Oxidation of organic impurities in the recycle and reclaim loops of ultra-pure water plants

 The oxidation of trace organic impurities in ultrapure water by ultraviolet light (UV), ozone, and the combination of UV/ozone is investigated. The emphasis is on the development of a global model to simulate the process that take place in the typical oxidation reactors used in ultrapure water plants. The study also focuses on reaction mechanism for oxidation of multi-component organic impurities. Eighteen organic model compounds are chosen as representative contaminants. The results demonstrate and confirm a significant synergistic effect between UV and ozone oxidation. A mechanism for the synergistic oxidation of organic impurities is proposed and validated with experimental data. The combination of the reaction and the reactor models is used to determine the fundamental kinetic parameters involved in the three oxidation processes. Received: 3 July 1998 / Accepted: 4 September 1998     

湿式空气非均相催化氧化处理有机废水中难降解有机物的研究

湿式空气催化氧化是曩为经济的环境友好型高级氧化技术之一,在处理有机废水中难降解有机物方面极具前景.为提高氧化效率,钌（Ru）、铑（Rh）、铂（Pt）、钯（Pd）等贵金属及铜（Cu）、铈（Ce）、锰（Mn）、铁（Fe）、镍（Ni）、铝（Al）、铬（Cr）及钴（Co）等金属氧化物等常作为非均相催化剂应用到湿式空气催化氧化体系中.本文对非均相催化湿式空气氧化处理有机废水中难降解有机物的非均相催化剂、工艺条件及反应机理进行了探讨,最后指出了催化剂的失效、解决方法及技术发展方向.     

Heterogeneous alternative catalysts: A bibliometric and systematic evaluation of their application in solar photocatalytic processes

The present study sought to objectively demonstrate how a researcher can, in a structured way, select relevant articles about alternative heterogeneous catalysts in photocatalytic processes. Therefore, the ProKnow-C (Knowledge Development Process – Constructivist) method was used to systematize the results found, with the application bibliometric and systematic analysis techniques for the evaluation of the results. The search string adopted as criteria was: solar photocatalysis AND heterogeneous catalysts OR alternative catalysts AND effluents. The databases were Web of Science, Science Direct and Scopus. The final bibliographic portfolio obtained for the research theme was made up of 19 articles. It was possible to verify advances in the number of publications on the theme over the evaluated period, with the Journal of Photochemistry and Photobiology A: Chemistry standing out in the final portfolio. Evaluating each article in the portfolio individually, it was possible to verify that most studies use combinations of catalysts already reported to create an alternative material to those already investigated in the literature. Those that use waste as catalysts chose to source this material from treatment plants and the steel industry. Around 58% of the papers used hydrogen peroxide in their processes, while 42% chose not to use it. Finally, approximately 63% of the papers in the portfolio used synthetic effluent in their processes, while the rest (37% of the research) chose to use real effluent. The results obtained in this research by applying the method can contribute to studies related to heterogeneous photocatalysis by alternative means over the years.     

Clean production with membrane technology

 Membrane processes, because of unique, specialized, and cost-effective applications, have the potential of playing a significant role in preventing pollution from occurring in manufacturing plants. Opportunities are seen in resource recovery, species purification, and energy savings. Emerging technologies of membrane reactors that combine separation with reaction in one physical unit are important developments also. In this paper we discuss the scope of membrane technologies in industrial applications as well as hurdles that must be overcome. Received: 15 April 1998 / Accepted: 9 August 1998     

高级氧化技术处理垃圾渗滤液的研究进展

本文介绍了包括化学氧化法、电化学氧化法、光催化氧化法、超声氧化法、辐照氧化法和催化湿式氧化法等在内的高级氧化技术的机理和运用于垃圾渗滤液处理的研究进展,并提出高级氧化技术与生物处理联合运用和各种高级氧化工艺之间的优化组合将是实现高级氧化技术在垃圾渗滤液处理中工程化运用的发展方向.     

