Immobilization of Heavy Metals in Soil Using Natural and Waste Materials for Vegetation Establishment on Contaminated Sites

Contaminated land is increasingly becoming an important issue worldwide. Many contaminants are persistent in soil for a large number of years. With the increase in public awareness regarding the consequences of contaminated soil, many researchers are concentrating on developing cost-effective and socially acceptable soil remediation technologies. Soils of many sites, which have been left derelict after industrial decline, harbor a broad suite of metal and organic contaminants. Land where such contaminants are deemed to pose a significant risk to receptors is considered contaminated under modern guidance. Remediation to break identified pollutant linkages would precede reclamation and plant establishment. One approach to break the pollutant receptor linkage is to utilize materials that effectively create soil conditions that immobilize contaminants whilst providing essential plant growth properties in terms of nutrition and water holding capacity. Materials that may achieve this include: 1) composts derived from materials such as sewage sludges and other municipal sources; 2) natural or synthetic zeolites; or 3) industrial by-products such as red-mud or other iron-rich materials such as iron grit or iron oxyhydroxides. Remediation techniques that utilize such materials may be cost-effective compared to more traditional methods and may effectively divert materials from the waste stream and could thereby make a dual contribution to sustainable development.     

Economic Costs of Childhood Diseases and Disabilities Attributable to Environmental Contaminants in Washington State, USA

This study estimates the economic costs associated with childhood diseases and disabilities attributable to environmental contaminants in Washington State, USA, including asthma, cancer, lead exposure, birth defects, and neurobehavioral disorders. The estimates are based on “cost of illness” models that include direct healthcare costs and indirect costs. The estimates are also based on an “environmentally attributable fraction” model which quantifies the proportions of each disease or disability that can reasonably be attributed to environmental contaminants. The study concludes that the annual cost of selected childhood diseases and disabilities attributable to environmental contaminants in Washington State is $1875 million in 2004 $, comprising $310.6 million in direct healthcare costs and $1565 million in indirect costs, and with a range of $1600–$2200 million a year. These estimates are consistent with other studies. Like the previous studies, a significant proportion of the estimated costs can be attributed to lead exposure. This estimate is equivalent to about 0.7% of the total Washington Gross State Product, and the estimated direct healthcare costs are equivalent to at least 0.2% of the total Washington State health expenditures. These costs could be lessened or prevented if exposures to environmental contaminants were reduced or eliminated. This study argues for the need for an ecosystem approach to human health in which the condition of the environment, in terms of exposures to environmental contaminants, must be addressed taking a systemic perspective.     

Assessing the Eco-efficiency of End-of-Pipe Technologies with the Environmental Cost Efficiency Indicator

The concept of eco-efficiency is increasingly being applied to judge the combined environmental and economic performance of product systems, processes, and/or companies. Ecoefficiency is often defined as the ratio of economic value added to environmental impact added. This definition is not appropriate for end-of-pipe treatment technologies because these technologies aim at improving the environmental performance of technical processes at the cost of financial expense. Therefore, an indicator for the assessment of end-of-pipe technologies has been proposed. This indicator, called environmental cost efficiency (ECE), is defined as the ratio of net environmental benefits to the difference in costs. ECE is applied to four end-of-pipe technologies for the treatment of municipal solid waste: sanitary landfill, mechanical-biological treatment, modern grate incineration, and a staged thermal process (pyrolysis and gasification). A life-cycle assessment was performed on these processes to quantify the net environmental benefit. Moreover, the approximate net costs (costs minus benefits) were quantified. The results show that, relative to grate incineration, sanitary landfills and mechanical-biological treatment are less costly but environmentally more harmful. We calculated the ECE for all combinations of technologies. The results indicate that the staged thermal process may be the most environmentally cost-efficient alternative to all other treatment technologies in the long run, followed by mechanical-biological treatment and grate incineration.     

