Research Article Environmental Informatics and Soft...

Research ArticleEnvironmental Informatics and Soft Computing Paradigm:Processing of Cocos Nucifera Shell Derived Activated Carbon forTreatment of Distillery Spent Wash—A Solution toEnvironmental Issue

N. B. Raut,1 Dinesh Kumar Saini,2 and G. B. Shinde3

1 Faculty of Engineering, Sohar University, Oman2 Faculty of Information Technology, Sohar University, Oman3Department of Chemical Engineering, SVIT, Nashik, Maharashtra, India

Correspondence should be addressed to Dinesh Kumar Saini; [email protected]

Received 31 December 2013; Accepted 26 June 2014; Published 11 November 2014

Academic Editor: Huu Hao Ngo

Copyright © 2014 N. B. Raut et al. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Soft computing techniques are very much needed to design the environmental related systems these days. Soft computing (SC) is aset of computationalmethods that attempt to determine satisfactory approximate solutions to find amodel for real-world problems.Techniques such as artificial neural networks, fuzzy logic, and genetic algorithms can be used in solving complex environmentalproblems. Self-organizing feature map (SOFM) model is proposed in monitoring and collecting of the data that are real time andstatic datasets acquired through pollution monitoring sensors and stations in the distilleries. In the environmental monitoringsystems the ultimate requirement is to establish controls for the sensor based data acquisition systems and needs interactive anddynamic reporting services. SOFM techniques are used for data analysis and processing. The processed data is used for controlsystem which even feeds to the treatment systems. Cocos nucifera activated carbon commonly known as coconut shell activatedcarbon (CSC) was utilized for the treatment of distillery spent wash. Batch and column studies were done to investigate the kineticsand effect of operating parameter on the rate of adsorption. Since the quantum of spent water generated from the sugar industryallied distillery units is huge, this low cost adsorbent is found to be an attractive economic option. Equilibrium adsorption datewas generated to plot Langmuir and Tempkin adsorption isotherm. The investigation reveals that though with lower adsorptioncapacities CSC seems to be technically feasible solution for treating sugar distillery spent. Efforts are made in this paper to buildinformatics for derived activated carbon for solving the problemof treatment of distillery spentwash.Capsule. Coconut shell derivedactivated carbon was synthesized, characterized, and successfully employed as a low cost adsorbent for treatment of distillery spentwash.

1. Introduction

The wastewater coming from distillery generally known asspent wash is dark brown in color, carries high organicload, and causes severe fouling of the atmosphere. Wastewater discharged by distillery from sugarcane molasses posesproblems of disposal to acceptable standards due to their highBOD, COD, and color. About 12–15 liters of spent wash isproduced per liter of alcohol produced. After fermentation ofmolasses, alcohol is separated by distillation and the residualliquor is discharged as spent wash. The effluent as such

discharged from the plant is hot, dark brown colored, acidicand possesses objectionable odor. The biological oxygendemand (BOD) value are extremely [1] high like the valuesof suspended solids, dissolved solid, chlorides, sulphates, andnitrogen which are also too high. The potassium contentof the effluent is used for irrigation. Though the distilleryeffluents do not contain any toxic substances, these createtoxic wastes resulting in massive fish kills, production offouls, odors, and decolorisation of streams. The distilleryeffluent is generally disposed off in open ponds or lagoons.Due to this, seepage and ground water pollution occurs. It

Hindawi Publishing CorporationAdvances in Environmental ChemistryVolume 2014, Article ID 737963, 11 pageshttp://dx.doi.org/10.1155/2014/737963

2 Advances in Environmental Chemistry

is a serious threat to soil and water quality because of themelanoid coloring compounds present in the effluent. Alsothe obnoxiuos odor of the spent wash which spreads a fewkilometers can cause serious health concerns.

This massive quantity, approximately 40 billion liters ofeffluent, from the distilleries are associated with very highorganic load with BOD andCOD levels in the range of 35,000to 60,000 and 60,000 to 1, 20,000mg/liter respectively. InIndia the population equivalent of distillery waste to organicpollution is approximately seven times more than the entirepopulation of India [2]. Environmental regulation in force inIndia requires that the effluent stress to have BOD less that100mg/liter for discharge on land and less that 30mg/literfor discharge into inland surface waters. These stipulationsnecessitate further treatment of effluent [3].

A number of conventional treatment technologies havebeen considered for treatment of wastewater contaminatedwith organic substances. Among them, adsorption processis found to be the most effective method. Adsorption asa wastewater treatment process has aroused considerableinterest during recent years. Commercial activated carbonis regarded as the most effective material for controlling theorganic load [4]. However due to its high cost and about 10–15% loss during regeneration, unconventional adsorbents likecoconut shells, fly ash, peat, lignite, bagasse pith, wood, sawdust, and so forth have attracted the attention of several inves-tigations and adsorption characteristics have been widelyinvestigated for the removal of refractory materials [5, 6]for varying degree of success. Activated charcoal is charcoalmade from wood, coconut shell, or bone, which has beentreated with oxygen to remove all the impurities sticking toits surface inside the pores. Activated charcoal, for example,can have a total surface area of up to 2000 square meters pergram [7]. There is lots of surface to hold molecules, whichremain in place by Vander Waals forces (physisorption). Thebigger its surface area, the more molecules it can trap on itssurface [8].

It is felt that the shells can be used for producingan adsorbent for treating distillery spent wash from sugarindustry using adsorption process [9].