深度氧化技术处理有机废水的研究进展

利用深度氧化技术处理有机废水是目前国内外废水处理的新技术,在美国和欧洲等发达国家,该技术已应用于各种废水和饮用水处理过程。针对我国石油、石化企业在外排废水中所含有毒有害有机物质大多难以降解的特点,经过调研,详细介绍了深度氧化技术处理有机废水的研究进展,并着重探讨了在光催化氧化技术、超声降解技术、超临界水氧化技术、湿式氧化技术等方面所做的工作及深度氧化过程除去水中有机污染物的原理。     

Decision Tree Algorithm for Detection of Spatial Processes in Landscape Transformation

The conversion of landscapes by human activities results in widespread changes in landscape spatial structure. Regardless of the type of land conversion, there appears to be a limited number of common spatial configurations that result from such land transformation processes. Some of these configurations are considered optimal or more desirable than others. Based on pattern geometry, we define ten processes responsible for pattern change: aggregation, attrition, creation, deformation, dissection, enlargement, fragmentation, perforation, shift, and shrinkage. A novelty in this contribution is the inclusion of transformation processes causing expansion of the land cover of interest. Consequently, we propose a decision tree algorithm that enables detection of these processes, based on three parameters that have to be determined before and after the transformation of the landscape: area, perimeter length, and number of patches of the focal landscape class. As an example, the decision tree algorithm is applied to determine the transformation processes of three divergent land cover change scenarios: deciduous woodland degradation in Cadiz Township (Wisconsin, USA) 1831–1950, canopy gap formation in a terra firme rain forest at the Tiputini Biodiversity Station (Amazonian Ecuador) 1997–1998, and forest regrowth in Petersham Township (Massachusetts, USA) 1830–1985. The examples signal the importance of the temporal resolution of the data, since long-term pattern conversions can be subdivided in stadia in which particular pattern components are altered by specific transformation processes.     

Application of environmental risk assessment for strategic decision-making in coastal areas: case studies in China

Environmental risk assessment (ERA) is a powerful technical tool for analyzing potential and extreme adverse environmental impacts, and has found wide application in supporting decision-making processes over the last two decades. However, to date there has been no interrelated application of ERA to support the processes of strategic decision-making (SDM), especially in coastal areas.

In this paper, we attempt to verify the feasibility of the proposed integrated ERA–SDM approach and its methodology by applying it to two case studies (in Xiamen Bay and Luoyuan Bay) of the principal coastal functional zoning (PCFZ, a kind of SDM and similar to the coastal and marine spatial planning in western). The results show that the integrated ERA–SDM approach could integrate ERA into the entire SDM process, directly support the PCFZ, and avoid or mitigate dire environmental risk that can be introduced by SDM processes.     

Experimental oxidative dissolution of sphalerite in the Aznalcollar sludge and other pyritic matrices

After the collapse on 25 Apr. 1998 of the Aznalcóllar mine tailings dike in southwestern Spain, 45 km2 of the Guadiamar valley were covered by a pyritic sludge containing up to 2% sphalerite (ZnS). Later, the sludge was mechanically removed and calcium carbonate was plowed into the soil to immobilize heavy metals. By June 2001 more than 60% of the sulfides in the residual sludge had oxidized and soil Zn contents reached locally phytotoxic levels. Therefore, the oxidative dissolution of sphalerite in the sludge and other pyritic samples was examined. Flow-through oxidation experiments showed that: (i) about 5 and 17% of the sludge Fe and Zn were in soluble form, respectively, because the sludge sample had been partly oxidized in the field; (ii) the oxidation rates of the residual pyrite and sphalerite were similar; (iii) the overall sulfide oxidation rate was relatively unaffected by the addition of calcite; and (iv) poorly crystalline Fe (hydr)oxides containing Zn in occluded form and Zn (hydroxi)carbonates were formed in the presence of calcite. The rate of oxidation of reference sphalerite greatly increased when it was incorporated in the sludge or in a reference pyrite matrix. This enhancement was due to galvanic interaction because pyrite oxidation was depressed in the presence of sphalerite. Oxidation by Fe3+ ions was less important because the oxidation rates of native sphalerite were not greater at low than at high pH. The fast oxidation rate of sphalerite in the Aznalcóllar sludge indicates a need for quick adoption of remediation measures in similar accidents elsewhere. The use of calcite amendments has little influence on the oxidation rate but does result in the accumulation of Zn in relatively insoluble forms.     

