不同处理方式条件下猪粪便CH4和N2O排放因子研究

研究了不同生长阶段猪的粪便在好氧和厌氧条件下发酵14天的CH4和N2O产生量,估算出母猪和育肥猪粪便CH4和N2O排放因子,并对比分析粪便与饲料成分的关系以及粪便在发酵前后成分的变化。结果表明…     

Development of an E-H2O2/TiO2 photoelectrocatalytic oxidation system for water and wastewater treatment

In this study, an innovative E-H2O2/TiO2 (E-H2O2 = electrogenerated hydrogen peroxide) photoelectrocatalytic (PEC) oxidation system was successfully developed for water and wastewater treatment. A TiO2/Ti mesh electrode was applied in this photoreactor as the anode to conduct PEC oxidation, and a reticulated vitreous carbon (RVC) electrode was used as the cathode to electrogenerate hydrogen peroxide simultaneously. The TiO2/Ti mesh electrode was prepared with a modified anodic oxidation process in a quadrielectrolyte (H2SO4-H3PO4-H2O2-HF) solution. The crystal structure, surface morphology, and film thickness of the TiO2/Ti mesh electrode were characterized by X-ray diffraction and scanning electron microscopy. The analytical results showed that a honeycomb-type anatase film with a thickness of 5 microm was formed. Photocatalytic oxidation (PC) and PEC oxidation of 2,4,6-trichlorophenol (TCP) in an aqueous solution were performed under various experimental conditions. Experimental results showed that the TiO2/Ti electrode, anodized in the H2SO4-H3PO4-H2O2-HF solution, had higher photocatalytic activity than the TiO2/Ti electrode anodized in the H2SO4 solution. It was found that the maximum applied potential would be around 2.5 V, corresponding to an optimum applied current density of 50 microA cm(-2) under UV-A illumination. The experiments confirmed that the E-H2O2 on the RVC electrode can significantly enhance the PEC oxidation of TCP in aqueous solution. The rate of TCP degradation in such an E-H2O2-assisted TiO2 PEC reaction was 5.0 times that of the TiO2 PC reaction and 2.3 times that of the TiO2 PEC reaction. The variation of pH during the E-H2O2-assisted TiO2 PEC reaction, affected by individual reactions, was also investigated. It was found that pH was well maintained during the TCP degradation in such an E-H2O2/TiO2 reaction system. This is beneficial to TCP degradation in an aqueous solution.     

Abundance and distribution of tetracycline resistance genes and mobile elements in an oxytetracycline production wastewater treatment system

We investigated the abundance and distribution of tetracycline resistance genes (tet genes) in an oxytetracycline (OTC) antibiotic production wastewater (APW) treatment system. Of sixteen tet genes and five mobile elements, nine tet genes (tet(A), tet(C), tet(G), tet(L), tet(M), tet(O), tet(Q), tet(W), and tet(X)) and two mobile elements (class 1 integron (intI1) and transposon Tn916/1545) were successfully quantified by real-time PCR. The relative abundance of tet genes in the effluent and activated sludge (1.2 × 10(-4) to 1.3 × 10(0)) of the APW treatment system were up to 2 orders of magnitude higher than those in the OTC fermentation residues (8.5 × 10(-5) to 6.7 × 10(-3)) (P < 0.01), and 1-4 orders of magnitude higher than those in sewage and nonantibiotic production wastewater treatment systems (P < 0.01), showing that the discharge of abundant tet genes from the APW treatment system is worthy of attention. The three most abundant genes in the APW treatment system, tet(A), tet(C), and tet(G), exhibited significant positive correlations with intI1 (R(2) = 0.73, 0.95, and 0.83, respectively; P < 0.05), suggesting that intI1 may be involved in their proliferation. This is the first study showing that some measures may be required to control the discharge of antibiotic resistance genes from treated APW and activated sludge.     