Using agro-industrial wastes for the cultivation of microalgae and duckweeds: Contamination risks and biomass safety concerns

Aquatic organisms, such as microalgae (Chlorella, Arthrospira (Spirulina), Tetrasselmis, Dunalliela etc.) and duckweed (Lemna spp., Wolffia spp. etc.) are a potential source for the production of protein-rich biomass and for numerous other high-value compounds (fatty acids, pigments, vitamins etc.). Their cultivation using agro-industrial wastes and wastewater (WaW) is of particular interest in the context of a circular economy, not only for recycling valuable nutrients but also for reducing the requirements for fresh water for the production of biomass. Recovery and recycling of nutrients is an unavoidable long-term approach for securing future food and feed production. Agro-industrial WaW are rich in nutrients and have been widely considered as a potential nutrient source for the cultivation of microalgae/duckweed. However, they commonly contain various hazardous contaminants, which could potentially taint the produced biomass, raising various concerns about the safety of their consumption. Herein, an overview of the most important contaminants, including heavy metals and metalloids, pathogens (bacteria, viruses, parasites etc.), and xenobiotics (hormones, antibiotics, parasiticides etc.) is given. It is concluded that pretreatment and processing of WaW is a requisite step for the removal of several contaminants. Among the various technologies, anaerobic digestion (AD) is widely used in practice and offers a technologically mature approach for WaW treatment. During AD, various organic and biological contaminants are significantly removed. Further removal of contaminants could be achieved by post-treatment and processing of digestates (solid/liquid separation, dilution etc.) to further decrease the concentration of contaminants. Moreover, during cultivation an additional removal may occur through various mechanisms, such as precipitation, degradation, and biotransformation. Since many jurisdictions regulate the presence of various contaminants in feed or food setting strict safety monitoring processes, it would be of particular interest to initiate a multi-disciplinary discussion whether agro-industrial WaW ought to be used to cultivate microalgae/duckweed for feed or food production and identify most feasible options for doing this safely. Based on the current body of knowledge it is estimated that AD and post-treatment of WaW can lower significantly the risks associated with heavy metals and pathogens, but it is yet unclear to what extent this is the case for certain persistent xenobiotics.     

Methodology for using contaminated soil leachability testing to determine soil cleanup levels at contaminated petroleum underground storage tank (UST) sites

The costs of environmental remediation at leaking petroleum underground storage tank (UST) sites are influenced significantly by soil cleanup levels. The use of conservative generic soil cleanup levels may be inappropriate at some sites contaminated by leaking petroleum USTs. At many contaminated sites, a primary objective of site remediation is long‐term protection of water resources (e.g., groundwater) from pollution. Leaching of pollutants from residual soil contamination to groundwater is a primary consideration in establishing site‐specific soil cleanup levels at fuel‐contaminated sites. The use of laboratory soil leachability testing methods may be useful in objectively evaluating the leaching potential of contaminants from residual soil contamination and estimating potential groundwater impacts. Developing soil cleanup levels that are protective of water resources must include a technically sound integration of site‐specific soil leachability data and contaminant attenuation factors. Evaluation of the leaching potentials of soil contaminants may also provide essential supplementary information for other site characterization methods that may be used to evaluate risks to human health. Contaminant leachability testing of soils may provide a cost‐effective and technically based method for determining soil cleanup levels that are protective of groundwater resources at contaminated petroleum UST sites.     

Insights into phytoremediation solutions for environmental recovery

Our environment is contaminated with organic and inorganic compounds released by anthropogenic activities that cause negative impacts on biological productivity and ecosystem sustainability and place human health at risk. Within the available remediation technologies, phytoremediation has emerged with high potential due to its reduced environmental impacts and economic costs. The research into phytoremediation has developed through a wide array of approaches, which also pertains to its inherent interdisciplinary characteristics, towards enhancing the potential of the technology for application in the field. Numerous patents present molecular solutions through which plants can be engineered to display improvements in key characteristics, such as the tolerance, uptake and accumulation of contaminants. The manipulation of plant growth and of the physico-chemical characteristics of the contaminated environments in order to enhance the remediation potential has also been the focus of several issued patents. This review attempts to highlight the most relevant patented advances in phytoremediation and to emphasise recent research efforts through which this green technology might be expected to develop into a commercially competitive alternative to other remediation methods.     

