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Journal of Scientific & Industrial ResearchVol. 65, October 2006, pp. 830-837

Aerobic and anaerobic treatment of fruit juice industry effluents

Emine Elmaslar Ozbas1,*, Nese Tufekci

1, Gulsum Yilmaz

1and Suleyman Ovez

2

1Istanbul University, Faculty of Engineering, Environmental Engineering Department, Avcilar, 34320, Istanbul, Turkey2Istanbul Technical University, Faculty of Civil Eng, Environmental Engineering Department, Maslak, 34469, Istanbul, Turkey

Received 02 December 2005; accepted 05 June 2006

This study investigates biological treatment of fruit juice industry effluents in sequencing batch reactor (SBR), activatedsludge reactor (ASR) and anaerobic upflow sludge blanket reactor (UASB). At anaerobic biological treatability studies, seedsludge was acclimated to the medium and 95% of COD removal was obtained within a few weeks. At the end of anaerobic

study, organic loading rate was increased to 5 kg COD/m3-day and the hydraulic retention time was decreased to 2.3 days.

At the aerobic biological treatability studies, 90-95% soluble COD removal was achieved for both wastewaters (sour cherryand apple) in SBR and in ASR. In addition to aerobic biological treatability studies, microbiological investigation, andkinetic and stociometric coefficients were determined. At the end of microbiological examination, fungi overwhelmingly

dominated the system.

Keywords: Activated sludge, Anaerobic up flow sludge blanket reactor (UASB), Fruit juice industry wastewater,Sequencing batch reactor (SBR)

IPC Code:C02F3/12

IntroductionWastewater effluents from the fruit juice industry

contain primarily high concentrations of organic

materials, which are occasionally discharged into the

municipal wastewater collection system and

processed in wastewater treatment plants along with

domestic wastewater. Major problems in the treatment

of raw effluents from the fruit juice industry are low

pH values, imbalance of nutrients, and the very

considerable fluctuations in the amount of effluent

and waste matter produced1,2. Sequencing batch

reactor (SBR) is successfully applied to the treatment

of strong wastewaters with effective organic carbon

and nutrient removal3-5

. Anaerobic upflow sludgeblanket reactor (UASB) is a simple and easily

operated anaerobic system. In such systems, sufficient

refining efficiency can be achieved at lowtemperatures, as well as high temperatures

6.

This study deals with the anaerobic and aerobictreatments of wastewater from fruit juice industry

before it is discharged into the municipal wastewater

treatment plant. In addition to treatability studies,

kinetic and stociometric coefficients (maximum

specific growth rate m and endogenous decay rate

bH) were determined for aerobic treatment systems.

Materials and MethodsUASB Reactor consisted of: total volume, 16.5 l;

internal diam, 12 cm; and height, 150 cm. Feeds were

prepared each day and pumped to the reactors using

variable speed peristaltic pumps. Anaerobic reactor is

thoroughly mixed due to influent input from the

bottom of tank and gas emission during treatment,

which also drag a portion of the biomass when rising.

Gas bubbles that are separated from the liquid and

solid phases at the bottom of the funnel, which is

placed to the precipitation section, leave the systemwith the gas line. In the mean time, released sludge

particles return to the body. Similarly, some amount

of sludge, which is dragged with the hydraulic up-flow, precipitates at the stable exterior part of the

funnel and returns to the body section. The treatmentefficiency is improved through efficient mixing and

contact of the effluent with biomass in the reactor.

Activated sludge reactor (ASR) and SBR were

operated with a hydraulic retention time (HRT) of

24 h, sludge age of 10 days and F/M ratio 0.5

(Table 1). After start-up period (24 h), SBR wasoperated with a cycle time of 12 h.