Linking soil O2, CO2, and CH4 concentrations in a Wetland soil: implications for CO2 and CH4 fluxes

Oxygen (O(2)) availability and diffusivity in wetlands are controlling factors for the production and consumption of both carbon dioxide (CO(2)) and methane (CH(4)) in the subsoil and thereby potential emission of these greenhouse gases to the atmosphere. To examine the linkage between high-resolution spatiotemporal trends in O(2) availability and CH(4)/CO(2) dynamics in situ, we compare high-resolution subsurface O(2) concentrations, weekly measurements of subsurface CH(4)/CO(2) concentrations and near continuous flux measurements of CO(2) and CH(4). Detailed 2-D distributions of O(2) concentrations and depth-profiles of CO(2) and CH(4) were measured in the laboratory during flooding of soil columns using a combination of planar O(2) optodes and membrane inlet mass spectrometry. Microsensors were used to assess apparent diffusivity under both field and laboratory conditions. Gas concentration profiles were analyzed with a diffusion-reaction model for quantifying production/consumption profiles of O(2), CO(2), and CH(4). In drained conditions, O(2) consumption exceeded CO(2) production, indicating CO(2) dissolution in the remaining water-filled pockets. CH(4) emissions were negligible when the oxic zone was >40 cm and CH(4) was presumably consumed below the depth of detectable O(2). In flooded conditions, O(2) was transported by other mechanisms than simple diffusion in the aqueous phase. This work demonstrates the importance of changes in near-surface apparent diffusivity, microscale O(2) dynamics, as well as gas transport via aerenchymous plants tissue on soil gas dynamics and greenhouse gas emissions following marked changes in water level.     

Photochemical production and consumption mechanisms of nitric oxide in seawater

Nitric oxide (NO?) is an active odd-nitrogen species that plays a critical role in determining the levels of ozone (O?) and other nitrogen species in the troposphere. Here, we provide experimental evidence for photochemical formation of NO? in seawater. Photoproduction rates and overall scavenging rate constants were measured by irradiation of surface seawater samples collected from the Seto Inland Sea, Japan. Photoproduction rates of NO? ranged from 8.7 × 10?12 M s?1 to 38.8 × 10?12 M s?1 and scavenging rate constants were 0.05-0.33 s?1. The steady state concentrations of NO? in seawater, which were calculated from the photoproduction rates and scavenging rate constants were in the range 2.4-32 × 10?11 M. Estimation from the scavenging rate constant showed that the NO? lifetime in seawater was a few seconds. Our results indicate that nitrite photolysis plays a crucial role in the formation of NO?, even though we cannot exclude minor contributions from other sources. Analysis of filtered and unfiltered seawater samples showed no significant difference in NO? photoformation rates, which suggests a negligible contribution of NO? produced by photobiological processes. Using an estimated value of the Henry's law constant (kH ≈ 0.0019 M atm?1), a supersaturation of surface seawater of 2 to 3 orders of magnitude was estimated. On the basis of the average values of the surface seawater concentration and the atmospheric NO? concentration, a sea-to-air NO? flux was estimated.     

Formation and destruction of CH2O in the exhaust system of a gas engine

A computational study of chemical reactions occurring in the exhaust system of natural gas engines has been conducted, emphasizing the formation and destruction of formaldehyde. The modeling was based on a detailed reaction mechanism, developed for describing oxidation of C1-C2 hydrocarbons and formaldehyde. The mechanism was validated against data from laboratory flow reactors and from the exhaust system of a full-scale gas engine. A parametric study of the exhaust system chemistry was performed, investigating the effect of temperature, stoichiometry, pressure, and exhaust gas composition. The results indicate a complex interaction between unburned hydrocarbons (UHC), formaldehyde, and nitrogen oxides. Above 850 K, partial oxidation of unburned hydrocarbons may occur, resulting in net formation or net destruction of CH2O depending on the unburned hydrocarbons/CH2O ratio and the reaction conditions. At the typical unburned hydrocarbons/CH2O ratio of 1.0-1.5% for gas engines, net formaldehyde formation may occur in the exhaust system if temperatures above 850 K are reached.     