石化废水深度处理用臭氧催化氧化体系的研究＊

文章就臭氧催化氧化体系在石化废水处理中的作用进行了深入研究,对催化剂载体、催化剂配伍体系以及臭氧的投加方式进行了优化筛选。根据实验,多元催化掺杂体系较一元催化体系氧化效果好,CODCr的去除率可由一元催化时的20%提高到多元催化时的33%;在臭氧的投加方式上,分段投加要优于单级投加,臭氧投加分配比例为6∶3∶1时,CODCr的去除率可由单一投加时的9%提高到分级投加时的19%。     

黄磷尾气中PH3液相催化净化研究

以Mn（Ⅱ）与Pd（Ⅱ）为催化剂的吸收净化溶液对黄磷尾气中的PH3进行了液相催化氧化研究。考察了混合气中02浓度、温度、入口PH3浓度、气体流量和吸收液pH变化与磷化氢净化效率曲线的关系。实验结果表明：混合气中较佳的氧含量为5％；在20℃至75℃范围内，低温对催化净化有利，较适宜的反应温度为20℃；较低的PH3入口浓度和低气速均有利于对PH3的净化；吸收液较高的pH有利于吸收液中催化剂催化效能的发挥。吸收液对PH3的净化效率可达100％，但因吸收液中的金属离子易与PH3产生的PO4^3-形成沉淀，使金属离子脱离液相催化氧化系统，吸收液失效较快。     

光催化氧化处理难降解污水的应用前景

随着工业的不断发展,环境污染日益严重,传统水处理工艺中的物理、生物方法不能满足水处理的需要。将光催化氧化法应用于气相和水相中一些难降解污染物的治理,研究结果表明,催化剂的选择、反应器的设计和对降解条件的优化是提高污染物光催化降解效率的关键因素。半导体光催化技术具有高稳定性、耐腐蚀、无毒的特点,在处理过程中不产生二次污染,有机污染物能被彻底无机化,因而这是一种洁净的处理技术。光催化技术为彻底解决水污染问题提供了新的手段,它在环境污染治理中有广阔的应用前景。     

Trends in Soil Erosion and Woody Shrub Encroachment in Ngqushwa District,Eastern Cape Province,South Africa

Woody shrub encroachment severely impacts on the hydrological and erosion response of rangelands and abandoned cultivated lands. These processes have been widely investigated at various spatial scales, using mostly field experimentation. The present study used remote sensing to investigate spatial and temporal patterns of soil erosion and encroachment by a woody shrub species, Pteronia incana, in a catchment in Ngqushwa district, Eastern Cape Province, South Africa between 1998 and 2008. The extreme categories of soil erosion and shrub encroachment were mapped with higher accuracy than the intermediate ones, particularly where lower spatial resolution data were used. The results showed that soil erosion in the worst category increased simultaneously with dense woody shrub encroachment on the hill slopes. This trend is related to the spatial patterning of woody shrub vegetation that increases bare soil patches—leading to runoff connectivity and concentration of overland flow. The major changes in soil erosion and shrub encroachment analysed during the 10-year period took place in the 5–9° slope category and on the concave slope form. Multi-temporal analyses, based on remote sensing, can extend our understanding of the dynamics of soil erosion and woody shrub encroachment. They may help benchmark the processes and assist in upscaling field studies.     

挥发性有机废气净化技术研究进展

本文对生物净化技术、等离子体净化技术、吸附和催化氧化技术在控制废气中挥发性有机物的研究进展及应用进行了综述。气体生物净化技术在VOCs混合物和改进设备工艺方面开展的研究工作较多,等离子体净化技术与催化技术的组合越来越受到关注。吸附和催化氧化方面则着重在吸附剂（活性炭和沸石）吸附性能的进一步研究和新型催化剂的研制。     

Oxidation kinetics of the combustible fraction of construction and demolition wastes

Proper disposal of construction and demolition wastes (CDW) has received wide attention recently due to significantly large quantities of waste streams collected from razed or retrofitted buildings in many metropolitan regions. Burning the combustible fractions of CDW (CCDW) and possibly recovering part of the heat content for economic uses could be valuable for energy conservation. This paper explores the oxidation kinetics of CCDW associated with its ash characterization. Kinetic parameters for the oxidation of CCDW were numerically calculated using thermal gravimetric analysis (TGA) and the resultant rate equations were therefore developed for illustrating the oxidation processes of CCDW simultaneously. Based on three designated heating rates, each of the oxidation processes can be featured distinctively with five different stages according to the rate of weight change at the temperature between 300 K and 923 K. In addition, Fourier transform infrared (FTIR) spectroscopy was employed, associated with a lab-scale fixed-bed incinerator for monitoring the composition of flue gas. Carbon dioxide (CO2) was found as a major component in the flue gas. The fuel analysis also included an ash composition analysis via the use of X-ray powder diffraction (XRD), atomic absorption (AA) spectroscopy, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDX). The ash streams were identified as nonhazardous materials based on the toxicity characteristic leaching procedure (TCLP). Overall, the scientific findings gained in this study will be helpful for supporting a sound engineering design of real-world CCDW incineration systems.     

