BIOCHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 3.8
Chunkai Huang,Han Zhang,Jincan Huang,Lu Zhang,Siqi Tong,Feng Wang,Guangbing Liu,Xuemin Yu,Haibo Xu,Weijing Liu
This study compared and elucidated the performance and mechanisms of aerobic and anoxic flocs in anoxic/aerobic-membrane bioreactor (A/O–MBR) for the printing and dyeing wastewater (PDW) treatment. The batch experiments were conducted with aerobic and anoxic flocs from our continuous laboratory-scale A/O–MBR for the PDW remediation. A distinct discrepancy between aerobic and anoxic activated sludge flocs for chemical oxygen demand (COD) and adsorbable organic halogens (AOX) removal was demonstrated. Specifically, the aerobic flocs exhibited considerable higher COD removal efficiencies (O1 59.0 %, O2 76.4 %) than the anoxic flocs (A1 56.5 %, A2 61.0 %) owing to the stronger organic biodegradability of aerobic respiration, while anoxic flocs exhibited greater performance on the AOX removal (A1 87.8 %) than aerobic flocs (O1 76.8 %) after 12 h biodegradation due to the greater abundance of AOX degradation relevant gene in anoxic flocs. Meanwhile, the study also revealed that the biodegradation was the principal mechanism for COD removal in PDW, whereas, both biodegradation and biosorption contributed to the AOX removal. This study provides valuable insights into the upgrading and reconstruction of A/O process in PDW treatment plants.
研究领域:
环境工程
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水处理技术
·
环境微生物学
·
废水生物处理
·
膜分离技术
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2015
·
IF 2.752
Bo Guo,Huan Yu,Baoyu Gao,Hongyan Rong,Hongyu Dong,Defang Ma,Ruihua Li,Shuang Zhao
In this study, novel cationic polyamidine (Pa) was synthesized and used as coagulant aid with aluminum sulfate (AS) for kaolin-humic acid simulated water treatment. The effects of Pa on coagulation performance and floc properties were investigated. Results showed that Pa addition significantly enhanced the removal of turbidity, ultraviolet absorbance at 254 nm wavelength (UV 254 ) and dissolved organic carbon (DOC). AS–Pa exhibited high coagulation efficiency at border pH range and increased floc size and growth rate significantly. Floc recovery ability was also improved, while floc fractal dimension was lower with Pa addition. This would be attributed to high cationic charge density and long chain of Pa, which could enhance the effect of charge neutralization and adsorption bridging.
研究领域:
环境科学
·
化学工程
✓ 已验证
DOI
高影响因子
CHEMOSPHERE
·
2020
·
IF 5.778
Hongyang Wu,Yanfang Huang,Bingbing Liu,Guihong Han,Shengpeng Su,Wenjuan Wang,Shuzhen Yang,Yubin Xue,Shuangqing Li
Hazardous metal pollution became a severe environmental issue in China. An efficient precipitation-flotation process was developed to achieve fast removal for metal-ions from wastewater. Structure and strength of precipitate particles/flocs significantly influence the flotation removal of metal-ions. Formation and growth-evolution of precipitate flocs in precipitate flotation were studied by stage analysis of precipitate particles-formation, flocs-regulation and flotation separation. The results demonstrate that early formed precipitates MHA(humics-metal complexing particles) have small particle size, high fractal dimension, low strength and recovery factor. The addition of Fe 3+ and CTAB(cetyl trimethyl ammonium bromide) reagents make the precipitate particles aggregated to flocs(MHA-Fe, MHA-Fe-CTAB) much more large, loose, coarse, and small-density. The final generated MHA-Fe-CTAB flocs are hard to be broken up, easy to be recovered and efficient to be separated by flotation process. The flotation removal of MHA-Fe-CTAB flocs is clearly higher than that of MHA or MHA-Fe. The flotation results of MHA-Fe-CTAB are as follows: flotation removal of 98.7 ± 0.40%–99.9 ± 0.10%, residual TOC of 0.96 ± 0.38–1.35 ± 0.41 mg/L and turbidity of 0.44 ± 0.09–0.63 ± 0.16 NTU. Introducing Fe 3+ and CTAB reagents into flotation solution contributes to the growth-evolution of precipitate flocs, which could intensify the metal-ions removal via precipitate flotation process and result in more ideal purification indexes for metal-containing wastewater.
