Showing papers in "Critical Reviews in Environmental Science and Technology in 2006"
TL;DR: In this paper, the complex mechanisms of Fenton and Fenton-like reactions and the important factors influencing these reactions, from both a fundamental and practical perspective, in applications to water and soil treatment, are discussed.
Abstract: Fenton chemistry encompasses reactions of hydrogen peroxide in the presence of iron to generate highly reactive species such as the hydroxyl radical and possibly others. In this review, the complex mechanisms of Fenton and Fenton-like reactions and the important factors influencing these reactions, from both a fundamental and practical perspective, in applications to water and soil treatment, are discussed. The review covers modified versions including the photoassisted Fenton reaction, use of chelated iron, electro-Fenton reactions, and Fenton reactions using heterogeneous catalysts. Sections are devoted to nonclassical pathways, by-products, kinetics and process modeling, experimental design methodology, soil and aquifer treatment, use of Fenton in combination with other advanced oxidation processes or biodegradation, economic comparison with other advanced oxidation processes, and case studies.
3,218 citations
TL;DR: There is an essential relation between poverty and fluorosis as malnutrition is found to play an aggressive role in its severity, as the lack of access to clean water denies the most essential of all rights, the right to life.
Abstract: ‘Water is life,’ so central to human life, yet over one billion people across the world have no access to safe drinking water. Of late, there has been increasing global attention focused on resolving water quality problems especially in developing countries, as the lack of access to clean water denies the most essential of all rights, the right to life. The latest estimates suggest that around 200 million people, from among 25 nations the world over, are under the dreadful fate of fluorosis. India and China, the two most populous countries of the world, are the worst affected. India is plagued with numerous water quality problems due to prolific contaminants mainly of geogenic origin and fluoride stands first among them. The weathering of primary rocks and leaching of fluoride-containing minerals in soils yield fluoride rich groundwater in India which is generally associated with low calcium content and high bicarbonate ions. The unfettered ground water tapping exacerbates the failure of drinking water so...
1,116 citations
TL;DR: In this paper, the authors present the components of organic matter present in WWTP effluents and various treatment methods that may be employed for reduction of EfOM, including flocculation, adsorption, biofiltration, ion exchange, advanced oxidation process, and membrane technology.
Abstract: Wastewater reuse is being increasingly emphasized as a strategy for conservation of limited resources of freshwater and as a mean of safeguarding the aquatic environment due to contaminants present in wastewater. Although secondary and tertiary treated wastewater is often discharged into surface waters, it cannot be reused without further treatment. One of the parameters of concern for human and environmental health is components of organic matter originating from wastewater treatment plant (WWTP) effluents. This effluent organic matter (EfOM) should be carefully characterized in order to find an optimum treatment method for water reuse. This review presents the components of EfOM present in WWTP effluents and various treatment methods that may be employed for reduction of EfOM. These processes include flocculation, adsorption, biofiltration, ion exchange, advanced oxidation process, and membrane technology. The removal efficiency is discussed in terms of removal of total organic carbon, endocrine-disrupt...
551 citations
TL;DR: A review of the current research on the synthesis, properties, and environmental applications of nanoscale iron-based materials is reviewed and summarized in this paper, where different physical and chemical methods used for synthesizing nano-iron-based particles with desired size, structure, and surface properties are described.
Abstract: Due to their special properties, people have been increasingly interested in studying applications of nanoscale metal materials in environmental engineering. Literature about the current research on the synthesis, properties, and environmental applications of nanoscale iron-based materials is reviewed and summarized in this article. Different physical and chemical methods used for synthesizing nano-iron-based particles with desired size, structure, and surface properties are described. We also emphasize important properties of nano-iron-based particles, including the density and intrinsic reactivity of surface sites. These properties directly influence the chemical behavior of such particles and, consequently, affect their applications in water and wastewater treatment and in air pollution control. Environmental applications of nano-iron particles are discussed in detail, including removal of chlorinated organics, heavy metals, and inorganics.
406 citations
TL;DR: The state of the art with respect to anaerobic membrane bioreactors is summarized, the types of wastewaters for which AnMBRs would be best suited, and the research required to increase implementation are identified.
Abstract: Membranes provide exceptional suspended solids removal and complete biomass retention that can improve the biological treatment process, but their commercial application to anaerobic treatment has been limited. This review summarizes the state of the art with respect to anaerobic membrane bioreactors (AnMBRs), determines the types of wastewaters for which AnMBRs would be best suited, and identifies the research required to increase implementation. AnMBRs have been tested with synthetic, food processing, industrial, high solids content, and municipal wastewaters at laboratory, pilot, and full scale. Chemical oxygen demand removal ranges from 56% to 99%, while the reported design membrane fluxes range from 10 to 40 L/m2/h. AnMBRs should be immediately applicable to highly concentrated, particulate waste streams like municipal sludges where the membrane can decouple the solids and hydraulic retention times. Opportunity for application to dilute wastewaters also appears strong, while application to highly con...
402 citations
TL;DR: A review of DON compounds in wastewater and wastewater effluents is given in this article, where the authors show that wastewater-derived dissolved organic nitrogen (DON) accounts for up to 80% of dissolved nitrogen in nitrified-denitrified effluent.
