Influence of Magnetic Field on The Efficiency of The ...

International Review of Chemical Engineering (I.RE.CH.E.), Vol. 5, N.4 July 2013

Influence of Magnetic Field on The Efficiency of The Coagulation Process to Remove Turbidity From Water Waleed M. Sh. Alabdraba1, Mohamed B. A. Albayati2, Ahmed Y. Radeef3, Mustafa M. Rejab4

Abstract – The effect of magnetic field on the coagulation process and the possibility of reduce the coagulant dose with different cases of shedding the magnetic field on the two samples of water was studied, and the results showed that the magnetic field affects clearly and strongly on increasing the efficiency of removing the impurities from water (turbidity reduced from 662 NTU to 0.36 NTU and from 45.25 NTU to 0 NTU), and on reduction of the chemical coagulant (reduced optimal dose about 10 mg/L) by subjected water to magnetic field with optimal intensity in the periods of rapid and slow mixing and sedimentation at the third bottom of the tank. Copyright ©

2009 Praise Worthy Prize S.r.l. - All rights reserved. Keywords: Magnetic field, Turbidity, Coagulation Process

I.

Introduction

Water is a basic necessity of life, not only for people but for every type of plant and animal as well. Much of our fresh water is also used outdoors for watering lawns, flower beds, and vegetable gardens, as well as washing cars and filling swimming pools, therefore the water must be treated to make it safe for human consumption, aesthetically acceptable, and suitable for use by industries and other uses.[1] Many processes used for treatment of surface water and ground water consists of primary sedimentation, coagulation, filtration, disinfection, conditioning, softening, fluoridation, removal of tastes and odors, corrosion control, algae control, and aeration.[2]. Chemical coagulation is an important process in water treatment that helps produce clear, finished water which is aesthetically acceptable to the consumer. Flocculation is gentle stirring or agitation to encourage the particles thus formed aggregates with masses large enough to settle or be filtered from solution. In these processes colloidal particles (20-2000Å)[1 Å = 10-4 μm = 10-10 m] and very fine solid suspensions initially present in water are combined into larger agglomerates that can be separated by primary sedimentation, flocculation, filtration, or other separation methods. [3]. The colloids commonly found in water are stable because of the very large surface area relative to their mass and the electrical charge that they carry. The charge of colloids can be positive or negative. However, most colloidal particles in water have a negative charge. Because of

Copyright © 2013 Praise Worthy Prize S.r.l. - All rights reserved

their large surface area and electrical charge, colloidal particles settle very slowly. Aluminum or iron salts are utilized to neutralize these surface charges and to cause the colloids to coalesce and become large enough so that they will readily settle.[4]. A magnet is a material or object that produces a magnetic field. A magnetic field is generated when electric charge carriers such as electrons move through space or within an electrical conductor. This magnetic field is invisible but is responsible for the most notable property of a magnet.[5]. Liquid water is affected by magnetic fields [6], [7] and such fields can assist its purification. [8] Water is diamagnetic and may be affected by very high magnetic fields (10 Tesla(T), compare Earth's magnetic field 50 μT) [9]. Other studies show an increase in cluster size in liquid water is caused by a magnetic field [7]. Salt mobility is enhanced in strong magnetic fields (1-10 T) causing some disruption to the hydrogen bonding [10]. However this only causes a net reduction in hydrogen bonding at high salt concentrations (for example 5 M NaCl), whereas at lower concentrations (1 M NaCl) the increase in water hydrogen bonding in the presence of such high magnetic fields more than compensates for this effect [10]. Lo and others studied high turbidity raw water treated by magnetic aggregation method with applied magnetic field and the operating parameters were appropriate dosage of magnetite particles, water quality parameters and the strength of applied magnetic field, the modified jar tests were used in this study by adding pre-chemosynthesis