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 Environmental Sciences
·
2019
·
IF 3.556
Xuejun Xiong,Hui Xu,Beiping Zhang,Xiaohui Wu,Hongyan Sun,Dongsheng Wang,Zhengyang Wang
Membrane filtration combined with pre-coagulation has advantages in advanced wastewater treatment . As a model of a microbial polysaccharide , research on the effect of sodium alginate (SA) on alum hydrolysis has been rare; therefore, it is necessary to gain insight into the interface interaction between SA molecules and Al species, and the role SA plays during floc formation. In this study, the interaction mechanism between SA and Al species has been investigated, by evaluating the effect of SA on floc characteristics and membrane fouling during coagulation–ultrafiltration with different Al species coagulants (AlCl 3 and preformed Al 13 ). Al 2p X-ray photoelectron spectroscopy (XPS) confirmed that the complexation of ligands and Al species strongly affects the reaction pathways for Al hydrolysis and the final nature of the flocs, as Al 13 can be decomposed into octahedral precipitates when SA is added. The presence of SA can affect floc properties, which have important impacts on the characteristics of the cake layer and membrane fouling. Due to the bridging ability of SA, the floc strength increased by about 50% using Al a , which was much better than preformed Al 13 , with a percentage increase of only about 6%. Moreover, the recovery factor of HA-flocs was decreased from 96% to 43% with SA addition of 0.5 mg/L. It was concluded that SA can affect the characteristics of the cake layer and membrane fouling through participating in the formation of primary flocs and altering the Al hydrolysis pathway.
研究领域:
环境科学
·
水处理工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL TECHNOLOGY
·
2021
·
IF 3.247
Peng Du,Xing Li,Yanling Yang,Xiaoyan Fan,Tingting Zhang,Nan Wang,Hang Li,Siyang Ji,Zhiwei Zhou
In a coagulation-flocculation process, optimal separation of the resultant aggregates plays a decisive role on coagulation performance and provides a lower burden for subsequent treatment units. This separation highly depends on the stability of the micro-flocs formed during the initial, rapid stage of coagulation. In this work, a two-stage addition of aluminium sulphate (alum, Al2(SO4)3) was employed by adding 0.04 and 0.08 mM Al2(SO4)3 at the beginning and the end of rapid mixing, respectively. The coagulation performance and floc characteristics were compared to conventional single addition with the same total coagulant dosage, and the effects of variable rapid-mixing speeds (160–850 rpm) and duration time (10–120 s) were investigated. The results showed that the residual turbidity of two-stage coagulant addition was 85.1% lower than single addition when applied at a mixing speed of 580 rpm and a duration time of 120 s. The underlying coagulation mechanism revealed that the two-step addition more effectively neutralized colloids and formed larger aggregates that settled better and could more easily be removed. Moreover, the aggregates were less firm, which was attributed to different interactions among the micro-flocs, the second addition of Al2(SO4)3 and destabilized colloids. The present work provides data to broaden the window of rapid-mixing environments for more effective coagulation.
研究领域:
环境科学
·
水处理工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMOSPHERE
·
2018
·
IF 4.427
Wenyu Wang,Qinyan Yue,Ruihua Li,Fan Bu,Xue Shen,Baoyu Gao
This study investigated membrane fouling in a coagulation/ultrafiltration (C-UF) process by comparing the floc properties and humic acid (HA) removal efficiency of three hydrous Al(III) species (Al a , Al b , and Al c ). The results indicated that the coagulation and membrane mechanisms were different for all three Al species because of the differences in floc properties. The HA removal efficiency increased with increasing Al dosage until an equilibrium was reached at the optimal dosage of 6 mg L −1 . In addition, membrane fouling gradually decreased as the Al dosages increased. Regardless of coagulant type, the OH and COOH functional groups of HA reacted with the Al species. Both external and internal membrane fouling were strongly dependent on the porosity of the cake layer and on the size distribution of the floc particulates, respectively. The pore area of the cake layer formed by the Al a -coagulated effluent was large because of the strong charge neutralization. Moreover, Al a generated large and loose flocs with a porous cake layer that mitigated external fouling. However, the internal fouling with the Al c coagulant was significant because the concentration of residual aggregates in the membrane pores was high.
