Degradation of Organic Pollutants in Drinking Water by Non-thermal Plasma
05 Mar 2018-pp 235-246
TL;DR: In this paper, a closed process based on non-thermal plasma is proposed for water purification in conditions where it is difficult to maintain a supply infrastructure, which can be adopted according to pollution levels and also operated as batch process by a discontinued power supply.
Abstract: Water is a scarce resource that is continuously threatened by pollution, growing population and strain on available reservoirs due to fast developing economies. A problem of considerable concern is posed by anthropogenic pollutants, foremost artificial organic compounds. Especially pharmaceutical residues with their intended stability are found in increasing concentrations in potable water in regions such as Chennai. Despite high standards and blanket coverage of water purification technologies for water, currently available methods most likely fail to remove many of the accumulating pharmaceuticals sufficiently. This shortcoming includes advanced oxidation technologies that are currently investigated, such as UV exposures, ozonation, hydrogen peroxide admixture and combinations of these approaches. The objective of this paper is the development of a novel and flexible technology for water purification. The immediate target is the removal of pharmaceutical residues in drinking water but other pollutants and also wastewaters will be addressed as well. Using non-thermal plasma, the closed process does not require chemical supplies or direct manual processes control. Therefore, the technology is appropriate in conditions where it is difficult to maintain a supply infrastructure. The method is only relying on electrical energy and can be adopted according to pollution levels and also operated as batch process by a discontinued power supply. With this approach, methods based on electrical power only are intended as a corner stone of a smart water treatment management that can be implemented at different locations along the supply chain on different scale. Accordingly, it is specifically anticipated a suitable enabler of smart grids.
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TL;DR: From the large number of ground water samples that were taken from agricultural areas in Germany, no contamination by antibiotics was detected except for two sites, which indicates that intake from veterinary applications to the aquatic environment is of minor importance.
2,070 citations
TL;DR: It could be shown that the second-order rate constants determined in pure aqueous solution could be applied to predict the behavior of pharmaceuticals dissolved in natural waters.
Abstract: This study investigates the oxidation of pharmaceuticals during conventional ozonation and advanced oxidation processes (AOPs) applied in drinking water treatment. In a first step, second-order rate constants for the reactions of selected pharmaceuticals with ozone (k(O3)) and OH radicals (k(OH)) were determined in bench-scale experiments (in brackets apparent k(O3) at pH 7 and T = 20 degrees C): bezafibrate (590 +/- 50 M(-1) s(-1)), carbamazepine (approximately 3 x 10(5) M(-1) s(-1)), diazepam (0.75 +/- 0.15 M(-1) s(-1)), diclofenac (approximately 1 x 10(6) M(-1) s(-1)), 17alpha-ethinylestradiol (approximately 3 x 10(6) M(-1) s(-1)), ibuprofen (9.6 +/- 1.0 M(-1) s(-1)), iopromide ( 5 x 10(4) M(-1) s(-1), indicating that these compounds are completely transformed during ozonation processes. Values for k(OH) ranged from 3.3 to 9.8 x 10(9) M(-1) s(-1). Compared to other important micropollutants such as MTBE and atrazine, the selected pharmaceuticals reacted about two to three times faster with OH radicals. In the second part of the study, oxidation kinetics of the selected pharmaceuticals were investigated in ozonation experiments performed in different natural waters. It could be shown that the second-order rate constants determined in pure aqueous solution could be applied to predict the behavior of pharmaceuticals dissolved in natural waters. Overall it can be concluded that ozonation and AOPs are promising processes for an efficient removal of pharmaceuticals in drinking waters.
1,483 citations
TL;DR: Recent progress of advanced oxidation of aqueous pharmaceuticals is reviewed and ozonation and advanced oxidation processes are likely promising for efficient degradation of pharmaceuticals in water and wastewater.