In most of the coastal cities and towns across the globe,Cocos nucifera commonly known as coconut trees is plentifuland the green empty coconuts finds their way in the citiesrefuse. In some places the green nuts are dried and the fibersare removed for various purpose like ropemaking, floormatsor rubberized coir mattresses, and so forth; however, theshells are not much used other than for use as fuel. Coconutshells are made up of “stone cells” and are hard, porous,impregnated with lignins and tannin and a little oil.

Steam activation and chemical activation are the twocommonly used processes for the manufacture of activatedcarbon. However coconut shell based activated carbon unitsare adopting the steam activation process to produce goodquality activated carbon [10].

Lowering of pH value of the stream, increase in organicload, depletion of oxygen content, destruction of aquatic life,and bad smell are some of the major pollution problemsdue to distillery wastewater. One of the main advantages ofCOD [4] reduction by using coconut shell ash over the other

Table 1: Required containers, preservation techniques, and holdingtimes for samples.

Maximumholding time Preservative Container Parameter

14 days Cool 4∘C P.G. Acidity14 days Cool 4∘C P.G. Alkalinity48 hours Cool 4∘C P.G. BOD

28 days Cool 4∘C,H2SO4 to pH < 2

P.G. COD

28 days Cool 4∘CH2SO4 to pH < 2

G. Phenols

0 hours None required P.G. pH0 hours None required G. DO48 hours Cool 4∘C P.G. Nitrate7 days Cool 4∘C P.G. Residue volatile7 days Cool 4∘C P.G. TSS

chemical treatment methods is that it is available as a wastematerial in abundance and easy availability makes it a strongchoice in the investigation of economic way of COD removal[11].

2. Material and Methods

2.1. Sample Collection and Pretreatment. The distillery spentwash sample was taken from Niphad Sahakari SakharKarkhana, Niphad, Dist. Nashik, and Maharashtra India.Once a sample is taken, the constituents of the sample shouldbe maintained in the same condition, as when collected.When it is not possible to analyze collected samples imme-diately, samples should be preserved properly in such a waythat the biological activity (microbial respiration), chemicalactivity (precipitation or pH change), and physical activity arethe minimum. Methods of preservation [12] include cooling,pH control, and chemical addition as shown in Table 1.Freezing is usually not recommended. The length of time inwhich a constituent inwastewaterwill remain stable is relatedto the character of the constituent and preservation methodused.

2.2. Production of Activated Carbon. The coconut shellsderived from various waste sources were cleanly shaved toremove all the fibers on its surface. Cleaned shells were cutinto 3mm to 8mm pieces. These pieces were washed withdistilled water to remove surface dust and dried in sunlightfor two to three days.

The cleaned and dried coconut shells were then brokeninto small pieces to allow insertion into a muffle furnace{KW = 0.3, AMP = 13, TYPE = MFRA, PHASE = Single}and subjected to destructive distillation in the absence ofair. The temperature of the furnace was maintained at 400∘Cfor three hours to avoid reactions with atmospheric oxygen,thereby preventing formation of ash. This resulted in theformation of black carbonized matter.The carbonized matterwas washed [13] with distilled water and dried at 100∘C.These

Advances in Environmental Chemistry 3

Table 2: Characteristics of adsorbents.

Sr. no. Characteristics CSC CAC1 Moisture, % 16.26 6.372 Ash content, % 0.33 4.513 Bulk density, g/cc 0.67 0.574 Matter soluble in water, % 1.32 1.315 Matter soluble in acid, % 2.25 1.396 pH 2.40 8.507 Decolorizing power, mg/g 39 788 Surface area, m2/g 1.69 337

pieces were broken down into fine powder with the help ofgrinder and size separation which is done by screening usingstandard sieves [4]. Commercial activated carbon (CAC)was procured from M/s Dayo Scientific Sales, Nashik Road,Nashik, Maharashtra, India. The typical properties of CSCand CAC are summarized in Table 2.

2.3. Batch Adsorption Tests. To study the effect of importantparameters like initial pH, adsorbent dose (gm), contacttime (𝑡), initial concentration (𝐶

𝑜), adsorbent particle size,

and agitation speed on the adsorptive removal of COD byCSC and CAC, batch experiments were conducted at 30∘C.For each experimental run, 50mL of distillery spent washsolution of known𝐶

𝑜, pH, and a known amount of adsorbent

dose was taken in a 100mL stoppered conical flask. Thismixture was agitated in a temperature controlled shakingwater bath at a constant speed of 90 rpm at 30∘C. Sampleswere withdrawn at appropriate time intervals and analyzedfor COD. The effect of pH on COD removal was studiedover a pH range of 3 to 11. pH was adjusted by the additionof dilute aqueous solutions of NaOH (0.10M) or HCl. Forthe optimum amount of adsorbent dose (gm), a 50mL ofdistillery spent wash solution was contacted with differentamounts of CSC and CAC till equilibrium was attained.

The kinetics of adsorption was determined by analyzingadsorptive [14, 15] uptake of COD from the distillery spentwash at different time intervals. For adsorption isotherms,distillery spent wash samples of different concentrationswere agitated with the known amount of adsorbent till theequilibrium was achieved. The samples were then analyzedfor COD removal.The effect of speed of agitation was studiedby agitating the samples at different known speed of agitationand analyzing agitated samples for COD.

