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Showing papers in "Critical Reviews in Environmental Science and Technology in 2014"


Journal ArticleDOI
TL;DR: Advanced oxidation processes (AOPs) constitute important, promising, efficient, and environmental-friendly methods developed to principally remove persistent organic pollutants (POP) from waters and wastewaters.
Abstract: Advanced oxidation processes (AOPs) constitute important, promising, efficient, and environmental-friendly methods developed to principally remove persistent organic pollutants (POPs) from waters and wastewaters. Generally, AOPs are based on the in situ generation of a powerful oxidizing agent, such as hydroxyl radicals (•OH), obtained at a sufficient concentration to effectively decontaminate waters. This critical review presents a precise and overall description of the recent literature (period 1990–2012) concerning the main types of AOPs, based on chemical, photochemical, sonochemical, and electrochemical reactions. The principles, performances, advantages, drawbacks, and applications of these AOPs to the degradation and destruction of POPs in aquatic media and to the treatment of waters and waste waters have been reported and compared.

1,550 citations


Journal ArticleDOI
TL;DR: In this article, the authors review the current status of the recycling processes of spent lithium ion batteries, introduce the structure and components of the batteries, and summarize all available single contacts in batch mode operation, including pretreatment, secondary treatment, and deep recovery.
Abstract: Lithium-ion battery (LIB) applications in consumer electronics and electric vehicles are rapidly growing, resulting in boosting resources demand, including cobalt and lithium. So recycling of batteries will be a necessity, not only to decline the consumption of energy, but also to relieve the shortage of rare resources and eliminate the pollution of hazardous components, toward sustainable industries related to consumer electronics and electric vehicles. The authors review the current status of the recycling processes of spent LIBs, introduce the structure and components of the batteries, and summarize all available single contacts in batch mode operation, including pretreatment, secondary treatment, and deep recovery. Additionally, many problems and prospect of the current recycling processes will be presented and analyzed. It is hoped that this effort would stimulate further interest in spent LIBs recycling and in the appreciation of its benefits.

610 citations


Journal ArticleDOI
TL;DR: A comprehensive and critical review of the literature on the effectiveness of a number of sorbents, especially some novel ones that have recently emerged, in removing and recovering phosphate can be found in this article.
Abstract: Sorption is an effective, reliable, and environmentally friendly treatment process for the removal of phosphorus from wastewater sources which otherwise can cause eutrophication of receiving waters. Phosphorus in wastewater, if economically recovered, can partly overcome the future scarcity of phosphorus resulting from exhaustion of natural phosphate rock reserves. The authors present a comprehensive and critical review of the literature on the effectiveness of a number of sorbents, especially some novel ones that have recently emerged, in removing and recovering phosphate. Mechanisms and thermodynamics of sorption, as well as regeneration of sorbents for reuse using acids, bases, and salts, are critically examined.

461 citations


Journal ArticleDOI
TL;DR: In this article, a review combines patchwise ENM research using natural soils with the much wider literature on ENM performed in standard tests or on the fate of colloids in soils, and an analysis of diverse ENM characteristics determining availability from the soil organisms' perspective to assess the main soil characteristics that determine the fate, speciation, and ultimately bioavailability of ENM in natural soils.
Abstract: Interactions within natural soils have often been neglected when assessing fate and bioavailability of engineered nanomaterials (ENM) in soils. This review combines patchwise ENM research using natural soils with the much wider literature on ENM performed in standard tests or on the fate of colloids in soils, and an analysis of the diverse ENM characteristics determining availability from the soil organisms’ perspective to assess the main soil characteristics that determine the fate, speciation, and ultimately bioavailability of ENM in natural soils. Predominantly salinity, texture, pH, concentration, and nature of mobile organic compounds and degree of saturation determine ENM bioavailability.

355 citations


Journal ArticleDOI
TL;DR: This review provides a comprehensive overview about nonextractable residue (NER) formation and attempts to classify the various types and a model to prospectively estimate bioNER formation in soil is proposed.
Abstract: This review provides a comprehensive overview about nonextractable residue (NER) formation and attempts to classify the various types. Xenobiotic NER derived from parent pesticides (or other environmental contaminants) and primary metabolites sorbed or entrapped within the soil organic matter (Type I) or covalently bound (Type II) pose a considerably higher risk than those derived from productive biodegradation. However, biogenic nonextractable residues (bioNER) (Type III) resulting from conversion of carbon (or nitrogen) from the compounds into microbial biomass molecules do not pose any risk. Experimental approaches to clearly distinguish between the types are provided, and a model to prospectively estimate bioNER formation in soil is proposed.