International Review of Chemical Engineering, Vol. 5, N. 4

International Review of Chemical Engineering (I.RE.CH.E.), Vol. 5, N.4 July 2013 (Fe3O4) nanoparticles into the high turbidity water. Magnetite particles (Fe3O4) were synthesized by chemical precipitation method in this study. The results indicate that it has better efficiency of magnetic aggregation after magnetic particles being further magnetized and the method of magnetic aggregation and separation can reduce the turbidity of raw water of different initial turbidity and from different areas at different pH values [4]. While Banejad and Abdosalehi studied the effect of magnetic field on water hardness reducing. In this study, they have been chosen amounts of water influent 4 L/h and 30 L/h and magnetic field intensities of zero Tesla,0.05(Tesla), 0.075(Tesla), and 0.1 (Tesla), with doing examination by 3 times and analyze the results, they have shown that changing magnetic field intensity, amounts of water influent, and also together, influence on water hardness, and the result shown that it will increase the efficiency of magnetic treatment, when magnetic field intensity is changing and\or amounts of water influent with significant effects at level of 99% on reducing of water Hardness [11]. Monica Chin and Fan studied the effects of applied magnetic field strength during settling of aggregates and total organic carbon (TOC) concentration, on the removal of turbidity that exceeds 10,000 NTU resulted from typhoon and that caused to shut down the water treatment plants. After addition of proper dosage of magnetite nanoparticles (Fe3O4) (1 g/L), turbid particles settled down more quickly and the turbidity was significantly lowered from about 10000 to less than 300 NTU, and in the presence of external magnetic field during sedimentation, the turbidity could be reduced to about 30 NTU and all that is under 1000 NTU which is acceptable for potable water treatment plant to work [12]. Alkhazan and saddiq studied the two cases of magnetic field applied to the water (static and shaking) and found The results of pH value increase with increasing magnetic intensity in static and shaking treatment. decrease in EC values with an increase of both magnetic intensity and time, and decreases in (P, Ca, Cu, Na and Cl ) concentration were ( 82, 27, 30, 6 and 18%), respectively in static state, while they were ( 82, 37, 54, 2 and 12%), respectively in shaking state [13]. The main objectives of this study was: 1- Study the effect of the magnetic field on the coagulation process.


2- Selection the perfect case with appropriate depth for shed the magnetic field. 3- Study the possibility of reducing the optimal dose of coagulant by using a magnetic field.

II. Materials and Methods -

Sampling site :

Water samples were collected from The Tigris River near the location of suction pipes that transport the raw water from the river to The Tikrit University Plant For Water Supply, where the physical and chemical characteristics of the water affected by pollution that happened to river by the rain and the disposal of the wastewater. -

Physical And Chemical Analysis Of Water Samples :

The physical properties of the samples such as turbidity, pH, temperature, EC and TDS, were measured by using turbidity meter HANNA model 93703 and pH, temperature, EC and TDS, measured by using multi_parameter PCS model 35.The hardness were measured in the laboratory of Water and Environment, in department of Environmental Engineering In Tikrit University, by titration method.

III. Experimental Procedure Water samples were collected over a period for more than a month as the characteristics of the river were variable depending on rainfall periods and change in the amount of rain. Water samples ;in the laboratory, in all studied cases were put in the six circular jars(1L) of the jar test device that in each one there are a paddle with (6cm) length and (2cm) width , and in all experiments the jar test was used with 250 rpm with gradient velocity (G= 62/sec) as a Rapid mixing for 1 minute ,to produce a good mixed solution, and then 30 rpm as a slow mixing for 30 minutes with gradient velocity (G= 15.8/sec) and (G*T=2.84*104) as a period of fluctuation, then the jars were left for 20 minutes as a period of sedimentation [14], [15]. These samples were subjected to the magnetic fields with different intensities [measured in Tesla unit (T)]


International Review of Chemical Engineering (I.RE.CH.E.), Vol. 5, N.4 July 2013 (1.38 T,2.76 T,4.14 T,5.52 T,6.9 T,8.28 T) by using number of magnetic bars, which tied around the beakers (jars). The number of experiments was worked, in all experiments Alum( Aluminum Sulfate) was used as a coagulant,(which prepared by dissolved 1 gm of dry alum in 1 liter of distilled water), the physical and chemical analyzes(turbidity, pH, EC,TDS, temperature and Hardness) have been made for all samples before the jar test and after it for all experiments. The research was carried out in number of stages on a laboratory scale as below: The First Stage included the examination of the jar without exposure to a magnetic field and then choose the optimal dose of alum. The Second Stage included choosing the optimal magnetic field with the optimal dose for the same sample(same water sample properties). The Third Stage includes the use of static magnetic intensity with a fixed dose and study the different situations of exposure to magnetic field at different heights (at the bottom third and middle third and upper third) and tying magnets once vertically and once horizontally (to choose optimal tying situation of magnetic bars) ,and also included exposure to the magnetic field from the bottom and the case of tying magnets on the Paddle surface . The Fourth Stage included the use of optimal dose with optimal situation of tying the magnetic bars with optimal magnetic intensity with change the period of exposure to the magnetic field to show where the magnetic field strongly affects exactly (in rapid mixing or in slow mixing or in sedimentation period or in two of them or in all steps).