___________*Author for correspondenceTel: +90 212 4737070/17732; Fax: +90 212 4737180

E-mail: [email protected]

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OZBAS et al: AEROBIC & ANAEROBIC TREATMENT OF FRUIT JUICE INDUSTRY EFFLUENTS 831

Analytical Methods

The reactors pH and temperature were controlledcontinuously. The main parameters including COD,

alkalinity, total suspended solids (TSS), volatile

suspended solids (VSS) and sludge volume index

(SVI) were measured. All analyses were carried out in

accordance with Standard Methods7. Maximum

growth yield and endogenous decay rate were

determined by using respirometric method2.

Wastewater Characterization

As fruit juice wastewater is poor in nutrients

(Table 2), NH4Cl and Na2PO4were added to influent

to improve C:N:P in anaerobic studies

(C/N/P=300/5/1) and in aerobic studies

(C/N/P=100/5/1). Besides, in anaerobic studies,

system was fed with NaHCO3 in order to provideenough alkalinity in the reactor and to buffer the CO2

and volatile acids. Temperature (35-37C) and pH

(6.5-7.8) within the reactor were maintained in

anaerobic studies. pH was maintained around 7.0 by

NaOHaddition during aerobic studies. Reactors were

inoculated with the sludge taken from Pasabahce

Tekel Raki Factory.

Results and Discussion

Anaerobic Treatability Studies

During the start-up period, main parameters in

reactor were: Organic loading rate (OLR), 1.40 kgCOD/m

3/day; HRT, 5.7 days; VSS concentration,

7700 mg/l; andpH, 7-8. In this period, the seed sludge

was acclimated to the medium and 95% of COD

removal was obtained within a few weeks (Fig. 1).

This period was observed for 73 days with no

problems.

After the start up period, OLR was increased

to 3.47 COD/m3/day and HRT was decreased to

2.3 days. In the first few days, the efficiency dropped

due to instability of pH and increase in OLR

was observed. Buffering the feeding effluent with

NaHCO3 resulted in 90% of COD removal inthe system within 10 days. During this period,

OLR was kept at 3.37-5 kg COD/m3/day for 30 days

and 90% of COD removal was obtained on the

average. The effluent COD value was kept between

600-800 mg/l except for the over loadings (Fig. 1).During the study, biogas production in the UASB

reactor was about 0.395 m3 CH4/kg COD removed

and the average CO2 ratio in the biogas was 20%

(Table 3).

Table 1Characteristics of activated sludge and

sequencing batch reactors

Characteristics Activated sludge

reactor

Sequencing batch

reactor

Liquid volume, l 4 4Internal diam (), cm 12 14Height, cm 80 64.5

Sludge age, day 10 10F/M (F= COD;M=MLVSS) ratio

0.5 0.5

Table 2Characterization of wastewaters

Parameters CODmg/l

TKNmg/l

TPmg/l

Sourcherry juicewastewater

1000-8000 3.3-55 0.104-10

Sourcherry juice

concentrate1.000.000 3000 95

Apple juicewastewater

1600-2500 73-114 0.63-0.98

Apple juiceconcentrate

124.800 5694 49.14

Table 3Biogas production in the UASB reactor

Parameter Min. Max. Average St. deviation

Volatile loading rate,kgCOD/m3 day

2.3 21.1 5.7 2.2

Biogas production,

m3/day 880 11.000 5.500 1.980

Fig. 1COD removal efficiency values determined in UASB

reactor for fruit juice effluent. CODi: Influent COD; CODe:

Effluent COD

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J SCI IND RES VOL 65 OCTOBER 2006832

Aerobic Treatability Studies

Studies with Sour Cherry Juice Wastewater

Reactors were operated using sour cherry juicewastewater during 133 days with HRT of 24 h and

80-96% COD removal. Aeration and settling period

used in ASR were approx 23 h and 30 min,respectively. The durations for filling, aeration,

settling and withdraw phases were 45 min, 22 h and

15 min, 30 min and 30 min, respectively, for SBR.