204 citations


Journal ArticleDOI
TL;DR: In this article, the authors provide an overview on the applications of ultrasonic technology in sludge solubilization and subsequent digestion, sludge sanitization, enhancement of enzymatic activity, resource recovery, extraction of chemicals, ultrasound assisted lysis-cryptic growth, and degradation of hazardous pollutants.
Abstract: During the past decades, ultrasonic technology has gained wide interest as an effective mechanical pretreatment method for sludge, due to its excellent performance, good technical and operational stability, compactness, and environmentally friendly processing. This review is intended to provide an overview on the applications of ultrasonics in sludge solubilization and subsequent digestion, sludge sanitization, enhancement of enzymatic activity, resource recovery, extraction of chemicals, ultrasound assisted lysis–cryptic growth, and degradation of hazardous pollutants. Moreover, the working mechanisms behind the treatment and the influence of various process conditions, including power density/intensity, specific energy input, ultrasonic frequency, duration of ultrasonication (i.e., partial and complete ultrasonication, solids concentration, and type of sludge on the ultrasonic processing of sludge is specifically emphasized. Also, a discussion is included on the future research directions, an economical...

153 citations


Journal ArticleDOI
TL;DR: Prospective and retrospective risk assessments of AS, AES, AE, LAS, and LCOH demonstrate that these substances, although used in very high volume and widely released to the aquatic environment, have no adverse impact on the aquatic or sediment environments at current levels of use.
Abstract: This paper brings together over 250 published and unpublished studies on the environmental properties, fate, and toxicity of the four major, high-volume surfactant classes and relevant feedstocks. The surfactants and feedstocks covered include alcohol sulfate or alcohol sulfate (AS), alcohol ethoxysulfate (AES), linear alkylbenzene sulfonate (LAS), alcohol ethoxylate (AE), and long-chain alcohol (LCOH). These chemicals are used in a wide range of personal care and cleaning products. To date, this is the most comprehensive report on these substance's chemical structures, use, and volume information, physical/chemical properties, environmental fate properties such as biodegradation and sorption, monitoring studies through sewers, wastewater treatment plants and eventual release to the environment, aquatic and sediment toxicity, and bioaccumulation information. These data are used to illustrate the process for conducting both prospective and retrospective risk assessments for large-volume chemicals and categories of chemicals with wide dispersive use. Prospective risk assessments of AS, AES, AE, LAS, and LCOH demonstrate that these substances, although used in very high volume and widely released to the aquatic environment, have no adverse impact on the aquatic or sediment environments at current levels of use. The retrospective risk assessments of these same substances have clearly demonstrated that the conclusions of the prospective risk assessments are valid and confirm that these substances do not pose a risk to the aquatic or sediment environments. This paper also highlights the many years of research that the surfactant and cleaning products industry has supported, as part of their environmental sustainability commitment, to improve environmental tools, approaches, and develop innovative methods appropriate to address environmental properties of personal care and cleaning product chemicals, many of which have become approved international standard methods.

139 citations


Journal ArticleDOI
TL;DR: A review of the up-to-date research on the treatment of micropollutants by UV-based processes is provided in this article, with emphasis on the peer-reviewed papers in the last three years (2009-2011).
Abstract: This paper provides a review of the up-to-date research on the treatment of micropollutants by UV-based processes. More than 140 scientific publications in the past 10 years were reviewed and analyzed, with emphasis on the peer-reviewed papers in the last three years (2009–2011). Previous studies showed that UV-based advanced oxidation processes (AOPs) could be efficient for the removal of a number of micropollutants in drinking water and wastewater although direct UV photolysis at disinfection dosages was proven not effective in removing most micropollutants. Among those UV-based AOPs, UV-oxidation with hydrogen peroxide (H2O2) has attracted great attention and shown numerous advantages as an advanced technology for micropollutants control. The public concern about the impact of micropollutants on the safety of drinking water and the increasing needs of safe water reuse will likely facilitate the application of UV-based processes for micropollutants control in drinking water treatment and water reuse.