2.4. Column Adsorption Tests. Columns are mounted ver-tically one above the other. It is often good practice tooperate columns in upflow as this reduces the opportunity forchanneling. It is also preferred where suspended solids createa high-pressure drop. For downflow or percolation systeman influent line should be installed at the top of columnwith effluent line at bottom. To develop reasonably good datafrom scaleup to full plant design, it is important to haveoperation of the pilot column system as near as possible tothe anticipated conditions.Themost critical factors, flow rateand feed impurity concentration, must be constant for the

entire test run. The adsorbent bed should be at least 60 cmdeep with a 4 cm internal diameter. A smaller column isnot recommended as the wall effect becomes significant. Theadsorbent bed can be supported by glass wool, wire cloth,and so forth. Columns and fixtures can be constructed fromglass, plastic, reinforced fiberglass, ormetal. Borosilicate glassis commonly used. It is essential that all columns used in thepilot system have at least the same diameter [16].

A bed volume is the volume occupied by the adsorbentincluding adsorbent volume and void volume. The quantityof effluent is expressed in the number of adsorbent volumespassing through the column per hour. As the flow rateand quantity of liquor are the most important controllablevariables in developing design data, a feed pump suitablefor accurate and continuous flow is required. Depending onthe size of the pilot column system, the use of peristaltic,diaphragm, piston type, and centrifugal pumps is recom-mended if the effluent is viscous.

When loading the column care should be taken to avoidentrapping air in the adsorbent bed. Entrapped air can causechanneling during operation preventing complete contact ofthe process effluent with the adsorbent. In small columnsentrapped air can be avoided by pouring out the adsorbentin the boiling water just before loading of most of the excesswater can be poured off, along with most of the adsorbentparticles. Before starting the test the complete system shouldbe checked by running on water for several hours. Aftersetting the appropriate flow rate, the effluent to be treated canbe fed to the columns and this will displace thewater. Samplesof effluent after each column should be taken at regularintervals of time.When the effluent from the parallel columnsor last column in series exceeds the purity requirement, thetest should be stopped [17].

3. Results and Discussion

3.1. Distillery Spent. Characteristics of spent wash varywidely depending upon the quality of raw material, pro-cess technology, energy conservation, and effluent treatmentstrategies. The typical composition of spent wash fromNiphad Sahakari Sakhar Karkhana, Niphad, Tal Niphad, Dist.Nashik, is given in Table 3. India, which is one of the largestproducers of sugar, produces the poorest quality of molasses.Indian molasses contain the lowest amount of sugars andthe highest amount of impurities and nonfermentable sugars.This impuremolasses typically contains the higher amount ofmineral matter, calcium oxide, and potash which is furtherdegraded by poor storage facilities at the sugar factories,before it is lifted by the distilleries. During the short storagetime at the sugar mills, dust and other extraneous materialsof unknown origin contaminate it. Most of the componentsfound in molasses are from the sugarcane and find theirway to molasses because of the rigorous extraction [18]procedures to molasses because of the intensive extractionprocess. In Brazil, for example, which is also a large sugarproducer, the processes of sugar extraction and recovery aremild and, as consequence, the composition of molasses issuperior. Similarly, in other sugarcane producing countries,no attempt is made to recover maximum quantity of sugar


Table 3: Typical composition of distillery spent wash. From NiphadSahakari Sakhar Karkhana, Niphad, Dist, Nashik.

Sr. no. Parameter Spent wash analysis1 pH 7.872 Suspended solids 56,891mg/lit3 Total dissolved solids 2,41,066.6mg/lit4 B.O.D. at 27∘C for 3 days 24,000mg/lit5 C.O.D. 39,840mg/lit6 Oil and grease 23.0mg/lit7 Sulphate 4,000mg/lit8 Potassium 1,3000mg/lit9 Chloride 1,00,000mg/lit10 Sodium 1,200mg/lit11 Calcium 2,600mg/lit12 Magnesium 2,700mg/lit13 Iron 61mg/lit14 Total nitrogen 1,350mg/lit15 Colour Dark brown16 Odor Smell of burnt sugar17 Temperature 90–95∘C

from the cane. Lately sugar factories have begun to use certainspecific chemicals such as biocide, flocculating agents, color,and viscosity reducing agents which all ultimately make theirway into molasses, making it more difficult to be degraded bymicroorganism.

The composition of the effluent is a reflection of thecomposition of the molasses. A bad molasses produces a badeffluent.Thus, the poor quality of the canemolasses producedby the sugar mills is responsible for the complex character ofthe distillery effluent. The composition of the molasses fromdifferent sugar mills used in different distilleries in India alsovaries, due to different processes of sugar manufacture.

In matter of characteristics, effluent is normally a dilutedreplica of themolasses pressed in the production of alcohol. Ifmolasses differ in composition, as a natural corollary it wouldyield an effluent, which would also differ in compositionand as a consequence the extent of BOD reduction duringprimary treatment of the effluent would also differ [19]. Thismakes the situationmore complicated as no single technologycould produce similar results in all types of effluents andreduce the BOD to an identical level. The effluents of Indianmolasses based distilleries have the highest BOD/COD andcontain a high percentage of inorganic and organic dissolvedmatter, compared to the effluents of other countries. Thehighly dissolved organic matter, which cannot be utilized byyeast and which ultimately finds its way into the effluents,is primarily responsible for escalating the high biologicaloxygen demand (BOD). In addition, during the fermentationof molasses by yeast, the yeast cells multiply and also produceother organic compounds such as organic acids and so forth,in addition to alcohol. The yeast cells and organic acids alsoform a part of the effluent and contribute to the BOD. Amolasses rich in salts and other minerals allows the yeastto produce a higher amount of organic components, some

20

40

60

80

100

30 35 40 50 60

COD

rem

oval

(%)

CACCSC

Temperature (∘C)

Figure 1: Effect of temperature on COD removal, 𝐶𝑜

= 13120mg/L,time = 1 hr, and adsorbent dose = 2 gms.

of which may not be easily degraded. In India both thecomposition of molasses as well as the effluent is complexprimarily because of the sugar recovery process. In othercountries, the BOD of the effluent is low and is thereforeamenable to easy degradation. The Indian cane molasseseffluent contains a very high BOD and its treatment needsspecial technology [14].

