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
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产品关联
DOI
PubMed
高影响因子
Journal of Water Process Engineering
·
2024
·
IF 6.3
Denglong Lu,Shanshan Zhang,Yang Song,Huanying Ge,Zhaoguang Yang,Haipu Li
Large amounts of waste activated sludge are generated daily worldwide, posing significant environmental challenges. A promising sludge management method is urgently needed. This study innovatively introduces humic acid (HA) into a sodium percarbonate (SPC) sludge treatment system to enhance dewatering and dissolution processes. Therein, SPC was activated by dissolved iron (Fe(II) or Fe(III)) or solid phase iron (zero-valent iron or magnetite (Fe 3 O 4 )). Results confirmed that Fe(III)/SPC/HA could improve the dewaterability of sludge without pH adjustment, with the capillary suction time decreasing from 123.6 ± 1.32 s (control) to 58.10 ± 4.35 s, which was comparable with that of the Fe(III)/SPC at pH 3.0. Meanwhile, Fe 3 O 4 /SPC/HA significantly enhanced sludge dissolution, and the released protein and polysaccharide levels were 2.98 and 7.08 times higher than that in the control. Both Fe(III)/SPC/HA and Fe 3 O 4 /SPC/HA reduced heavy metals and pathogens in the sludge while increasing HA content in filtrates, all of which were beneficial for subsequent sludge disposal and HA recycling, offering cost-effective technologies for sludge treatment.
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
CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Jialin Liang,Siwei Zhang,Maoyou Ye,Jinjia Huang,Xian Yang,Shoupeng Li,Shaosong Huang,Shuiyu Sun
Zero-valent iron (ZVI) combined with oxidants is a promising conditioning strategy for improving sewage sludge dewaterability. However, challenges, such as a low dewatering rate and utilization efficiencies of ZVI, restrict further application of ZVI/oxidant treatments. This study employs, for the first time, rapid and cost-effective in-situ generation of Fe 2+ combined with common oxidants, namely H 2 O 2 , Na 2 S 2 O 8 , and KMnO 4 , to effectively improve sludge dewaterability. A comparative investigation of a standalone ZVI/oxidants treatment and when combined with a thermal and acid-wash (TA) pretreatment (TA/ZVI/oxidants) was systematically conducted to determine the sludge dewatering efficiency. Under the optimal operational conditions, the average water content of dewatered cake (Wc) was 18.47% less with the TA/ZVI/oxidants treatment when compared with the ZVI/oxidants treatment. The Wc values decreased to 54.81, 58.06, and 59.32 wt%, after the TA/ZVI/H 2 O 2 , TA/ZVI/Na 2 S 2 O 8 , and TA/ZVI/KMnO 4 treatments, respectively. The potential mechanism by which the TA/ZVI/oxidants treatment enhanced dewatering was investigated by determining the characteristics of both the sludge and the ZVI surface structure. Results indicate that the TA/ZVI/oxidants process caused more Fe 2+ dissolution, more strong oxidizing radicals and more strong flocculating Fe 3+ . The large amount of strong oxidizing radicals and strong flocculating Fe 3+ caused cell lysis and disrupted the protein-like and polysaccharide-like materials in the EPS, thereby decreasing the particle size, negative zeta potential, viscosity and colloidal forces, which then released the bound water trapped within the net-like floc and led to improved sludge dewaterability. In the ZVI reuse experiment, the TA/ZVI/oxidants treatment remained highly effective for sludge dewatering even after four cycles. Furthermore, economic analysis indicates that the TA/ZVI/H 2 O 2 treatment can save approximately 52.32% per year compared with using the traditional polyacrylamide (PAM) treatment.