How to estimate the cost of point-of-care CD4 testing in program settings: an example using the Alere Pima Analyzer in South Africa

Integrating POC CD4 testing technologies into HIV counseling and testing (HCT) programs may improve post-HIV testing linkage to care and treatment. As evaluations of these technologies in program settings continue, estimates of the costs of POC CD4 tests to the service provider will be needed and estimates have begun to be reported. Without a consistent and transparent methodology, estimates of the cost per CD4 test using POC technologies are likely to be difficult to compare and may lead to erroneous conclusions about costs and cost-effectiveness. This paper provides a step-by-step approach for estimating the cost per CD4 test from a provider''s perspective. As an example, the approach is applied to one specific POC technology, the Pima™ Analyzer. The costing approach is illustrated with data from a mobile HCT program in Gauteng Province of South Africa. For this program, the cost per test in 2010 was estimated at $23.76 (material costs = $8.70; labor cost per test = $7.33; and equipment, insurance, and daily quality control = $7.72). Labor and equipment costs can vary widely depending on how the program operates and the number of CD4 tests completed over time. Additional costs not included in the above analysis, for on-going training, supervision, and quality control, are likely to increase further the cost per test. The main contribution of this paper is to outline a methodology for estimating the costs of incorporating POC CD4 testing technologies into an HCT program. The details of the program setting matter significantly for the cost estimate, so that such details should be clearly documented to improve the consistency, transparency, and comparability of cost estimates.     

Phytoremediation of organic contaminants in soils

Soil pollution, a very important environmental problem, has been attracting considerable public attention over the last decades. Unfortunately, the enormous costs associated with the removal of pollutants from soils by means of traditional physicochemical methods have been encouraging companies to ignore the problem. Phytoremediation is an emerging technology that uses plants to clean up pollutants in the environment. As overwhelmingly positive results have become available regarding the ability of plants to degrade certain organic compounds, more and more people are getting involved in the phytoremediation of organic contaminants. Phytoremediation of organics appears a very promising technology for the removal of these contaminants from polluted sites.     

Phytoremediation of toxic aromatic pollutants from soil

The enormous growth of industrialization, and the use of numerous aromatic compounds in dyestuffs, explosives, pesticides and pharmaceuticals has resulted in serious environmental pollution and has attracted considerable attention continuously over the last two decades. Many aromatic hydrocarbons, nitroaromatic compounds, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, diauxins and their derivatives are highly toxic, mutagenic and/or carcinogenic to natural microflora as well as to higher systems including humans. The increasing costs and limited efficiency of traditional physicochemical treatments of soil have spurred the development of new remediation technologies. Phytoremediation is emerging as an efficient treatment technology that uses plants to bioremediate pollutants from soil environments. Various modern tools and analytical devices have provided insight into the selection and optimization of remediation processes by various plant species. Sites heavily polluted with organic contaminants require hyperaccumulators, which could be developed by genetic engineering approaches. However, efficient hyperaccumulation by naturally occurring plants is also feasible and can be made practical by improving their nutritional and environmental requirements. Thus, phytoremediation of organics appears a very promising technology for the removal of contaminants from polluted soil. In this review, certain aspects of plant metabolism associated with phytoremediation of organic contaminants and their relevant phytoremediation efforts are discussed.IMTECH Communication No. 013/2002     

Phytoextraction: an assessment of biogeochemical and economic viability

Phytoextraction describes the use of plants to remove metals and other contaminants from soils. This low-cost technology has potential for the in situ remediation of large areas of contaminated land. Despite more than 10 years of intensive research on the subject, very few commercial phytoextraction operations have been realised. Here, we investigate the viability of phytoextraction as an effective land-treatment technology. A Decision Support System (DSS) was developed to predict the effect of phytoextraction on soil metal concentration and distribution, as well as the economic feasibility of the process in comparison to either inaction or the best alternative technology. Changes in soil metal concentration are mechanistically predicted on the basis of plant water use, metal concentration in soil solution, soil density, plant root distribution and our so-called root-absorption factor. The root-absorption factor is a `lumped parameter' describing the xylem/soil solution metal concentration quotient. Phytoextraction is considered to be a viable option if it can satisfy environmental regulations and simultaneously be shown to be the most cost-effective technology, either alone, or in combination with other remediation technologies. To date, commercial phytoextraction has been constrained by the expectation that site remediation should be achieved in a time comparable to other clean-up technologies. However, if phytoextraction could be combined with a profit making operation such as forestry, then this time constraint, which has often been considered to be the Achilles heel of phytoextraction, may be less important.     