中密度纤维板废水处理系统的工艺分析

中密度纤维板在生产过程中产生的废水成分复杂、浓度高、可生化降解的有机物含量低、处理难度大,采用普通污水处理厂的处理设备很难将其净化。本文采用生物净化的方法处理中密度纤维板厂产生的废水,使处理后废水的各项指标均达到GB 8978—2002《污水综合排放标准》中规定的二级排放标准,且净化后的废水可以在厂内循环利用,节约水力资源,保护环境。同时,产生的活性污泥可以转化为有机肥料,作为企业的副产品销售,进一步为企业创收效益。     

超滤/纳滤技术深度处理肠衣废水的研究

采用超滤/纳滤技术对肠衣废水进行深度处理,研究操作压力和处理时间对膜性能的影响。结果表明,适宜的超滤压力为0.25MPa,运行1h后,肠衣废水的COD(chemical oxy-gen demand)、BOD(biochemical oxygen demand)的平均去除率分别大于60%和35%,平均膜通量大于580L/(m2.h);适宜的纳滤压力为1.4～1.6MPa,连续运行3h后,肠衣废水COD、BOD和氯离子的平均去除率分别大于70%、90%和98%,平均膜通量大于60L/(m2.h);最终出水的水质可以达到中水回用的要求。     

人工湿地系统应用于化机浆废水深度处理展望

阐述了人工湿地系统的基本概念、特点和原理。与化学浆中段水和二次纤维废水比较,高度封闭循环的化机浆生产线用水量少,排放废水具有浓度高、污染物处理难度大等特点,在物化絮凝和二级生化处理之后,需要进一步处理,以达到GB3544-2008标准第二阶段指标的要求。目前的化机浆废水深度处理手段,投资大、运行费用高,急需技术上的突破和升级,而人工湿地废水处理系统,具有投资省、运行费用低、实施容易等特点,可望作为化机浆废水深度处理手段的选项。     

Atmospheric chemistry of N-methyl perfluorobutane sulfonamidoethanol, C4F9SO2N(CH3)CH2CH2OH: kinetics and mechanism of reaction with OH

Relative rate methods were used to measure the gas-phase reaction of N-methyl perfluorobutane sulfonamidoethanol (NMeFBSE) with OH radicals, giving k(OH + NMeFBSE) = (5.8 +/- 0.8) x 10(-12) cm3 molecule(-1) s(-1) in 750 Torr of air diluent at 296 K. The atmospheric lifetime of NMeFBSE is determined by reaction with OH radicals and is approximately 2 days. Degradation products were identified by in situ FTIR spectroscopy and offline GC-MS and LC-MS/MS analysis. The primary carbonyl product C4F9SO2N(CH3)CH2CHO, N-methyl perfluorobutane sulfonamide (C4F9SO2NH(CH3)), perfluorobutanoic acid (C3F7C(O)OH), perfluoropropanoic acid (C2F5C(O)OH), trifluoroacetic acid (CF3C(O)OH), carbonyl fluoride (COF2), and perfluorobutane sulfonic acid (C4F9SO3H) were identified as products. A mechanism involving the addition of OH to the sulfone double bond was proposed to explain the production of perfluorobutane sulfonic acid and perfluorinated carboxylic acids in yields of 1 and 10%, respectively. The gas-phase N-dealkylation product, N-methyl perfluorobutane sulfonamide (NMeFBSA), has an atmospheric lifetime (>20 days) which is much longer than that of the parent compound, NMeFBSE. Accordingly,the production of NMeFBSA exposes a mechanism by which NMeFBSE may contribute to the burden of perfluorinated contamination in remote locations despite its relatively short atmospheric lifetime. Using the atmospheric fate of NMeFBSE as a guide, it appears that anthropogenic production of N-methyl perfluorooctane sulfonamidoethanol (NMeFOSE) contributes to the ubiquity of perfluoroalkyl sulfonate and carboxylate compounds in the environment.     