3.2. Adsorption Test

3.2.1. Effect of Temperature on COD Removal. Usually, theadsorption reactions are exothermic; high temperature orslow adsorption would seem to inhibit, but this is not usuallyfound to be a factor in most systems. Adsorption rate islimited by diffusion; variable that influences diffusion hassignificant effect on adsorption rate. Higher temperaturesmay obstruct adsorption sight, but they significantly speedup the pace of diffusion, offending any negative temperatureeffect. The temperature dependence of adsorption process isof a very complex nature. Thermodynamic parameter likeheat of adsorption and the energy of activation plays animportant role in predicting the adsorption behavior andboth are strongly temperature dependent. Heat of adsorptioninfluences the equilibrium absorption capacity and alsoindicates that the nature of interaction taking place betweenthe adsorbate and adsorbent is dependent of the energy ofactivation.

The decrease in adsorption with the rise in temperaturemay be due to weakening of adsorptive forces between theactive sites of the adsorbent and adsorbate species and alsobetween the adjacent molecules of the adsorbed phase [14,20]. Figure 1 shows the result of variation in adsorption ratewith temperature. It has been generally observed that with theincrease in temperature the percent removal of organicmatter


60

65

70

75

80

85

2 3 4 5 10 15Time (min)

COD

rem

oval

(%)

25mL/min20mL/min

30mL/min40mL/min

Figure 2: Effect of flow rate on COD removal (CSC), 𝐶𝑜

= 13120mg/L, bed depth = 45Cm, and temperature = 30∘C.

(COD) due to the adsorption decreases which is also evidentfrom our results.The rate of adsorption is optimumwithin 30to 45∘C.

It may be observed that the (COD) removal rate foractivated carbon is higher and slightly lower for coconut shellash. But due to the easy availability of coconut shells it is moresuitable adsorbent than commercial activated carbon. It maybe concluded that, at higher temperature, the decrease in theadsorption could be due to the possible exothermic natureof the adsorption process. In the present study, the optimum(COD) removal was found near at room temperature (25–35∘C).

3.2.2. Effect of Flow Rate on Adsorption. The effect of flowrate on removal of COD is shown in Figures 2 and 3.It may be observed that in general the percentage CODremoval decreases with increase in the flow rate. The rate ofadsorption decreases with increase in the flow rate due todecrease in the residence time for the contact of adsorbatewith adsorbent.The COD reduction was remarkable at a flowrate of 25mL/min dropping gradually but steadily in caseof CSC but it dropped sharply with CAC under the sameconditions.

3.2.3. Effect of pH on COD Removal. During adsorptionboth anions and captions have been removed from wastewater with adsorbent. Researchers have found that carbonexhibits preferential adsorption for ionic species in an orderof preference as Al+3 > Ca+2 > Li+ > Na+ > K+. Foranions, the NO

3ion is preferred over the Cl− ion. It is not

surprising that pH plays an important role in the adsorptioncharacteristics of these ions as the low pH provides largequantities of the preferred H+ ion, which may take the spaceof other ions on potential adsorption sites. Even without

60

65

70

75

80

85

2 3 4 5 10 15Temperature (∘C)

COD

rem

oval

(%)

25mL/min20mL/min

30mL/min40mL/min

Figure 3: Effect of flow rate on COD removal (CAC), 𝐶𝑜

= 13120mg/L, bed depth = 45Cm, and temperature = 30∘C.

0

10

20

30

40

50

60

70

80

3 5 7.87 9 11pH

CACCSC

COD

rem

oval

(%)

Figure 4: Effect of pH on COD removal (CAC), 𝐶𝑜

= 13120mg/L,agitation time = 1 hr., adsorbent dose = 2 gms, and temperature =30∘C.

pH variations inorganic compounds exhibit a wide range ofabsorbability on adsorbents.The adsorption by using coconutshell ash and commercial activated carbon was studied atdifferent pH values from 3 to 11. Figure 4 shows the removalof COD as a function of pH. Any adsorbate adsorbent systempHof the system affects the nature of the surface change of theadsorbent, extend of ionization, and the extent and the rate ofadsorption. From graph it may be seen that the COD removalincreases as pH increased from 3 to 5.Thereafter, the removaldecreases with further increase in pH. Similar observations


0

10

20

30

40

50

60

70

80

90

10 20 30 40 50 60 70Contact time (min)

CACCSC

COD

rem

oval

(%)

Figure 5: Effect of contact time on COD removal (CAC), 𝐶𝑜

=13120mg/L, adsorbent dose = 2 gms, and temperature = 30∘C.

have been reported for COD removal from distillery effluentsusing activated carbon.

3.2.4. Effect of Adsorbent Dose on COD Removal. The effectof adsorbent dose on removal of COD is shown COD inFigure 5. It may be observed that in general the percentageCOD removal increases with increase in the adsorbentdose. From graph it is noted that the rate of decrease ofpercentage COD removal has been found to be rapid in thebeginning, which slows down as the dose increased. The rateof adsorption increases with increase in dosage because ofincrease in surface area of the adsorbent [21].

