Research on Fluoride Removal from Membranes Rejected Water

Transcription

1 Environmental Engineering 10th International Conference eissn / eisbn Vilniu Gedimina Technical Univerity Lithuania, April 2017 Article ID: enviro DOI: Reearch on Fluoride Removal from Membrane Rejected Water Youef-Amine Bououga 1, Marina Valentukeviciene 2, Ramune Zuraukiene 3 1 Environmental Science Laboratory of Applied Chemitry Faculty of Science and Technology, Fez, Morocco 2 Department of Water Engineering Faculty of Environmental Engineering, Vilniu Gedimina technical Univerity, Vilniu, Lithuania 3 Department of Building Material Faculty of Civil Engineering, Vilniu Gedimina technical Univerity, Vilniu, Lithuania 1 bououga.youef@gmail.com; 2 marina.valentukeviciene@vgtu.lt (correponding author); 3 ramune.zuraukiene@vgtu.lt Abtract. The exce of fluoride in water intended for human conumption can caue ome problem in health of conumer from concentration over than 1.5 mg/l. A detailed tudy ha been carried out for the removal of fluoride from concentrated rejected water overcoming the drawback of membrane procee by uing orption techniue. Opoka mineral which i a natural orbent and polonite have been choen and valorized in thi preent work a fluoride orbent for rejected water by membrane of the water treatment plant. Thee orbent have been elected in order to reduce the treatment cot and to meet the tandard of rejected water epecially in term of fluoride. Opoka orbent and polonite have hown effective reult for fluoride removal from rejected water with efficiency over than 77%. In order to undertand the orption phenomenon and to validate the reult with orbent, we have applied experimental data on Freundlich Iotherm and SEM microcopic techniue. Keyword: fluoride removal, membrane rejected water, opoka, polonite. Conference topic: Water engineering. Introduction The occurrence of groundwater with high fluoride concentration i uually a cae of natural proce which i in general depending on the compoition of the rock and the occurrence of fluoride-containing mineral (Fawell et al. 2006). Fluoride can be diolve in groundwater naturally when condition favor the diolution of ome fluoride compound (Mohapatra et al. 2009). Groundwater contaminated by high concentration of fluoride i obtained in number countrie around the world, uually in India, China and USA (Azbar, Turkman 2000; Ayoob, Gupta 2006; Monda et al. 2007; Rao 2009; Vithanage, Bhattacharya 2015). In the wetern part of Lithuania, the concentration of natural fluoride in water i high and varie from 1.5 to 5 ppm (Peteren et al. 2000). In the region of Kretinga (Baltic region) groundwater contain many exceive ion, epecially fluoride with approximately 4 mg L 1 of concentration. A detailed decription on the highet concentration of fluoride reported in groundwater of ome region around the world baed on literature (Ayoob, Gupta 2006; Vithanage, Bhattacharya 2015). According to WHO recommendation (Fawell et al. 2006), the optimal fluoride level in drinking water i 1.5 mg/l, the ame concentration i reuired by European Directive and local Lithuanian Hygiene Norm. In ome cae, where fluoride level are higher than reuired in water intended for human conumption, the health of conumer can be affected negatively (Du Plei 1995). In thi cae, the exec of fluoride can induce dental and/ or keleton fluoroi. The main objective of defluoridation i to remove the exce of fluoride from drinking water, and to decreae it to acceptable limit. Adorption techniue and membrane eparation procee (nanofiltration and revere omoi and electro-dialyi) are the mot common method to deal with thi iue; other procee are alo ued for defluoridation uch a, coagulation precipitation and ion exchange (Agarwal et al. 2003; MenkouchiSahli et al. 2007). Each method ha their advantage and diadvantage, the cot effective and reliable procee are invetigated globally and locally (Mohapatra et al. 2009). All the above mentioned approache, which are invetigated by many cientit, are repreented in the following reference. The concentrate or the rejected water repreent one of the reidual of a membrane filtration proce, which mean that treatment of concentrate i neceary to avoid negative affect on the environment (Vithanage, Bhattacharya 2015). Method and material Through experiment the mot common orbent were reearched: natural opoka from Lithuania, artificial polonite from Sweden. The orbent adorbing propertie were compared with other globally ued orbent with the ame or imilar propertie Youef-Amine Bououga, Marina Valentukeviciene, Ramune Zuraukiene. Publihed by VGTU Pre. Thi i an openacce article ditributed under the term of the Creative Common Attribution (CC BY-NC 4.0) Licene, which permit unretricted ue, ditribution, and reproduction in any medium, provided the original author and ource are credited.