Optimization of Fenton's oxidation of chemical laboratory wastewaters using the response surface methodology

Establishing a treatment process for practical and economic disposal of laboratory wastewaters has become an urgent environmental concern of the Department of Chemical Engineering of the Universidade Estadual de Maringá (State University of Maringá), Brazil. Fenton and related reactions are potentially useful oxidation processes for destroying toxic organic compounds in water. In these reactions, hydrogen peroxide is combined with ferrous or ferric iron in the presence or absence of light to generate hydroxyl radicals (.OH). The feasibility of Fenton's reagent to treat waste chemicals from an academic research laboratory was investigated in this study. A response surface methodology was applied to optimize the Fenton oxidation process conditions using chemical oxygen demand (COD) removal as the target parameter to optimize, and the reagent concentrations, as related to the initial concentration of organic matter in the effluent, and pH as the control factors to be optimized. Maximal COD removal (92.3%) was achieved when wastewater samples were treated at pH 4 in the presence of hydrogen peroxide and iron in the ratios [COD]:[H2O2]=1:9 and [H2O2]:[Fe2+]=4.5:1. Under these conditions, it was possible to obtain simultaneously maximal COD removal and minimal chemical sludge after treatment, which is a residue that needs further processing.     

ACF表面化学官能团对影响脱硫性能的研究进展

活性炭纤维(ACF)作为第三代活性炭,是一种新型的高效吸附剂和催化剂。它具有独特的物理性能和化学性能,对烟气中的SO2具有很强的吸附和催化氧化作用,因此作为烟气脱硫方面极具前景的催化剂而受到人们的普遍关注。以聚丙烯腈基活性炭纤维(PAN-ACF)为代表,主要深入探讨了ACF表面化学官能团对脱硫性能的影响。     

Nickel recovery/removal from industrial wastes: A review

Nickel is an important metal, heavily utilized in industry mainly due to its anticorrosion properties. As a consequence, nickel containing wastes such as spent batteries and catalysts, wastewater and bleed-off electrolytes are generated in various processes. These wastes could have a negative impact on the environment and human health if they contaminate soil, water and air. The present review addresses the environmental and economical aspects of nickel recovery/removal from various types of wastes. The main physico-chemical technologies for processing various effluents and wastewaters containing nickel are reviewed and discussed. Nickel recovery from spent batteries, catalysts, electronic waste and other sources is described. Hydrometallurgical approaches are emphasized. Recovery of nickel from wastes is important not only for economical aspects, but also for environmental protection.     

DOWNSCALED CLIMATE AND STREAMFLOW STUDY OF THE SOUTHWESTERN UNITED STATES1

ABSTRACT: Downscaling coarse resolution climate data to scales that are useful for impact assessment studies is receiving increased attention. Basin-scale hydrologic processes and other local climate impacts related to water resources such as reservoir management, crop and forest productivity, and ecosystem response require climate information at scales that are much finer than current and future GCM resolutions. The Regional Climate System Model (RCSM) is a dynamic downscaling system that has been used since 1994 for short-term precipitation and streamflow predictions and seasonal hindcast analysis with good skill. During the 1997–1998 winter, experimental seasonal forecasts were made in collaboration with the NOAA Climate Prediction Center and UCLA with promising results. Preliminary studies of a control and 2°CO₂ perturbation for the southwestern U.S. have been performed.     

作业机废气减排技术研究

柴油发动机尾气排放中含有比汽油发动机更多的颗粒污染物。文章叙述了尾气净化装置反应原理,触媒及化学稳定性,柴油氧化催化剂和颗粒催化过滤器优点。通过外部加装尾气净化装置,解决了尾气污染问题,具有较好的发展前景、较强的实用性和可操作性。