O3-H2O2氧化法处理印染废水

采用O₃-H₂O₂氧化法对印染废水进行氧化处理,比较了O₃氧化法和O₃-H₂O₂氧化法对印染废水的处理效果,考察了初始废水pH、H₂O₂加入量、O₃流量和反应时间对废水的色度去除率和COD去除率的影响。实验结果表明：O₃-H₂O₂氧化法对废水的COD和色度的去除效果比O₃氧化法更好;在初始废水pH为11、H₂O₂加入量为13mmol/L、O₃流量为6g/h、反应时间为60min的最佳工艺条件下,处理后废水COD为61.50mg/L,COD去除率为95.73%,废水色度为5倍,色度去除率为99.75%,TOC为37.84mg/L,TOC去除率为85.10%,BOD₅为22.76mg/L,BOD₅去除率为90.20%,BOD₅/COD为0.37。     

阿什河水系枯水期氮污染特征与同位素源解析

在阿什河水系设置20个采样点,采用水质监测技术和稳定氮同位素示踪技术,研究了枯水期阿什河氮污染特征和硝酸盐氮污染来源。结果表明:(1)阿什河枯水期大部分采样点氨氮浓度较低,大部分区域达到或优于《地表水环境质量标准》(GB3838—2002)中Ⅲ类。上游河段硝酸盐氮浓度较低,中游河段较高,到下游河段略有降低。总氮浓度较高,最高达19.4mg/L。(2)阿什河水系采样点15 N的丰度(δ15 N)主要处于0.11%~0.21%、0.42%~0.78%、0.83%~0.88%和1.09%~1.26%。稳定15 N同位素示踪解析阿什河硝酸盐氮污染来源表明,阿什河上游污染源主要为大气沉降、土壤有机氮和人工化肥;中游主要受畜禽养殖污水和生活污水污染;下游主要受城镇生活污水和工业废水影响。     

Using multivariate regression modeling for sampling and predicting chemical characteristics of mixed waste in old landfills

Municipal solid waste landfills pose a threat on environment and human health, especially old landfills which lack facilities for collection and treatment of landfill gas and leachate. Consequently, missing information about emission flows prevent site-specific environmental risk assessments. To overcome this gap, the combination of waste sampling and analysis with statistical modeling is one option for estimating present and future emission potentials. Optimizing the tradeoff between investigation costs and reliable results requires knowledge about both: the number of samples to be taken and variables to be analyzed.This article aims to identify the optimized number of waste samples and variables in order to predict a larger set of variables. Therefore, we introduce a multivariate linear regression model and tested the applicability by usage of two case studies. Landfill A was used to set up and calibrate the model based on 50 waste samples and twelve variables. The calibrated model was applied to Landfill B including 36 waste samples and twelve variables with four predictor variables.The case study results are twofold: first, the reliable and accurate prediction of the twelve variables can be achieved with the knowledge of four predictor variables (Loi, EC, pH and Cl). For the second Landfill B, only ten full measurements would be needed for a reliable prediction of most response variables. The four predictor variables would exhibit comparably low analytical costs in comparison to the full set of measurements. This cost reduction could be used to increase the number of samples yielding an improved understanding of the spatial waste heterogeneity in landfills.Concluding, the future application of the developed model potentially improves the reliability of predicted emission potentials. The model could become a standard screening tool for old landfills if its applicability and reliability would be tested in additional case studies.     

蚯蚓生态滤池中蚯蚓与植物对污水净化的作用评估

构建具有不同蚯蚓和植物配置的4个单级蚯蚓生态滤池,依次编号为A(无蚯蚓无植物)、B(有蚯蚓无植物)、C(有蚯蚓栽种芦苇)和D(有蚯蚓栽种水生鸢尾)。通过比较4个滤池在6个月实验期间对化学需氧量(COD)和总氮(TN)的去除效率,系统分析蚯蚓和植物对滤池去除污染物的影响。实验分2个阶段进行:5月上旬至9月上旬,滤池进水碳氮比恒定为6;9月中旬至11月中旬,滤池每周进水碳氮比交替为3、6、9。研究结果表明,蚯蚓对滤池去除COD有一定的促进作用,且作用强度显著受到进水碳氮比的影响。植物的存在与种类对滤池去除COD效率没有显著影响。蚯蚓和植物对滤池的TN去除效率都没有显著影响。滤池进水的碳氮比是显著影响滤池去除TN效率的主要因素。     

Photocatalytic mechanisms of indoleamine destruction by the quinalphos metabolite 2-hydroxyquinoxaline: a study on melatonin and its precursors serotonin and N-acetylserotonin