138 citations


Journal ArticleDOI
TL;DR: In this paper, the microstructure and physicochemical properties of bivalve shells are described, and the current status of Bivalve shell studies and directions for future research are considered.
Abstract: Bivalve shells, available in abundance, have no eminent use and are commonly regarded as waste. Their improper disposal causes a significant level of environmental concern and also results in a waste of natural resources. Bivalve shell is formed by biomineralization and consists mainly of CaCO3 with a small amount of organic matrix, giving it a potential for use as raw material. Recycling shell waste could potentially eliminate the disposal problem, and also turn an otherwise useless waste into high value-added products. The present paper first describes the microstructure and physicochemical properties of bivalve shell, then focuses on its current applications. Finally, the current status of bivalve shell studies and directions for future research are considered.

121 citations


Journal ArticleDOI
TL;DR: In this paper, the present state and emerging trends in advanced oxidation based treatment techniques have been summarized, and reaction chemistries, process conditions, treatment efficiencies, and material and energy inputs required have been discussed.
Abstract: Biorecalcitrant organic pollutants pose a threat to the aquatic environment due to their several detrimental traits. A host of industries as well as municipal facilities are liable to discharge such pollutants. These pollutants cannot be effectively managed by conventional biological and/or physiochemical treatment methods. Advanced oxidation processes, based on very strongly oxidizing free radicals such as hydroxyl radicals, have been found to be effective in destroying these pollutants often leading to their mineralization. This paper attempts to summarize the present state and emerging trends in advanced oxidation based treatment techniques. Reaction chemistries, process conditions, treatment efficiencies, and material and energy inputs required have been discussed.

119 citations


Journal ArticleDOI
TL;DR: The aim of this review is to present and evaluate the wide variety of models used so far in the scientific literature to simulate and predict FIB concentrations in natural surface waters, and to better understand current models and more efficiently set up future ones.
Abstract: Microbiological quality of waters must be assessed to ensure that no health risk due to pathogenic microorganisms is associated with its use. As it is impossible to measure the abundance of all possible pathogens, it is general practice to quantify the abundance only of one or a few fecal indicator bacteria (FIB), organisms which are selected to be indicative of fecal pollution and can therefore serve as general indicators of microbiological water quality. Yet, even by focusing on this limited number of indicator organisms, it is still unfeasible to experimentally monitor their levels at the high spatiotemporal resolution often needed in real applications. Therefore, direct FIB measurements are increasingly combined with the use of models. The aim of this review is to present and evaluate the wide variety of models used so far in the scientific literature to simulate and predict FIB concentrations in natural surface waters. First, the distinction is made between regression-based and mechanistic models. Wh...

Journal ArticleDOI
TL;DR: Advances have been made in detecting iodine species at ambient groundwater concentrations, defining the nature of the organic matter and iodine bond, and quantifying the role of naturally occurring sediment microbes to promote iodine oxidation and reduction, which have led to a more mechanistic understanding of radioiodine biogeochemistry.
Abstract: 129I is commonly either the top or among the top risk drivers, along with 99Tc, at radiological waste disposal sites and contaminated groundwater sites where nuclear material fabrication or reprocessing has occurred. The risk stems largely from 129I having a high toxicity, a high bioaccumulation factor (90% of all the body's iodine concentrates in the thyroid), a high inventory at source terms (due to its high fission yield), an extremely long half-life (16M years), and rapid mobility in the subsurface environment. Another important reason that 129I is a key risk driver is that there is uncertainty regarding its biogeochemical fate and transport in the environment. We typically can define 129I mass balance and flux at sites, but cannot predict accurately its response to changes in the environment. As a consequence of some of these characteristics, 129I has a very low drinking water standard, which is set at 1 pCi/L, the lowest of all radionuclides in the Federal Register. Recently, significant advancements have been made in detecting iodine species at ambient groundwater concentrations, defining the nature of the organic matter and iodine bond, and quantifying the role of naturally occurring sediment microbes to promote iodine oxidation and reduction. These recent studies have led to a more mechanistic understanding of radioiodine biogeochemistry. The objective of this review is to describe these advances and to provide a state of the science of radioiodine biogeochemistry relevant to its fate and transport in the terrestrial environment and provide information useful for making decisions regarding the stewardship and remediation of 129I contaminated sites. As part of this review, knowledge gaps were identified that would significantly advance the goals of basic and applied research programs for accelerating 129I environmental remediation and reducing uncertainty associated with disposal of 129I waste. Together the information gained from addressing these knowledge gaps will not alter the observation that 129I is primarily mobile, but it will likely permit demonstration that the entire 129I pool in the source term is not moving at the same rate and some may be tightly bound to the sediment, thereby smearing the modeled 129I peak and reducing maximum calculated risk.

