Biological removal of selenate in saline wastewater by activated sludge under alternating anoxic/oxic conditions

Removal of selenate in saline wastewater by activated sludge was examined. Sequencing batch reactor was operated under alternating anoxic/oxic conditions. Above 97% removal of soluble selenium (Se) was achieved continuously. Major Se removal mechanism varied depending on the length of aeration period. Various Se-reducing bacteria likely contributed to coordinately to Se removal. Selenium (Se)-containing industrial wastewater is often coupled with notable salinity. However, limited studies have examined biological treatment of Se-containing wastewater under high salinity conditions. In this study, a sequencing batch reactor (SBR) inoculated with activated sludge was applied to treat selenate in synthetic saline wastewater (3% w/v NaCl) supplemented with lactate as the carbon source. Start-up of the SBR was performed with addition of 1–5 mM of selenate under oxygen-limiting conditions, which succeeded in removing more than 99% of the soluble Se. Then, the treatment of 1 mM Se with cycle duration of 3 days was carried out under alternating anoxic/oxic conditions by adding aeration period after oxygen-limiting period. Although the SBR maintained soluble Se removal of above 97%, considerable amount of solid Se remained in the effluent as suspended solids and total Se removal fluctuated between about 40 and 80%. Surprisingly, the mass balance calculation found a considerable decrease of Se accumulated in the SBR when the aeration period was prolonged to 7 h, indicating very efficient Se biovolatilization. Furthermore, microbial community analysis suggested that various Se-reducing bacteria coordinately contributed to the removal of Se in the SBR and main contributors varied depending on the operational conditions. This study will offer implications for practical biological treatment of selenium in saline wastewater.     

室内安全卫生现状及对策

室内安全卫生状况越来越受到人们的关注。美国环保署组织的调查表明 ,室内环境问题已成为影响人类健康的 4个主要环境因素之一 ,4 0 %的发病率是由室内环境差引起。 2 0世纪 90年代以来 ,欧美等国家在室内环境污染因素的识别、检测、评价、控制管理方面进行了系统的研究 ,笔者结合中国实际情况 ,综述以上 4个方面的系统研究 ,提出了我国在技术上和管理上提高室内安全卫生质量状况的初步设想     

Occupational safety and health in Spain

Occupational Health and Safety in Spain has improved considerably over the last decade, most likely due to a new concept where an overall concept of safety culture is defined. Important changes in industrial safety, hygiene, and psychosocial factors present an optimistic panorama for the future of Spain. Despite this general improvement, according to the European Convergence Program, Spanish statistics still offer far from good safety results. In fact, according to 1997 official statistics, Spain had the highest incidence rate for nonfatal occupational accidents of all European Union (EU) countries, and occupied third place for fatal accidents. This paper summarizes the organizational structure of the Spanish National System of Health & Safety at Work, its effective health and safety laws, and statistics on the Spanish work environment obtained from III Spanish National Survey on Work Conditions (1997). The researchers hope that the findings of this work will have an impact on Spanish industry that will subsequently bring about improvements in work conditions and develop assessment and intervention models in occupational health and safety, from a theoretical position integrating environmental, human, and organizational factors.     

Setting up the criteria and credit-awarding scheme for building interior material selection to achieve better indoor air quality

Methods, standards, and regulations that are aimed to reduce indoor air pollution from building materials are critically reviewed. These are classified as content control and emission control. Methods and standards can be found in both of these two classes. In the regulation domain, only content control is enforced in some countries and some regions, and asbestos is the only building material that is banned for building use. The controlled pollutants include heavy metals, radon, formaldehyde, and volatile organic compounds (VOCs). Emission rate control based upon environment chamber testing is very much in the nature of voluntary product labeling and ranking, and this mainly targets formaldehyde and VOC emissions. It is suggested that radon emission from building materials should be subject to similar emission rate control. A comprehensive set criteria and credit-awarding scheme that encourages the use of low-emission building material is synthesized, and how this scheme can be practiced in building design is proposed and discussed.     

旅游客源分析兼论宜州市旅游客源条件

本文分析了影响旅游资源的开发因素之一──客源的形成条件，在此基础上对广西宜州市旅游资源的客源条件进行了分析．     

CHANGING A GREAT CITY IN EASTERN EUROPE — CRACOW: ENVIRONMENTAL CHANGES1

ABSTRACT: The main factor in the location of medieval Cracow was drainage. In the 700-year history of the City, there were numerous changes in water conditions, particularly in channel network, runoff, ground water level, and ice phenomena. The most dangerous threat to surface water and ground water in Cracow in the last decades has been from industrial and municipal sewage. Currently there are no rivers that meet Drinking Water Quality standards in Cracow. The quality of the ground water has declined because of infiltration of contaminated river water, water from sewage disposal ponds, and pollution from the atmosphere and soil. Cracow does not have enough waste water plants to meet its needs. Most municipal and industrial sewage has not been treated or has been treated only partially. Because of considerable contamination of surface and ground waters in Cracow, more than half of the city's fresh water is pumped about 50 kilometers from a reservoir on the Raba River. A Polish government declaration of April 4, 1989, recognized Cracow as an area of particular protection, and directed that a number of actions be undertaken for the protection of environmental quality.     

