超声-电絮凝法处理吡啶类农药废水

采用电絮凝和超声-电絮凝处理吡啶农药废水,探讨影响结果的各种因素。电絮凝反应的最佳条件为:电解时间60min,电极间距3cm,电流密度20m A/cm~2,在此条件下,废水的CODCr、色度去除率分别达到37.06%、51.54%,反应过程符合二级反应动力学规律。在此条件下同时增加超声处理,得到CODCr、色度的去除率为65.20%、74.10%。相比单独电絮凝处效果有了很大的提高。而超声-电絮凝降解动力学过程符合一级反应动力学规律。     

制药废水生化处理后的深度处理方法比较研究

随着制药废水排放标准的提高,对制药废水进行深度处理是实现其达标排放的有效途径之一。试验比较了絮凝、高级氧化、吸附、超滤等方法对生化处理后的高浓度制药废水深度处理效果,结果表明:4种方法中,只有活性炭吸附对废水COD、浊度、色度、氨氮等都具有较好的去除效果,COD去除率最高能达到62%,可实现达标排放。     

电絮凝法处理电脱盐废水的实验研究

采用曝气和温度调节对电脱盐废水进行预处理,并通过电絮凝方法对电脱盐废水进行破乳除油。实验结果表明:一定的曝气可以起到均质调节作用,曝气15min时不稳定指数最大,而此时TOC也最大,说明通过曝气改变了体系的稳定状态;反应过程中一定的升温和曝气作用都可以有效提高处理效率,电絮凝处理电脱盐废水的过程中,最佳电流密度为5mA/cm2;从紫外三维荧光谱图可以看出,电絮凝过程破坏了物质的结构;采用电絮凝法处理电脱盐废水,可以有效去除废水的COD和浊度。     

常用氧化剂性能研究

用四种常用的氧化剂:高锰酸钾、漂白粉、NaClO和H2O2/Fe2+对大港油田港深11井酸化废水进行了处理。考察了氧化剂的投加量、氧化时间和pH值对酸化废水色度和COD去除率的影响。实验结果表明,在最佳条件下,H2O2/Fe2+对酸化废水的色度和COD的去除率最高;用高锰酸钾处理废水,其COD去除率较高,但脱色效果差;而漂白粉和NaClO的脱色率较高,但其氧化能力有限。建议油田用氧化法处理废水时应采用H2O2/Fe2+催化氧化体系。     

PAC和PASS对印染废水的混凝效果研究

主要研究PAC和PASS混凝剂对高浓度和低浓度印染废水的混凝处理效果。确定了PAC处理高浓度印染废水(pH:4.39;色度:18750倍;COD:6480;浊度:1462)的最佳pH、混凝时间、投药量为5～7、8min、24mL/L;PASS处理低浓度印染废水(pH:10.16;色度:2020倍;COD:168;浊度:36.4)的最佳pH、混凝时间、投药量为6～7、15min、12mL/L。PAC处理高浓度的印染废水效果较好,处理低浓度印染废水的效果较差;PASS处理低浓度印染废水的处理效果比PAC要好。     

辫带式生物填料在纺织印染废水处理中的应用

印染废水是高浓度难降解处理的工业废水之一,印染废水的色度大,有机污染物含量高,可生化性差,水量不稳定。针对废水特点,在生物膜法处理工艺中,采用辫带式生物填料作为微生物载体处理印染废水,取得了良好的处理效果。在进水COD浓度800～1200mg/L、色度350～500倍的情况下,经处理后出水COD浓度为200mg/L、色度在80倍以下,达到《纺织染整工业水污染物排放标准》(GB 4287—2012)表2间接排放标准。     

催化氧化法在钻井废水处理中的应用

在油气田深井钻探过程中产生的钻井液,经固-液分离处理后产生的废水具有化学需氧量高、色度高、矿化度高、含油量高等特点,须进一步进行处理。采用Fenton试剂对钻井废水进行了催化氧化处理实验。结果表明,处理后, 废水中化学需氧量(COD)去除率可达82%,色度去除率为98.5%。H2O2/Fe2+投量摩尔比、H2O2/初始COD摩尔比、pH值和反应时间对废水COD、色度的去除率均有较大影响。用Fenton试剂催化氧化工艺处理聚磺体系钻井废水还具有处理效率高、操作简便、适用范围广等优点。     

