CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Wei Xia,Yuyang Wang,Shaohang Shen,Hu Yang
Harmful algal blooms (HABs) are becoming increasingly frequent in freshwater lakes and coastal water. In this study, a novel actinia-shaped composite coagulant (ATP@CS) comprising cationic starch (CS) and attapulgite (ATP), covalently bonded by a silane coupling agent, was successfully designed and fabricated for HAB mitigation. ATP@CS showed superior performance in the harvesting of Microcystis aeruginosa , a kind of typical algae, with a maximum harvesting efficiency exceeding 98.0%. The embedded ATP in ATP@CS as the weighted inert remarkably improved the settlement properties of the formed flocs. Settling velocity increased with increased ATP content in this composite coagulant, and complete settlement was immediately achieved after coagulation by ATP@CS with an ATP-to-CS mass ratio higher than 2.0. A higher coagulant dosage was required to achieve the optimum alga removal efficiency due to the charge neutralization and bridging effects of the CS as the tentacle of this actinia-shaped composite coagulant. The presence of ATP in this composite coagulant promoted the formation of large, compact, durable, and rapidly regrown flocs during coagulation. ATP@CS as an efficient coagulant has notable potential applications in HAB removal from water owing to its remarkable advantages of enhanced settlement property, high ecological safe, notable HAB removal efficiency, low cost, and environment friendliness.
研究领域:
环境科学
·
水处理技术
✓ 已验证
产品关联
DOI
高影响因子
BIORESOURCE TECHNOLOGY
·
2021
·
IF 9.642
Long Huang,Liuyi Zhao,Zhuowen Wang,Zhiqiang Chen,Shengyong Jia,Yali Song
Polyhydroxyalkanoate (PHA) producer selection is a key step in mixed culture (MC) production. This study focused on incompatibility between PHA storage and floc settling of MCs in the selection process. In a selector using fermented waste activated sludge as substrate under varying organic loading, average maximum PHA content obtained in batch assays increased by ∼ 22 wt% and biomass concentration increased by ∼ 34% with the increasing of organic loading. However, poor floc settling occurred, causing decreased batch PHA production and costly downstream process. A flank community which can corporately use non-VFA organics existed in the selector. When organic loading increased, PHA producers had stronger negative interactions, but not cooperation with the flank community members. Thus, high PHA storage of MCs was bounded to the domination of core PHA producer. But the domination of Thauera bacteria under high organic loading indirectly induced a bloom of filamentous bacteria .
研究领域:
环境科学
·
微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL RESEARCH
·
2020
·
IF 5.715
Jinyu Ye,Huan Gao,Junkang Wu,Ran Yu
Despite the behaviors of ZnO nanoparticles (ZnO NPs) in wastewater treatment processes have been widely explored, the impacts of ZnO NPs on the activated sludge's flocculation and sedimentation performances for solid-liquid separation have rarely been involved yet. In this study, ZnO NPs were observed to exert a dose-dependent negative effect on the sludge's flocculation performance but did not significantly impact the sludge’ sedimentation behaviors. Furthermore, it was NPs themselves rather than the dissolved Zn 2+ who impaired on the sludge flocculation performance because the Zn 2+ alone would not compromise the sludge's flocculation efficiency. In addition, the sludge flocculation performance was revealed to be inversely related to the extracellular polymeric substances (EPS) content in the sludge and the direct contacts between ZnO NPs and the cells in the sludge should be the prerequisite to stimulate the secretion of the sludge EPS. The poor sludge flocculation performance could also be caused by the reduced protein/polysaccharide (PN/PS) ratio and the zeta ( ζ ) potential in the loosely bound (LB-EPS) after the sludge exposure to ZnO NPs. Fourier transform-infrared spectra (FT-IR) and three dimensional - excitation emission fluorescence spectra (3D-EEM) analysis further revealed that the decrease of the tyrosine PN-like substance level in the LB-EPS was probably the key reason for the decreased PN/PS ratio and ζ potential in the LB-EPS, which eventually induced the decline of the sludge flocculation performance under the ZnO NP stress. These results could potentially expand the knowledge on sludge flocculation and sedimentation in the presence of ZnO NPs.
研究领域:
环境科学
·
污水处理
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 115
·114405-114411
·
IF 3.289
Lijun Ye,Liyuan Chai,Qingzhu Li,Xu Yan,Qingwei Wang,Hui Liu
Solid–liquid separation and the settleability of sludge are always issues in copper wastewater treatment by chemical precipitation. To improve the settling performance of chemical precipitation sludge, controlled double-jet precipitation (CDJP) was used to treat wastewater by generating chemical precipitation granular sludge (CPGS). Several parameters such as the pH, copper oxide (CuO) seed dosage, stirring rate, adding rate and polyacrylamide dosage affecting the formation of the CPGS and wastewater treatment were investigated. Results show that the Cu(II) removal efficiency is over 99% and the settling velocity of the CPGS can reach up to 8.1 cm s−1 under optimized conditions, i.e., pH of 11, seed type of common CuO, seed dosage of 2.5 g L−1, stirring rate of 600 rpm, adding rate of 0.5 mL min−1 and PAM dosage of 20 g L−1. This settling velocity was about 18 times higher than that of chemical flocculent sludge. More importantly, the CPGS formation mechanism was explored. A three-step formation mechanism was proposed involving fresh precipitate growth on the seed surface, flocculation, and rearrangement with stirring.