研究领域:
环境工程
·
污水处理
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DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Chuhan Gu,Lei Song,Maofeng Shi,Yihong Wu,Jiaxian Zhang,Jingyu Lv
In this study, we investigated the efficiency of activation of CaO 2 by oxalic acid (OA) chelated with electrochemically (EF)-released Fe 2+ (EF-CaO 2 /OA) in improving the performance of sludge dewatering under neutral conditions. We also explored the mechanism of OA-reinforcement of EF-CaO 2 in enhancing the performance of wastewater-activated sludge dewatering by investigating the water content (Wc), specific resistance to filtration (SRF), pH, bound water content, extracellular polymers in the sludge, the secondary structure of proteins, the soluble ferric ions, and the morphology of the sludge. The EF-CaO 2 /OA process was better than the EF-CaO 2 process in terms of sludge dewatering. OA introduction significantly inhibited the increase of solution pH, which in turn promoted CaO 2 dissolution and persistent H 2 O 2 generation. The persistent oxidative reaction contributed to the degradation of hydrophilic protein fractions in EPS and the reduction of the proportion of hydrophilic structures in the secondary structure of proteins, which in turn improved the hydrophobicity of the sludge. The changing profile of DNA content in EPS proved that EF-CaO 2 /OA led to the damage of more sludge cells. It suggested that OA enhanced the oxidizing efficacy of EF-CaO 2 , which in turn promoted the release of bound water from more sludge cells. Moreover, OA significantly increased the amount of dissolved iron in solution by chelating the electrochemically released iron, which contributed to the stabilization of the oxidation reaction. Under the optimal conditions, sludge Wc and SRF treated by EF-CaO 2 /OA were reduced by 30.1% and 96.9%, respectively, and the dewatered sludge cake remained neutral. In conclusion, EF-CaO 2 /OA may be an efficient and feasible technique for deep sludge dewatering.
研究领域:
环境科学
·
污水处理
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DOI
高影响因子
Journal of Cleaner Production
·
2019
·
IF 6.395
Dongdong Ge,Wenrui Zhang,Haiping Yuan,Nanwen Zhu
Extracellular polymeric substances (EPS), especially proteins, exert a vital role in sludge dewatering. Tannic acid (TA), a plant secondary metabolite , is capable of bonding with proteins, and herein we employed it as a novel conditioner for sludge dewatering . The results indicated that TA enhanced sludge dewaterability with high reductions of 81.3% capillary suction time, 87.5% specific resistance of filtration and 13.4% water content of dewatered sludge under the optimized process parameters: TA dosage of 0.15 mmol/gTS, stirring speed of 200 r/min for 1 min, and settling time of 15 min. TA altered sludge properties pronouncedly including viscosity, particle size, zeta potential , pH and EPS contents and correlation analysis revealed their associations with sludge dewaterability. Moreover, EPS fluorescent components, sludge functional groups and surface morphology were detected for a better understanding of TA conditioning mechanism. The findings provide not only the feasibility of TA but also the potential of TA-containing plant waste in sludge treatment .
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
International Journal of Environmental Research and Public Health
·
2022
·Vol. 19
·期 22
·14726
·
IF 4.614
Hong Xiao,Qing Liu,Yingjun Wang,Ying Zhu,Dexin Fang,Ganxue Wu,Zhenxing Zeng,Hong Peng
Fe(II)-activated potassium periodate (KIO4) oxidation was used to improve the dewaterability of waste-activated sludge for the first time. Compared with those of raw sludge, the capillary suction time (CST), specific resistance filtration (SRF), and water content of filter cake (WC) of sludge treated using the Fe(II)/KIO4process under the optimal conditions (i.e., the initial pH = 6.8, KIO4dose = 1.4 mmol/g volatile suspended solids, Fe(II)/KIO4molar ratio = 1.2) decreased by 64.34%, 84.13%, and 6.69%, respectively. For conditioned sludge flocs, the Zeta potential and particle size were increased, and hydrophilic proteins in extracellular polymeric substances (EPS) were partly degraded, accompanied by the transformation of tightly bound EPS into soluble EPS and the conversion of dense sludge flocs into loose and porous ones. During Fe(II)/KIO4oxidation, Fe(IV) and the accompanying•OH were determined as the predominant reactive species and the underlying mechanism of sludge EPS degradation was proposed. This work provides a prospective method for conditioning the sludge dewaterability.Keywords:sludge dewaterability;ferrous ion;potassium periodate;extracellular polymeric substances
研究领域:
环境工程
·
废水处理
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产品关联
DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2020
·
IF 6.551
Dongdong Ge,Yanting Dong,Wenrui Zhang,Haiping Yuan,Nanwen Zhu
As an essential section before final sludge disposal, sludge dewatering has currently been one of the focus issues. In this study, an innovative Fe 2+ /persulfate/tannic acid (TA) process was verified to further strengthen systemic efficacy on enhancing sludge dewaterability, compared with the conventional Fe 2+ /persulfate process. With the efficient TA/Fe 2+ (molar ratio) of 0.25 added in Fe 2+ (0.3 mmol/gTS (total solid))/persulfate (0.6 mmol/gTS) process, sludge dewaterability was enhanced remarkably. Capillary suction time, specific resistance to filtration, and water content of dewatered sludge cake were further reduced by 61.5%, 35.3%, and 6.4% than these in Fe 2+ /persulfate. Sludge supernatant viscosity was further reduced by 86.7% due to the more removal of extracellular polymeric substances (EPS). The secondary structure of EPS protein changed apparently and fluorescent components of EPS decreased distinctly. Sludge functional group contents were observed to be lower. TA effectually increased sludge particle size and heightened sludge flocculability, rendering the large and compact aggregations. Moreover, TA accelerated the recovery of Fe 2+ , facilitating persulfate activation to generate more SO 4 ·− and · OH for EPS disruption and cell lysis in the conditioning system. These findings provided a novel approach based on the Fe 2+ /persulfate process in sludge treatment for desirable dewaterability.