2 Bououga, Y.A.; Valentukeviciene, M; Zuraukiene, R Reearch on fluoride removal from membrane rejected water To perform the laboratory experiment a fluoride compound rejected by membrane filtration from groundwater of Kretinga region water treatment plant were ued. Groundwater uality can be een from Table 1. Table 1. Groundwater uality in Kretinga (Lithuania) Parameter Unit Max value Min value ph Conductivity µs cm-1 at 25 C Fe total µg.l Mn µgl F- mgl NH4+ mgl SO4 mgl Cl- mgl NO3 mgl COD mgo2l Al µg L A µg L Cd µg L Cr µg L Ni µg L Pb µg L Cu mgl Na mgl Invetigation of microtructure wa carried out by employing Scanning Electroni Microcope SEM Quanta 250 with SE detector. Adorbent, before the firt experiment, were cruhed and ieved through a ieve with pore width being 0.63 mm. With uch a method the ize of orbent adorbing urface area i maximized. All aborbent before the experiment were dried for 24 hour in the drying oven in a contant 105 C degree a to remove of reidual moiture. After drying orbent powder wa hermetically kept in deiccator. Eual amount of 500 ml membrane rejected water wa poured into a cone-haped 1000 ml capacity flak, adding 5.0 g dry orbent and obtained mixture wa mixed in the mixer for 120 rotation per minute. After 0.5 h of aborbing, obtained olution in tatic condition wa filtered through paper Wathman No 5 filter and GF/A Wathman filter. Collected filtrate wa immediately analyed. In firt tage laboratory reearch, eeking to determine orption efficiency depended on ph, the ph of water wa meaured before and after the orption. 1. To get tatitically reliable data every experiment wa repeated 5 time. Statitically unreliable data wa rejected and for calculation only the reliable reult were ued. 2. In the econd reearch tage data wa collected in laboratory condition to determine elected for reearch orbent adorption iotherm by adorbing fluoride compound from membrane rejected water. Adorption iotherm were created by evaluating the initial fluoride concentration in the olution and 1 g adorbent adorbed fluoride uantity. Freundlich aborbance iotherm euation parameter are calculated by uing the experiment reearch reult. Aborbance iotherm are done at water temperature near 10 C±0.5 C (ground water temperature). According to thi tage laboratory reearch data aborbance iotherm are made for thee aborbent: 1 opoka, particle ize maller than 0.63 mm; 2 polonite, particle ize maller than 0.63 mm. Sorption iotherm are created (Fig. 1) alo with real ground water ph value: ph = 6.0, ph = 6.5, ph = 7.0, ph = 7.5, ph = 8.0. To determine the mot appropriate aborbent doage when preparing groundwater according to the reuired uality drinking water uch a propoed cheme (e. g. ee Fig. 1) i ued: 1 fluoride orption curve when the fluoride concentration i highet in membrane rejected water; 2 the ame when the fluoride concentration in rejected water i the lowet. 2