Journal ArticleDOI
TL;DR: In this paper, the authors provide a thorough review of the advances in sensor technology for measurement of common water quality parameters (pH, turbidity, free chlorine, dissolved oxygen, and conductivity) in drinking water distribution systems.
Abstract: Online drinking water quality monitoring technologies have made significant progress for source water surveillance and water treatment plant operation. The use of these technologies in the distribution system has not been favorable due to the high costs associated with installation, maintenance, and calibration of a large distributed array of monitoring sensors. This has led to a search for newer technologies that can be economically deployed on a large scale. This paper includes a brief description of important parameters for drinking water and current available technologies used in the field. The paper also provides a thorough review of the advances in sensor technology for measurement of common water quality parameters (pH, turbidity, free chlorine, dissolved oxygen, and conductivity) in drinking water distribution systems.

Journal ArticleDOI
TL;DR: This review documents the context in which CR must be considered, before comparing the relative efficacies and bottlenecks of potential technologies, expediting identification of the major knowledge gaps and future research requirements.
Abstract: Conventional water treatment consumes large quantities of coagulant and produces even greater volumes of sludge. Coagulant recovery (CR) presents an opportunity to reduce both the sludge quantities and the costs they incur, by regenerating and purifying coagulant before reuse. Recovery and purification must satisfy stringent potable regulations for harmful contaminants, while remaining competitive with commercial coagulants. These challenges have restricted uptake and lead research towards lower-gain, lower-risk alternatives. This review documents the context in which CR must be considered, before comparing the relative efficacies and bottlenecks of potential technologies, expediting identification of the major knowledge gaps and future research requirements.

Journal ArticleDOI
TL;DR: In this article, a critical review integrated scattered knowledge on the effects of either pipe scales or pipe-anchored biofilm systems on contaminant destabilization and subsequent release into water.
Abstract: Safety and security are two important features of urban drinking-water distribution systems (UDWDS), worldwide, that are often compromised by a suite of physical, hydraulic, and chemical factors adversely impacting quality of potable water reaching consumer taps. Growth of scales and biofilm conglomerates (SBC) coupled with sorption of water chemicals and planktonic microorganisms by SBC has been increasingly recognized as underestimated contaminant sources in aging pipe networks of UDWDS. The main objective of this study was to provide an updated review of factors and processes associated with the increasing frequency of deteriorated finished water quality incidences as a result of SBC effects in UDWDS. This critical review integrated scattered knowledge on the effects of either pipe scales or pipe-anchored biofilm systems on contaminant destabilization and subsequent release into water. It was emphasized that little information exists on combined or concomitantly studied effects of SBC on finished water...

Journal ArticleDOI
TL;DR: In this paper, the authors review controls on nitrogen cycling in natural and modified environments to identify important processes and influences within biofilters, including plant-microbial interactions, root architecture, plant strategy, and moisture heterogeneity.
Abstract: Biofiltration systems harness the treatment capabilities of plants, microorganisms, and soil to mitigate impacts of polluted stormwater. However, their effectiveness for nitrogen removal can vary, from concentration reductions exceeding 70% to net leaching. Performance is particularly sensitive to plant species selection, presence of a saturated zone with carbon source, and the frequency of inflows. The authors review controls on nitrogen cycling in natural and modified environments to identify important processes and influences within biofilters. Key factors include plant-microbial interactions, root architecture, plant strategy, and moisture heterogeneity. They note a critical lack of studies comparing nitrogen removal through denitrification and plant assimilation.

Journal ArticleDOI
TL;DR: In other developed countries only a fraction of the e-waste is properly recycled, the rest is either incinerated or sent to landfills, which cause serious secondary problems.
Abstract: Even as the world has been unsuccessfully trying to dispose off the rising quantities of its municipal solid waste (MSW) and hazardous waste (HW) in a clean manner, it has been confronted with an even more complex problem—of e-waste. Only a few countries in the developed world are able to scientifically recycle or dispose the e-waste they generate. In other developed countries only a fraction of the e-waste is properly recycled, the rest is either incinerated or sent to landfills—which are solutions that cause serious secondary problems. Worse still, a sizeable portion of the e-waste generated in the developed world is exported to developing countries where it is recycled or dumped without any concern for the gross pollution that is being caused. It can be said that if the situation vis-a-vis e-waste is posing a challenge in most developed counties, it is alarmingly bad in the developing world. In an attempt to contain the e-waste problem most of the developed world and several countries in the developing...

Journal ArticleDOI
TL;DR: In this paper, the ability of cyclodextrin derivatives to form a ternary pollutant-cyclodesxtrin-iron complex allows discussing about promising integrated treatments requiring modified Fenton treatments such as electro-Fenton process with or without combination to a biological step and a recirculation loop.
Abstract: Soils contaminated by hydrophobic organic pollutants are a common concern because they are extremely difficult to remove and their potential toxicological impacts are significant. As an alternative to traditional pump-and-treat technologies, soil washing and soil flushing are conceivable and efficient approaches. Extracting agents such as cyclodextrins are compared to traditional surfactants, cosolvents, and less conventional agents. Ability of cyclodextrin derivatives to form a ternary pollutant-cyclodextrin-iron complex allows discussing about promising integrated treatments requiring modified Fenton treatments such as electro-Fenton process with or without combination to a biological step and a recirculation loop.

Journal ArticleDOI
TL;DR: In this paper, an overview of two types of biodegradable soil amendments: low molecular weight organic acids and surfactants, evaluating the feasibility of their application in the frame of soil remediation throughout enhanced phytoremediation.
Abstract: The contamination of soils with inorganic and organic pollutants is a diffuse environmental issue of significant relevance. Phytoremediation has been proposed as an economically feasible and sustainable remediation technology even if low bioavailability of contaminants constitutes one of the main limitations restricting the success of phytotechnologies. To overcome this constraint the addition of biodegradable amendments has been recently proposed in alternative to synthetic ones. This article presents an overview of two types of biodegradable soil amendments: low molecular weight organic acids and surfactants, evaluating the feasibility of their application in the frame of soil remediation throughout enhanced phytoremediation.

Journal ArticleDOI
TL;DR: In this article, a meta-analysis approach was used to investigate inorganic and organic phosphorus in organic fertilizers, soils and waters, including quantification of organic phosphorous forms such as monoesters, diesters, and inositol hexakisphosphate.
Abstract: Phosphorus is known to be an important contributor to eutrophication of aquatic systems,1 but the role of organic phosphorus is often overlooked. This review uses a meta-analysis approach to investigate inorganic and organic phosphorus in organic fertilizers, soils and waters, including the quantification of organic phosphorous forms such as monoesters, diesters, and inositol hexakisphosphate. Across these media, organic phosphorus comprised 22–46% of the total phosphorus (by mass of phosphorus). Bioavailable organic phosphorus appears to be more mobile than recalcitrant forms. Organic phosphorus may represent a significant risk for eutrophication, and the risk may vary according to the season, but conclusions are hampered by a lack of data.

Journal ArticleDOI
TL;DR: The authors present the current knowledge of the entire process of airborne transmission of microorganisms—from suspension and transportation until deposition and infection—and their relation to dust.
Abstract: Large amounts of airborne microorganisms are emitted from livestock production. These emitted microorganisms may associate with dust, and are suspected to pose a risk of airborne infection to humans in vicinity and to animals on other farms. However, the extent to which airborne transmission may play a role in the epidemic, and how dust acts as a carrier of microorganisms in the transmission processes is unknown. The authors present the current knowledge of the entire process of airborne transmission of microorganisms—from suspension and transportation until deposition and infection—and their relation to dust. The sampling and the mitigation techniques of airborne microorganisms and dust in livestock production systems are introduced as well.