研究领域:
环境科学
·
水处理工程
✓ 已验证
DOI
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2016
·Vol. 24
·期 2
·1757-1768
·
IF 2.76
Zhao Yanxia,Sun Yangyang,Tian Chang,Gao Baoyu,Wang Yan,Shon Hokyong,Yang Yanzhao
Titanium-based coagulation is expected to achieve both efficient water purification and sludge recycling. This study is the first attempt to use titanium tetrachloride (TiCl 4 ) for silver nanoparticle (AgNP)-humic acid composite contaminant removal in a coagulation-ultrafiltration (C-UF) process, where characterization of flocs and membrane fouling under varied coagulant dose, initial solution pH, and AgNP concentration conditions are the main contents. Results suggested that the TiCl 4 achieved high AgNP removal in the form of silver nanoparticle through adsorption and sweep flocculation and simultaneously exerted additional 68.2 % higher dissolved organic carbon removal than Al 2 (SO 4 ) 3 . The TiCl 4 produced larger and stronger flocs but with weaker recoverability and less compact degree than did Al 2 (SO 4 ) 3 . Floc properties were independent of AgNP concentration except floc fractal dimension, which was negatively correlated with AgNP concentration. The TiCl 4 precoagulation caused less membrane fouling within wider pH range than Al 2 (SO 4 ) 3 did in the C-UF process. Incorporation of AgNPs during the TiCl 4 pretreatment process facilitated the mitigation of membrane fouling, which was, however, negligibly influenced by AgNP concentration in the case of Al 2 (SO 4 ) 3 .
研究领域:
环境工程
·
水处理技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2014
·
IF 4.331
Zhen Yang,Haijiang Li,Han Yan,Hu Wu,Hu Yang,Qian Wu,Haibo Li,Aimin Li,Rongshi Cheng
In this work, a novel chitosan-based flocculant, carboxymethyl chitosan- graft -poly[(2-methacryloyloxyethyl) trimethyl ammonium chloride] (CMC- g -PDMC), was designed and prepared successfully. Flocculation performance of CMC- g -PDMC was systematically evaluated using kaolin suspension, humic acid (HA) solution and kaolin-HA mixed suspension as synthetic wastewater under acidic, neutral and alkaline conditions, respectively. The experimental results demonstrated that CMC- g -PDMC exhibited lower optimal dosage, higher contaminant removal efficiency, wider applicable pH range, lower effluent toxicity and better floc properties for handling and disposal, in comparison with polyaluminum chloride. The high flocculation performance of CMC- g -PDMC was ascribed to two structural advantages of improved both positive charges and molecular weight. In addition, flocs characteristics including flocs formation, breakage, regrowth and fractal structure, were studied by an in-situ light scattering system during the flocculation process. Detailed analysis clearly illuminated the differences and relationship among floc size, fractal dimension and floc strength. Based on analysis of floc properties in combination with zeta potential measurements, flocculation mechanisms in different synthetic wastewater at various pHs were deeply discussed: charge neutralization or patching played the key role under different conditions, and the relationship between flocculation mechanisms and floc properties has been built. The effective and environment-friendly flocculant bear significant application potentials in water treatment fields.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Wei Wu,Xuesong Li,Bo Zhou,Zhiwei Wang
While chemical conditioning is the most commonly used conditioning process for sludge dewatering, the dewaterability of chemically conditioned sludge is found to be significantly affected by shear force. However, relevant studies are still lacked, which obstructed an in-depth understanding on sludge conditioning. In this study, we systematically investigated the impacts of floc breakage induced by shearing on the sludges conditioned with polyacrylamides (PAMs)/inorganic salts. Although PAM-conditioned sludges had better structural strength and dewaterability than the ones conditioned with inorganic salts, they exhibited a drastically deteriorated dewaterability upon floc breakage after shearing. Further analysis revealed that the PAM-conditioned flocs were mainly wrapped by polymer chains and thus floc breakage would lead to a substantial release of extracellular polymeric substance (EPS) and exposure of massive non-neutralized negative charge. In comparison, the coagulation by inorganic salts was mainly completed by charge neutralization and compression of EPS, which resulted in a conditioned sludge with a much less deteriorated dewaterability after shearing. Accordingly, PAMs are suggested as the chemical agents if screw pump is used for the sludge conditioning, while extra shearing should be minimized in the conditioning process. Inorganic salts are more applicable for the conditioning layout with a flexibly located equalization tank due to their relatively low coagulation kinetics but well-maintained sludge dewaterability. This study fills some critical knowledge gaps in the fundamental understandings on chemical conditioning process and offers a guideline for the selection of practical conditioning strategy.