3 Bououga, Y.A.; Valentukeviciene, M; Zuraukiene, R Reearch on fluoride removal from membrane rejected water Fig. 1. Optimal orbent doage determining cheme When preparing one or another orbent to ue for water treatment it i important to pay attention not only to the orption capacity but alo the orbent cot efficiency, it exploration propertie, regeneration poibilitie and etc. With a teady temperature (14±10 C) and uing the ame amount of aborbent, the amount of fluoride wa changed and, uing pectrophotometer Spectronic Geney 20 a well a calibration curve, the aborbed fluoride amount wa determined. By uing obtained reult following orbent adorption capacity wa evaluated a well a Freundlich euation parameter. Mathematical orption iotherm expreion i provided in Formula 1: = a C, (1) b F F where: S aborbed fluoride amount, mg/g of aborbent; C S balance of aborbed material concentration in olution, mg/l; a F and b F Freundlich contant, a F i aborbent orption capacity, ml/g; b F contant unit-le, decribing orbent chemical compoition homogeneity (value fluctuate between 1 and 0, when homogeneity lower the contant value approache zero). Reult and dicuion SEM intrument provided enlarged picture of orbent urface and ome compoition of compound (e. g. ee Fig. 2). In thi tage performed laboratory reearch, all obtained reult give enough information about reearched aborbent amount reuired for reducing fluoride concentration to the reuired limit and their hared aborbance capacity. The aborbent particle ize wa maller than 0.63mm. It can be een in the Figure 2 that every aborbent particle i covered in mall crytal, mainly flat form crytal, which ize i about 1 micrometer. Small flat form crytal on particle urface enlarge every particle urface area. Fig. 2. SEM picture with enlarged adorbent urface Here all reult in weight % according to proceing option when all element analyzed (normalized): O 50.16; Al 4.98; Si 30.94; K 1.40; Ca 10.45; Cu

4 Bououga, Y.A.; Valentukeviciene, M; Zuraukiene, R Reearch on fluoride removal from membrane rejected water Two orption iotherm are preented In Figure 3, when polonite wa ued a an aborbent, while fluoride in one intance were determined in artificially prepared water, in other in membrane rejected water. In later intant it wa attempted to determine what influence to the orption proce doe the attenuation of different ion. While creating aborption iotherm according to Freudlich euation, for every curve contant a F and b F were calculated. The bigger a F value, the better aborption reult. Fig. 3. Sorption iotherm, when polonite i ued (particle ize <0.63 mm): X1 orption in artificially prepared water, X2 orption in membrane rejected water In prepared water (curve X1) and membrane rejected water (curve X2) Freundlich aborption formula have uch expreion: = C, (2) = C, (3) When aborbing fluoride in prepared water a F = ml/g, while in membrane rejected water a F = ml/g, that i to conclude, in ditilled water polonite orption capacity i about 11% higher. Cruhing the aborbent make it urface area much more acceible, making aborption capacity increae with it. That i why there were created two more natural opoka iotherm: one for orbent, which particle diameter i <0.63 mm, and another for orbent, which particle diameter i <0.14 mm. Iotherm hown in Figure 4 Freudlich formula accordingly had uch expreion: = C, (5) = C, (6) Fig. 4. Sorption iotherm, orbent with particle ize <0.14mm and <0.63 mm 3 particle ize <0.14mm, X4 particle ize <0.63mm Here, maller particle ize orbent efficiency roe lightly (about 5.5%). Polonite (iotherm X4) Freundlich formula ha thi expreion: = C. (7) Comparing aborbent polonite and natural orbent opoka powder propertie a 2.4% aborption capacity increae i determined when uing polonite. 4