Journal ArticleDOI
TL;DR: In this article, the role and reactivity of dissolved organic matter (DOM) in oxidation, reduction, hydrolysis, and photochemical reactions of contaminants occurring on mineral surfaces is analyzed.
Abstract: This review analyzes the role and reactivity of dissolved organic matter (DOM) in oxidation, reduction, hydrolysis, and photochemical reactions of contaminants occurring on mineral surfaces. DOM affects transformation via competition for adsorption sites on the mineral surface, dissolution of minerals and exposing new reactive surface sites on the mineral surface, and by electron shuttling. Most of the data suggest that DOM reduces oxidation and hydrolysis, and increases reduction of contaminants by minerals. Alternatively, mineral surfaces can enhance redox transformations of contaminants due to interactions with DOM. DOM impact on transformation of contaminants varies as a function of its molecular composition and chemical properties. In some cases, the influence of dissolved small organic molecules on the transformation of contaminants by minerals may be opposite to the bulk DOM effect. In addition, fractionation of DOM on the mineral surface can also influence the contaminant-mineral interactions. Bas...

Journal ArticleDOI
TL;DR: An overview on carbon nanotubes functionalization and their application as an adsorbent for scavenging heavy metals and radionuclide from wastewater systems can be found in this article.
Abstract: Carbon nanotubes (CNTs) are the engineered nanomaterial that has a very simple chemical composition and structure. Extremely high aspect ratios, molecularly smooth hydrophobic graphitic walls, and nanoscale inner diameters of CNTs give rise to the peculiar adsorption properties. This review provides an overview on CNTs functionalization and their application as an adsorbent for scavenging heavy metals and radionuclide from wastewater systems. A summary of recent information obtained using batch studies and deals with mechanisms involved during the adsorption have been reported. Adsorption capacity of CNTs has been observed by numerous investigators to increase substantially after functionalization/treatment with oxidizing agents such as NaOCl, HNO3, H2SO4, KMnO4, and other oxidizing agents. However, the selectivity of CNTs toward metal ions depends on both the route used for their synthesis and reagent employed for purification. The recovery of metal ions and the regeneration of CNTs have minimal impact o...

Journal ArticleDOI
TL;DR: An overview of nitrate treatment options can be found in this paper, highlighting the most recent advances and elucidating costs and common problems in application, while new technologies continue to be investigated to effectively remove nitrate while limiting cost and maximizing sustainability.
Abstract: Nitrate contamination of drinking water sources has become one of the most important water quality concerns across the United States. Nitrate presents unique water treatment challenges and small water systems are particularly affected by the high costs of addressing nitrate impacted supplies. The goal of this investigation was to provide an overview of nitrate treatment options, highlighting the most recent advances and elucidating costs and common problems in application. No single treatment option is ideal for all situations; new technologies continue to be investigated to effectively remove nitrate while limiting cost and maximizing sustainability.

Journal ArticleDOI
TL;DR: In this paper, it was found that radical generating electrodes show strong tendencies of chlorate and perchlorate formation in aqueous systems containing chloride ions, and that bromate, perbromate and bromates are new inorganic criterions in environmentally oriented water treatment.
Abstract: Advanced oxidation processes (AOPs) are widely used and suggested for environmentally oriented applications. New combinations of single methods are described in literature. An overview about methods is given focusing on innovative papers of the previous years. At the same time, there are an increasing number of indications and evident demonstrations that the occurrence of harmful by-products is possible. Chlorate, bromate, and perchlorate belong to these by-products of inorganic nature. Corresponding cases are considered and discussed. By studying electrochemical advanced oxidation processes (EAOPs) it was found that radical generating electrodes show strong tendencies of chlorate and perchlorate formation in aqueous systems containing chloride ions. Also, bromate and perbromate formation is possible. Therefore, the authors propose these components as new inorganic criterions in environmentally oriented water treatment. A new project is described considering electrochemical drinking water disinfection in ...

Journal ArticleDOI
TL;DR: In this paper, the authors provide an overview of wind, wave, geothermal, and solar renewable energy technologies for fresh water production, hybrid systems are assessed, and scale-up and economic factors are considered.
Abstract: Recent trends and challenges in applications of renewable energy technologies for water desalination are critically reviewed with an emphasis on environmental concerns and sustainable development. After providing an overview of wind, wave, geothermal, and solar renewable energy technologies for fresh water production, hybrid systems are assessed. Then scale-up and economic factors are considered. This is followed with a section on regulatory factors, environmental concerns, and globalization, and a final segment on selecting the most suitable renewable energy technology for conventional and emerging desalination processes.

