生物铁-复合菌处理牛仔布印染废水

针对生化池1种或几种菌种启动慢、抗冲击负荷能力差和污泥处理效率低的问题,提出用生物铁法结合生物强化技术、投加复合优势菌的处理方法,应用于牛仔布染整废水处理,COD去除率、脱色率分别达到96%、99%,产泥量可减少80%以上,每吨水节约成本60%,吨水处理费用1.6~1.9元,无二次污染,可推广应用。     

A comparison of two models with Landsat data for estimating above ground grassland biomass in Inner Mongolia,China

Two models, artificial neural network (ANN) and multiple linear regression (MLR), were developed to estimate typical grassland aboveground dry biomass in Xilingol River Basin, Inner Mongolia, China. The normalized difference vegetation index (NDVI) and topographic variables (elevation, aspect, and slope) were combined with atmospherically corrected reflectance from the Landsat ETM+ reflective bands as the candidate input variables for building both models. Seven variables (NDVI, aspect, and bands 1, 3, 4, 5 and 7) were selected by the ANN model (implemented in Statistica 6.0 neural network module), while six (elevation, NDVI, and bands 1, 3, 5 and 7) were picked to fit the MLR function after a stepwise analysis was executed between the candidate input variables and the above ground dry biomass. Both models achieved reasonable results with RMSEs ranging from 39.88% to 50.08%. The ANN model provided a more accurate estimation (RMSE_r = 39.88% for the training set, and RMSE_r = 42.36% for the testing set) than MLR (RMSE_r = 49.51% for the training, and RMSE_r = 53.20% for the testing). The final above ground dry biomass maps of the research area were produced based on the ANN and MLR models, generating the estimated mean values of 121 and 147 g/m², respectively.     

Field experiment on biological contact oxidation process to treat polluted river water in the Dianchi Lake watershed

In this study two types of biological contact oxidation processes (BCOP), a step-feed (SBCOP) unit and an inter-recycle (IBCOP) unit, were designed to investigate the treatment of heavily polluted river water. The Daqing River, which is the largest pollutant contributor to the Dianchi Lake, one of the most eutrophic freshwater lakes in China, was taken for the case study. It was found that the SBCOP had higher adaptability and better performance in the reduction of COD, TN, and TP, which made it applicable for the treatment of polluted river water entering the Dianchi Lake. Nitrification rate was observed to be greatly affected by the influent temperature. During each season, the nitrification in the SBCOP was higher than that in the IBCOP. TN removal efficiency in the SBCOP was higher than that in the IBCOP during the winter and spring but poorer during the summer, possibly due to the inhibition of denitrification by higher dissolved oxygen level in the summer. Moreover, symbiotic algaebacteria growth may be conducive to the removal of pollutants.     

Relationships of nitrous oxide fluxes with water quality parameters in free water surface constructed wetlands

The effects of chemical oxygen demand (COD) concentration in the influent on nitrous oxide (N₂O) emissions, together with the relationships between N₂O and water quality parameters in free water surface constructed wetlands, were investigated with laboratoryscale systems. N₂O emission and purification performance of wastewater were very strongly dependent on COD concentration in the influent, and the total N₂O emission in the system with middle COD influent concentration was the least. The relationships between N₂O and the chemical and physical water quality variables were studied by using principal component scores in multiple linear regression analysis to predict N₂O flux. The multiple linear regression model against principal components indicated that different water parameters affected N₂O flux with different COD concentrations in the influent, but nitrate nitrogen affected N₂O flux in all systems.     