3.2.5. Effect of Contact Time on COD Removal. In columnadsorption the rate of adsorption goes on decreasing with thepassage of timewhich is shown in Figure 5 because as the timepasses the adsorption sites of the adsorbent are utilized forthe adsorption of the organic matter and the stage is reachedwhen all the sites are used and the adsorbent is saturated.In batch study it is concluded that the optimum time foradsorption is up to 60–70min only. After that the removalrate was very low. Generally, the rate of adsorption increaseswith time and after some time it remains constant [22] due toequilibrium condition.

3.2.6. Effect of Adsorption on Color Removal. Colorizationof distillery effluent has been a cause of major concern andeven after the primary treatment and two-stage biologicaltreatment (anaerobic followed by aeration) the color is notdestroyed. Adsorption experiments were carried on distilleryeffluent using coconut shell ash and commercial activatedcarbon. Color removal of 40–50% was observed in caseof coconut shell ash while in case of activated carbon as

30

40

50

60

70

80

90

20 50 90Agitation speed (rpm)

COD

rem

oval

(%)

CACCSC

Figure 6: Effect of agitation speed on COD removal (CAC),𝐶𝑜

= 13120mg/L, adsorbent dose = 2 gms, agitation time = 1 hr.,temperature = 30∘C, and 𝑉 = 50mL.

adsorbent (dose of 20 gm/L) color removal of 70–75% wasobserved.

From Figure 6, it can be seen that there is an increasein the rate of COD removal with respect to the increase inagitation speed of the mechanical shaker. This is becausethe resistances to the mass transfer, which is mainly presentaround the surface of the adsorbents, breaks down withincreasing agitation speed [23]; as a result more amount oforganic matter penetrates into the adsorbents with ease.

3.2.7. Effect of Concentration on Adsorption. The effect ofconcentration on adsorption is shown in Figure 7. It can beconcluded that from highly concentrated effluent the CODremoval quantity is more than dilute. So this indicates thatthe effluent can be directly used for the treatment withoutdilution. At low concentration COD removed quantity is low.The COD reduction is optimum at a concentration above8500mg/lit for both CAC and CSC.

3.2.8. Effect of Adsorbent Bed Depth on COD Removal. Theeffect of adsorbent bed depth on adsorption, that is, CODremoval in this case, was studied by packing the adsorptioncolumn with different depths of the adsorbent (20 cm, 30 cm,and 45 cm).The results are shown in Figure 8.The adsorptionincreased with increasing the adsorbent bed depth in agree-ment with the earlier work [18, 20]. The effect of adsorbentbed depth on COD removal was studied with respect todifferent flow rates 20mL/min., 30mL/min., and 45mL/min.of the effluent.

3.2.9. Bed Depth Service Time (Bohart Adam’s Model). Incontinuous flow experiments, it is essential to predict theexhaustion rate of adsorbent bed on how long the bedwill last


20

25

30

35

40

45

50

55

2665 4592 8380 11075 12464Concentration (mg/L)

COD

rem

oval

(%)

CACCSC

Figure 7: Effect of concentration on COD removal, adsorbent dose= 2 gms.

before regeneration is necessary. In this method the servicetime of a fixed bed adsorbent, treating a solution of singleadsorbate, can be expressed as a function of operationalvariables as shown by (1).

The straight line plots of breakthrough time versus bedheight were obtained as shown in Figure 9 indicating theapplicability of Bohart Adam’s model:

ln(𝐶0

𝐶𝑏

− 1) = ln(𝐾𝑁𝑜𝐻

𝑉

) − 1 − 𝐾𝑏𝐶0𝑇𝑏,

𝑇𝑏= (

𝑁0

𝐶0𝑉

)𝐻 − (

𝑉

𝐾𝑏𝑁0

) ln(𝐶0

𝐶𝑏

− 1) ,

(1)

where 𝐶𝑏= breakthrough concentration {mg/L}, 𝐶

0= initial

concentration {mg/L},𝐻 = critical bed depth {m}, 𝑉 = linearflow velocity {m/min.},𝐾

𝑏= rate constant,𝑇

𝑏= breakthrough

time {Min.}, and𝑁0= adsorptive capacity {mg/m}.

The breakthrough time is found to increase with increasein the adsorbent bed height. Thus, column test shows theapplicability of BDST model [8].

3.2.10. Effect of Particle Size of Adsorbent on COD Removal.The effect of using various particle sizes of CSC on CODremoval was studied by using CSC adsorbent of three dif-ferent particle sizes, namely, 425 microns, 610 microns, and750 microns for the column experiments. The Co was keptconstant at 20480mg/lit. and all the experiments were carriedout at natural pH of 7.87 and temperature 30∘C.

From the results (Figure 10) it is clear that the rate ofadsorption increases with decrease in particle size. This isbecause increase in the surface area with the decreasingparticle size of adsorbents and since adsorption process isa surface phenomenon the rate of adsorption increases withdecrease in particle size.Thus the smaller the particle size, the

0

0.25

0.5

0.75

1

0 30 60 90 120 150 180Time (min)

CAC1CSC1CSC2CAC2CAC3

CSC3CAC4CSC4CAC5CSC5

Ct/Co

Figure 8: Effect of adsorbent bed height on rate of COD removal𝐶𝑜

= 13120mg/L, temperature = 30∘C 1 = 𝐻 = 20Cm, flow rate =20mL/min, 2 =𝐻 = 30Cm, flow rate = 20mL/min, 3 =𝐻 = 45Cm,flow rate = 20mL/min, 4 =𝐻 = 20Cm, flow rate = 30mL/min, 5 =𝐻 = 30Cm, flow rate = 30mL/min, 6 =𝐻 = 45Cm, and flow rate =30mL/min.