After the start-up period, ASR was operated at:

HRT, 24 h; aeration period, 23 h; and settling period,

30 min. After 45thday, SBR reactor was operated with

a cycle time of 12 h. During second stage, the

durations of filling, aeration, settling and withdraw

phases for SBR were 45 min, 10 h and 15 min, 30 minand 30 min, respectively. After start-up period,

average COD removal were achieved for ASR and

SBR as 92% (Table 4) and 93% (Table 5),

respectively. MLSS and MLVSS decreased after day

50, because a little amount of microorganism was

removed from the reactor to maintain the sufficient

settling (Table 4). When OLR changed, COD removal

values decreased because of insufficient aeration. In

SBR, when operating cycle was changed as 12 h,

microorganism concentration increased rapidly. SVI

values varied for ASR (30-90 ml/g) and for SBR

(30-80 ml/g).

Studies with Apple Juice Wastewater

Reactors were fed with apple juice wastewater. In

this period, ASR was operated with a cycle time of

24 h, and SBR with a cycle time of 12 h. The

durations of filling, aeration, settling and withdraw

phases for SBR were 45 min, 10 h and 15 min, 30 min

and 30 min, respectively.After 35 days, the influent

COD was increased from 1600 mg/l to 2750 mg/l.

COD removal efficiencies were 90% or higher until

45 days of operation. After initial COD increased,

COD removal decreased from 90% to 70-75% during

15 days in both reactors (Tables 6 and 7). Because ofthis, operation cycle time was increased (24 h) and

VSS concentration was decreased (4000 mg/l) in

SBR. Beginning from 65thday, COD removal values

of both reactors reached 85% and above. COD

removal values reached 90% in the 90thday (Tables 6

and 7). SVI values were recorded as 30 ml/g in ASR

and 43 ml/g in SBR on the 36thday and remained at

the same level until the 45th day. When initial COD

values were increased, sludge settling was worst until

100th day. Beginning from 100

th day, sludge settling

Table 4Main parameters of sour cherry juice for ASR

Timedays

CODimg/l

CODemg/l

COD removalefficiency, %

TSSmg/l

MLVSSmg/l

13 2875 5890 533014 1145 45 9620 1200 90 92 4520 415026 1400 70 9434 1260 135 89 3600 3590

39 750 125 8342 950 60 9443 950 145 85 3540 337049 990 85 92

50 3940 360056 1145 95 9274 1000 130 86 2760 261075 1310 95 92

76 1310 180 8683 1085 130 88 2990 281090 1190 90 9297 1500 85 92 4320 4160

104 1350 45 97 2390 2310111 2990 2740116 1030 45 96120 2550 2420

123 1600 75 95133 1100 50 95 3080 2870

Average 1257 93.42105 91.368 3547.5 3330Standard deviation 432.3023 38.47 4.119 999.17 890.372

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Table 5Main parameters of sour cherry juice for SBR

Timedays

CODimg/l

CODemg/l


TSSmg/l

MLVSSmg/l

13 2875 305 89 2400 2310

14 1145 55 9520 1200 70 94 2720 255026 1400 70 95

34 1260 75 94 3440 303039 750 145 8142 950 80 9243 950 105 89 3860 3440

49 990 90 9150 3620 336056 1145 50 9674 1000 130 86 3310 3130

75 1310 110 9176 1310 160 88

83 1085 70 93 3830 358090 1190 105 91

97 1500 50 95 5070 4800104 1350 45 97 3360 3240111 4130 3840116 1030 35 97

120 5850 5620123 1600 40 98133 1100 65 94 4960 4750

Average 1257 92.75 92.3 3879.167 3637.5

Standard deviation 432.3 60.94 4.193 996.415 972.776

Table 6Main parameters of apple juice for ASR

Time

days

CODi

mg/l

CODe

mg/l

COD removal

efficiency, %

TSS

mg/l

MLVSS

mg/l

3 1650 55 97 2790 24907 1625 90 948 1625 60 96

10 1600 90 9415 1600 95 94

16 1585 105 9317 1600 105 93 3560 344022 1600 55 9723 1600 70 96

31 1600 208 8736 1900 195 90 6610 645039 2735 400 8443

45 2740 1440 4849 5920 580051 1980 196052 1755 1130 60 2530 2440

5658 2900 360 8759 4180 391061

62 2970 720 76 3470 325065 2500 320 8769 2160 2040

(Contd)