高级氧化技术在印染废水处理中的应用

高级氧化技术治理印染废水具有反应速度快、处理完全、无公害、适用范围广等优点,已引起各国重视并相继开展了研发.综述了近几年国内外采用湿式氧化法、超声氧化法、光催化氧化法、超临界氧化法、电化学法、Fenton法、臭氧氧化法等高级氧化技术;介绍了各种高级氧化技术的基本原理及在染料废水处理中的应用进展,并指出了高级氧化技术在染料废水处理中的发展趋势.     

论制浆造纸废水深度处理新技术

在我国造纸产量跃居世界第一的新形势下,国家环保部颁布的<制浆造纸工业水污染物排放标准>(GB3544-2008)对我国造纸行业提出了新的考验,为国内废水处理技术的健康发展,为造纸废水深度治理奠定了良好基础.介绍和评述了国内造纸废水深度处理工程新技术;成熟的深度处理技术,将会给中国造纸工业节能减排作出重要贡献.     

制浆造纸废水絮凝/Fenton深度处理工程应用的技术经济性分析

根据某大型造纸企业废水处理厂深度处理工艺的运行数据,评价了"絮凝/Fenton"深度处理工艺对制浆造纸废水有机物的处理效果,同时分析了该工艺的运行费用。结果表明:制浆造纸废水二级出水经该工艺处理后,出水COD最优水平值(Technology Achievable Limit,TAL-3.84%)可达43mg/l,出水COD保证值(TAL-95%)为56mg/l,保证值可以满足《山东省海河流域水污染物综合排放标准》的排水要求。COD去除率最优值(TAL-3.84%)为88.3%,去除率保证值(TAL-95%)为83.7%。COD去除率稳定,适合作为制浆造纸废水处理的末端保障工艺。该深度处理工艺的平均成本为1.46元/m3,成本主要分布在1.21~1.71元/m3范围内。运行成本中,药剂费用所占比例最大,约为60%。     

Reduction of N2O and NO generation in anaerobic-aerobic (low dissolved oxygen) biological wastewater treatment process by using sludge alkaline fermentation liquid

This paper reported an efficient method to significantly reduce nitrous oxide (N(2)O) and nitric oxide (NO) generation in anaerobic-aerobic (low dissolved oxygen) processes. It was found that by the use of waste-activated sludge alkaline fermentation liquid as the synthetic wastewater-carbon source, compared with the commonly used carbon source in the literature (e.g., acetic acid), the generation of N(2)O and NO was reduced by 68.7% and 50.0%, respectively, but the removal efficiencies of total phosphorus (TP) and total nitrogen (TN) were improved. Both N(2)O and NO were produced in the low dissolved oxygen (DO) stage, and the use of sludge fermentation liquid greatly reduced their generation from the denitrification. The presences of Cu(2+) and propionic acid in fermentation liquid were observed to play an important role in the reduction of N(2)O and NO generation. The analysis of the activities of denitrifying enzymes suggested that sludge fermentation liquid caused the significant decrease of both nitrite reductase activity to NO reductase activity ratio and NO reductase activity to N(2)O reductase activity ratio, which resulted in the lower generation of NO and N(2)O. Fluorescence in situ hybridization analysis indicated that the number of glycogen accumulating bacteria, which was reported to be relevant to nitrous oxide generation, in sludge fermentation liquid reactor was much lower than that in acetic acid reactor. The quantitative detection of the nosZ gene, encoding nitrous oxide reductase, showed that the use of fermentation liquid increased the number of bacteria capable of reducing N(2)O to N(2). The feasibility of using sludge fermentation liquid to reduce NO and N(2)O generation in an anaerobic-low DO process was finally confirmed for a municipal wastewater.     