提高农业用水有效性的水文学研究

中国北方15个省、区、市耕地面积占全国的55%,灌溉面积占全国灌溉总面积的48%,而水资源总量仅占全国的20%。区域水资源短缺和农业的进一步发展,要求提高农业用水有效性。本文从水文学角度,研究了华北、西北和东北3个地区水土资源特征;分析了作物熟制和适水种植的节水效益、农田供水量与产量的函数关系、农田棵间蒸发量和控制措施,以及提高高产农田用水有效性等水文试验研究结果;介绍了河北省南皮节水农业试验区的研究模式。     

Health and safety implications of alternative energy technologies. II. Solar

No energy technology is risk free when all aspects of its utilization are taken into account. Every energy technology has some attendant direct and indirect health and safety concerns. Solar technologies examined in this paper are wind, ocean thermal energy gradients, passive, photovoltaic, satellite power systems, low- and high-temperature collectors, and central power stations, as well as tidal power. For many of these technologies, insufficient historical data are available from which to assess the health risks and environmental impacts. However, their similarities to other projects make certain predictions possible. For example, anticipated problems in worker safety in constructing ocean thermal energy conversion systems will be similar to those associated with other large-scale construction projects, like deep-sea oil drilling platforms. Occupational hazards associated with photovoltaic plant operation would be those associated with normal electricity generation, although for workers involved in the actual production of photovoltaic materials, there is some concern for the toxic effects of the materials used, including silicon, cadmium, and gallium arsenide.Satellite power systems have several unique risks. These include the effects of long-term space travel for construction workers, effects on the ozone layer and the attendant risk of skin cancer in the general public, and the as-yet-undetermined effects of long-term, low-level microwave exposure. Hazards may arise from three sources in solar heating and cooling systems: water contamination from corrosion inhibitors, heat transfer fluids, and bactericides; collector over-heating, fires, and out-gassing and handling and disposal of system fluids and wastes. Similar concerns exist for solar thermal power systems. Even passive solar systems may increase indoor exposure levels to various air pollutants and toxic substances, eitherdirectly from the solar system itself or indirectly by trapping released pollutants from furnishings, building materials, and indoor combustion.Operated by Union Carbide Corporation under contract W-7405-eng-26 for the U.S. Department of Energy.     

Natural resources and 'gradual' reform in Uzbekistan and Turkmenistan

Among low‐income transition reformers, natural resource rents are an important initial condition that helps explain choice of reform strategy. Resource‐rich Uzbekistan and Turkmenistan and resource‐poor China and Vietnam all claim to pursue gradual reform, but their strategies differ. In China and Vietnam, low resource rents have nurtured developmental political conditions and encouraged efficient resource use, which initially promoted agriculture as a dynamic market sector, capable of absorbing labour from the lagging state sector. In contrast, the scale and ease of natural resource rent extraction in the Central Asian countries has consolidated authoritarian governments that postpone reform. Despite high energy rents, Uzbekistan and Turkmenistan still extract agricultural rents in ways that repress farm incentives, perpetuate environmental degradation and liquidate irrigation assets. Uzbekistan uses its rents to subsidize a manufacturing sector, that is neither dynamic nor competitive. As its dynamic sector, Turkmenistan promotes natural gas exports that depend on volatile markets. Resource‐driven development models suggest that reform is required in both countries to avert a growth collapse. Turkmenistan's large energy rent‐stream may postpone a collapse for some years, but Uzbekistan's position is already precarious: it has run down its rural infrastructure and accumulated sizeable foreign debts and will require external assistance to recover from a growth collapse. Such assistance should be made conditional on accelerated economic and political reform.     

Biodegradation of Fuel Oil Under Laboratory and Arctic Marine Conditions

The aerobic biodegradation of the components of a fuel oil under Arctic summer conditions follows a pattern that is indistinguishable from that exhibited under temperate conditions. Straight chain alkanes and small aromatics are degraded first, followed by branched alkanes and larger and alkylated aromatics. We present data on the biodegradation of heptadecane as a representative n-alkane, pristane as a representative iso-alkane, and naphthalene, phenanthrene, and chrysene and their alkylated forms as representative two-, three- and four-ring aromatic hydrocarbons. In particular, the pattern of degradation of the alkylated aromatics allows the identification of biodegradation in samples collected from the field and the estimation of the extent of biodegradation that occurred in the In-Situ Treatment of Oiled Sediment Shorelines Field Trials.