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Table 6Main parameters of apple juice for ASRContd

Timedays

CODimg/l

CODemg/l


TSSmg/l

MLVSSmg/l

72 2650 405 8578 2635 300 88

84 2500 240 90 252091 3400 299097 3340 310098 2750 216 92 3270 3025

116 2470 130 95

117 4220 3980125 2560 110 96 4550 4277131 2500 144 94 5290 5025139 2500 125 95 5830 5538

Average 2166 286.72 88.32 3860 3732.188Standard deviation 527.51 339.88 11.589 1383.97 1365.53

Table 7Main parameters of apple juice for SBR

Timedays

CODimg/l

CODemg/l


TSSmg/l

MLVSSmg/l

3 4610 44607 1650 55 97

8 1625 45 9710 1625 70 9615 1600 50 9716 1600 115 93

17 1585 110 93 5040 465022 1600 80 9523 1600 55 9731 1600 80 95

36 1600 208 97 4710 4500

39 1900 184 9043 2735 761 70 8320 806045 2775 640 76

49 2740 11280 1029051 3780 376052 4400 420056 1755 675 75

58 3480 334059 2900 1340 54

6162 4080 388065 2970 930

69 2500 380 85 3730 356072 5170 490078 2650 70 97

84 2635 375 86 445091 2500 380 85 3440 322097 3900 360098 4610 4240

116 2750 192 93

117 2470 217 91 5170 4940125 6460 6201131 2560 105 96 6560 6232139 2500 128 95 5610 5330

Average 2177 301.875 89.13043 5200 4964.611Standard deviation 537.542 335.842 10.943 1909.77 1799.33

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begun to be good. SVI value was 80 ml/g in SBR and

50 ml/g in ASR in the 125th day8.

Determination of Kinetic Coefficients

Determination of Endogenous Decay Rate (bH)

A reactor (vol, 2 l; initial biomass conc, 2000 mg/l)

was started for the determination of bH.

Oxygen consumption rates (OCRs) were measured

during 10 days for sour cherry juice wastewater.

During 12 days, OCRs were measured for apple

juice wastewater. Then, a graphic was drawn

for each wastewater using these values (Figs 2a and

3a). Slope of the curve on graph is equal to bH, which

for sour cherry juice wastewater and apple juice

wastewater was 0.32 day-1 and 0.13 day-1,

respectively.

Determination of Maximum Specific Growth Rate (m)

A reactor (2 l) with F/M=4 mgCOD/mgMLVSSwas prepared for each wastewater. OCRs were

measured during 1 h. A graphic was drawn using

these values for each wastewater (Figs 2b and 3b).

Slope of the curve on graph is equal to (m-bH). The

m values were determined for sour cherry juicewastewater and apple juice wastewater as 5.15 day-1

and 6.18 day-1, respectively.

Microbiological Examination and Monitoring of Aerobic

Reactors Systems

Microbiological examination of apple juice

production wastewater treatability research inboth aerobic reactors was begun at 69

th day and

continued for the following 20 days. Most interes-ting observation was the overwhelming dominance of

fungi,Aspergillus spp. (Fig. 4).This does not support

the previous arguments that growth rates associated

with bacteria are higher than fungi9. These

filamentous fungi cells have septa and foot cellbelonging to Aspergillus genus. Abundance of fungi

filaments was classified10,11 as excessive or

dominant. The number of the filaments was over 50

within each floc, almost completely covering them.

