Radioactive decontamination of water by membrane processes - A review
15 Jul 2013-Desalination (Elsevier)-Vol. 321, pp 77-92
TL;DR: In this article, a review of membrane technology is classified into different processes and, for each process, progress made since the onset of this millennium in the radioactive decontamination of water is shown.
Abstract: The recent accident at the Fukushima Daiichi Nuclear Power Plant caused by the Great East Japan Earthquake of March 11, 2012 reminded us vividly of the serious hazards of radioactive substances spread over a wide range of the affected region. Currently, there is a great concern over the effect of contaminated soil and water on the health and safety of the inhabitants of the region. Hence, the advancement in the technologies of nuclear waste treatment is of vital importance if we decide to live with nuclear power to maintain our modern civilization. Among various separation technologies used, membrane technologies have been chosen in this article since they are considered as one of the emerging technologies with many advantages over the conventional processes. In this review the membrane technology is classified into different processes and, for each process, progress made since the onset of this millennium in the radioactive decontamination of water is shown. The new directions are shown by considering the progress made in membrane manufacturing and membrane processes. Thus, the combined efforts of the researchers who are engaged in membrane and membrane process design with those who are engaged in nuclear waste treatment near the plant sites were highlighted.
TL;DR: In this paper, the authors provide insights into the physico-chemical properties and fabrication approaches of different classes of inorganic membranes and discuss the transport mechanisms associated to their unique structural features.
Abstract: The sustainability of global clean and safe water supply is one of the grand challenges facing the world. Membrane technology based on polymeric membranes is one of the most important and widely recognized technologies for desalination and wastewater treatment. While polymeric membranes are known to be plagued with some bottlenecks, the technical progress and the accompanying knowledge in inorganic membrane development have grown inexorably to solve some of the underlying issues. Aside from the conventionally used ceramic membranes which based on metal oxides, nanostructures such as zeolites, metal organic frameworks and carbon based materials have sparked enormous interest in the preparation of inorganic membranes owing to their tunable nanoscaled structural properties that can render excellent rejection and/or ultrafast water transport. This review provides insights into the physico-chemical properties and fabrication approaches of different classes of inorganic membranes. The transport mechanisms that are associated to their unique structural features are also discussed. Furthermore, the performance evaluation of these inorganic membranes in a wide spectrum of desalination and wastewater treatment applications are also elaborated. Finally, the challenges in the development of inorganic membrane for practical commercial application are identified and the future perspectives are presented.
TL;DR: In this paper, the authors surveyed the recent progress in the development of polymeric membranes for membrane adsorption (MA) and showed that nanoparticles are potentially useful as fillers in the host membrane to enhance its performance.
Abstract: Application of polymeric membranes for the adsorption of hazardous pollutants may lead to the development of next-generation reusable and portable water purification appliances. Membranes for membrane adsorption (MA) have the dual function of membrane filtration and adsorption to be very effective to remove trace amounts of pollutants such as cationic heavy metals, anionic phosphates and nitrates. In this review article, recent progresses in the development of MA membranes are surveyed. In addition, recent progresses in the development of advanced adsorbents such as nanoparticles are summarized, since they are potentially useful as fillers in the host membrane to enhance its performance. The future directions of R&D in this field are also shown in the conclusion section.
TL;DR: This review attempts to offer a holistic view with regard to the state of the art of technology for decontamination of radioactive wastewater as well as shed lights on the challenges forward.
Abstract: Radioactive substances have been widely used in many industrial sectors, e.g. nuclear power station, biomedical engineering, etc. With increasing applications of nuclear technology, more and more radioactive wastewater is being generated via different channels, which indeed is posing an emerging challenge and threat to the environment and human health. Given such a situation, this review attempts to offer a holistic view with regard to the state of the art of technology for decontamination of radioactive wastewater as well as shed lights on the challenges forward. Different from reclamation of other types of wastewaters, the most challenging issue in decontamination of radioactive wastewater is the effective stabilization and solidification of soluble radioactive nuclides present in wastewater, which are critical for final disposal. Moreover, the potential risk of human exposure to wastewater radiation needs to be carefully assessed, and this issue should also be taken into consideration in the selection, design and operation of the radioactive wastewater treatment process. These clearly differentiate the treatment principle of radioactive wastewater from those of traditional industrial and municipal wastewaters. Lastly, the challenges from the perspectives of technology development, environmental and human health impacts and possible solutions forward are also elucidated.
