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Fluorki w środowisku wodnym – zagrożenia i metody usuwania

Bodzek M., Konieczny K.

Inżynieria i Ochrona Środowiska

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2018

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T. 21, nr 2

113--141

EN

High fluorine concentrations in aquatic environment, even above 30 mg/L, are often detected in many parts of the world. Due to fluorine effects on health, World Health Organization (WHO) as well as national health authorities have established its maximum permissible concentration in drinking water at the level of 1.5 mg/L. This review article aims to provide detail information on researchers’ efforts in the field of fluorides removal during potable water production. The contaminant elimination methods have been broadly divided in three sections, i.e. coagulation/precipitation, adsorption and membrane techniques. Both, precipitation with the use of calcium salts or coagulation with aluminum sulphate and ferric salts followed by sedimentation are used for fluorine removal. In electrocoagulation, a coagulant is generated in situ by means of oxidation of anode usually made of aluminum or iron. The removal of fluorides from water and wastewater can be performed with the use of many different types of adsorbents, which are either applied already at industrial scale or still tested in the laboratory or pilot scale. The adsorption on activated aluminum oxide is already a common technology of fluorine removal from water and wastewater, and it is also indicated as the one of the best available technique (BAT) in this field. However, the adsorbent price is relatively high, while its efficiency mostly depends on pH and co-ions presence. Recently, a lot of effort has been devoted to develop an effective method of aluminum oxide modification with the use of metals’ oxides impregnation, which reveal significant defluoridation efficiency. The applicability of carbon based sorbents is less efficient than of aluminum compounds, hence a number of studies on modification of carbon based materials towards defluoridation improvement are carried out. The special attention is dedicated to carbon nanotubes. Among many natural materials, which are usable to fluorine adsorption, many different types of clays and minerals have been tested. Biosorbents, especially modified chitosan, also offer promising results in fluorine removal process. Additionally, a group of waste materials, which contain metal oxides, have also been examined to fluorides concentration decrease in contaminated aqueous streams, and those can be considered as alternative cheap sorbents. Synthetic layered double hydroxides (LDHs), hydrocalcite like compounds and nanosorbents have also gained a lot of attention as potential fluorine adsorbent, as they reveal high affinity toward the contaminant. Among membrane techniques reverse osmosis, nanofiltration, ultrafiltration in integrated systems, electrodialysis and Donnan dialysis have been discussed. The most important benefits offered by membrane processes are very high removal efficiency (up to 98%), single stage treatment, simultaneous water disinfection and low requirement for additional chemicals. However, the removal of other anions present in treated water is a serious disadvantage of those techniques, as it results in the need of water remineralization to assure the proper quality of finally produced potable water. Additionally, membrane processes are quite expensive due to relatively high initial concentrated solution containing fluorine may become a significant problem.

PL

Występowanie fluorków (F-) w wodach naturalnych jest związane z ich obecnością w skorupie ziemskiej, jak również aktywnością przemysłową człowieka. O ile obecność jonów F- w wodzie do picia w ilości 0,5÷0,7 mg/l zabezpiecza przed próchnicą zębów, o tyle ich nadmiar jest uważany za poważny problem zdrowotny. Regularne spożywanie wysoce fluorowanej wody, zawierającej 1,5÷4 mg F/l, wywołuje wiele chorób związanych z tkanką kostną (fluoroza, artretyzm i osteoporoza), chorobę Alzheimera, utratę pamięci i inne neurologiczne dolegliwości. Według World Health Organization, a także polskich przepisów, maksymalne stężenie fluorków w wodzie do picia nie może przekraczać 1,5 mg/l, a rekomendowany jest zakres 0,5÷1 mg/l. Opracowano szereg metod usuwania fluorków, które można podzielić na trzy grupy procesów: koagulacja i wytrącanie, membranowe techniki separacji oraz adsorpcja/wymiana jonowa.

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Removal of fluoride ions by batch electrodialysis

Majewska-Nowak K., Grzegorzek M., Kabsch-Korbutowicz M.

Environment Protection Engineering

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2015

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Vol. 41, nr 1

67--81

EN

Suitability of conventional batch electrodialysis to fluoride removal from aqueous solutions has been investigated. The experiments were conducted with the use of laboratory installation PCCell BED-1 System at a constant current density (1.56 or 2.34 mA/cm2). The influence of initial fluoride and salt (NaCl) concentration, as well as the presence of organic matter on the process performance was studied. It was found that the separation efficiency increased upon decrease of initial fluoride content in model solutions. Permissible final concentration of fluorides in the product water (1.5 mg/dm3) was obtained for experiments with solutions of initial fluoride concentration equal to 5 mg F–/dm3 and 10 mg F–/dm3. The presence of humic acids in fluoride solutions subjected to electrodialysis treatment has no adverse effect on the defluorization and desalination efficiency. The calculated electrical energy demand depended on composition of fluoride solution and varied from 0.121 to 0.895 kWh/m3.

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Badania sorbentów do usuwania fluorowodoru z gazów przemysłowych

Bratek Ł., Chmielarz A., Kamiński K.

Rudy i Metale Nieżelazne

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2004

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R. 49, nr 7

326-330

PL

Omówiono problem usuwania związków fluoru z gazów metalurgicznych bogatych w SO2, kierowanych do utylizacji w fabrykach kwasu siarkowego. Przedstawiono wyniki badań w skali laboratoryjnej oczyszczania gazów z HF z zastosowaniem różnych sorbentów. Dla każdego z testowanych sorbentów wyznaczono skuteczności usuwania fluorowodoru i pojemności sorpcyjne.

EN

The paper describes the problem of fluorine compounds removal from SO2-rich metallurgical off-gases, directed for utilisation in the sulphuric acid plants. Results of laboratory-scale investigation on HF removal process with the use of different types of absorbents are presented. The process efficiency and the sorptive capacity of each tested absorbent have been determined.