Inhibition effect of magnetic field on nitrous oxide emission from sequencing batch reactor treating domestic wastewater at low temperature

This study aims to investigate the effect of a magnetic field on nitrous oxide(N_2O) emission from a sequencing batch reactor treating low-strength domestic wastewater at low temperature(10℃).After running for 124 days in parallel,results indicated that the conversion rate of N_2O for a magnetic field-sequencing batch reactor(MF-SBR) decreased by34.3% compared to that of a conventional SBR(C-SBR).Meanwhile,the removal efficiencies for total nitrogen(TN) and ammonia nitrogen(NH4-N) of the MF-SBR were 22.4% and 39.5% higher than those of the C-SBR.High-throughput sequencing revealed that the abundances of AOB(Nitrosomonas),NOB(Nitrospira) and denitrifiers(Zoogloea),which could reduce N_2O to N_2,were promoted significantly in the MF-SBR.Enzyme activities(Nir) and gene abundances(nos Z nir S and nir K) for denitrification in the MF-SBR were also notably higher compared to C-SBR.Our study shows that application of a magnetic field is a useful approach for inhibiting the generation of N_2O and promoting the nitrogen removal efficiency by affecting the microbial characteristics of sludge in an SBR treating domestic wastewater at low temperature.     

Magnetic micro-particle conditioning–pressurized vertical electro-osmotic dewatering (MPEOD) of activated sludge: Role and behavior of moisture and organics

In this study, a magnetic micro-particle conditioning–pressurized vertical electro-osmotic dewatering (MPEOD) process with magnetic micro-particle conditioning–drainage under gravity–mechanical compression–electrical compression (MMPC–DG–MC–EC) stages was established to study the distribution and migration of water, extracellular polymeric substances (EPS), and other organic matter in the activated sludge (AS) matrix at each stage. Results showed that the MPEOD process could attain 53.52% water content (WC) in dewatered AS with bound water (BW) and free water (FW) reduction rates of 82.97% and 99.67%, respectively. The coagulation and time-delayed magnetic field effects of magnetic micro-particles (MMPs) along the MMPC–DG–MC stages initiated the transformation of partial BW to FW in AS. EC had a coupling driving effect of electro-osmosis and pressure on BW, and the changes in pH and temperature at EC stage induced the aggregation of AS flocs and the release of partial BW. Additionally, MMPs dosing further improved the dewatering performance of AS by acting as skeleton builders to provide water passages. Meanwhile, MMPs could disintegrate sludge cells and EPS fractions, thereby reducing tryptophan-like protein and byproduct-like material concentrations in LB-EPS as well as protein/polysaccharide ratio in AS matrix, which could improve AS filterability. At EC stage, the former four Ex/Em regions of fluorescence regional integration analysis for EPS were obviously reduced, especially the protein-like substances in LB- and TB-EPS, which contributed to improvement of AS dewaterability.     

Mechanistic insights into sequestration of U(VI) toward magnetic biochar: Batch, XPS and EXAFS techniques

The magnetic iron oxide(Fe_3O_4) nanoparticles stabilized on the biochar were synthesized by fast pyrolysis of Fe(II)-loaded hydrophyte biomass under N_2 conditions. The batch experiments showed that magnetic biochar presented a large removal capacity(54.35 mg/g)at pH 3.0 and 293 K. The reductive co-precipitation of U(VI) to U(IV) by magnetic biochar was demonstrated according to X-ray diffraction, X-ray photoelectron spectroscopy and X-ray absorption near edge structure analysis. According to extended X-ray absorption fine structure analysis, the occurrence of U-Fe and U-U shells indicated that high effective removal of uranium was primarily inner-sphere coordination and then reductive co-precipitation at low pH. These observations provided the further understanding of uranium removal by magnetic materials in environmental remediation.     

磁性絮团形成的最佳参数及机理研究

通过对高岭土配制的浊度水投加磁粉、聚合氯化铁和聚丙烯酰胺进行磁絮凝反应，研究了形成含磁絮体的最佳工艺参数及机理。结果表明，形成含磁絮体的最佳工艺参数：磁粉粒度应小于10μm，磁粉必须和聚合氯化铁同时先于聚丙烯酰胺投加，且投加时的搅拌速度以250r／min左右为宜，磁粉的适宜加入量与污染物浓度有关。磁粉的加入没有改变絮凝荆的絮凝作用机理，有磁种参与的磁絮凝反应与没有磁种参与的絮凝反应没有本质区别。     

孔板管路对磁力泵工作的安全保护

磁力泵作为石化流程用无泄漏泵 ,由于自身结构的原因 ,必须保证泵输送流量不小于最小热流量。另一方面 ,泵输送流量也不能大于允许最大流量。否则都将造成磁力泵的损坏 ,引起事故。笔者提出在磁力泵管路系统增设辅助管路并安装最小流量孔板和主管线安装允许最大流量孔板即可同时解决上述两方面问题 ,进行泵系统性能曲线合成分析 ,并通过磁力泵实例 ,给出了最小热流量孔板和允许最大流量孔板的设计方法。这一技术用于重要的石化流程装置具有实际意义。     

Holoprosencephaly: Prenatal diagnosis by sonography and magnetic resonance imaging

Magnetic resonance (MR) imaging was performed on two women at the 33rd and 34th pregnancy week, respectively, after ultrasonographic detection of a brain malformation. Fetal neuromuscular blockade was induced by pancuronium bromide injected into the umbilical vein under continuous ultrasound (US) guidance. MR images supported the echotomographic diagnosis of holoprosencephaly, improving the image quality and offering additional information in such cases of difficult differential fetal diagnosis. Holoprosencephaly was finally confirmed by neonatal US and autopsy (case 1), US, CT and MR (case 2).     

壳聚糖包缚草酸铁处理含酚废水研究

在此以ZnFe2O4为磁性内核,利用液体石蜡作有机分散介质、甲醛、戊二醛作交联剂,通过反相悬液交联法制备出了单分散、窄分布的磁性ZnFe2O4壳聚糖核壳微球,并利用其吸附作用来处理苯酚废水溶液,同时使用紫外分光光度计来测其吸光度的变化.分吸附剂的投加量,pH值的变化,吸附时间不同的3种情况来讨论.     

Removal of petroleum tar from bird feathers utilizing magnetic particles

A previously reported acute temperature dependency for the effective removal of tarry residue from feather clusters, utilising magnetic particles, has also been demonstrated to occur for the plumage of whole birds, whereby a maximum removal of up to 96% may be achieved. The experimental design allows an approximate equilibrium constant, for the distribution of contaminant between the residue and the magnetic particles, to be estimated at each temperature. This allows the thermodynamics of the process to be examined via application of the van't Hoff equation, suggesting an explanation for the phenomenon.     

磁在混凝处理废水中的应用研究

对磁强化混凝处理废水的净化方法进行研究，用地面水、印染废水和含油废水分别进行试验，结果表明：磁处理可以提高混凝去除浊度和非溶解性COD的效果，并对其机理进行探讨。     

去离子水,自来水,城市污水磁处理实验研究

实验研究了外界磁场对水体（去离子水、自来水城市污水）理化性质的影响以及对城市污水ＣＯＤ浓度的影响。结果表明，水体的电导率、表面张力、蒸散发能力、透光度等理化性质会发生一定变化，变化大小与外界磁场强度腾；磁场强度变化，城市污水的ＣＯＤ去除率也随之变化。