TL;DR: The experimental results showed that DCMD process can separate almost all Cs(+), Sr(2+ and Co(2+) from wastewater, and the experimental permeate flux values fitted well with that calculated by DGM.
Abstract: Direct contact membrane distillation (DCMD) was used to treat low level radioactive wastewater (LLRW). The dusty gas model (DGM) was used to analyze the mass transfer mechanism and calculate the permeate flux. The operating parameters such as feed temperature, feed velocity and feed concentration were studied. The experimental results showed that DCMD process can separate almost all Cs(+), Sr(2+) and Co(2+) from wastewater. The permeate flux decreased linearly when NaNO3 concentration increased from 1.0 to 200 g/L. The permeate flux remained about 60% of its initial flux even when NaNO3 concentration in feed solution was as high as 200 g/L. The dusty gas model can be successfully applied to estimate the mass transfer, and the experimental permeate flux values fitted well with that calculated by DGM. DCMD is a promising separation process for low level radioactive wastewater treatment.
TL;DR: In this paper, the authors present an overview on sorption of cesium from wastewaters and review several critical parameters such as sorption capacity, percentage efficiency and the influence of several factors on ceium uptake by various adsorbents.
Abstract: Due to rapid population growth, technological advancement and industrial revolution, the rate of generated waste effluents has become a grave concern. Cesium which possesses high fission yield is generally transferred to liquid wastes especially those emanated from the nuclear power plants, reprocessing of spent fuels, nuclear weapon testing and radionuclides production facilities for medical applications etc. Radiocesium (137Cs) is one of the hazardous radionuclides creating adverse effects on human health and environment. Due to its physical (T1/2 = 30.17y) and chemical characteristics (alkalinity, solubility etc.), it can be easily assimilated by the living organisms. As a result, the removal of cesium from wastewater is imperative from the health point of view. Several techniques are implemented but in recent time, adsorption has been gaining increasing attention to the scientific community owing to a number of reasons. Hence, this paper presents an overview on sorption of cesium from wastewaters. Consequently, several critical parameters such as sorption capacity, percentage efficiency and the influence of several factors on cesium uptake by various adsorbents have been reviewed in details.
TL;DR: In this article, the applicability of ammonium molybdophosphate-polyacrylonitrile (AMP-PAN) on the adsorptive removal of Co, Sr and Cs in the radioactive laundry wastewater generated from nuclear power plants was investigated.
Abstract: Applicability of ammonium molybdophosphate–polyacrylonitrile (AMP–PAN) on the adsorptive removal of Co, Sr and Cs in the radioactive laundry wastewater generated from nuclear power plants was investigated. Single- and bi-solute competitive adsorptions of Co 2+ , Sr 2+ and Cs + onto AMP–PAN were investigated. The influencing factors such as co-existing metal ion and surfactants were investigated. Adsorption of Co 2+ , Sr 2+ and Cs + onto AMP–PAN occurs via both physical adsorption due to weak van der Waals forces and ion exchange of ammonium molybdophosphate. The results of adsorption model analyses showed that AMP–PAN has high selectivity for Cs + . The maximum adsorption capacities were 0.16, 0.18 and 0.61 mmol/g for Co 2+ , Sr 2+ and Cs + , respectively. In bi-solute competitive adsorptions, adsorption of one metal ion was suppressed by the presence of competing metal ion. Alkali metal (Na + ) inhibits adsorption of Cs + and the presence of Ca 2+ ion decreased the adsorption of Co 2+ onto AMP–PAN. Adsorption behaviors of Co 2+ , Sr 2+ and Cs + onto AMP–PAN in the presence of surfactants were quiet different. The presence of cationic (OTMA and HDTMA) and anionic surfactants (SDBS and SOBS) decreased adsorption of Co 2+ , Sr 2+ and Cs + onto AMP–PAN, but that of non-ionic surfactants (Tween 80 and Triton X-100) did not.
