Preparation of nZVI embedded modified mesoporous carbon for catalytic persulfate to degradation of reactive black 5

• The MCNZVI is prepared as an interesting material for PS activation. • Graphitized carbon shells facilitate electron transfer from Fe⁰. • The MCNZVI exhibits excellent performance to degrade RB5 by ¹O₂. • The MCNZVI has high stability and reusability in the oxidation system. High-efficiency and cost-effective catalysts with available strategies for persulfate (PS) activation are critical for the complete mineralization of organic contaminants in the environmental remediation and protection fields. A nanoscale zero-valent iron-embedded modified mesoporous carbon (MCNZVI) with a core-shell structure is synthesized using the hydrothermal synthesis method and high-temperature pyrolysis. The results showed that nZVI could be impregnated within mesoporous carbon frameworks with a comparatively high graphitization degree, rich nitrogen doping content, and a large surface area and pore volume. This material was used as a persulfate activator for the oxidation removal of Reactive Black 5 (RB5). The effects of the material dosage, PS concentration, pH, and some inorganic anions (i.e., Cl⁻, SO₄²⁻) on RB5 degradation were then investigated. The highest degradation efficiency (97.3%) of RB5 was achieved via PS (20 mmol/L) activation by the MCNZVI (0.5 g/L). The pseudo-first-order kinetics (k = 2.11 × 10⁻² min⁻¹) in the MCNZVI/PS (0.5 g/L, 20 mmol/L) was greater than 100 times than that in the MCNZVI and PS. The reactive oxygen species (ROS), including ¹O₂, SO₄^·−, HO^·, and ·O₂⁻, were generated by PS activation with the MCNZVI. Singlet oxygen was demonstrated to be the primary ROS responsible for the RB5 degradation. The MCNZVI could be reused and regenerated for recycling. This work provides new insights into PS activation to remove organic contamination.     

变频介质阻挡放电去除甲苯的实验研究

以甲苯为目标污染物,采用变频交流电源,利用介质阻挡放电(DBD)对其进行去除。实验过程中,场强、频率、气体流速和初始浓度是影响甲苯去除效果的4个主要因素。通过多因素正交实验,分析4个因素对去除效果影响的主次关系,获得了最优方案。进行单因素趋势实验,研究各因素单独对甲苯去除效果的影响趋势,得出各因素对甲苯降解效果影响的变化曲线,并对结果作出分析。实验结果表明,当场强为9.7 kV/cm,频率为400 Hz,气体流速为2.5 cm/s,初始浓度为700 mg/m3时,甲苯去除率可达80.9%。     

Emissions of parent, nitrated, and oxygenated polycyclic aromatic hydrocarbons from indoor corn straw burning in normal and controlled combustion conditions

Emission factors （EFs） of parent polycyclic aromatic hydrocarbons （pPAHs）, nitrated PAHs （nPAHs）, and oxygenated PAHs （oPAHs） were measured for indoor corn straw burned in a brick cooking stove under different burning conditions. The EFs of total 28 pPAHs, 6 nPAHs and 4 oPAHs were （7.9 ±3.4）, （6.5 ±1.6）×10^-3, and （6.1 ±1.4）×10^-1mg/kg, respectively. Fuel charge size had insignificant influence on the pollutant emissions. Measured EFs increased significantly in a fast burning due to the oxygen deficient atmosphere formed in the stove chamber. In both restricted and enhanced air supply conditions, the EFs of pPAHs, nPAHs and oPAHs were significantly higher than those measured in normal burning conditions. Though EFs varied among different burning conditions, the composition profiles and calculated isomer ratios were similar, without significant differences. The results from the stepwise regression model showed that fuel burning rate, air supply amount, and modified combustion efficiency were the three most significant influencing factors, explaining 72%-85% of the total variations.     

水体中氨氮测定方法的比较——纳氏试剂光度法、靛酚蓝比色法

纳氏试剂光度法是氨氮的经典测定方法,但该方法的灵敏度不高。靛酚蓝比色法对氨氮具有特殊的敏感性和相关性,具有较高的准确度、精确度和敏感度。同时用两种方法对水样进行了测定,结果显示无显著性差异,但是靛酚蓝比色法较为方便,准确,易于操作,极大地减轻了分析人员的劳动强度,具有积极的现实意义。     

Macroscale and microscale analysis of Anammox in anaerobic rotating biological contactor

Inoculated with conventional anaerobic activated sludge, the Anammox process was successfully developed in an anaerobic rotating biological contactor (AnRBC) fed with a low ratio of C/N synthetic wastewater. Operated in a single point feed mode, the AnRBC removed 92.1% (n = 126) of the influent N at the highest surface load of 12 g/(m².day). The biomass increased by 25% and 17.1 g/(m².day) of maximum N removal surface load was achieved by elevating flow rate with another feed point. Fluorescence in situ hybridization and polymerase chain reaction analysis indicated that the Anammox genus Candidatus Kuenenia stuttgartiensis dominated the community. Both Anammox and denitrifying activity were detected in biofilm by the application of microelectrodes. In the outer layer of the biofilm (0-2500 μupm), nitrite and ammonium consumed simultaneously in a ratio of 1.12/1, revealing the occurrence of Anammox. In the inner layer (> 2500 μupm), a decrease of nitrate was caused by denitrification in the absence of nitrite and ammonium.     