IV. Result and Discussion The table (1) below shows the characteristics of the two samples of water used in this study. TABLE 1 THE CHEMICAL AND PHISICAL CHARACTRISTICS OF THE TWO WATER SAMPLE

Properties TU (NTU) pH EC (µS/cm) SALT (ppm) TDS (ppm) T (◦C) Hardness (mg/L)

Sample (1)

Sample (2)

45.25 7.99 456 324 215 14.3 240

662 7.40 495 236 351 16.7 240

As it shows that characteristics of the sample (1) had changed after rain, as shown in the characteristics of the sample (2), the effect of magnetic field was studied by using these two samples. The first step is to choose the optimum dose of coagulant by jar test for the two samples. The optimal dose for a sample (1) was (20 mg / L) and (30 mg / L) for the sample (2) as showing in the fig.(1) Note: the optimal dose was reduced in the first sample to show the effect of the magnetic field clearly and to examine the possibility of using a lower dose than the optimal dose.

**These stages were held twice, once on a high sample turbidity and again on a low sample turbidity, but in low turbidity samples we chose the lowest dose to show the effects of magnetic field obviously, and to show the possibility of reduce the optimal dose by using optimal magnetic field . The Fifth Stage included using the optimal magnetic intensity for specific water quality (previous samples) with other new water sample (different water quality) without choose a new magnetic intensity for this new sample, to study the possibility of use the optimal magnetic intensity .


Fig.1. The relation between alum dose and turbidity for samples (1) and (2)


International Review of Chemical Engineering (I.RE.CH.E.), Vol. 5, N.4 July 2013 In the second stage a several magnetic intensity were used (1.38, 2.76, 4.14, 5.52, 6.9 and 8.28) Tesla. The tests shows that the optimal intensity for sample (1) is 4.14 T, and 5.52 T. as shown in fig (2).

After the choice of the optimum dose of coagulant and appropriate magnetic field intensity and appropriate depth to shed the magnetic field, appropriate period to begin the process to shed the magnetic field are choosing, and had been shown that the magnetic field affected largely in the sedimentation (same result as compared with [11]) and lesser affected in the slow mixing and rapid mixing , but it is better to be a shed the magnetic field during the three processes (slow and rapid mixing and sedimentation) to achieve high efficiency, as shown in the fig (4) and (5).

Fig. 1. The relation between magnetic intensity and turbidity for sample (1) with alum dose 10(mg/L) and sample (2) with alum dose 30 (mg/L)

In the third stage by using the optimum dose of coagulant in the samples with shed optimum magnetic intensity (fixed dose with constant magnetic intensity) to choose an appropriate depth to shed magnetic intensity and appropriate way to tying magnetic bars .

Fig. 4. The relation between turbidity and the different periods of exposure to the optimal magnetic field for sample(1)

As can be seen that the magnetic intensity must be shed in the bottom third of the jar and with the horizontal position of the bars, and the worst case is shedding the magnetic field down the jar or on the Paddle surface, (because of the effect of the magnetic field on the movement of the paddle) as shown in fig. (3).

Fig. 5. The relation between turbidity and the different periods of exposure to the optimal magnetic field for sample (2)

The effect of the magnetization can be observed clearly by comparing the efficiency of removal on the same sample with and without the shedding of the magnetic field, where shown that with the shedding of the magnetic field with optimal intensity increase the efficiency of coagulation process. Fig. 3. The relation between the turbidity and the diffrent sites and cases of shed the bar



International Review of Chemical Engineering (I.RE.CH.E.), Vol. 5, N.4 July 2013 As shown in the fig. (6) for the first sample and fig.(7) for the second sample.