A^2/O+MBBR集成工艺处理印染废水

简要介绍印染废水的水质特点及改良传统活性污泥法(A2/O)+移动床生物膜反应(MBBR)工艺集成技术;重点介绍A2/O+MBBR工艺处理印染污水的运行效果。结果显示,在进水量20~60 L/h,溶解氧(DO)质量浓度1.5~4.5 mg/L,污泥回流比50%~90%,硝化液回流比250%~350%,好氧池污泥质量浓度(MLSS)2.0~3.5 g/L,好氧池悬浮填料装填比25%(体积比)的操作条件下连续稳定运行200天后,出水COD去除效果、氨氮去除效果、总磷去除效果、总氮去除效果远远优于《城镇污水处理厂污染物排放标准》的一级A标准。     

印染废水处理中的自控系统

阐述一种PLC和上位机两级控制结构的自动化控制系统在印染废水处理工艺中的应用.整套控制系统由上位机系统,可编程序控制器系统(PLC),I/0柜,就地操作箱,一次仪表和电源系统等组成,重点介绍了该系统的性能,处理污水工艺的方式以及该系统的特点.     

Conversion of CHF3 to CH2=CF2 via reaction with CH4 and CaBr2

Reaction of CHF3 and CH4 over CaBr2 was investigated at 400-900 degrees C as a potential route for transforming the highly potent greenhouse gas, CHF3, into the valuable product CH2=CF2. The homogeneous reaction of CHF3 with CH4 was also studied to assist in understanding the chemistries involved. Compared to the gas phase reaction, the addition of CaBr2 as a reactant increases the conversion of CHF3 and CH4 significantly at low temperatures while to a lesser extent at higher temperatures. In the absence of CaBr2, besides the target product, CH2=CF2, a large amount of C2F4 forms. On addition of CaBr2, the rate of formation of C2F4 drops dramatically to near zero, while the rate of formation of CH2=CF2 increases considerably at temperatures below 880 degrees C. Experimental and theoretical studies suggest that CHF3 strongly interacts with CaBr2, resulting in the fluorination of CaBr2 to CaF2, the release of active Br species results in the selective formation of CBrF3. The subsequent reactions involving Br, methane, and CBrF3 play a major role in the observed enhanced yield of CH2=CF2.     

印染废水深度处理技术及回用的现状和发展

根据印染废水深度处理及回用现状，介绍了若干深度处理方案，并对其优缺点进行了评述；从环境效益和经济效益双赢的目标出发，提出重视推广综合治理、不断优化的回用方案；继续开发膜集成技术是印染废水回用的研究发展方向。     

制浆造纸节水与高效水处理技术

2013年开始实施的国家《造纸产品取水定额》GB/T 18916.5-2012,明确规定13种浆纸产品平均取水量必须降低15.8%。本研究组将某BCTMP化机浆厂工艺过程分为3个独立用水单元,将TS作为主要污染指标,估算出3个操作单元的极限数据,采用水节点技术对3个用水系统进行了优化设计,从而使清水用量由初始的41.1m3/A D t减少到31.1m3/A D t,节约新鲜水用量达26.1%。同时介绍了一种新型的Petax精细过滤系统,可以过滤去除白水中20μm以上的细小纤维,处理后白水用在网压部的高压喷淋,解决了喷嘴堵塞问题。膜技术和制浆造纸综合废水回用工程应用实例表明,深度处理技术可同时减少废水排放量和COD排放量,达到良好的经济效益和环境效益。     

造纸污水光催化处理及过程控制系统

在用GC-MS方法分析广州某二次纤维造纸厂各工段污水成分的基础上,利用自制的纳米TiO2胶体分别光催化处理二次纤维造纸混合污水及经过SBR生化处理后的造纸污水;利用金卤灯模拟太阳光,进行了太阳光光催化处理造纸污水的研究;并设计了间歇式光催化处理造纸污水系统及其自动控制系统。研究表明,光催化氧化法处理污水,尤其是造纸过程产生的含有大量木质素、有机氯酚高分子化合物的污水,效果显著。