·Cl引发3种环状含有NH结构有机化合物的大气转化机制及动力学

氯自由基(·Cl)的高氧化性及其内陆来源的新发现使得·Cl在评估有机污染物的大气归趋方面起着比以往更为重要的作用。含有NH_x(x=1,2)结构的有机化合物不仅是大气中一类潜在的有机污染物,也是大气中致癌性亚硝胺的前驱体—N中心自由基的重要来源。前人研究发现,·Cl与含有NH_x(x=1,2)结构的有机化合物具有独特的相互作用且其反应具有结构依赖性。目前,大多数研究只关注链状含有NH_x(x=1,2)结构有机化合物的反应,而对于环状含有NH结构有机化合物的反应研究却很少。本研究使用量子化学和动力学模拟相结合的方法研究·Cl引发3种环状含有NH结构有机化合物(吗啉(MOR)、哌啶(PIP)和吡咯烷(PYR))的大气转化机制及动力学。结果发现,·Cl夺取3种环状含有NH结构有机化合物中N—H的H原子形成N中心自由基是最可行的反应路径。在298 K和1 atm下,计算的反应速率常数分别为5.0!10-10(MOR)、5.1!10-10(PIP)和4.9!10-10(PYR) cm~3·molecule-1·s-1,且具有正的温度依附性。结合可获得的·OH引发反应的反应速率常数,评估·Cl对MOR和PIP转化的贡献分别为·OH的2.6%～26%和6.9%～69%。上述研究结果为将来建立·Cl引发含有NH_x(x=1,2)结构有机化合物反应的结构-活性关系、全面评估含有NH_x(x=1,2)结构有机化合物的大气归趋和环境风险提供数据支持。     

过硫酸铵含铜废液预处理工艺改造

采用离子交换工艺对过硫酸铵含铜废液预处理原有工艺进行改造,改造后降低了废液预处理成本,减少二次污染,提高铜资源的回收率,达到综合利用的目的,具有很高的环境效益及经济效益。     

RTCA与CCK-8法用于检测柴油废气颗粒物致支气管上皮细胞毒性的比较研究

运用实时无标记细胞分析系统(RTCA)和Cell Counting Kit-8(CCK-8)法分别检测柴油废气颗粒物(DEP)致支气管上皮细胞(HBE)细胞毒性,从而对2种方法进行比较研究.分别以浓度为0、3.5、7、14、28和56 mg·L-1 2种柴油废气标准参考颗粒物(Standard Reference Material 1650b,SRM 1650b;Standard Reference Material 2975,SRM 2975)对 HBE 细胞进行暴露处理,分别暴露6、12、24和48 h后,检测不同DEP致HBE细胞毒性,比较各组之间细胞存活率或标准化细胞指数(normalized cell index,NCI)值的差异,考察2种方法的优缺点.并用细胞凋亡实验检测各差异组之间的凋亡率.在相同染毒浓度及暴露时间,与SRM 1650b相比,SRM 2975对HBE细胞的毒性更强.在RTCA检测DEP致HBE细胞毒性时,低浓度DEP组的NCI值已经表现出与对照组有统计学差异(P＜0.05),而相同时间条件下,CCK-8法在更高浓度的DEP组才检测出显著的细胞活性下降(P＜0.05).且由细胞凋亡实验证实,与对照组相比,低浓度DEP组的细胞凋亡率已经有统计学差异.相对于CCK-8法,RTCA更适用于检测DEP致贴壁HBE细胞毒性.CCK-8法更适用于检测DEP致悬浮细胞的细胞毒性或与气液暴露装置联用时的贴壁/悬浮细胞毒性.     

Electro-catalytic activity of CeOx modified graphite felt for carbamazepine degradation via E-peroxone process