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The magnetic field must be shed in the bottom third of the jar and with the horizontal position of the bars. The worst case of magnetic field shedding when the magnetic field shed from down the jar or from the Paddle surface. We can reduce the optimal dose of coagulant by using an optimum magnetic field and thus reducing the health impact of coagulant on the health of consumers.

References [1] Diersing, Nancy, Water Quality: Frequently Asked Questions, PDA. NOAA (2009). Fig. 6. comparison for sample (1) after jar test between using coagulant only and coagulant with magnetic field

[2] De Zuane, J., Handbook Of Drinking Water Quality ( Jone Wiley & Sons Inc. 2nd'' edition 1997 ). rd

[3] Lanubusch, E. J., Water Quality and Treatment (McGraw-Hill, 3 edition. 1971). [4] Lo, Shang-Lien, Yung-Li Wang and Ching-Yao Hu, High Turbidity Reduction During The Storm Period By Applied Magnetic Field, J. Environ. Eng. Manage. 17 (2007) 365-370. [5] Griffiths, David J, Introduction to Electrodynamics ( Prentice Hall 3rd edition 1999). [6] Pang, X. F. and Deng, B., Investigation Of Changes In Properties Of Water Under The Action Of A Magnetic Field, Sci China Ser GPhys Mech Aston 51(2008) 1621-1632. [7] Cai R. Yang H, He J, Zhu W., The Effects Of Magnetic Fields On Water Molecular Hydrogen Bonds, Journal of Molecular Structure 938 (2009) 15-19.

Fig. 7. comparison for sample (2) after jar test between using coagulant only and coagulant with magnetic field.

[8] Ambashta, R. D. and Sillanpää, M., Water Purification Using Magnetic Assistance, J Hazard Mater. 180 (2010) 38-49. [9] Zaslavsky, B. Y, Aqueous Two-Phase Partitioning, Journal of Dispersion Science and Technology 16 (1995) 393-394.

V. Conclusions 



The efficiency of coagulation process greatly increase when the magnetic field with optimal intensity is used. The magnetic field affected greatly in the sedimentation and lesser effect in the slow mixing and rapid mixing, but it is better to be shed the magnetic field during the three processes (slow and rapid mixing and sedimentation) to achieve high efficiency.


[10] Chang, K.-T. and Weng C.-I., An Investigation Into The Structure Of Aqueous Nacl Electrolyte Solutions Under Magnetic Fields, Computational Materials Science 43 (2008) 1048–1055. [11] Banejad, H. and Abdosalehi, E., The Effect Of Magnetic Field On Water Hardness Reducing, IWTC 13 (2009) 117-128. [12] Monica Chin, Ching-Ju and Fan Zhen-Guo,, Magnetic Seeding Aggregation Of High Turbid Source Water, J. Environ. Eng. Manage., 20 (2010), 145-150. [13] Alkhazan, Molouk and Saddiq, Amna, The Effect Of Magnetic Field On The Physical, Chemical And Microbiological Properties Of The Lake Water In Saudi Arabia, Journal of Evolutionary Biology Reasearch 2 (2010) 7-14.


International Review of Chemical Engineering (I.RE.CH.E.), Vol. 5, N.4 July 2013 [14] American Water Works Association, Operational Control of Coagulation and Filtration Processes (Manual of Water Supply Practices – M37 Edition 1992). [15] Ammirtharajah, A. and Trusler, S.L., Destabilization of Particles by Turbulent Rapid Mixing, J. Environ. Eng. 112 (1986) 1085-1108.

AUTHORS’ INFORMATION Waleed M. Sh. Alabdraba born in IraqMosul Jan-6-1976. PhD Environmental Engineering, Mosul University, College of Engineering, Mosul, Nenava, Iraq 2005. He research in the field of Water and Wastewater Treatment, Biofuel Cell, Solid Waste Management and Industrial Wastewater. Asst. Prof. Alabdraba is a faculty member at Environmental Engineering Department, Tikrit University, member of Iraqi Engineers Union. Email: [email protected]. Mohamed B. A. Albayati born in IraqKirkuk Jan-6-1984. M.Sc. Environmental Engineering, Tikrit University, College of Engineering, Tikrit, Salah-Aldeen, Iraq 2010. He research in the field of Water and Wastewater Treatment, Industrial Wastewater. Asst. Lect. Albayati is a faculty member at Environmental Engineering Department, Tikrit University