研究领域:
环境科学
·
污水处理
✓ 已验证
DOI
高影响因子
BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY
·
2022
·Vol. 110
·期 1
·1-7
·
IF 2.807
Du Changsheng,Chen Haijun,Gao Weidong,Sun Wu,Peng Lei,Xu Nan
The nano-zero valence iron (nZVI) via green synthesis for heavy metal remediation has attracted many attentions due to its low-cost, environmental-safety, relative reproductivity, and high stability. However, influence of synthesis conditions on the physiochemical properties of nZVI via green tea extracts and the responding suspensibility, which is required for high reactivity, has not been fully elucidated. In this study, we investigated the zeta potentials, sedimentation and lead (Pb 2+ ) removal capacity of various nZVIs synthesized using green tea extracts. The results showed that the tea extracts extracted at 80 o C presented an excellent activity, which contributed to the outstanding suspensibility and reaction activity of nZVI synthesized in a volume ratio of 1:1 (tea extraction versus Fe 2+ solution). Thus, the optimized nZVI was successfully prepared with a Pb 2+ removal capacity (377.3 mg/g), which was seven times stronger than 50.31 mg/g of traditional chemical synthesized nZVI.
研究领域:
环境科学
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Desalination and Water Treatment
·
2024
·
IF 1
Zhaoyang Su,Xing Li,Yanling Yang,Peng Du,Xiaobo Fang
Appropriate mixing conditions are always favorable during enhanced coagulation for the desirable performance. However, up to now, there are little studies systematically investigated the effects of mixing duration and intensity on coagulation–flocculation efficiency based on a comprehensive consideration. Different mixing intensity and duration were applied in coagulation and flocculation, respectively, using aluminum sulfate as the coagulant at a predetermined dosage where significant hydroxide precipitate occurs. Flocs formation, breakage and regrowth were monitored using a ‘turbidity fluctuation’ technique, photometric dispersion analyzer (PDA) measurement. In addition, the flocs images were in situ captured using a charged-coupled device camera to further the knowledge of flocs characteristics, such as fractal dimension and settleability. The results indicated that a slightly prolonged rapid mixing time (120 s) improved floc density with better settleability when the mixing intensity in coagulation stage was maintained at a central level. In contrast, a little higher mixing intensity (40.2 s –1 ) in flocculation stage induced more compact flocs, however, with smaller homogeneous size. The compensatory interaction of mixing conditions between coagulation and flocculation stages was verified. Particularly, this work was expected to provide a useful suggestion on optimizing coagulation and flocculation separately, and thus the desirable performance can be obtained by the optimized operational design.
研究领域:
环境工程
·
水处理技术
·
颗粒物去除
·
过程优化
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Zhe Lin,Chengxuan Li,Xuezhi Zhang,Haiyang Zhang
Fluidized bed flocculator is a novel and efficient flocculation reactor. It has an efficiency that directly affected by flow field parameters. However, the structural characteristics of flocs and their influence on subsequent settling performance in fluidized bed flocculators are not clear. In this study, a multi-stage velocity gradient fluidized bed flocculator (MGF) was constructed for the continuous flocculation-sedimentation of kaolinite to investigate the growth and sedimentation behaviour of flocs. Additionally, MGF was compared with traditional mechanical stirring flocculation (MSF). Results showed that MGF achieved a higher removal efficiency (97.6 ± 0.7 %) with less coagulant and flocculant than MSF. Moreover, flocs generated in the MGF yielded a faster settling performance, which can reduce the sedimentation time by 60 times. Comparative analysis of floc structural characteristics, as well as their relationship with the settling velocity, demonstrated that flocs in MGF were more compacted than those in MSFs and thus achieved higher settling velocity. The settling velocity was collaboratively dominated by the size and fractal dimension of flocs. A modified Stokes’ settling velocity equation introducing the structural characteristics of flocs was derived, and verified by actual data to accurately and quantitatively describe the settling velocity of irregular flocs. These results indicated that MGFs have a better flocculation and sedimentation performance than MSFs for solid–liquid separation, and may lay a theoretical foundation for the design of efficient fluidized bed flocculators and popularize their application in practical engineering.
