA, and the presence of CS–TA aromatic rings confirmed the conjugation of CS with TA. Moreover, the conditioning of CS–TA yielded the best dewatering performance at 30 mg g TS−1 with the water content of sludge cake by press filtration (Wsc) of 59.78% ± 0.3% and capillary suction time (CST) of 11.8s ± 0.35 s, compared to 98.2% ± 0.15% and 56.2 s ± 0.16 in raw sludge. The results of different influencing factors (e.g. pH and temperature) on flocculation efficiency indicated that CS–TA possessed the capacity for enhancing sludge dewaterability over a wide range of pH, and the optimal temperature was observed to be 35 °C. Furthermore, the increase of particle size and zeta potential implied the addition of CS–TA favoured the formation of larger particles charge neutralisation and adsorption bridging effect. In addition, extracellular polymer substances (EPS) analysis indicated that the decrease in the polysaccharide and protein contents in EPS after CS–TA addition could increase the relative hydrophobicity of sludge. Moreover, the contents of heavy metals in sludge and their leaching toxicity and environmental risk were reduced. This study provides comprehensive insights into the exploration of CS–TA for sludge dewatering and the maintenance of ecological security in an eco-friendly.
研究领域:
环境科学
·
污水处理
✓ 已验证
产品关联
DOI
PubMed
高影响因子
BIOCHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 4.446
Lei Wang,Qi-meng Lu,Tao Zeng,Jing-wen Yang,Xue-qin Hu,Hong-bin Zhang
As a promising material in the field of wastewater treatment , polysaccharide-modified flocculants have received increasing attention due to their environmental friendliness. In this study, an efficient and environmentally friendly flocculant was synthesized using a graft copolymerization reaction of dextran and [2-(methacryloyloxy) ethyl] trimethylammonium chloride (METAC). The reaction conditions were optimized at 3 mol/mol METAC/dextran, 60 g/L dextran concentration, 3 h reaction time, 60 ℃ and pH 7. The results of elemental analysis, Fourier transform infrared (FTIR) spectroscopy, NMR hydrogen spectroscopy ( 1 H NMR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA) and viscosity measurement confirmed that the graft copolymerization reaction was successful. When flocculating a kaolin suspension used as synthetic wastewater, the flocculant showed effective flocculation performance at a low dosage. The results indicate that this cationic polysaccharide flocculant removed 98.2% of the kaolin solid suspended particles. Investigation of the flocculation mechanism showed that the flocculation process consisted of charge neutralization, charge patching and adsorption bridging mechanisms. When flocculating an E. coli culture medium, this flocculant showed high efficiency under acidic, neutral and alkaline conditions. In addition, this flocculant can be easily biodegraded by the enzymatic method . As a biomaterial, this cationic dextran derivative can contribute to future treatment of industrial wastewater and harvesting of microbial cells.
研究领域:
环境科学
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材料科学
·
废水处理
✓ 已验证
DOI
高影响因子
Scientific Reports
·
2016
·Vol. 6
·期 1
·1-11
·
IF 5.228
Yu Lei,Tang Qing-wen,Zhang Yu-jia,Chen Rong-ping,Liu Xin,Qiao Wei-chuan,Li Wen-wei,Ruan Hong-hua,Song Xin
In this work, the effect of cultivation factors on the flocculation efficiency (FE) of bioflocculant P-GS408 from Klebsiella oxytoca was optimized by the response surface methodology. The most significant factor, i.e . culture time, was determined by gray relational analysis. A total of 240 mg of purified P-GS408 was prepared from 1 liter of culture solution under the optimal conditions. GC-MS analysis results indicated that the polysaccharide of P-GS408 mainly contains Rhamnose and Galactose, and the existence of abundant hydroxyl, carboxyl and amino groups was evidenced by FTIR and XPS analyses. With the aid of Fe 3+ , the FE of kaolin solution by P-GS408 could achieve 99.48% in ten minutes. Functional groups of polysaccharide were involved in the first adsorption step and the zeta potential of kaolin solution changed from −39.0 mV to 43.4 mV in the presence of Fe 3+ and P-GS408. Three-dimensional excitation-emission (EEM) fluorescence spectra demonstrates that the trivalent Fe 3+ and Al 3+ can bind efficiently with P-GS408, while those univalent and divalent cations cannot. With the help of SEM images, FTIR, zeta potential and EEM spectra, we proposed the P-GS408 flocculation mechanism, which consists of coordination bond combination, charge neutrality, adsorption and bridging, and net catching.