钡盐沉淀法处理纳米银工业废水

液相化学还原法制备纳米银是近些年的研究热点之一,但工艺过程产生的工业废水处理问题未有关注。首次采用钡盐沉淀法处理纳米银工业废水,考察了反应温度、p H值、钡盐种类等因素对废水COD (化学需氧量)及色度去除率的影响。其最佳工艺条件如下:反应温度15℃,初始p H值10. 5,反应时间1h,每100mL废水投加二水氯化钡8g;废水COD去除率为85. 6%,色度去除率高达97. 1%。傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)等表明:纳米银工业废水中存在醌-氢醌类化合物,此羟基醌类化合物可与溶液中的钡离子反应生成沉淀而得以去除;另外,新生成的硫酸钡细微颗粒带正电,絮凝沉降过程对废水中的羟基醌类化合物存在吸附作用。     

混凝沉降-生物膜法处理制革废水

采用混凝沉降-生物膜法处理蓝湿牛皮制革废水。工程实践证明:该法对废水COD和BOD的去除率可达94%以上,且对废水的脱色效果良好,是一种合理有效的处理皮革废水工艺路线。     

臭氧高级氧化法处理染料废水的研究

采用臭氧高级氧化技术对某染料废水进行处理,探究不同条件对染料废水COD以及色度的去除效果的影响,确定最佳工艺条件。在最佳条件下,采用单独臭氧、单独紫外、臭氧-紫外、臭氧-双氧水以及臭氧-铁炭五种氧化方法对染料废水进行处理。结果表明:臭氧氧化技术最佳条件为pH值=8,臭氧流量80 L/h,反应时间为2 h;采用最佳处理方案,采用臭氧-紫外高级氧化技术处理染料废水,其脱色率为98.3%,COD去除率为67.0%。     

Provincial development plans in Zimbabwe: an analysis of their content,structure and methodology

Zimbabwean provincial plans were instituted to help in the achievement of the national goal of the creation of an egalitarian, socialist and integrated society. The national goal itself was adopted as an antithesis to the dualist society characterised by spatial, economic, social, politican and technological inequalities that Zimbabwe inherited from colonialism. This meant that provincial plans had to play both a functional (or growth allocating/distribution) and a territorial (or redistribution) role.

This paper reviews their role in achieving the national goal by examining their functions, content, structure and methodology. The paper concludes that because of their nature, provincial plans are not suitable tools for the achievement of the national goal.     

BIOLOGICAL INDICATORS AND BIOLOGICAL EFFECTS OF ESTUARINE/COASTAL POLLUTION1

ABSTRACT: Sustained interest in and concern about the health status of the aquatic environment has resulted in extensive research focused on (1) effects of pollution on survival, growth, and reproduction of resource species at all life stages; (2) diseases of fish and shellfish, as they may be related to pollution and as they may serve as indicators of environmental stress; and (3) contaminant body burdens in fish and shellfish - their effects on the aquatic animals and their potential effects on humans. Effects, lethal and sublethal, of pollutants on life history stages of fish and shellfish have been documented, as have impacts on local stocks in badly degraded habitats, but as yet there has been no adequate quantitative demonstration of effects on entire aquatic species - probably because of the difficulty in sorting out relative effects of the many environmental factors that influence abundance. Sublethal effects, especially those that result in disease, have been examined intensively, and some diseases and disease syndromes have been associated statistically with pollution. Other pollution indicators (biochemical, physiological, genetic, behavioral, and ecological) have also received some attention, as have body burdens of contaminants in aquatic species. Research, especially that conducted during the past decade, has done much to clarify the many pathways and toxic effects of contaminants on aquatic animals, and has also helped to identify mechanisms for survival of fish and shellfish in the presence of environmental changes caused by human activities.     