0

1

2

3

4

5

6

7

8

20 30 45

Flow

rate

(mL/

min

)

Breakthrough time (min)

CAC = 0.2

CAC = 0.3

CAC = 0.5CSC = 0.2

CSC = 0.3

CSC = 0.5

Figure 9: Bohart Adam’s model.

greater the interfacial area for adsorption of COD. But withthe reduced sizes, there may be other problems like cloggingduring the operation particularly with continuous operationsresulting in high- pressure drops.

3.2.11. Effect of Series Arrangement of CSC and CAC Columns.Figure 11 shows that if the CSC column is arranged in series


0

10

20

30

40

50

60

70

8020 40 60 80 10

012

014

016

018

020

022

024

026

028

030

032

034

0

COD

rem

oval

(%)

Time (min)CSC particle size = 425micronsCSC particle size = 610micronsCSC particle size = 750microns

Figure 10: Effect of particle size on COD removal (CAC), 𝐶𝑜

=20480mg/L,𝐻 = 12 cm, flow rate = 45mL/min.

0

10

20

30

40

50

60

70

80

90

100

15 90 165 240 315Time (min)

COD

rem

oval

(%)

CSC bed ht. = 15 cm, CAC bed ht. = 5 cmCSC bed ht. = 20 cm, CAC bed ht. = 10 cm

Figure 11: Effect of CSC column in series with CAC bed on CODremoval, 𝐶

𝑜

= 20480mg/L.

with CAC column for adsorption operation, the efficiencyof carbon utilization is increased. Thus, more quantity ofCSC adsorbent and less quantity of CAC adsorbent canbe effectively used for treating distillery spent. Though thepercentage COD removal using series combination is slightlyless than that using the two columns separately but the lowcost of CSC makes it an attractive option.

3.3. Adsorption Isotherms

3.3.1. Langmuir Adsorption Isotherm. The equilibrium datafor removal of COD by using CSC and CAC in the present

0

5

10

15

0 0.5 1 1.5 2 2.5 3

CACCSC

1/qe(10−4)

1/Ce (10−4)

Figure 12: Langmuir adsorption isotherm 𝐶𝑜

= 13120mg/L.

investigations were analyzed using Langmuir adsorptionmodel. The linear plots of 1/𝑞

𝑒versus 1/𝐶

𝑒are shown

in Figure 12. The values of 𝜃 and 𝑏 were determined asintercept = 1/𝜃0 and slope = 1/𝜃0𝑏. The adsorption data werefitted to the linear form of Langmuir isotherm. The essentialcharacteristics of Langmuir isotherm may be expressed interms of dimensionless equilibrium parameter 𝑅 using fol-lowing equation:

𝑅 =

1

(1 + 𝑏𝐶0)

. (2)

The values of 𝑅 lie between “0” and “1” at initial adsorbateconcentrations showing favorable adsorption of organic mat-ter on the adsorbent.

For CSC, 𝑏CSC = 4.9685 × 10−4 𝑅CSC = 0.133.For CAC, 𝑏CSC = 1.24 × 10−5 𝑅CAC = 0.860.

3.3.2. TempkinAdsorption Isotherms. Aplot of 𝑞𝑒versus ln𝐶

𝑒

enables the determination of the isotherm constants 𝐵1and

𝐾𝑡from the slope and the intercept, respectively. 𝐾

𝑡is the

equilibrium binding constant (1/mol) corresponding to themaximum binding energy and constant 𝐵

1is related to the

heat of adsorption.The Tempkin isotherm plots for CSC and CAC are shown

in Figure 13.From Figure 13, slope = 𝐵

1= 31.389 and intercept = 75.

Now,

𝑞𝑒= 𝐵1ln𝐾𝑡+ 𝐵1ln𝐶𝑒. (3)

For CSC, 𝐵1= 31.389 and𝐾

𝑡= 10.90.

From Figure 13, slope = 57.93 and intercept = 90.For CAC, 𝐵

1= 119.94 and𝐾

𝑡= 4.72.

3.4. Adsorption Kinetics. The rate of adsorption of organicmatter on to CSC and CAC was studied and the rate constant


0

50

100

150

200

250

8 8.2 8.4 8.6 8.8 9 9.2 9.4

CACCSC

qe

(mg/

g)

lnCe

Figure 13: Tempkin adsorption isotherm 𝐶𝑜

= 13120mg/L.

0

1

2

3

4

5

0 20 40 60 80 100Time (min)

CACCSC

ln(q

e−q)

Figure 14: Lagergren plot 𝐶𝑜

= 13120mg/L, adsorbent dose = 2 gms,Temp = 30∘C.

𝐾ad of the process for organic matter was determined usingLagergren rate equation. Figure 14 represents the Lagergrenplot for the above system:

ln (𝑞𝑒− 1) = ln 𝑞

𝑒− (

𝐾ad2.303) 𝑡, (4)

where 𝑞 = amount adsorbed at time “𝑡”, 𝐾ad = adsorptionconstant, and 𝑞

𝑒= equilibrium uptake.

