Search results for "Purification"
showing 10 items of 271 documents
Adsorption of a dye on clay and sand. Use of cyclodextrins as solubility-enhancement agents.
2007
Abstract Laboratory-scale studies were aimed at elucidating the physico-chemical aspects on the removal process of crystal violet (CV) from waters and solid substrates. The laponite clay (RD) and sand were chosen for the double aim at investigating them as CV adsorbents for water treatment and as substrates which mime the soil components. Sand is very effective in removing CV from waters. The cyclodextrins (CDs) were exploited as solubility-enhancement agents to remove CV from the solid substrates. They are powerful solvent media because they extract the CV from sand forming water-soluble CV/CD inclusion complexes and do not show affinity for sand. Optimum performance was shown by the modif…
Monitoring WWTP performance using size-exclusion chromatography with simultaneous UV and fluorescence detection to track recalcitrant wastewater frac…
2018
Abstract A trial monitoring of a typical full-scale municipal WWTP in Central Finland was aimed to explore applicability of high performance liquid chromatography – size exclusion chromatography (HPSEC) with simultaneous UV and fluorescence detection as a tool for advanced routine monitoring of wastewater treatment. High, intermediate, and low molecular weight (MW) fractions of untreated wastewater (influent) and treated wastewater (secondary effluent) were characterized in terms of UV absorbance at 254 nm (UVA254) and specific fluorescence representing tyrosine-like, tryptophan-like, and humic/fulvic-like compounds. The activated sludge treatment removed 97 ± 1% of BOD, 93 ± 2% of COD, 71 …
Desulfurization: Critical step towards enhanced selenium removal from industrial effluents
2017
Abstract Selenium (Se) removal from synthetic solutions and from real Flue Gas Desulfurization (FGD) wastewater generated by a coal-fired power plant was studied for the first time using a commercial iron oxide impregnated strong base anion exchange resin, Purolite ® FerrIX A33E. In synthetic solutions, the resin showed high affinity for selenate and selenite, while sulfate exhibited a strong competition for both oxyanions. The FGD wastewater investigated is a complex system that contains Se (∼1200 μg L −1 ), SO 4 2− (∼1.1 g L −1 ), Cl − (∼9.5 g L −1 ), and Ca 2+ (∼5 g L −1 ), alongside a broad spectrum of toxic trace metals including Cd, Cr, Hg, Ni, and Zn. The resin performed poorly again…
Ferric sludge derived from the process of water purification as an efficient catalyst and/or support for the removal of volatile organic compounds
2019
Ferric chloride solutions are used as coagulants or flocculants in water treatment operations for human consumption. This treatment produces large amounts of clay-type solids formed mainly of montmorillonite with iron oxides and humic substances. This ferric sludge can be used as an efficient catalyst for the removal of volatile organic compounds (VOCs) by total oxidation. This waste isolated in the purification process has been activated by calcinations in air, characterized by several physicochemical techniques and employed as a catalyst for the removal by total oxidation of representative VOCs: toluene, propane and mixtures of toluene/propane with or without water. This ferric sludge has…
Electrochemical treatment of aqueous solutions of organic pollutants by electro-Fenton with natural heterogeneous catalysts under pressure using Ti/I…
2018
The treatment of toxic organic pollutants by electro-Fenton (EF) presents some drawbacks such as the necessity to work at low pH and the low solubility of oxygen in water contacted with air or oxygen at room pressure that results often in slow and relatively low abatements. Here, the coupled adoption of natural heterogeneous catalysts and of relatively high pressure was proposed in order to improve the performances of EF for the treatment of organic pollutants. Caffeic acid (CA) and 3-chlorophenol were used as model resistant organic pollutants. EF process was performed using both conventional homogeneous FeSO4 and natural heterogeneous catalysts (pyrite, chalcopyrite, Fe2O3 and Fe3O4) as i…
Biotrickling filter modeling for styrene abatement. Part 2: Simulating a two-phase partitioning bioreactor.
2017
Abstract A dynamic model describing styrene abatement was developed for a two-phase partitioning bioreactor operated as a biotrickling filter (TPPB-BTF). The model was built as a coupled set of two different systems of partial differential equations depending on whether an irrigation or a non-irrigation period was simulated. The maximum growth rate was previously calibrated from a conventional BTF treating styrene (Part 1). The model was extended to simulate the TPPB-BTF based on the hypothesis that the main change associated with the non-aqueous phase is the modification of the pollutant properties in the liquid phase. The three phases considered were gas, a water–silicone liquid mixture, …
Electrospun nanofibers: role of nanofibers in water remediation and effect of experimental variables on their nano topography and application process…
2021
Water is the elixir of life and the most elementary need for the survival of human beings on planet Earth. With rapid industrialization, globalization and human exploitation, natural water resources are diminishing at a startling rate wherein availability of potable water has drastically decreased in recent times and hence membrane technology is a highly pursued area for water purification. The simple and cost-effective electrospinning technique has evolved to be a state-of-the-art method for developing nanofibers of tailored thickness and diameters by combining a broad range of starting materials. This comprehensive review emphasizes on the demonstration of electrospun nanofibers based on …
Features and application of coupled cold plasma and photocatalysis processes for decontamination of water
2020
Dielectric barrier discharge plasma and photocatalysis have been proposed as tools for decontamination of process water, especially in food industry. The present investigation aims to redefine and identify the features of coupling the two technologies in terms of degradation efficiency of a model compound. Results show that, when the process is carried out in plasma activated water in the presence of irradiated TiO2, the efficiency of the integrated process is lower than the sum of the two processes acting separately. It is proposed that afterglow species, e.g. hydrogen peroxide and/or peroxynitrites could be activated by UVA light irradiation producing hydroxyl radicals in the liquid phase…
A survey of photocatalytic materials for environmental remediation
2012
Abstract Heterogeneous photocatalysis is an advanced oxidation process which has been the subject of a huge amount of studies related to air cleaning and water purification. All these processes have been carried out mainly by using TiO 2 -based materials as the photocatalysts and ca. 75% of the articles published in the last 3 years is related to them. This review illustrates the efforts in the search of alternative photocatalysts that are not based on TiO 2 , with some exceptions concerning particularly innovative modifications as nanoassembled TiO 2 or TiO 2 composites with active carbon, graphite and fullerene. Papers reporting preparation, characterization and testing of binary, ternary…
Efficiency of wastewater treatment facilities: The influence of scale economies.
2018
The water cycle, from catchment to discharge, is a sector that involves an important investment and operation and maintenance costs. In particular, sewage treatment is a challenge for governments because they are having to consider economic, environmental, and social aspects. Within the European Union, implementation of Directive 91/271/EEC is responsible for the location of wastewater treatment facilities in the territory, due to the requirement that all urban areas must have this infrastructure to reduce the environmental impact of treated water in water bodies. Different sizes of municipalities affect the design of each wastewater treatment plant (WWTP) and cause variations in the operat…