•CeO_x/GF-EP process had the better degradation efficiency than GF-EP process. •CeO_x/GF-EP process had the flexible application in the pH range from 5.0 to 9.0. •CeO_x could enhance surface hydrophilicity and reduce the charge-transfer resistance. •The interfacial electron transfer process was revealed. E-peroxone (EP) was one of the most attractive AOPs for removing refractory organic compounds from water, but the high energy consumption for in situ generating H₂O₂ and its low reaction efficiency for activating O₃ under acidic conditions made the obstacles for its practical application. In this study, cerium oxide was loaded on the surface of graphite felt (GF) by the hydrothermal method to construct the efficient electrode (CeO_x/GF) for mineralizing carbamazepine (CBZ) via EP process. CeO_x/GF was an efficient cathode, which led to 69.4% TOC removal in CeO_x/GF-EP process with current intensity of 10 mA in 60 min. Moreover, CeO_x/GF had the flexible application in the pH range from 5.0 to 9.0, TOC removal had no obvious decline with decrease of pH. Comparative characterizations showed that CeO_x could enhance surface hydrophilicity and reduce the charge-transfer resistance of GF. About 5.4 mg/L H₂O₂ generated in CeO_x/GF-EP process, which was 2.1 times as that in GF-EP process. The greater ozone utility was also found in CeO_x/GF-EP process. More O₃ was activated into hydroxyl radicals, which accounted for the mineralization of CBZ. An interfacial electron transfer process was revealed, which involved the function of oxygen vacancies and Ce³⁺/Ce⁴⁺ redox cycle. CeO_x/GF had the good recycling property in fifth times’ use.     

·Cl引发萘的大气氧化机制及动力学

氯自由基(·Cl)内陆来源的新发现增强了其对转化大气有机污染物的贡献,因此,需要更深入地研究·Cl引发有机污染物的转化机制和动力学.萘(Nap)是一种重要的化学品,也是城市大气浓度最高的多环芳烃,前人针对羟基自由基(·OH)引发Nap的大气氧化开展了研究.然而,目前对于·Cl引发Nap的大气氧化机制还不清楚.本研究通过量子化学计算(ωB97XD/6-311++G(3 df,2pd)//ωB97XD/6-31 +G(d,p))和动力学模拟相结合的方法研究了·Cl引发Nap的大气氧化机制与动力学,发现·Cl主要加成到Nap分子的C5位置,形成加成中间体·C10H8Cl(R1).随后,O2加成到R1的C2和C6位置生成过氧自由基(RO2·)R1-2OO-s/a和R1-6OO-s/a(s/a=syn/anti,syn表示O2加成方向和·C1加成方向相同,anti表示O2加成方向和·C1加成方向相反).这4种RO2·的环化、氢迁移和氯迁移反应均很难(能垒＞20 kcal· mol-1)发生.因此,在低NO浓度条件下,RO2·主要和HO2·反应生成氢过氧化合物(QOOH)和烷氧自由基(RO ·)R1-2O-s/a和R1-6O-s/a;在高NO浓度条件下,RO2·将主要与NO反应生成RO· (R1-2O-s/a和R1-6O-s/a)和有机硝酸酯(C10 H8 ClNO3).生成的RO·进一步通过单分子环化反应生成双环产物R1-21O-s/a和R1-61O-s/a.重要的是,生成的有机氢过氧化合物和有机硝酸酯的水生毒性比其母体化合物Nap更强,表明·Cl引发Nap反应增加了Nap释放的环境风险.揭示的机制对理解大气Nap化学及Nap释放导致的环境风险具有重要意义.     

Isolation,identification, and the degradation characteristics of a BDE-47 degrading strain北大核心CSCD

In an effort to remove BDE-47 residues from the environment, a bacterial strain that is capable of utilizing BDE-47 as the sole carbon source was isolated and screened from soil collected from an e-waste recycling area in Tianjin to analyze the degradation properties. The strain was preliminarily identified as Enterobacter sp. according to a 16S rDNA gene sequence analysis. The strain degraded 35.8% of 525 μg/L of BDE-47 in 35 d when the initial concentration of bacteria was 7.1 × 105 cells/ mL. The product of the biodegradation of BDE-47 was BDE-28. The biodegradation of BDE-47 fit well with first-order kinetics, and its degradation kinetics was ln Ct = - 0.104t + 6.22. With the addition of an electron acceptor, such as Fe3+, SO4 2- and NO3 -, the BDE-47 degradation rate was significantly increased to 49.8%, 59.1%, and 67.3%, respectively. The above results revealed that the strain could degrade BDE-47, which is of importance in the application of environmental bioremediation of BDE-47. © 2018 Science Press. All rights reserved.