Abstract: A vast number of pharmaceuticals have been detected in surface water and drinking water around the world, which indicates their ineffective removal from water and wastewater using conventional treatment technologies. Concerns have been raised over the potential adverse effects of pharmaceuticals on public health and aquatic environment. Among the different treatment options, ozonation and advanced oxidation processes are likely promising for efficient degradation of pharmaceuticals in water and wastewater. Recent progress of advanced oxidation of aqueous pharmaceuticals is reviewed in this paper. The pharmaceuticals and non-therapeutic medical agent of interest include antibiotics, anticonvulsants, antipyretics, beta-blockers, cytostatic drugs, H2 antagonists, estrogenic hormone and contraceptives, blood lipid regulators, and X-ray contrast media.
861 citations
TL;DR: This review tries to present part of the knowledge that is currently available with regard to the occurrence of pharmaceutical residues in aquatic matrices, the progress made during the last several years on identification of such compounds down to trace levels, and of new, previously unidentified, pharmaceuticals such as illicit drugs, metabolites, and photo-products.
Abstract: Pollution from pharmaceuticals in the aquatic environment is now recognized as an environmental concern in many countries. This has led to the creation of an extensive area of research, including among others: their chemical identification and quantification; elucidation of transformation pathways when present in wastewater-treatment plants or in environmental matrices; assessment of their potential biological effects; and development and application of advanced treatment processes for their removal and/or mineralization. Pharmaceuticals are a unique category of pollutants, because of their special characteristics, and their behavior and fate cannot be simulated with other chemical organic contaminants. Over the last decade the scientific community has embraced research in this specific field and the outcome has been immense. This was facilitated by advances in chromatographic techniques and relevant biological assays. Despite this, a number of unanswered questions exist and still there is much room for development and work towards a more solid understanding of the actual consequences of the release of pharmaceuticals in the environment. This review tries to present part of the knowledge that is currently available with regard to the occurrence of pharmaceutical residues in aquatic matrices, the progress made during the last several years on identification of such compounds down to trace levels, and of new, previously unidentified, pharmaceuticals such as illicit drugs, metabolites, and photo-products. It also tries to discuss the main recent findings in respect of the capacity of various treatment technologies to remove these contaminants and to highlight some of the adverse effects that may be related to their ubiquitous existence. Finally, socioeconomic measures that may be able to hinder the introduction of such compounds into the environment are briefly discussed.
744 citations
TL;DR: In this paper, the synthesis of ozone in electrical discharges is discussed, and the generation and plasma chemical reactions of several chemically active species, such as H2O2, O•, OH•, HO2•, O3*, N2*, e-, O2-, O-, O*, O2+, etc.
Abstract: There is a continuing need for the development of effective, cheap and environmentally friendly processes for the disinfection and degradation of organic pollutants from water. Ozonation processes are now replacing conventional chlorination processes because ozone is a stronger oxidizing agent and a more effective disinfectant without any side effects. However, the fact that the cost of ozonation processes is higher than chlorination processes is their main disadvantage. In this paper recent developments targeted to make ozonation processes cheaper by improving the efficiency of ozone generation, for example, by incorporation of catalytic packing in the ozone generator, better dispersion of ozone in water and faster conversion of dissolved ozone to free radicals are described. The synthesis of ozone in electrical discharges is discussed. Furthermore, the generation and plasma chemical reactions of several chemically active species, such as H2O2, O•, OH•, HO2•, O3*, N2*, e-, O2-, O-, O2+, etc, which are produced in the electrical discharges are described. Most of these species are stronger oxidizers than ozone. Therefore, water treatment by direct electrical discharges may provide a means to utilize these species in addition to ozone. Much research and development activity has been devoted to achieve these targets in the recent past. An overview of these techniques and important developments that have taken place in this area are discussed. In particular, pulsed corona discharge, dielectric barrier discharge and contact glow discharge electrolysis techniques are being studied for the purpose of cleaning water. The units based on electrical discharges in water or close to the water level are being tested at industrial-scale water treatment plants.}
623 citations