5 Bououga, Y.A.; Valentukeviciene, M; Zuraukiene, R Reearch on fluoride removal from membrane rejected water In foreign (USA and Scandinavia) cientific-technical literature it ha been claimed, that orption proce can be influenced by water ph. Ruian cientit that carried out an experiment with variou aborbent didn t determine uch influence. Due to contradictory information an extra experiment wa carried out by aborbing with opoka powder fluoride compound from membrane rejected water with variation from 6 to 8 ph value (thee value are conventional for Lithuania groundwater). Analying hown reult in Figure 5 water fluoride concentration dependency after aborption due to ph value wa determined aborption efficiency increaed when ph value decreaed. Fig. 5. Reidual fluoride concentration dependent on water ph Membrane rejected water treatment with opoka adorbent being alo invetigated in order to improve the adorption capacity and looking for a better efficiency with natural adorbent. Opoka orbent amount related to different concentration of fluoride in membrane rejected water can be een in Figure 6. From all of the reult from membrane rejected water fluoride, approximately imilar amount of fluoride were found in all ample of both removal uing opoka and polonite orbent and it can be ued to improve water uality at the outlet of water treatment plant. Fig. 6. Opoka orbent amount ued according to different concentration of fluoride Concluion By analying reearch reult, it wa determined that: 1. reearched aborbent (polonite and natural opoka) powder can have a practical adjutment, when it i neceary to remove fluoride from membrane rejected water; 2. natural opoka powder aborption capacity increaed a water ph value decreaed; 3. adorbed fluoride uantity ha an influence to membrane rejected water uality, the more variou compound there will be in water, the more maller aborption efficiency will be in one compound apect; 4. laboratory reearch confirmed, that aborption iotherm method, together with Freudlich aborption formula, i very convenient and reliable method (with R 2 more than 0.96) for determining orbent orption propertie; 5

6 Bououga, Y.A.; Valentukeviciene, M; Zuraukiene, R Reearch on fluoride removal from membrane rejected water 5. by comparing opoka and polonite powder orption propertie from fluoride apect it wa determined a 2.4% aborption capacity increae when uing polonite. Since the increae i mall, it wa decided that natural orbent opoka powder will be accepted and in the future experiment opoka will be ued. Acknowledgement We would like to expre our gratitude to the colleague from JSC Kretingo Vandeny (Kretinga, Lithuania), to the technical worker and SEM image laboratory for valuable comment and to Englih language pecialit who helped a lot with editing ervice. We are grateful to all Termoinulation intitute technical upport in reearch activitie and peronally to everyone who helped with practical conultancy. Reference Agarwal, M.; Rai, K.; Shrivatav, R.; Da, S Defluoridation of water uing amended clay, Journal of Cleaner Production 11: Ayoob, S.; Gupta, A. K Fluoride in drinking water: a review on the tatu and tre effect, Critical Review in Environmental Science and Technology 36(6): Azbar, N.; Turkman, A Defluoridation in drinking water, Water Science et Technology 42(1 2): Du Plei, J. B What would be the maximum concentration of fluoride in water that would not caue dental fluoroi?, in Proceeding of Fluoride and Fluoroi : The Statu of South African Reearch in Pilaneberg National Park Pilaneberg National Park, North Wet Province, 4. Fawell, J.; Bailey, K.; Chilton, J.; Dahi, E.; Fewtrell, L.; Magara, Y Fluoride in drinking-water. World Health Organization. MenkouchiSahli, M. A.; Annouar, S.; Tahaikt, M.; Mountadar, M.; Soufiane, A.; Elmidaoui, A Fluoride removal for underground brackih water by adorption on the natural chitoan and by electrodialyi, Dealination 212(1 3): Mohapatra, M.; Anand, S.; Mihra, B. K.; Gile, D. E.; Singh, P Review of fluoride removal from drinking water, Journal of Environmental Management 91: Monda, K. W. M.; Maamba, W. R. L.; Fabiano, E A tudy of fluoride groundwater occurrence in Nathenje, Lilongwe, Malawi, Phyic and Chemitry of the Earth, Part A/B/C 32(15 18): Peteren, P. E.; Alekejuniene, J.; Chritenen, L. B.; Eriken, H. M.; Kalo, I Oral health behavior and attitude of adult in Lithuania, Acta Odontologica Scandinavica 58(6): Rao, N Fluoride in groundwater, Varaha River Bain, Viakhapatnam Ditrict, Andhra Pradeh, India, Environmental Monitoring Aement 152: Vithanage, M.; Bhattacharya, P Fluoride in the environment: ource, ditribution and defluoridation, Environmental Chemitry Letter 13: