REMOVAL OF CHROMIUM FROM INDUSTRIAL WASTEWATER USING MEMBRANE SEPARATION

Under guidance of :- Dr. S. M. ChavanBy Pratiksha A. PatilRoll No. 609007

INTRODUCTION

Chromium is one of the hard & fragile metals that is applied in electroplating, metallurgy, firebrick, aircraft painting, leather tanning, dyeing, cement industry etc.

1 to 5 milligram per liter is the discharge limit for chromium(III) into water bodies.

In aquatic system, chromium exist in trivalent & hexavalent states.There are many processes for the treatment of wastewater .Membrane separation has become increasingly attractive for the treatment

& recovering heavy metals as it is high efficiency, easy to operate & low in cost.

Selection selectivity depends on the particular membrane process & on the membrane type.

ULTRAFILTRATION

UF is usually applied where the solute dimensions are significantly larger than the solvent dimensions.

Cellulose acetate/sulfonates poly(ether ether keton) blend UF membrane with water soluble microligand (PVA) used for separating chromium.

UF achieve more than 90% of removal efficiency with a metal concentration ranging from 10-112 mg/lit at ranging from 5-9.5 & at 2-5 bar of pressure.

In the absence of microligand, UF process cannot be directly applied for ionic level rejection with large pore size membrane.

ADVANTAGE:- lower driving force, smaller space require due to its high packing density.

DISADVANTAGE:- decrease UF performance due to membrane fouling.

The formation of a metallic complex MLx according to M + Lx MLxIs characterised for each cation M by stability constant Kx = In UF the complexation can be measured by rejection = 1- The permeate flux was calculated by J = Where, J = permeate flux (l ) Q = quantity of permeate collected (l) A = membrane surface area () = sampling time (h)

Effect of various parameter

Effect of :- If the increases then permeate flux decreases & rejection increases for different concentration.

Effect of chromium concentration:- At any concentration pure cellulose acetate membrane offer a lower permeate flux & higher rejection value.

Effect of trans-membrane pressure:- for lower trans-membrane pressure; lower is permeate flux & higher rejection value vice versa.

Effect of concentration of PVA:- As PVA concentration increases, the permeate flux decrease and percent rejection increase.

NANOFILTRATION

NF is newer technology than RO. Often used to separate small organic & inorganic compound & multivariable ions from solvent.

High efficiency of separation at lower pressure of operation makes the NF to be best of other membrane system.

NF separation mechanism involves Donnan effect. At neutral value complete rejection of polar rejection is possible with NF.NF effectively remove metal at range of 3-8 & at pressure 3-4 bar.ADVANTAGE:- ease of operation, reliability & comparatively low energy

consumption as well as high efficiency of pollution removal.DISADVANTAGE:- high cost and maintenance of used.

Pure water flux = Permeate flux = Chromium rejection %R = (1- )* 100Where, = pure water flux (/s.) = volume of pure water permeate collected per unit time (/s) = permeate flux (/s.) = volume of permeate collected per unit time (/s) A= area of membrane () t = time (sec)

EFFECT OF OTHER PARAMETER

Effect of permeate flux:- permeate flux linearly decreasing with increasing operating pressure.

Effect of feed concentration:- At higher feed concentration rejection higher than lower feed concentration.

Effect of operating pressure:- higher operating pressures slightly more successful in rejection chromium.

Effect of feed PH:- Higher rejection in alkaline & lower in acidic.

REVERSE OSMOSIS

The rejection % of RO over 97% with a metal concentration ranging from 21- 200 mg/lit.

RO work effectively at range of 3-11 and at 4.5-15 bar of pressure.Higher the pressure, higher the efficiency & higher the energy

consumption.RO completely remove Cd(II), Cr(III), Cu(II), Ni(II) & Zn(II) with initial

concentration of 50 mg/lit with lower cost.ADVANTAGE:- 1) high water flux rate, high salt rejection, resistance to

biological attack 2) mechanical strength 3)chemical stability & the ability to withstand high temperature.

DISADVANTAGE:- 1)due to suspended solids or oxidized compound such as chlorine oxide membrane fouling 2)membrane replacement increase operational cost 3)membrane performance decreases with time resulting decrease permeate flow rate 4)scaling 5) need for experience person to run process.

EFFECT OF VARIOUS PARAMETER

Effect of :- value within 3-6 solution was stable. Over 6 flocculation occurred & it fallen to bottom of vessel. Carbonate decompose at 4.5 completely.

Effect of concentration:- If Cr(III) concentration in feed is higher than permeate flux decreases. If we take value constant no significant change in rejection.

Effect of temperature:- when temperature increases the permeate flux also increases.

Feature Ultrafiltration Nano-filtration

Reverse osmosis

polymers Ceramic,polysulfone,polyvinylidene fluoride etc.

Thin film composites cellulosic.

Thin film composites cellulosic, polysulfone

Pore size range(micron) 0.01-0.1 0.0001-0.001 <0.0001

Mol. Wt. cut off range (Daltons)

2000- 100,000 300-1000 100-300

Operating pressure range (psi)

20-100 50-300 225-1000

Osmotic pressure effects Slight Moderate High

Concentration capability High Moderate Moderate

Permeate purity High Moderate-high High

Energy usage Low Low-moderate Moderate

Membrane stability High Moderate Moderate

Suspended solid, dissolved organic & inorganic removal.

Yes Yes Yes

CASE STUDY

Objective:- use of thin-film composite membranes to separate Cr(VI) in industrial pilot plant.

Material & Method:- NF membrane made by aromatic polyamide is used. They are made by thin-film composite method on porous polysulfone substrate.

1) sample containing Cr(VI):- 1-120 ppm 2) pressure up to 4 MPa. 3) feed cross-flow around 800L/h 4) temperature 25oCResult:- rejection value for Cr(VI) as a function of concentration and

pressure. NF process with high rejection for Cr(VI) > 95% for feed concentration from 1-120 ppm.

Rejection of Cr(VI) at different feed concentration and operating pressures

Feed concentration

(ppm) 10 15 20 25 30 35 40

1 95.5 95.5 96.1 96.4 96.9 97.4 97.6

20 97.4 97.6 97.7 97.8 97.9 98.1 98.2

40 97.9 98.0 98.0 98.2 98.3 98.4 98.4

60 98.4 98.5 98.6 98.6 98.7 98.7 98.7

80 98.3 98.4 98.4 98.5 98.6 98.6 98.6

120 98.4 98.4 98.4 98.5 98.5 98.6 98.6

Rejection (%) at different pressures

CONCLUSION

Each methods has its own merits and limitations. UF assisted by complexation or UF with microligand are promising separation technique for purification of effluents containing heavy metal.

RO membrane can achieve the highest effluent water purity, they must operate at higher pressure. For this reason, NF has attracted increasing attention.

High cost & technical complications are the problem associated with RO.NF has high efficiency of separation at lower pressure of operation makes it

the best out of other membrane systems. Metal removal using membrane processes is become more widely accepted

as new evidences is gathered highlighting their lower cost, ease of operation selectivity & efficiency.

REFERANCES International Conference on Trade, Tourism and Management (ICTTM'2012)

December 21-22, 2012 Bangkok (Thailand), Farhang Hakimzadeh Zargar. a. aliane1*, n. bounatiro1, a.t. cherif2, and d. e. akretche2 1Laboratoire d’analyse et de

traitement des e uents. Centre de de´ veloppement des mate´ riaux, BP 43 Draria, fflAlgeria and 2Laboratoire de valorisation des minerais - USTHB . BP 32 El-Alia, Algeria

Berna Kiril Mert • Kadir KestiogluPavel Kocurek, Karel Kolomazník and Michaela Bařinová PAVEL KOCUREK, KAREL KOLOMAZNÍK and MICHAELA BAŘINOVÁ

Department of Automation and Control Technologies Tomas Bata University in Zlín Nad Stráněmi 4511, 760 05, Zlín CZECH REPUBLIC kocurek@fai.utb.cz http://www.utb.cz

S. A. Mousavi Rad, S. A. Mirbagheri, and T. Mohammadi Hani Abu Qdaisa*, Hassan Moussab 'Department of Civil Engineering, Department of

Chemical Engineering, Jordan University of Science and Technology, PO Box 3030, Irbid 22110, Jordan Tel. +962 (2) 709-5111; Fax +962 (2) 709-5018; email: hgdais@just.edujo

Thank you !