研究领域:
环境科学
·
污水处理
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产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2017
·
IF 2.714
Zhaoyang Su,Xing Li,Yanling Yang
Breakage and regrowth of flocs has been studied for several years, however little attention was paid to the regrowth ability of broken micro-flocs which are mainly formed during the initial flocculation stage. In this paper, a continuous optical monitoring method was employed to investigate the kinetics of flocs formation, and especially more evident flocs properties (strength and recovery factor) were also explored. The results showed that breakage at the beginning of flocculation stage can improve flocs regrowth to greater sizes when the coagulation was initially dominated by charge neutralization at a predetermined dosage. Furthermore, second dose of different coagulants during this breakage process improved kaolin particles removal efficiency to varying degrees. Separately, the second dose of Al 2 (SO 4 ) 3 continuously enlarged the floc size with the increasing dosage, contrarily that of PACl reduced the floc size. Based on the analysis of flocs properties, this phenomenon can be well explained by the difference between coagulation mechanisms under the second dose of Al 2 (SO 4 ) 3 and PACl respectively: newly formed hydroxides of Al 2 (SO 4 ) 3 enhanced broken flocs regrowth to larger sizes and entrapped more particles (lower residual turbidity) by sweep flocculation; that of PACl formed compact flocs due to stronger electric density of Al hydroxides. It was worth noting that turbidity removal performance was even better when the overall dosage by second dose only counted for ∼70% of one-time dose. Importantly, this study aimed at providing a feasible economic dose strategy for the real coagulation-flocculation application.
研究领域:
环境工程
·
水处理技术
·
胶体化学
·
过程工程
·
颗粒物控制
✓ 已验证
DOI
高影响因子
Journal of the Taiwan Institute of Chemical Engineers
·
2016
·
IF 2.848
Wenyu Wang,Qinyan Yue,Baoyu Gao,Ruihua Li
In this study, the tendency of coagulation performances, floc characteristics and membrane resistances under different pH conditions in coagulation–ultrafiltration hybrid process was investigated by different Al species and chitosan (CS). Results indicated that CS as coagulation aid was independent of aluminum species. Coagulation efficiencies of three Al species (Al a , Al b and Al c ) combined with CS were enhanced comparing with Al species used alone and shown similar variation tendencies during the pH range. The values of floc size and strength/recovery factor were relatively high at pH 6, and the maximum fractal dimension was achieved under alkaline conditions generally due to adsorption sweeping. Al a /Al b /Al c combined with CS contributed to larger flocs, higher recovery factors and smaller fractal dimension values than those without CS. The results of ultrafiltration experiments shown that membrane resistances during alkaline ranges were higher than those of acidic conditions, which indicated membrane fouling was more serious in alkaline range. In addition, the total membrane resistance was decreased significantly by CS addition.
研究领域:
环境科学
·
水处理技术
✓ 已验证
DOI
高影响因子
DESALINATION
·
2020
·
IF 7.098
Peng Du,Xing Li,Yanling Yang,Zhiwei Zhou,Xiaoyan Fan
A novel coagulation strategy, where floc property was regulated by varying dosing sequence of dual coagulants of aluminum sulfate (AS) and chitosan (CS) with floc breakage, was applied as the pre-treatment of ultrafiltration to treat algae-laden water. The river water (TW), and TW spiked with intracellular organic matter (IOM) and extracellular organic matter (EOM) respectively (TW-IOM and TW-EOM) were tested. The results indicate that floc breakage applied in successive dosing of AS and CS in TW and TW-IOM water samples formed compact flocs through charge neutralization and bridging, generating dense cake layer to control irreversible fouling; and mitigated irreversible fouling (R ir ) caused by protein-like and humic-like species in the molecular weight (MW) of 950–3000 Da. For TW-EOM water sample, the successive addition of CS and AS can relieve R ir by removing protein-like species and soluble by-products in the MW of 500–3000 Da via charge neutralization, sweeping flocculation and bridging together, while the applied breakage aggravated membrane fouling . The obtained results provide a novel coagulation strategy to control membrane fouling during algae-laden water treatment .
研究领域:
环境工程
·
水处理技术
✓ 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）