研究领域:
环境工程
·
水处理技术
✓ 已验证
DOI
高影响因子
LANGMUIR
·
2021
·
IF 3.882
Li Shixu,Zhou Jing,Liu Jun,Fu Jie,Yu Miao,Qi Song
Magnetorheological fluid (MRF) is an intelligent material, which can be controlled by an external magnetic field. It is widely used in damping, finishing, mechanical transmission, sealing, and other engineering fields due to its magnetorheological (MR) effect. However, despite decades of research and experimental development, the wide application of MRF is still restricted by its serious settlement problem owing to the density difference between the magnetic particles and carrier liquid. Here, using the coprecipitation method, a kind of Fe3O4-modified nanolignocellulose (Fe3O4/NLC) composite fiber was characterized by its unique advantages such as low density, soft magnetism property, and high specific surface. These Fe3O4/NLCs were used as a kind of reinforcing particle with carbonyl iron powder in the new bidisperse MRF system. The performances of MRF samples were enhanced by these superior properties. We found that all MRF samples with composite fibers exhibited excellent antisettlement and dynamic mechanical characteristics and cooperativity between Fe3O4 and NLCs. Furthermore, redispersibility of MRF is qualitatively evaluated by a shearing test in this paper, explaining the high property of antihardening. This composite fiber improves the comprehensive performance of MRF and has the potential to be repeatedly used in engineering applications.
研究领域:
材料科学
·
工程学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Yingdi Dong,Lingyu Rao,Yong Zeng,Tao Peng,Jiahao Huang,Yanxiu Wang,Yuping Fan,Zhiyong Gao,Honghu Tang,Wei Sun
The solid–liquid separation of coal tailings is crucial for enhancing coal resource utilization and water circulation. With the mining and processing of low-quality coal, the coal flotation tailings (CFT), characterized by fine particle size, variable mineral composition and complex particle surface properties, presented significant challenges to efficient solid–liquid separation. This study synthesized a series of polycarboxylate ether (PCE) reagents with tunable structure to optimize solid–liquid separation performance and investigate their interaction mechanisms with CFT. The results showed that increasing the carboxyl acid ratio in PCE significantly improved settling and filtration performance. Increasing the carboxyl acid ratio in PCE from 2:1 to 6:1 improved settling rate by 6.5 times and sediment solid content by 9.13 wt%, while reducing specific filtration resistance by 42.86% and filter cake moisture by 3.14%. Analysis of particle surface electrical property and wettability indicated that an increase in the carboxyl acid ratio in PCE enhanced its ability to neutralize the negative charges on the particle surface and its hydrophobic ability. The growth behavior and properties of flocs were investigated by means of focused beam reflectance measurement microscopic observation and fractal dimension analysis. The results showed that an increase in carboxyl acid ratio in PCE promoted floc growth, regrowth, and shear resistance. The floc size increased by 10.48%, and the fractal dimension increased from 1.532 to 1.636, resulting in the formation of flocs with a denser structure. These improvements in floc properties were closely related to the enhancement of CFT settling and dewatering performance. This study provided new insights into the mechanisms of PCE in enhancing solid–liquid separation of coal tailings and highlighted its potential for treating complex tailings.
研究领域:
化学工程
·
矿物加工
·
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF SOLID STATE CHEMISTRY
·
2021
·
IF 3.498
Chentao Hou,Huayang Liu,Fahim Bakhtari Mohammad
In this study, the transformation relationship between HTiOF 3 and TiOF 2 under hydrothermal conditions was discussed first. With the progress of hydrothermal reaction , HTiOF 3 with small hexagonal structure gradually transformed into TiOF 2 with large cubic structure. Secondly, the effects of alkaline hydrothermal treatment and ion-exchange treatment on the phase and morphology of HTiOF 3 and TiOF 2 were investigated. It was confirmed that hexagonal HTiOF 3 can be used as precursor to prepare fluorine doped H 2 Ti 3 O 7 (F–H 2 Ti 3 O 7 ) nanosheets with ordered mesoporous structure by simple alkaline hydrothermal and ion-exchange methods. The prepared F–H 2 Ti 3 O 7 nanosheets have ordered mesoporous structure, providing a high specific surface area of 404.08 m 2 /g and a macroporous volume of 0.46 cm 3 /g. F–H 2 Ti 3 O 7 can be adsorb tetracycline hydrochloride (TCH) on its surface and then degraded it via photocatalytic processes. Furthermore, herein for the first time the photocatalytic degradation path of TCH by F–H 2 Ti 3 O 7 through the synergistic effect of sensitization and LMCT was proposed. Besides, the reusability study showed that F–H 2 Ti 3 O 7 has the ability to degrade the tetracycline hydrochloride efficiently after five cycles and slightly its high degradation rate change from 92.90% to 82.10% under simulated sunlight. In addition, F–H 2 Ti 3 O 7 has good sedimentation performance, which provides the possibility for the practical application of the photocatalyst .
研究领域:
材料科学
·
环境科学
·
纳米技术
·
光催化
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）