Hydrocarbon phytoremediation in the family Fabaceae--a review

Currently, studies often focus on the use of Poaceae species (grasses) for phytoremediation of hydrocarbon-contaminated soils. Research into the use of Fabaceae species (legumes) to remediate hydrocarbons in soils has been conducted, but these plants are commonly overlooked due to slower recorded rates of degradation compared with many grass species. Evidence in the literature suggests that in some cases Fabaceae species may increase total degradation of hydrocarbons and stimulate degradative capacity of the soil microbial community, particularly for contaminants which are normally more recalcitrant to degradation. As many recalcitrant hydrocarbons have negative impacts on human and ecosystem health, development of remediation options is crucial. Reconsideration of Fabaceae species for removal of such contaminants may lead to environmentally and economically sustainable technologies for remediation of contaminated sites.     

Panax quinquefolius: An overview of the contaminants

The root of Panax quinquefolius has been used as a food supplement and botanical drug throughout the world for many years. During growth, harvest, processing, and storage, it can be polluted by molds, pesticides, heavy metals, and other chemicals, resulting in contamination with mycotoxins, pesticide residues, and heavy metals, as well as other substances. These contaminants may be harmful to human health. In this review, we summarize the contaminants and significant advances that have been made in the study of these contaminants, focusing on the analytical methods and contamination management techniques for P. quinquefolius that have been developed over the last several decades.     

Quantifying the drivers of long-term prices in materials supply chains

Raw materials costs form an increasingly significant proportion of the total costs of renewable energy technologies that must be adopted at unprecedented rates to combat climate change. As the affordable deployment of these technologies grows vulnerable to materials price changes, effective strategies must be identified to mitigate the risk of higher input costs faced by manufacturers. To better understand potential threats to deployment, a market modeling approach was developed to quantify economic risk factors including material demand, substitutability, recycling, mining productivity, resource quality, and discovery. Results demonstrate that price changes are determined by interactions between demand growth, mining productivity, and resource quality. In the worst cases with high demand and low productivity, development of material substitutes and large recycling rates help reduce the prevalence of price risk from over 90% to under 10%. Investing in these strategies yields significant benefits for manufacturers and governments concerned about costs of materials critical to decarbonization and other advanced technologies.     

Estimates and implications of the costs of compliance with biosafety regulations in developing countries

Estimating the cost of compliance with biosafety regulations is important as it helps developers focus their investments in producer development. We provide estimates for the cost of compliance for a set of technologies in Indonesia, the Philippines and other countries. These costs vary from US $100,000 to 1.7 million. These are estimates of regulatory costs and do not include product development or deployment costs. Cost estimates need to be compared with potential gains when the technology is introduced in these countries and the gains in knowledge accumulate during the biosafety assessment process. Although the cost of compliance is important, time delays and uncertainty are even more important and may have an adverse impact on innovations reaching farmers.     

Current approaches for the assessment of in situ biodegradation

Considering the high costs and technical difficulties associated with conventional remediation strategies, in situ biodegradation has become a promising approach for cleaning up contaminated aquifers. To verify if in situ biodegradation of organic contaminants is taking place at a contaminated site and to determine if these processes are efficient enough to replace conventional cleanup technologies, a comprehensive characterization of site-specific biodegradation processes is essential. In recent years, several strategies including geochemical analyses, microbial and molecular methods, tracer tests, metabolite analysis, compound-specific isotope analysis, and in situ microcosms have been developed to investigate the relevance of biodegradation processes for cleaning up contaminated aquifers. In this review, we outline current approaches for the assessment of in situ biodegradation and discuss their potential and limitations. We also discuss the benefits of research strategies combining complementary methods to gain a more comprehensive understanding of the complex hydrogeological and microbial interactions governing contaminant biodegradation in the field.     

Single-layer centrifugation separates spermatozoa from diploid cells in epididymal samples from gray wolves, Canis lupus (L.)

Sperm samples may be used for assisted reproductive technologies (e.g., farmed or endangered species) or as a source of haploid DNA or sperm-specific RNA. When ejaculated spermatozoa are not available or are very difficult to obtain, as is the case for most wild endangered species, the epididymides of dead animals (e.g., animals that have been found dead, shot by hunters or poachers, or that that require euthanasia in zoological collections) can be used as a source of sperm. Such epididymal sperm samples are usually contaminated with cellular debris, erythrocytes, leukocytes, and sometimes also bacteria. These contaminants may be sources of reactive oxygen species that damage spermatozoa during freezing or contribute undesired genetic material from diploid cells. We used single-layer centrifugation through a colloid formulation, Androcoll-C, to successfully separate wolf epididymal spermatozoa from contaminating cells and cellular debris in epididymal samples harvested from carcasses. Such a procedure may potentially be applied to epididymal sperm samples from other species.     