研究领域:
环境科学
·
污水处理
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产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 47
·27593-27601
·
IF 3.049
Lu Luo,Yongjian Ge,Shuyu Yuan,Yanghai Yu,Zhou Shi,Shiqing Zhou,Jing Deng
Ever-increasing efforts have been made to develop rapid and practical conditioning methods of sludge dewatering. This study demonstrated an innovative combination of potassium permanganate (KMnO4) and peroxymonosulfate (PMS) for sludge dewatering. The combined use of KMnO4 and PMS (KMnO4/PMS) showed its superiority in improving sludge dewaterability over the separate use of KMnO4 or PMS. By dosing 4 mmol g−1 VSS KMnO4 and 3 mmol g−1 VSS PMS, the dewaterability of waste activated sludge (WAS) significantly enhanced as capillary suction time (CST) decreased from 73.65 s to 24.65 s while the water content of dewatered sludge cake (WC) decreased from 78.96% to 70.47%. Apart from CST and WC, the KMnO4/PMS process could also affect negative zeta potential, sludge flocs size and the concentrations of protein and polysaccharide in extracellular polymeric substances (EPS). The enhanced sludge dewaterability and changes of the physicochemical characteristics of the WAS samples during the KMnO4/PMS process were actually ascribed to sulfate radicals (SO4˙−) and hydroxyl radicals (HO˙) in situ generated via PMS activation by manganese oxides (MnOx) in the states of MnO2 and Mn3O4 transferred from KMnO4 oxidation, which was verified by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) techniques and radical scavenging experiments. Moreover, the Fourier transform infrared spectroscopy (FTIR) analysis further confirmed that the in situ generated SO4˙− and HO˙ could improve sludge dewaterability. Thus, the KMnO4/PMS process could be considered as a promising conditioning method of sludge dewatering.
研究领域:
环境科学
·
污水处理
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产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Jie Ye,Yue Lai,Chao Wang,Raymond Jianxiong Zeng,Changgeng Liu,Hao Lin,Shungui Zhou,Zhen He
Sulfate radical ( SO 4 · - )-based advanced oxidation processes (SR-AOPs) are promising for sludge dewatering. In this work, an electrochemically driven Fe 0 -activated sulfite system (E/Fe/sulfite) was developed and demonstrated for sustainably releasing Fe 2+ to activate sulfite for dewatering waste activated sludge. Under the optimal conditions (sulfite dosage = 40 mg/g dry solids, current density = 30 mA/cm 2 , pH = 6, and time = 60 min), the reduction of capillary suction time and water content of sludge cake were 87.9 ± 2.8 % and 73.1 ± 0.8 %, respectively. The improved dewatering performance was attributed to the degradation of tightly-bound extracellular polymeric substances, along with the decreased live/dead cell ratio and the increased permeability of sludge flocs. The thermal effect (∼21–59 °C) in the E/Fe/sulfite system accelerated the release of intracellular proteins, which could be effectively degraded by the strong oxidizing SO 4 · - . The results also suggested that electrochemical oxidation and thermal effect in the E/Fe/sulfite system had a synergistic impact on improving sludge dewaterability. According to the density functional theory calculation, the hydrophobic amino acids produced from protein degradation were favorable for forming the drainage channels and enhancing sludge dewaterability. This study provides new insights for understanding the SR-AOPs and their applications to sludge treatment.