At equilibrium, COD removal is Nil. So, 𝑞𝑒= 0:

ln (𝑞𝑒− 𝑞) = ln 𝑞

𝑒− (

𝐾ad2.303) 𝑡. (5)

For CSC, from Figure 14, slope is [𝐾ad/2.303] = 5.111 −3.084/20 − 70 = −0.04054:

𝐾adcsc = 0.09336min−1. (6)

For CSC, from Figure 14, slope is [𝐾ad/2.303] = 4.892 −2.324/10 − 50 = −0.0642:

𝐾adcac = 0.1478min−1. (7)

The linear plots of ln(𝑞𝑒−𝑞) versus 𝑡 for COD removal shown

in Figure 14, indicate the applicability of Lagergren first orderequation.

3.5. Cost Analysis. One of the most challenging elements ina design will be estimating the cost to build and operate thewastewater treatment facility that is designed. Cost estima-tion is also an important element when selecting betweenalternative designs [24].

For treating 1 liter of distillery spent wash, using CAC asadsorbent, time required = 22.22 minutes, amount of CACrequired = 32 gms, cost of adsorbent CAC = Rs. 300 per kg,and cost of adsorbent CAC required to treat 1 liter of distilleryspent wash = Rs. 9.60.

For treating 1 liter of distillery spent wash, using CSC asadsorbent, time required = 22.22 minutes, amount of CSCrequired = 36 gms, and cost of adsorbent CSC = Rs. 100 perkg.

Cost of adsorbent CSC required to treat 1 liter of distilleryspent wash = Rs. 3.60. On comparing the cost of treatmentof distillery spent wash using both CSC and CAC, it canbe observed that treatment using CSC as adsorbent is muchcheaper than that using CAC as adsorbent.

However, as far as the production of sugar is concerned,0.4–0.45 tone of molasses is produced per ton of sugar. About90% of the total molasses produced is utilized for productionof alcohol. For producing 1 liter of alcohol about 10–15 litersof spent wash is produced. Hence for producing 1 liter ofalcohol, treatment cost of spent wash is about Rs. 96 by usingcommercial activated carbon as adsorbent and Rs.36/- byusing coconut shell as adsorbent.Thus it can be observed thatfor treating 1 liter of distillery spent wash, there is a differenceof Rs. 6 between the treatments by two adsorbents {CSC andCAC}.

4. Conclusions

Coconut shell activated carbon was synthesized and charac-terized for comparison of adsorption capacities with com-mercial activated carbon.The results revealed that CAC givesthe best result between the two adsorbents, that is, coconutshell carbon {CSC} and commercial activated carbon {CAC}tested for COD reduction from distillery spent wash. How-ever, CSC also showed quiet effective adsorbent capacities.Though the adsorption capacity of CSC is lower than thatof commercial grade activated carbon, the low material costmakes it an attractive option for the treatment of effluents.The treatment of distillery spent with CSC becomes highlyeffective, as it is a readily and locally available low costabsorbent which needs not be regenerated.


With the increase in adsorbent dosage there is an increasein percentage COD removal from the distillery spent wash.Change in natural pHof the distillery spentwash caused colorremoval due to the structural changes being affected in theadsorbent molecules. COD removal by both adsorbents, thatis, CAC and CSC, is the maximum at a pH between 3 and 5.Effect of initial concentration on COD removal by both CSCand CAC shows that the percentage COD removal increaseswith increase in initial concentration (above 8580mg/lit) forinitial contact time intervals and decreases with increase ininitial concentration as the saturation of adsorbent is reached.Adsorption capacity decreases with increase in temperaturefor both the adsorbents. Breakthrough time increases withincrease in bed height and decrease in flow rate for thecolumn adsorption. By operating CSC column in series withCAC column the efficiency of carbon utilization is increased.

The equilibrium time was nearly one hour for both CACand CSC adsorbents.The correlation for equilibrium adsorp-tion data were well fitted by the Langmuir and Tempkinadsorption isotherm for both the adsorbents. Bohart Adam’sequationwas found to be applicable for the column study.Theadsorption kinetics was well in agreement with the Lagergrenplots revealing first order rate.

From the results obtained it can be stated that thoughCAC is more efficient adsorbent than CSC, but due to highcost and 15 to 20% loss of CAC during regeneration CSCis more preferable than CAC for COD removal from sugar-distillery spent wash. However, for evaluation of the technicaland economical feasibility, more research is required on pilotplant scale, so that this low cost adsorbent can be used onlarger commercial scale for removal of COD from distilleryspent wash.

5. Future Insights

Expansion of this technology to large-scale applicationsshould be encouraged. As used coconut shells find their wayas urban and rural refuse; exploitation of this waste for wastewater treatment will dispose this waste in a safer manner.

Besides the gold mining industries, the breweries, andsoft drink industries that currently use activated carbon,other potential users such as the textile industries, soapmanufacturing industries, vegetable oil nulls, and the Waterand Sewerage Corporation can also be sensitied to use thiscommodity, thereby creating more market for the product.The pilot studies to develop a national capability for theproduction of activated carbon form coconut shells will,among several benefits, contribute tomeasures for abating theenvironmental degradation caused by dumping of agricul-tural wastes. Improved public education to ensure awarenessof the technology and its benefits, both environmental andeconomic, is recommended.

More experimental work on removal of organic matterfrom other industrial effluents by using coconut shell ash asadsorbent should be encouraged in order to prove the suit-ability of this low cost adsorbent for waste water treatment.

Adsorption column studies should be carried out fordifferent column configurations to get the characteristicdependence of the adsorption capacity and other parameters.

Design parameters for scaled up adsorption column shouldthereafter be fixed for the removal of COD from distilleryspent wash. Costing of the adsorption based on industrialscale treatment system should be carried out to popularize theadsorption technique. Computing,modeling, and simulationwill be carried out for the large-scale plants based on thecomputations proposed.