TL;DR: In this article, a review of recent published researches that are concerned with testing and application of different treatment options as a part of the integrated radioactive waste management practice is presented, highlighting the scientific community interest in important problems that affect different treatment processes.
Abstract: Radioactive wastes are generated during nuclear fuel cycle operation, production and application of radioisotope in medicine, industry, research, and agriculture, and as a byproduct of natural resource exploitation, which includes mining and processing of ores, combustion of fossil fuels, or production of natural gas and oil. To ensure the protection of human health and the environment from the hazard of these wastes, a planned integrated radioactive waste management practice should be applied. This work is directed to review recent published researches that are concerned with testing and application of different treatment options as a part of the integrated radioactive waste management practice. The main aim from this work is to highlight the scientific community interest in important problems that affect different treatment processes. This review is divided into the following sections: advances in conventional treatment of aqueous radioactive wastes, advances in conventional treatment of organic liquid wastes, and emerged technological options.
TL;DR: The present review describes the recent advances made in radioactive waste treatment using membrane separation technology and discusses the membrane methods for collective separation of radionuclides.
Abstract: Radiation hazards of radionuclides arising from nuclear plant facilities are well known. Separation technologies are used to concentrate the radionuclides and prevent the spread of this hazard to the environment. The present review describes the recent advances made in radioactive waste treatment using membrane separation technology. The first part discusses the membrane methods for collective separation of radionuclides and the second part discusses the membrane methods for selective separation of individual radionuclides. For the collection separation of radionulides, methods include reverse osmosis, precipitation followed by ultrafiltration or microfiltration and membrane distillation. Individual elements have been separated using liquid supported membranes, polymer inclusion membranes, solid polymer based electrolysis, nanofiltration, electrochemical salt-splitting process and other advanced separation methods.
TL;DR: In this article, the advantages of membrane distillation over other processes commonly used for the processing of liquid low-level radioactive waste (LLLW) are discussed in the paper.
Abstract: The paper addresses some aspects of liquid low-level radioactive waste (LLLW) purification. Since the volume of liquid low-level wastes is usually large and the activity is rather low, the radioactive substances separated from the non-active portion have to be concentrated into the small volume for subsequent conditioning and disposal. The need for the improvement of decontamination and minimisation of the costs have led to new specific methods being under examination and development. The method proposed in the paper is membrane distillation. The experimental work described below supports the statement that membrane distillation can be an attractive alternative for liquid radioactive waste treatment. The advantages of membrane distillation over the other processes commonly used for the processing of LLLW are discussed in the paper.
TL;DR: In this paper, the authors proposed reverse osmosis (RO) and membrane distillation (MD) as an alternative for liquid low-level radioactive waste concentration for liquid waste treatment.
Abstract: Membrane methods can be considered as the most energy-saving separation techniques. Separation abilities of membranes allow the elimination of many non-effective and energy consuming methods and their replacement by new, modern technologies, friendly environment friendly. An application of membrane methods for liquid radioactive wastes treatment requires solving many problems connected with the proper selection of the membranes, membrane modules and other equipment according local conditions: chemical and radiochemical composition of the effluents treated, their activity and total salinity. The installations working in nuclear industry have to fulfil very strict requirements. They ought to be reliable, constructed from special materials defined by separate regulations. Only small number of manufacturers of membrane devices has for their products the certificates of International Atomic Energy Agency. Reverse osmosis (RO) as a method for liquid waste treatment has been examined at laboratory and pilot plant installations. The experience with the process led to design and construction of the industrial plant, 1 m3 capacity, composed of three RO stages. The plant will be included into the system for liquid radioactive wastes purification operating at Institute of Atomic Energy in Swierk near Warsaw, treating the liquid waste from all of Poland. Membrane distillation (MD) can be an alternative for liquid radioactive waste concentration. On the basis of previous laboratory tests a pilot plant for liquid radioactive wastes concentration employing direct contact MD was constructed. Pilot plant experiments showed MD is interesting solution for liquid low-level radioactive waste treatment. As MD is characterised by high retention, large decontamination factors were obtained in separation of radionuclides, which are present in liquid low-level radioactive wastes mainly in an ionic form. The RO and MD plants for liquid low level radioactive wastes treatment are presented in the paper and the evaluation of both methods, as well.