The redox-active quinalphos main metabolite, 2-hydroxyquinoxaline, is particularly effective under excitation by light. We have studied the photocatalytic destruction of melatonin and its precursors, because the cytoprotective indoleamine has been detected in high quantities in mammalian skin. In photooxidation reactions, in which melatonin, N-acetylserotonin and serotonin are destroyed by 2-hydroxyquinoxaline, the photocatalyst is virtually not consumed. Rates of melatonin and serotonin destruction are not changed by the singlet oxygen quencher 1,4-diazabicyclo-(2,2,2)-octane, indicating that this oxygen species is not involved in the primary reactions, so that the persistence of 2-hydroxyquinoxaline has to be explained by redox cycling. This should imply formation of an organic radical, presumably the quinoxaline-2-oxyl radical, from which 2-hydroxyquinoxaline is regenerated by electron abstraction from indolic radical scavengers. Electron donation by 2-hydroxyquinoxaline is demonstrated by reduction of the 2,2′-azino-bis-(3-ethylbenzthiazolinyl-6-sulfonic acid) cation radical under ultrasound excitation. The compound 2-hydroxyquinoxaline interacts with the specific superoxide anion scavenger Tiron. Formation of oligomeric products from melatonin and serotonin is strongly inhibited by sodium dithionite. Products from photocatalytic indolamine conversion are predominantly dimers and oligomers. No kynuramines were detected in the case of serotonin oxidation, and melatonin's otherwise prevailing oxidation product N ¹-acetyl-N ²-formyl-5-methoxykynuramine, another cytoprotective metabolite, is only formed in relatively small quantities. The proportion between products from melatonin is changed by 1,4-diazabicyclo-(2,2,2)-octane: singlet oxygen, also formed under the influence of excited 2-hydroxyquinoxaline, only affects secondary reactions.     

Corynebacterium glutamicum as an indicator for environmental cobalt and silver stress–A proteome analysis

Cobalt and silver are toxic for cells, but mechanisms of this toxicity are largely unknown. Analysis of Corynebacterium glutamicum proteome from cells grown in control and cobalt or silver enriched media was performed by two dimensional gel electrophoresis (2DE) followed by mass spectrometry. Our results indicate that the cell adapted to cobalt stress by inducing five defense mechanisms: Scavenging of free radicals, promotion of the generation of energy, reparation of DNA, reparation and biogenesis of Fe-S cluster proteins and supporting and reparation of cell wall. In response to the detoxification of Ag⁺ many proteins were up-regulated, which involved reparation of damaged DNA, minimizing the toxic effect of reactive oxygen species (ROS) and energy generation. Overexpression of proteins involved in cell wall biosynthesis (1,4-alpha-glucan branching enzyme and nucleoside-diphosphate-sugar epimerase) upon cobalt stress and induction of proteins involved in energy metabolism (2-methylcitrate dehydratase and 1, 2-methylcitrate synthase) upon silver demonstrate the potential of these enzymes as biomarkers of sub-lethal Ag⁺ and Co toxicity.     

Plant steroid hormones produced under Ni stress are involved in the regulation of metal uptake and oxidative stress in Brassica juncea L

Brassinosteroids (BRs) are involved in the amelioration of various biotic and abiotic stresses. With an aim to explore the role of BRs under heavy metal stress, plants of Brassica juncea L. were grown in pots. The plants were subjected to various concentrations of Nickel metal (0.0, 0.2, 0.4 and 0.6 mM) and harvested on 60th day in order to observe the expression of these hormones. The isolated BRs from the leaves of Brassica plants characterized by GC-MS include 24-Epibrassinolide (24-EBL), Castasterone, Dolicholide and Typhasterole. The effect of isolated 24-EBL was studied on Ni metal uptake and antioxidative defense system in 60 d old plants of Brassica. It was observed that 24-EBL significantly increased the activities of stress ameliorating enzymes and lowered the metal uptake in plants. This is the first report in B. juncea L. plants showing the expression of BRs under metal treatments and effect of the isolated 24-EBL on metal uptake and in oxidative stress management.     

纳米生态基对水产养殖污水的处理效果

采用三因子四水平的正交设计,实验研究了纳米生态基在不同温度、溶解氧和水力停留时间下对水产养殖污水的处理效果,确定了纳米生态基处理养殖污水的最佳条件。结果表明,含氨氮和亚硝氮浓度较高的模拟养殖污水用纳米生态基挂膜,所需时间约为22 d。纳米生态基对氨氮的去除效果明显,平均去除率达到93.5%。对氨氮去除率的影响程度,水力停留时间>温度>溶解氧。当温度为30℃,DO为5.43 mg/L,HRT为0.33 h时,纳米生态基对氨氮的处理能力最佳,去除率达到94.6%。纳米生态基对亚硝氮的平均去除率为69.3%。对亚硝氮去除率的影响程度,水力停留时间>溶解氧>温度。当温度为21℃,DO为6.40 mg/L,HRT为0.33 h时,纳米生态基对亚硝氮的处理能力最佳,去除率为71.5%。纳米生态基处理养殖污水的最佳条件:温度为30℃,DO为6.40 mg/L,HRT为0.33 h。     

溶解氧对好氧颗粒污泥影响的研究进展

好氧颗粒污泥技术是一种新颖废水处理技术。溶解氧(DO)是好氧颗粒污泥形成和稳定运行的一个重要参数。好氧颗粒污泥需要的曝气量大,能耗高。高曝气量带来的高DO浓度不利于氨氮通过SND去除。当DO扩散在颗粒内部受到限制时,颗粒中心形成的厌氧层不利于颗粒污泥的长期稳定运行。本文系统分析了DO浓度对好氧颗粒污泥影响的国内外研究现状,对好氧颗粒污泥中DO浓度这一重要参数的研究进行了总结。研究在低DO浓度下保持好氧颗粒污泥的稳定性有利于降低运行成本,采取合适的方法降低颗粒内部的扩散限制有利于增强颗粒的稳定性能。