研究领域:
微生物学
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环境科学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2025
·Vol. 15
·期 1
·48-57
·
IF 4.6
Boxuan Li,Shaoxin Wen,Jiacheng Li,Dedong He,Yongming Luo,Xiangqian Zheng,Dingkai Chen
Polysilicate-ferric-calcium-lanthanum (PSFCL) was synthesized through a co-polymerization method in order to treat the yellow phosphorus wastewater. Its morphology, composition and functional group were analyzed by X-ray Diffraction (XRD), Fourier Transform-Infrared Spectroscopy (FTIR), Scanning Electron Microscopic (SEM) and X-ray Photoelectron Spectroscopy (XPS), respectively. The optimization of the flocculant was also investigated, including La/Si molar ratio, pH, agitation time, dosage and sedimentation time. Results showed that PSFCL has reached an excellent removal efficiency of 95% and 97% towards phosphorus and fluoride, respectively. It could be inferred that charge neutralization, bridging effect and ligand exchange were the main coagulation mechanisms. As a whole, after the introduction of lanthanum, PSFCL was found to be a promising flocculant in yellow phosphorus wastewater treatment owing to its high removal efficiency and simple synthesis route.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY
·
2017
·
IF 1.591
Shuang Zhang,Ting Lü,Dongming Qi,Hongting Zhao
Chitosan (CS)-based flocculants, denoted as CS-g-PAM and CS-g-PDBC, were successfully prepared via graft copolymerization of CS with acrylamide (AM) or dimethyl acryloyloxyethyl benzyl ammonium chloride (DBC). The grafting was confirmed by Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS). The flocculation performance of CS-g-PAM and CS-g-PDBC, as well as flocculants such as cationic polyacrylamide (CPAM), polyaluminum chloride (PAC), and CS, was evaluated and compared for treating emulsified oil wastewater. It was found that CS-g-PDBC exhibited excellent flocculation performance under both acidic and neutral conditions, while CS showed better flocculation ability under alkaline condition. The flocculation mechanism of CS and CS-g-PDBC was investigated via zeta potential measurements. Results showed that different flocculation mechanisms were involved at various pH levels. As regarding CS, the flocculation mechanism is mainly charge neutralization, patching, and sweep floc under acidic, neutral, and alkaline conditions, respectively, while for CS-g-PDBC, patching was the dominant mechanism under both acidic and neutral conditions.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Zhihong Yin,Liandong Zhu,Xiaowen Shi,Francesco G. Gentili,Yohanes Kristianto Nugroho
Flocculation is one of the promising methods for harvesting microalgae. In this study, a series of grafted cationic chitosan-cyclodextrin composite flocculants (CTS/β-CDs) with different structural properties were prepared from chitosan and cyclodextrin. The results showed that the harvesting efficiency of CTS/β-CD-1 for C. vulgaris reached 99.91%. The chain type of polymeric flocculants with moderate graft chain lengths (L = 10–20) and tighter branched chain density distribution (D = 1.0–1.8) was favorable for C. vulgaris harvesting. The addition of CTS/β-CDs caused the discrete C. vulgaris cells to be flocculated and aggregated, and the reorganization of particles resulted in larger particles after flocculation, improving the dewatering performance of microalgae flocs. CTS/β-CDs had no significant inhibitory effect on the extraction of lipids, proteins and carbohydrates, and did not affect the extraction and quality of fatty acid methyl esters, and the re-cultivation experiments of the harvested water showed that chitosan-based flocculant was able to effectively reduce the cost of microalgae harvesting. Electrostatic interactions and bridging were the main harvesting mechanisms between CTS/β-CD-1 and C vulgaris . E-DLVO modeling suggested that flocculation is mainly a result of electrostatic and acid-base interactions when the distance between particles is small. At higher pH, the harvesting efficiency of CTS/β-CD-1 with C. vulgaris decreased. The study contributes to a better understanding of the structure–activity relationship between the structural characteristics of flocculants and the harvesting performance.
研究领域:
生物技术
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Qinzheng Zhao,Tianyin Huang,Zihao Cang,Yonghai Gan,Bin Xu,Bingdang Wu
Preloading the flocs on the membrane surface is beneficial to enhance the removal of contaminants and alleviate membrane fouling in the membrane-filtration process, but the appropriate flocs and its mechanism of action need to be further clarified. The present study first focused on the flocs generated by titanium xerogel coagulant (TXC) with PFS and PACl as comparation. Three flocs were separately pre-loaded on the ultrafiltration membrane to explore their performance of removing four toxic heavy metals (As(III), As(V), Sb(III) and Sb(V)) and alleviating membrane fouling. Results showed that the flocs produced by TXC and PFS could adsorb toxic oxygenates continuously, and the removal performance of TXC flocs is better than that of PFS, while the removal performance of PACl flocs is limited. After long-term operation, the membrane fouling of pre-loaded TXC floc was minimal, and the irreversible fouling was 1/3 and 1/6 of that of PFS and PACl, respectively. Meanwhile, the backwash time was 2.0 and 2.2 times longer than PFS and PACl, respectively. The mechanism of membrane fouling alleviation by floc preloading was clarified by floc characterization and model calculations. According to the n value in the model after fitting, an intermediate blocking mechanism dominated with the larger and more loose flocs in TXC system (n = 1.54), while a complete pore blocking mechanism dominated in the PFS (n = 1.98) and PACl (n = 2.11) systems. The results demonstrated that preloading the TXC flocs were superior to that of PFS and PACl in the membrane-filtration process.
研究领域:
环境科学
·
水处理工程
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2022
·
IF 8.025
Min Wang,Lin Yue,Sobia Niazi,Imran Mahmood Khan,Yin Zhang,Zhouping Wang
The modified natural biopolymers , recognized as environmentally friendly flocculants, are gaining tremendous attention in the field of water treatment. In this study, a novel hybrid flocculant with antibacterial activity , cinnamic acid (CA) conjugated N-(2-hydroxy)-propyl-3-trimethylammonium chitosan chloride (HTCC) derivative (HTCC-CA), was prepared via quaternary ammonium and amide reactions. The characterization, flocculation , and antibacterial activities were carried out to access the structural properties and potential application. The results of UV–vis, FT-TR, and 1 H NMR confirmed the successful synthesis of HTCC-CA1-3 derivatives. XRD and TGA revealed the lower crystallinity and thermal stability of HTCC-CA1-3 derivatives than chitosan (CS). Bacterial flocculation and antibacterial tests indicated the excellent flocculation effect of HTCC-CA1-3 derivatives and showed high antibacterial activity for Escherichia coli suspension. Moreover, the mechanism of action of the derivatives was investigated via zeta potential measurements and scanning electron microscope, which can be summed up as the effective interaction between charges. The results proved that HTCC-CA derivatives are promising agents for wastewater treatment.
研究领域:
环境科学
·
生物化学
·
材料科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）