Definition Procedures Have Little Effect on Performance of Environmental Classifications of Streams and Rivers

Mapped environmental classifications are defined using various procedures, but there has been little evaluation of the differences in their ability to discriminate variation in independent ecological characteristics. We tested the performance of environmental classifications of the streams and rivers of France that had been defined from the same environmental data using geographic regionalization and numerical classification of individual river valley segments. Test data comprised invertebrate assemblages, water chemistry, and hydrological indexes obtained from sites throughout France. Classification performance was measured by analysis of similarity (ANOSIM). Geometric regions defined by a regular grid and without regard to environmental variables and a posteriori classifications based on clustering the test datasets defined lower and upper bounds of performance for a given number of classes. Differences in classification performances were generally small. The ANOSIM statistics for the a posteriori classifications were around twice that of all environmental classifications, including geometrically defined regions. The hydro-ecoregions performed slightly better for the invertebrate data and the network classification performed slightly better for the chemistry and hydrological data. Our results indicate that environmental classifications that are defined using different procedures can be comparable in terms of their ability to discriminate variation of ecological characteristics and that alleged differences in performance arising from different classification procedures can be small relative to unexplained variation. We conclude that definition procedures might have little effect on the performance of large-scale environmental classifications and decisions over which procedures to use should be based primarily on pragmatic considerations.     

Journalists' views of advertiser pressures on agricultural news

All major journalism ethical codes explicitly state that journalists should protect editorial copy from undue influence by outside sources. However, much of the previous research on agricultural information has concentrated on what information various media communicate (gatekeeping studies) or communication's role in increasing innovation adoption (diffusion studies). Few studies have concentrated specifically on organizational and structural constraints that might adversely affect agricultural journalists' ethical standards; those that have, focus largely on farm magazines. A study of newspaper reporters who cover agricultural news found that the most pressing ethical concern is the effect of advertiser (agri-business) pressure on editorial copy, and that their concerns in general parallel those of farm magazine writers and editors. The majority reported being in situations in which they might be exposed to advertiser pressure, including pressures to change or withhold editorial copy. Large minorities suggested that advertising pressures affect the overall environment in which agricultural journalists work, and more than one in ten said they allow advertiser pressures to influence editorial decisions. The newspaper reporters who cover agricultural beats showed slightly more resistance to advertiser pressure than did farm magazine editors in a parallel study.     

National minerals policies and stakeholder participation for broad-based development in the southern African development community (SADC)

This paper explains how the well-accepted concept of improved stakeholder participation during mineral policy development leads to a national mineral policy that accommodates the diverging views and interests that allows wide acceptance of decisions, enhancing the success of implementation and, ultimately, national benefits. This process is based on lessons learnt during the South African experience and has been successfully applied in the development of the Namibian and Malawian national minerals policies. An effective policy in the SADC will engineer the delicate balance between poverty reduction and an internationally competitive minerals sector. This balance enhances the possibility of long-term economic growth and development in the SADC region. The overriding advantage of this strategy is that it generates ‘home-grown’ policy instruments and implementation of mineral law with which stakeholders can identify. This process presents a new challenge to traditional policy formulation strategies in emerging economies and the bottom-up approach, linked to wide political support, allows the potential realisation of national objectives.     

Effect of Light on Biodegradation of Estrone, 17β‐Estradiol,and 17α‐Ethinylestradiol in Stream Sediment

Biodegradation of [A‐ring ¹⁴C] Estrone (E1), 17β‐estradiol (E2), and 17α‐ethinylestradiol (EE2) to ¹⁴CO₂ was investigated under light and dark conditions in microcosms containing epilithon or sediment collected from Boulder Creek, Colorado. Mineralization of the estrogen A‐ring was observed in all sediment treatments, but not epilithon treatments. No difference in net mineralization between light and dark treatments was observed for ¹⁴C‐E2. Net mineralization of ¹⁴C‐E1 and ¹⁴C‐EE2 was enhanced in light treatments. Extents of ¹⁴CO₂ accumulation and rates of mineralization were significantly greater for E2 than E1 under dark conditions, but were comparable under light conditions. These results indicate substantial differences in the uptake and metabolism of E1 and E2 in the environment and suggest biorecalcitrance of E1 relative to E2 in light‐limited environments. The extent of ¹⁴CO₂ accumulation and rate of mineralization for EE2 in dark treatments were less than half of that observed for E2 and generally lower than for E1, consistent with previous reports of EE2 biorecalcitrance. However, ¹⁴CO₂ accumulation and rates of mineralization were comparable for EE2, E2, and E1 under light conditions. These results indicate photoactivation and/or phototransformation/photodegradation processes can substantially enhance heterotrophic biodegradation of estrogens in sunlit environments and may play an important role in estrogen transport and attenuation.     