This situation was probably caused by wastewatercomposition of fruit juice production andpH. Because

the content of wastewater of fruit juice production had

very rich fruit sugar and other carbohydrates. pH of

the system has decreased to 6-6.5 and even under 6

even though the systempH was everyday adjusted to

7-7.5. Slightly acidic pH values and high

carbohydrate concentration are very favorable to

fungi, so they can multiply faster than other

competitors and get advantage to dominate the

system. Fungi can tolerate acidic conditions and

Fig. 2Determination for sour cherry juice wastewater of:a) Endogenous decay rate; b) Maximum specific growth rate

Fig. 3Determination for apple juice wastewater of:

a) Endogenous decay rate; b) Maximum specific growth rate

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adverse environments better than bacteria. Another

important cause of fungi domination is nutrient,

especially nitrogen (N) and phosphorus (P) is that

bacteria can flourish and multiply even in very low

concentrations of N and P9. N and P concentrations in

wastewaters of fruit juice production are very low

(N: 3.3-114 mg/l; P: 0.104-0.98 mg/l). This kind of

wastewater composition can provide advantage

primarily to fungi. It can be said that fungi are good

and valuable microorganisms to treat this kind ofwastewaters. On the other hand, this can be a problem

in aeration tank for bulking and in final sedimentation

tank for settlement of solids. These problems can

cause process control and low effluent quality

problems11

.

Filamentous fungi (Aspergillusspp.) has increased

rapidly and dominated to the systems after 78th day.

Abundance of filamentous fungi reached excessive

numbers and caused solid separation and bulking

problems in apple juice production wastewater

treatability research. This problem has been

determined by microscopic examinations of the

activated sludge and the result of SVI measurements

(>150 ml/g). Fungi domination has not caused

significant decrease in COD removal yield other than

some slight decline. Zoogleal floc structure of the

activated sludge was very good and appearance was

normal. During the microbiological examinations, a

few kinds of ciliated, attached and flagellated

protozoa, a filamentous bacterium species, afilamentous fungus, and gram-negative and gram-

positive bacteria have been observed in floc structure.

An unidentified filamentous bacterium, which

contributed to floc macro-structure with 2-3

filaments/flock in normal times, has helped to

overcome settlement problem of the activated sludge.

Filamentous bacterium has caused settlement problem

when the filaments spread into bulk solution from the

floc, causing a decrease in density of the floc. It has

not caused settlement and bulking problems when it

Fig. 4Microphotos belonging to reactors

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stayed in the floc structure. Fungi filaments haveincreased their numbers overwhelmingly in 100thday

of operation, and all flocs have been completely

covered by fungi filaments and even flocs could notbe seen due to the abundance of filaments. Fungi

spores have also contributed to this structure. Therewas no settlement or bulking problems in these

situations. Probably, the reason is that, eukaryotic

cells (fungi cells) are bigger, heavier and longer than

prokaryotic cells (filamentous bacteria), so they could

settle easily. Whenever filamentous bacteria haveincreased their numbers and spread out from the flock

towards the bulk solution, settlement and bulking

problems have occurred.

ConclusionsIn anaerobic treatment of fruit juice industry

wastewaters (90%) COD removal efficiencies were

obtained with an organic loading up to 5 kg

COD/m3/day. In aerobic treatability studies, high

COD removal ( 90%) was obtained at treatment

studies of each wastewater at cycle time of 12 h in

SBR. Sometimes, COD removal values decreased.

When OLRs were changing and if there was not

enough aeration, low COD removal values were

observed. There were not settling problems in aerobic

treatability studies. Sometimes, SVI values increased

depending on pH. The difference in the endogenousdecay coefficient and maximum specific growth rate

constant for apple juice and sour cherry juice

wastewaters was caused by the different easily

biodegradable fractions of wastewaters. At the end of

microbiological examination, fungi overwhelminglydominated the system. But, there were no settlement

or bulking problems in these situations.

AcknowledgementsThis research was supported by the Research Fund

of Istanbul University (Project Number: BYP-

281/03112003).

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