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
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Xiaoping Liu,Yunbo Zhai,Zhixiang Xu,Liming Liu,Wanying Ren,Yu Xie,Caiting Li,Yun Zhu,Min Xu
The high water content of sewage sludge increases the processing costs and hampers its further disposal. Fenton technology has proven to be efficient and been widely used to enhance sludge dewaterability, but it usually needs acidification and subsequent neutralization, thus consuming a lot of chemicals. It’s well documented that hydroxyl radicals produced in various Fenton or Fenton-like reactions play a crucial role in sludge dewatering. Based on the latest study, Cu + and Cu + /H 2 O 2 pretreatments for the enhanced dewaterability of sludge without extra pH adjustment were proposed. Results showed that Cu + with and without H 2 O 2 can significantly improve the dewatering performance of sludge, which was ascertained by a capillary suction time (CST) reduction rate of about 80 %. The proteins and polysaccharides in tightly-bound extracellular polymeric substance (TB-EPS) were decreased, while increased in soluble extracellular polymeric substance (S-EPS). In addition, a hydrophobic and porous surface was formed, and zeta potential increased after conditioned. These changes may release bound water and thus improve sludge dewaterability. The results of electron spin resonance and scavenging tests signaled that the Cu 3+ was mainly accountable for the dissolution of EPS, rather than the hydroxyl radicals ( OH). Our results substantiate and untangle a distinct reinforcement mechanisms for sludge dewatering by high valent copper (Cu 3+ ). This study demonstrates for the first time that Cu 3+ plays an important role in sludge dewatering, which has long been credited to hydroxyl radicals. It also urges re-evaluation of the Fenton(-like) system for sludge dewatering, given that Cu 3+ could also cause potential oxidative destruction of EPS compared with reactive oxygen species.
研究领域:
环境科学
·
污水处理
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Science of Advanced Materials
·
2019
·Vol. 11
·期 6
·842-853
·
IF 1.158
Xu Qiyao,Liu Hongxia,Zheng Huaili,Liang Jianjun
In this study, a new cationic polyacrylamide (CPAM) was successfully synthesized through UV-H2O2-initiated polymerization technique using acryloyloxyethyl trimethyl ammonium chloride (DAC) and acrylamide (AM) as monomers, and applied to sludge dewatering experiments.
Parameters affecting the molecular weight and conversion of the polymers, including total monomer concentration, monomer concentration of DAC, H2O2 concentration, pH and illumination time were examined. Fourier transform infrared spectroscopy (FT-IR), 1H nuclear
magnetic resonance spectroscopy (1H NMR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were employed to characterize the properties of the polymers. The results showed that CPAM was successfully synthesized and possessed a coarse and porous surface morphology
and inferior thermal stabilities. When the dosage of polymer was 40 mg L–1 and the initial sludge pH value was 7.0, PAD-3 (cationic degree: 40%, molecular weight: 6.89 × 106 Da) showed a more excellent sludge dewatering performance (FCMC: 70.6% SRF: 2.8 ×
1012 m · kg –1; d
50: 436.802 μm, Df
: 1.59). During the sludge flocculation process, three mechanisms containing charge neutralization, patching and bridging co-contributed to a prominent flocculation performance.
研究领域:
环境科学
·
高分子化学
✓ 已验证
DOI
高影响因子
WATER AIR AND SOIL POLLUTION
·
2023
·Vol. 234
·期 10
·630
·
IF 2.9
Liu Jianbo,Lv Gongcheng,Liu Xiaocong,Liu Junpeng,Jia Shouhao
The supernatant fluid and sludge produced by traditional polyacrylamide flocculant (PAM) flocculation of municipal sewage emit a strong odor, and the dewatering performance of flocculant flocculating sludge based on acrylamide as the main synthetic raw material remains undesirable. In this study, we investigated a new green bioflocculant called SDF. This bioflocculant was made using 3-chloro-2-hydroxypropyl-modified starch as the raw material, acrylamide as the monomer, cerium nitrate as the initiator, and dextrin and bone gum as fillers. The results of the study indicated that the SDF-flocculated sludge exhibited a larger pore structure, superior dewatering performance, and a lower intensity of malodorous substances in the supernatant compared to PAM. Furthermore, it was found that the component with the strongest odor in the supernatant detected through purge and trap-gas chromatography–mass spectrometry was ethanethiol, and it was observed that the signal intensity released from the SDF supernatant was 30.62% lower on the first day and 7.91% lower cumulatively over the course of 7 days when compared to PAM. As a consequence, the SDF materials offer promising potential for treating odorous gas and reducing sludge in sewage treatment plants due to their easy fabrication, low cost, and superior dewatering performance.
研究领域:
环境工程
·
高分子材料
·
水处理技术
·
生物化学工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）