ENVIRONMENTAL RESEARCH
·
2022
·
IF 8.431
Qiming Zhang,Guodong Cui,Xiao He,Zheng Wang,Tian Tang,Qing Zhao,Yangsheng Liu
Electro-dewatering technology shows a good application prospect because of its high efficiency in removing water from sludge and low energy consumption, but the potential mechanisms of sludge electro-dewatering have not been investigated in depth, which seriously limits the further development and application of electro-dewatering technology. In this study, the effects of voltage and pressure on sludge electro-dewatering performance, physicochemical characteristics and extracellular polymeric substances (EPS) compositions and distributions were investigated. The spatial distributions of EPS main components, including polysaccharide (PS) and protein (PN), were characterized by a confocal laser scanning microscopy (CLSM). The experimental results showed that under the conditions of a voltage of 40 V and a pressure of 90 kPa, the moisture content of sludge was reduced from 83.15% to 53.12%, and the bound water content of sludge in the anode layer, middle layer and cathode layer were decreased significantly from 1.16 g/g dry solid (DS) to 0.20, 0.47 and 0.35 g/g DS, respectively. The PN content of EPS in anode layer was significantly lower than that in cathode layer due to the electrochemical oxidation , while the variation of PS content showed the opposite trend, which agreed with the results visualized by CLSM. Pearson's correlation coefficient and hierarchical cluster analysis revealed that PN in TB-EPS was the major factor influencing the effect of sludge electro-dewatering. This work can be helpful to understand the potential mechanisms of electro-dewatering and provide theoretical support for the further popularization and application of electro-dewatering technology.
研究领域:
环境科学
·
污水处理
✓ 已验证
DOI
PubMed
高影响因子
PHYSICS OF FLUIDS
·
2024
·Vol. 36
·期 1
·
IF 4.1
Guo Kai,Du Ling,Lü Yuling,Bai Yin,He Limin,Luo Xiaoming
Electric dehydration is the most widely used physical technology for separating water from crude oil. However, natural surfactants stabilize the oil–water interface, resulting in low dehydration efficiency and failure of the electric dehydrator due to electric field collapse. To explore the physical methods of weakening the influence of surfactants on electric dehydration, this study synchronously increased magnetization during the electric dehydration. Based on high-speed microscopy experiments, it has been demonstrated that synchronous magnetization weakens the hindrance of surfactants to droplet coalescence during electric dehydration. Within the experimental conditions, the influence of magnetization on the growth coefficient C 1 ranges from 2.9% to 26.6%. In addition, based on molecular dynamics simulation, the mechanism of magnetization weakening the influence of surfactants was studied at the molecular level. It was found that water molecules and surfactant molecules undergo significant molecular clusters after magnetization, reducing the influence degree of surfactants on unit area. When the surfactant concentration increases, the decrease in the influence degree is balanced by the increase in the number of molecules, which also explains the law that the improvement rate Δ C 1 decreases with the increase in surfactant concentration. The results of this work will be potentially valuable for weakening surfactant barriers to demulsification and oil–water separation.
研究领域:
化学工程
·
石油工程
·
分子生物学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Mofan Li,Donghai Yang,Hongxu Zhong,Jie Pan,Liangyu Cai,Jiaxu Miao,Haotian Liu,Limin He
The rapid development of shale oil and offshore oil extraction has exacerbated brine contamination in crude oil, presenting challenges for conventional electric dehydration and desalination processes. Electric-magnetic coupling technology emerges as a promising alternative, while its underlying mechanisms and economic viability remain underexplored. In this study, we coupled a stabilized magnetic field with a high-frequency (greater than 1 kHz) pulsed alternating current electric field, enhancing the critical coalescence condition of salty droplets across a concentration range of 8.25 to 18.65 g·L −1 . Molecular dynamics simulations based on oil–water interface reveal that this enhancement is attributed to a reduction in the density and transport rate of surface charge on the droplets, influenced by ion electro enrichment and migration, ultimately allowing the electric field force to be insufficient against the capillary forces driving coalescence. Additionally, emulsion separation experiments show that the electric–magnetic coupling field increased separation efficiency by 33 % compared to the original electric field, achieving a rapid reduction of water content in high-salinity emulsions to 0.5 wt% within 20 min (includes 10 min of synchronized coupled field action). Furthermore, results of the techno-economic calculations based on our developed electric–magnetic coupling separation system indicate that the coupled-field system demonstrated a 8.26 % reduction in total costs due to lower energy consumption, highlighting its economic advantages in lower interest rate and high electricity price scenarios. Our findings provide novel insights into droplet coalescence dynamics and interfacial responses, paving the way for energy-efficient dehydration and desalination of crude oil.
研究领域:
石油工程
·
能源技术
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
WATER RESEARCH
·
2017
·
IF 6.942
Haoxuan Li,Yili Wang,Huaili Zheng
The feasibility of using Fe 0 /S 2 O 8 2− conditioning (zero valence iron (ZVI)/persulfate (ps)) integrated with horizontal electro-dewatering (HED) to improve the dewaterability of activated sludge (AS) was evaluated. The removal and migration of free and bound water in the ZVI/ps–HED process were determined, along with the organic matter migration between the solid and liquid phases of AS biosolids . Results showed that the optimum conditioning dosages were determined as 0.35 g ZVI/g dry solids (DS) and 0.15 g ps/g DS on the basis of capillary suction time variation. The lowest final water content (WC) of 83.67% in AS occurred after the HED treatment at 40 V and 120 min as determined using the response surface methodology . Despite the disruption of AS flocs and microbial cells through SO 4 − · oxidation during the ZVI/ps conditioning, the particle size and mass fractal dimension of the AS flocs remained relatively stable as the zeta potential increased from −8.5 mV to −4.6 mV. The coagulation of Fe 3+ from the oxidation of Fe 2+ by ps contributed to the relatively stable condition, which favored the subsequent momentum of the electroosmotic flow. Moreover, the ZVI/ps conditioning decreased the bound water content (BWC, from 1.83 g/g DS to 1.38 g/g DS) and increased the free water content (FWC, from 60.27 g/g DS to 60.91 g/g DS), indicating a transformation from free water to bound water. After the ZVI/ps–HED process, the FWC and BWC were removed significantly with ratios of 96.32% and 79.78%, respectively. Along with water removal through the ZVI/ps–HED process, the organic matter in the supernatant/filtrate initially increased and further rose at the HED stage. The analysis of the extracellular polymeric substance (EPS) content showed that the proteins (PNs) and polysaccharides (PSs) at the liquid and solid phases decreased due to oxidative degradation. Furthermore, the ZVI/ps stage significantly reduced the PNs content of slime to 57.22%, the PSs content of EPS to 68.50%, and the PN-like substances in the slime and tightly bound EPS to 74.90% and 52.47%, respectively. In addition, the WC of AS correlated with the contents of PN and microbial by-product-like material in slime, as well as tryptophan in TB-EPS, and the low EPS content in AS indicated good dewaterability. Thus, ZVI/ps should be selected as a pretreatment prior to HED.
研究领域:
环境科学
·
污水处理
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）