Recombinant viral insecticides: Delivery of environmentally safe and cost-effective products

Biological control agents such as baculovirus insecticides have many attributes which make them attractive alternatives to synthetic chemical pesticides. However, there have been several economic and agronomic barriers to their widespread use. Among the obstacles to commercialization of viral insecticides have been high production costs, the lack of efficacious formulation and application technologies, and a slow speed of action. Biotechnology has contributed several advances toward overcoming these obstacles. The high cost ofin vivo production can be reduced significantly using a newly developed high-density rearing system termed HeRD. The HeRD technology can be used to rear many different species of lepidopterous larvae for production of viral insecticides, as hosts for parasitoid production, or for sterile-male release programs. Using this technology, the baculovirus production costs are equivalent to sprayable Bt toxins. The field efficacy of viral pesticides and other biological control agents requires cost effective, biologically based formulation and application technologies. Based on current field efficacy evaluations of baculovirus pesticides, formulation/application technologies must be improved for viral pesticides to compete effectively and consistently in most pesticide markets. Through recombinant DNA technology, it is now possible to insert foreign pesticidal genes into viral pesticides, resulting in faster time to death or, more importantly, time to cessation of feeding of the target pests. However, the commercial use of recombinant pesticides has raised several potential environmental issues, including possible effects on non-target organisms, ecological interactions, mitigation and genetic stability. Genetic strategies have been developed to mitigate most of the potential problems associated with recombinant baculovirus pesticides. Five field tests have been conducted in the U.S. to evaluate these strategies. The laboratory and field results illustrate that the genetic strategies employed ensure environmental safety while also reducing production costs.     

A sensitivity analysis of process design parameters,commodity prices and robustness on the economics of odour abatement technologies

The sensitivity of the economics of the five most commonly applied odour abatement technologies (biofiltration, biotrickling filtration, activated carbon adsorption, chemical scrubbing and a hybrid technology consisting of a biotrickling filter coupled with carbon adsorption) towards design parameters and commodity prices was evaluated. Besides, the influence of the geographical location on the Net Present Value calculated for a 20 years lifespan (NPV20) of each technology and its robustness towards typical process fluctuations and operational upsets were also assessed. This comparative analysis showed that biological techniques present lower operating costs (up to 6 times) and lower sensitivity than their physical/chemical counterparts, with the packing material being the key parameter affecting their operating costs (40–50% of the total operating costs). The use of recycled or partially treated water (e.g. secondary effluent in wastewater treatment plants) offers an opportunity to significantly reduce costs in biological techniques. Physical/chemical technologies present a high sensitivity towards H₂S concentration, which is an important drawback due to the fluctuating nature of malodorous emissions. The geographical analysis evidenced high NPV20 variations around the world for all the technologies evaluated, but despite the differences in wage and price levels, biofiltration and biotrickling filtration are always the most cost-efficient alternatives (NPV20). When, in an economical evaluation, the robustness is as relevant as the overall costs (NPV20), the hybrid technology would move up next to BTF as the most preferred technologies.     

水生生态环境中捕食信息素的生态学效应

捕食信息素是捕食者释放的,能够引发猎物反捕食反应的化学信号。在水生生态系统中,捕食信息素在捕食者和猎物之间信息传递及协同进化过程中发挥着重要的作用,其生态学效应在国际上受到广泛关注。捕食信息素的来源有多种形式,研究中常使用养殖过捕食者的水溶液作为捕食信息素的来源。捕食信息素的作用效果受到捕食者和猎物的种类、信息素的浓度、观察的指标等多方面因素的影响。捕食信息素可以对水生生物的行为、形态和生活史特征等方面造成影响。水生生物通过感知捕食信息素来提前预知潜在的被捕食风险,并作出适应性调整,以降低被捕食的风险。在某些情况下,捕食信息素可以与污染物产生交互作用,从而干扰污染物对水生生物的毒性。对水生环境中捕食信息素的研究现状做了综述,介绍了当前对捕食信息素来源和理化性质等本质问题的认识,总结捕食信息素对水生生物行为、形态和生活史特征的影响,以及捕食信息素对污染物毒性的干扰,并分析了这一研究领域尚存在的困难和今后的研究方向。加强对捕食信息素的研究,将为解析水生环境中捕食者和猎物的生态关系提供新依据。