Bioremediation of Soils by Plant–Microbe Systems

Abstract

Sustainable ecosystems can be designed to eliminate environmental toxins and reduce pathogen loads through the direct and indirect consequences of plant and microbial activities. We present an approach to the bioremediation of disturbed environments, focusing on petroleum hydrocarbon (PHC) contaminants. Treatment consists of incorporating a plant-based amendment to enhance ecosystem productivity and physiochemical degradation followed by the establishment of plants to serve as oxidizers and foundations for microbial communities. Promising amendments for widespread use are entire plants of the water fern Azolla and seed meal of Brassica napus (rapeseed). An inexpensive byproduct from the manufacture of biodiesel and lubricants, rapeseed meal is high in nitrogen (6% wt/wt), stimulates >100-fold increases in populations of resident Streptomyces species, and suppresses fungal infection of roots subsequently cultivated in the amended soil. Synergistic enzymatic and chemical activities of plant and microbial metabolism in root zones transform and degrade soil contaminants. Emphasis is given to mechanisms that enable PHC functionalization via reactive molecular species.     

A DISTRIBUTED DYNAMIC WATERSHED MODEL1

ABSTRACT: A distributed watershed model was developed to mathematically simulate overland and channel flow for a single-event storm. The modeled watersheds in the study were subdivided into rectangular grid elements. All hydrologically significant parameters, such as land slope, rainfall and precipitation excess, were assumed to be uniform within each element. The Green-Ampt method was adopted to generate precipitation excess for each element during the simulation period. A two-dimensional diffusion wave model was used for overland flow routing and an iterative Alternative Direction Implicit scheme was used to solve the simultaneous overland flow equations. Once the overland flow became inflow to the channel, a one-dimensional dynamic wave flood routing technique, based on a four-point, implicit, non-linear finite difference solution of the St. Venant equation of unsteady flow, was applied. A limited number of comparisons were made between simulated and observed hydrographs for areas of about one square mile. Given the appropriate parameters, the model was able to accurately simulate runoff for single-event storms. This paper describes a distributed watershed model developed to simulate overland and channel flow. Comparisons were made between simulated and observed hydrographs for three watersheds. The model was able to accurately simulate the runoff for single-event storms using 61-m by 61-m (200 ft by 200 ft) watershed grid elements.     

Energetics and environmental costs of agriculture in a dry tropical region of India

The present article, based on a study of five village ecosystems, assesses the energy efficiency of rain-fed agriculture in a dry tropical environment and the impact of agricultural activity on the surrounding natural ecosystems. Agronomic yield is insufficient to meet the food requirement of the human population, hence 11.5%–49.7% of the required amount of food grains are imported from the market. Energy requirements of five studied agroecosystems are subsidized considerably by the surrounding forest in the form of fodder and firewood. Natural ecosystems supply about 80%–95% of fodder needs and 81%–100% of fuelwood needs. The output-input ratio of agriculture indicated that, on average, 4.1 units of energy are expended to obtain one unit of agronomic energy. Of this, 3.9 units are supplied by the natural ecosystem. In addition, 38% of the extracted firewood is marketed. The illegal felling and lopping of trees result in ever-increasing concentric circles of forest destruction around the villages and together with excessive grazing results in savannization. The forests can be conserved by encouraging fuelwood plantations (0.7 ha/ha cultivated land) and developing village pastures (1.6 ha/ha cultivated land) and reducing the livestock numbers. Agricultural production in the region can be stabilized by introducing improved dry farming techniques such as intercropping, planned rainwater management, and adequate use of fertilizers.     

INTEGRATED WATER RESOURCES MANAGEMENT WHO SHOULD LEAD,WHO SHOULD PAY?1

ABSTRACT: Improving water management to meet future global needs will certainly require technical advances, but the main challenge is to integrate the viewpoints of diverse societal interests into decisions about allocation of water resources. The integration cannot be done solely by the market because it requires a balancing among interests which do not respond well to market forces, nor by the state alone because of institutional problems. The concept of “integrated water resources management” has been developed to provide the framework for the required balancing of interests, and, like similar concepts in industries other than water, it has a dual purpose - to link stakeholders and apply best practices to management actions. To clarify the process of integrated water management, the paper focuses on two questions: who should lead integrated water resources management and who should pay for it? Several examples are given to illustrate a range of situations. The paper concludes with a call to improve paradigms of integrated water management, a proposition that water organizations should accept and budget for their external responsibilities as well as their direct missions, affirmation of the need for state and federal agencies to be involved with local interests, a call for better scientific and public information, and identification of the need for continued work to improve the process of integrated water management.