Abstract: Wastewater-derived dissolved organic nitrogen (DON) accounts for up to 80% of dissolved nitrogen in nitrified-denitrified effluent. The sturdiness of DON measurements hindered the characterization of DON, especially in wastewater matrix, leading to an unsatisfying knowledge level. Measurement of DON and DON species is imortant not only as a measure of treatibility of wastewater in treatment plants, but also for the possible algal growth-stimulating effects after their discharge into receiving waters. In addition, wastewater-derived DON compounds may act as precursors to several disinfection by-products during intentional or unintentional reuse of wastewater. A review of DON compounds in wastewater and wastewater effluents is given.
148 citations
TL;DR: A review of the current trends and developments in the field of slow rate systems is given in this article, focusing on those systems in which effluent application is based on plant water requirements.
Abstract: Land treatment systems constitute a viable alternative solution for wastewater management in cases where the construction of conventional (mechanical) wastewater treatment plants (WWTPs) are not affordable or other disposal options are not available. They have proven to be an ideal technology for small rural communities, clusters of homes, and small industrial units due to low energy demands and low operation and maintenance costs. In addition, slow rate systems (SRS) may be designed using the “zero discharge” concept. The purpose of this article is to review the current trends and developments in the field of SRS, focusing on those systems in which effluent application is based on plant water requirements. Vegetation has an important role in treatment efficiency through its effects on hydraulic loading rate, nutrient removal, and biomass production. In addition, vegetation may affect the fate of trace elements and the degradation/detoxification of recalcitrant organics. Detailed knowledge of the basic pr...
74 citations
TL;DR: In this article, the authors present a comprehensive review of risk analysis and management strategies for application in the water utility sector at the strategic, program, and operational levels of decision making, including risk analysis strategies and techniques traditionally applied to public health protection, assessing competition risks, and potential threats to the security of supplies.
Abstract: Financial pressures, regulatory reform, and sectoral restructuring are requiring water utilities to move from technically inclined, risk-averse management approaches toward more commercial, business-oriented practices. Risk analysis strategies and techniques traditionally applied to public health protection are now seeing broader application for asset management, assessing competition risks, and potential threats to the security of supplies. Water utility managers have to consider these risks alongside one another, employ a range of techniques, and devise business plans that prioritize resources on the basis of risk. We present a comprehensive review of risk analysis and management strategies for application in the water utility sector at the strategic, program, and operational levels of decision making.
71 citations
TL;DR: A review of state regulations was conducted to determine C&D debris disposal facility requirements, including specific requirements for liners, leachate collection, groundwater monitoring, location restrictions, operator training, waste spotters, final cover, financial assurance, and recycling as discussed by the authors.
Abstract: Construction and demolition (C&D) debris comprises a significant portion of the solid waste stream in the United States. Because C&D debris is largely regulated at the state level, the requirements for C&D debris disposal facilities vary from state to state. A review of state regulations was conducted to determine C&D debris disposal facility requirements, including specific requirements for liners, leachate collection, groundwater monitoring, location restrictions, operator training, waste spotters, final cover, financial assurance, and recycling. This review found that little consistency exists in the regulation of C&D debris facilities among states. Twenty-three states require liners, while 27 require groundwater monitoring. Seventeen states reported having regulations pertaining to recycling C&D debris. Several states are currently in the process of reviewing and updating their C&D debris regulations, an indication of the greater recognized importance of this fraction of the solid waste stream.
67 citations
TL;DR: In this paper, the conditions driving recycling, selection of pro-recycling policies, and recycling statistics are compared for 14 countries across Europe, Asia, North America, South America, and Oceana.
Abstract: Many national, regional, and local governments have introduced policies to encourage recycling. Their varied experiences allow examination of the effectiveness of alternative policy options. The conditions driving recycling, selection of pro-recycling policies, and recycling statistics are compared for 14 countries across Europe, Asia, North America, South America, and Oceana. The best policy for any particular country is a function of practicality, affordability, and political and social acceptability. National programs with the highest recycling rates typically target both supply and demand through incentives that encourage source separation and recycled content, with regulatory measures used to close loopholes and provide minimum performance requirements.
31 citations
TL;DR: This article was retracted on the basis of a statement of retraction issued by the editor of the Daily Telegraph on Thursday, 3 March 2017.
Abstract: DNAzymes are biocatalysts with a promising capacity to selectively identify charged organic and inorganic compounds at ultratrace levels in industrial waste streams, chemical emissions, environmental samples, or biological systems for a variety of applications. Combining the specificity of nano-biological recognition probes and the sensitivity of laser-based optical detection, DNAzymes are capable of detecting and differentiating chemical constituents of complex systems to provide unambiguous identification and accurate quantification. This article reviews the state of the science of DNAzymes, as well as challenges to be met toward their widespread implementation. The results indicate that these nanosensors are transitioningfrom the proof-of-concept stage to field testing and commercialization. Promising areas of application include in situ monitoring of contaminated media, or industrial process streams that contain mixed organic wastes, such as heavy metals, organometallics, antibiotics, and other charged compounds. A new generation of DNAzyme-based sensors coupled with fiber-optic technology is emerging rapidly, exhibiting many advantages over state-of-the-art affinity sensors with applicability in environmental sensing. Although significant strides have been made in the area of selectivity, sensitivity, and catalytic rates of DNAzymes, challenges, by and large, remain in the development of efficient signal transduction technology for in situ applications.