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper.

References

[1] B. Subba Rao, Aerobic Composting of Spent Wash, Environmen-tal Protection Research Foundation, Sangli, India, 2008.

[2] A. G. Patil, V. V. Deshpande, and P. L. Kulkarni, DistillerySpentWash: A Source for Production of Chemicals, Deccan SugarInstitute, Pune, India, 2009.

[3] B. S. Rao, S. V. Ranade, and J.M. Gadgil, “Wealth fromwaste,” inProceedings of the 3rd International Conference on AppropriateWaste Management Technologies for Developing Countries, pp.25–26, NEERI, Nagpur, India, 1995.

[4] L. M. Arulanantham, T. V. Ramkrishna, and S. N. Bal, “Studieson fluoride removal by Coconut shell carbon,” Indian Journal ofEnvironmental Protection, vol. 12, no. 7, 1992.

[5] G. N. Pandey and G. S. Carney, Environmental Engg, TATAMcGraw-Hill, New York, NY, USA, 2010.

[6] I. A. Rahman, Y. Y. Singh, M. F. Bari, and B. Saad, “Adsorptionof paraquat by treated and untreated rice husks studied byflow injection—analysis,” Research Journal of Chemistry andEnvironment, vol. 9, no. 1, pp. 17–22, 2005.

[7] R. Shyamala, S. Sivakamasundari, and P. Lalitha, “Comparisonof the adsorption potential of biosorbents-waste tealeaves andrice husk, in the removal of chromium (VI) from waste water,”Journal of Industrial Pollution Control, vol. 21, no. 1, pp. 31–36,2005.

[8] S. D. Foust and O. M. Aly, “Adsorption process for watertreatment,” Science Report, 1986.

[9] M. K. B. Gratuito, T. Panyathanmaporn, R.-A. Chumnanklang,N. Sirinuntawittaya, and A. Dutta, “Production of activatedcarbon from coconut shell: optimization using response surfacemethodology,” Bioresource Technology, vol. 99, no. 11, pp. 4887–4895, 2008.

[10] S. D. Khattri and M. K. Singh, “Adsorption of basic dyesfrom aqueous solution by natural adsorbent,” Indian Journal ofChemical Technology, vol. 6, no. 2, pp. 112–116, 1999.

[11] A. S. Dadhich, S. K. Beebi, and G. V. Kavitha, “Adsorption ofNi (II) using agrowaste, rice husk,” Journal of EnvironmentalScience and Engineering, vol. 46, no. 3, pp. 179–185, 2004.

[12] R. J. Krupadam and A. V. S. Prabhakar Rao, “Removal oflead from industrial effluents using coconut shell carbon,”Environmental Pollution Control Journal, vol. 56, no. 2, pp. 52–53, 1997.

[13] S. A. Raj, “Adsorption behaviour of nickel on activated carbon,”Indian Journal of Environmental Protection, vol. 24, no. 7, pp.530–533, 2004.

[14] K. Vasanth Kumar and K. Subanandam, “Studies on decolorisa-tion of basic dye onto carbonized agro based waste adsorbent,”Environmental Pollution Control Journal, vol. 5, no. 2, p. 8, 2002.


[15] K. V. Kumar, “Studies on adsorption of basic dyes on toagro-based wastes—part I: kinetic studies,” Indian Journal ofEnvironmental Protection, vol. 22, no. 11, pp. 1236–1240, 2002.

[16] K. Palanivelu and N. Elangovan, “Phosphate removal studiesusing Al impregnated coconut shell carbon,” Indian Journal ofEnvironmental Protection, vol. 16, no. 3, pp. 183–185, 1996.

[17] S. T. M. L. D. Senevirathna, S. Tanaka, S. Fujii et al., “Adsorptionof perfluorooctane sulfonate (n-PFOS) onto non ion-exchangepolymers and granular activated carbon: batch and columntest,” Desalination, vol. 260, no. 1–3, pp. 29–33, 2010.

[18] S. Sohail Ayub, S. Iqbal Ali, N. A. Khan, and H. S. Danish,“Treatment of waste water by agricultural waste—a review,”Environmental Pollution Control Report, 1998.

[19] S. Rengaraj, B. Arabindoo, and V.Murugesan, “Preparation andcharacterisation of activated carbon from agricultural wastes,”Indian Journal of Chemical Technology, vol. 6, no. 1, pp. 1–4, 1999.

[20] S. Dahiya and A. Kaur, “Studies on fluoride removal by coconutcoir pith carbon,” Indian Journal of Environmental Protection,vol. 19, no. 11, pp. 811–814, 1999.

[21] D.S. Ramteke, S.R. Wate, and C.A. Moghe, “Comparativeadsorption studies of distillerywaste on ativated carbon,” IndianJournal of Environmental Health, vol. 31, no. 1, pp. 17–24, 1989.

[22] S. Satyanarayan, A. Juwarkar, and S. N. Kaul, “Distillery WasteWater Treatment—A case Study,” NEERI, Nagpur-20, 2009.

[23] S. Gupta and R. P. Singh, “Comparative adsorption study oftoxic metal by waste product,” Indian Journal of EnvironmentalProtection, vol. 24, no. 11, pp. 863–866, 2004.

[24] G. G. Stavropoulos and A. A. Zabaniotou, “Minimizing acti-vated carbons production cost,” Fuel Processing Technology, vol.90, no. 7-8, pp. 952–957, 2009.

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