Journal ArticleDOI
TL;DR: The hyporheic zone is the subsurface area below and adjacent to a stream where groundwater mixes with stream water, through vertical, lateral, and longitudinal flows.
Abstract: The hyporheic zone is the subsurface area below and adjacent to a stream where groundwater mixes with stream water, through vertical, lateral, and longitudinal flows. The hyporheic zone connects the stream to uplands and other terrestrial environments. It is a zone of distinct faunal communities, high biological diversity and ecological complexity, and is the site of chemical processing and transformations of ground- and stream waters. The hyporheic zone is important to the overall ecosystem ecology of the stream, and it can influence stream water chemistry. Flows, reactions, and biota in the hyporheic zone are heterogeneous and patchy, making it difficult to clearly describe the ecotone in a straightforward, general way. Nitrogen processing, especially denitrification, appears to be widespread in the hyporheic zone. The hyporheic zone, as with most aquatic systems, is often impacted by human activities. Stream restorations rarely consider potential effects on the hyporheic zone, but careful project choic...

Journal ArticleDOI
TL;DR: In recent years, considerable interest has arisen with regard to the fate and transport of radionuclides such as iodine-131 (131I), cesium-134 (134Cs), and cesiam-137 (137Cs) in aquatic environments as mentioned in this paper.
Abstract: In recent years, considerable interest has arisen with regard to the fate and transport of radionuclides such as iodine-131 (131I), cesium-134 (134Cs), and cesium-137 (137Cs) in aquatic environments. 137Cs is an important indicator of radioactive pollution in aquatic environments. The transport and fate of anthropogenic 137Cs is related to the chemical properties of ionic Cs (Cs+), which generally dictates a high degree of mobility and bioavailability of this radionuclide. The transport of 137Cs and its partitioning between abiotic and biotic components of aquatic ecosystems are complex processes that are considerably affected by a number of factors such as mineralogical composition of suspended and bottom sediments and the characteristic geochemistry of water. These factors influence sorption and desorption kinetics of 137Cs and the transport of particulate 137Cs. Nevertheless, substantial evidence suggests that direct biological 137Cs accumulation from the aquatic environment occurs readily in micro-org...

Journal ArticleDOI
TL;DR: A review of the main changes observed in the structure and activity of microbial communities during vermicomposting is discussed in this paper to provide further insight into the role of the earthworm gut as a soil a...
Abstract: Vermicomposting (i.e., the processing of organic waste by earthworms) is a low-cost rapid technique for transforming large amounts of waste into a safe and valuable product called vermicompost. The effects that earthworms have on microorganisms largely determine the rate of decomposition of organic matter during the process and, in turn, the quality of the final product. Recent studies highlight the importance of the earthworm gut as a major shaper of microbial communities. Passage of the material through the earthworm gut favors the existence of a reduced but more active microbial population in the egested material. The addition of these microbial communities to fresh organic matter has been shown to modify the level of activity and the functional diversity of microbial populations in vermicomposting systems. A review of the main changes observed in the structure and activity of microbial communities during vermicomposting is discussed, to provide further insight into the role of vermicompost as a soil a...

Journal ArticleDOI
TL;DR: In this article, a knowledge gap is perceptible on the basics of salt marsh halophyte adaptation/tolerance to the joint action of damaging factors such as high concentration of salt and presence of metals-metalloids.
Abstract: Salt marshes are widely distributed and most productive ecosystems in the temperate zones on the globe. These areas perform vital ecological functions and are populated mainly by halophytes—plants that are able to survive and reproduce in environments with exceptionally high salt concentrations. In salt marshes, in addition to tolerating high salt concentrations, salt marsh halophytes have to cope with damages caused by multiple anthropgenic pressures including metal and metalloid pollution. Extensive studies have been performed aiming at exploring naturally occurring endemic salt marsh halophytes with extraordinary potential for metals and metalloids remediation. However, a knowledge gap is perceptible on the basics of salt marsh halophyte adaptation/tolerance to the joint action of damaging factors such as high concentration of salt and presence of metals–metalloids. In light of available literature, the current paper is critical in: (i) highlighting ecological significance of salt marsh halophytes and ...