Performance and role of N-acyl-homoserine lactone (AHL)-based quorum sensing (QS) in aerobic granules

The present study investigated the relationship between N-acyl-homoserine lactone（AHL）-based quorum sensing（QS） and the physico-chemical properties of aerobic granules.Stable mature granules were observed in SBR2 and SBR3 with average diameters of 0.96,and1.49 mm,respectively. The sludge densities of aerobic granules in SBR2 and SBR3 were1.0246,and 1.0201 g/mL,respectively,which were higher than that of flocculent sludge in SBR1（1.0065 g/mL）. The results showed that the activity of AHL-based QS in SBR2 and SBR3 amounted to 2.4- and 2.1-fold induction,however,that in SBR1 with flocculent sludge was1.6-fold induction. In addition,the results also showed that the activity of AHL-based QS in the three reactors rose in the feast condition,and then dropped with the consumption of substrate. However,the activity of AHL-based QS in these three reactors recovered again in prolonged starvation. Furthermore,the results showed that the enhancement of AHL-based QS favored the extracellular polymeric substance production of microorganisms in activated sludge. Thus,it could be concluded that aerobic granules showed higher AHL-based QS than flocculent sludge,which resulted from the higher sludge density of aerobic granules than flocculent sludge. AHL-based QS was related to the metabolism energy in the feast condition; however,in prolonged starvation,microorganisms would emit more AHL-like molecules to protect themselves to resist starvation. Moreover,the enhancement of AHL-based QS favored the EPS component productivity of the microorganisms in activated sludge,which contributed to maintain the aerobic granular structure.     

Effects of two polybrominated diphenyl ethers (BDE-47, BDE-209) on the swimming behavior,population growth and reproduction of the rotifer Brachionus plicatilis

Polybrominated diphenyl ethers (PBDEs) are new kinds of persistent organic pollutants (POPs) and their potential threats to the equilibrium and sustainability of marine ecosystems have raised worldwide concerns. Here, two kinds of PBDEs, tetra-BDE (BDE-47) and deca-BDE (BDE-209) were applied, and their toxic effects on the swimming behavior, population growth and reproduction of Brachionus plicatilis were investigated. The results showed that: (1) The actual concentrations of BDE-47 and -209 in the seawater phase measured by GC–MS (Gas Chromatography−Mass Spectrometer) were much lower than their nominal concentrations. (2) In accordance with the 24-hr acute tests, BDE-209 did not show any obvious swimming inhibition to rotifers, but a good correlation did exist between the swimming inhibition rate and BDE-47 concentration suggesting that BDE-47 is more toxic than BDE-209. (3) Both BDE-47 and -209 had a significant influence on the population growth and reproduction parameters of B. plicatilis including the population growth rate, the ratio of ovigerous females/non-ovigerous females (OF/NOF), the ratio of mictic females/amictic females (MF/AF), resting egg production and the mictic rate, which indicate that these parameters in B. plicatilis population were suitable for monitoring and assessing PBDEs. Our results suggest that BDE-47 and -209 are not acute lethal toxicants and may pose a low risk to marine rotifers at environmental concentrations for short-term exposure. They also accumulate differently into rotifers. Further research data are needed to understand the mechanisms responsible for the effects caused by PBDEs and to assess their risks accurately.     

污水灌溉的研究进展

科学合理地利用污水灌溉,可以缓解日益紧张的水资源供需矛盾,充分利用污水的水肥资源,提高经济效益,保护生态环境.总结了国内外污水灌溉的发展概况和研究进展,包括污水灌溉对土壤理化特性的影响、对植物生长的影响以及对地下水的影响,并针对中国污水灌溉存在的问题,探讨了污水灌溉技术的发展方向.     

The levels and distribution of organochlorine pesticides (OCPs) in sediments from the Haihe River, China

The levels and distribution patterns of the selected organochlorine pesticides (OCPs=p,p'-DDT, o,p'-DDT, p,p'-DDE, p,p'-DDD, alpha-, beta-, gamma- and delta-HCH) in surficial sediments from the Haihe River and Dagu Drainage River of Tianjin were investigated by means of gas chromatography coupled with micro-electronic capture detector (GC-microECD). Concentrations of OCPs in the sediments from the Haihe River ranged from 1.88 to 18.76ng g(-1) (mean 7.33ng g(-1)) for sum HCH, 0.32-80.18ng g(-1) (mean 15.94ng g(-1)) for sum DDT. Compared with the Haihe River, the Dagu Drainage River was much more contaminated by HCHs and DDTs, wherein sum HCH ranged from 33.24 to 141.03ng g(-1) (mean 87.74ng g(-1)) and sum DDT ranged from 3.60 to 83.49ng g(-1) with a mean value of 35.52ng g(-1). The concentration distribution of sum DDT and sum HCH was different indicated their different contamination sources. Composition analyses indicated that a recent usage or discharge of HCH and DDT into the Dagu Drainage River.     

南京外秦淮河河岸带原生植被初步调查

对南京外秦淮河河岸带原生植被进行了初步调查.外秦淮河河岸带原生植被共有28科、50属、53种,其中漂浮植物4种,占7.55%,沉水植物1种,占1.89%,挺水和湿生植物13种,占24.53%,陆生草本和藤本植物24种,占45.28%,乔木和灌木11种,占20.75%.在概括外秦淮河自然环境和分析原生植被主要特征的基础上,提出在进行河岸带植被群落重建时应注重闸下段河岸带植被群落的重建,增加沉水植物、浮叶植物和观赏性植物的种植.另外,植被群落可按河道垂向的常水位以下区域、变化水位区域和洪水位以上区域来构建.