JouRNAL Or CUEMTcAL ErucrnEERrNGThe lnstitution of En tnegfs, BangladeshVol. GhE 27, No.

CONTENTS

Potentiality of Biodiesel Production From Non-Edible Oil: Bangladesh PerspectiveKaniz Ferdous, M. Rakib Uddin, Rehnuma Islam, Maksudur R. Khan and M. A. Islam

Optimization of Three-Step Method For Biodiesel Production From Waste Cook OilKaniz Ferdous, M. Rakib Uddin, M. Rahim Uddin, Maksudur R. Khan, M. A. Islam

Essential Latex Processing Plant (ELPP): A Pioneer Approach in the Production of ConcentrateLatex from Local Resource to Manufacture Male Contraceptive in BangladeshSadia Afreen, Kh. Rashedul Haque , Md. Shariful Islam, Dr M Kadrul Huda

Enzymatic Hydrolysis of Rice Straw to Fermentable Sugar: Kinetic StudyPradip saha, M. R. Khan, T. K. Deb, S. Majumdar, F. Alam and N. C Sarker

Operation and Maintenance of Secondary Reformer -Lessons from Plant experiencesSk Shafi Ahmed and Md. Enamul Haque

Extraction of Pectin from lemon peel: Technology developmentSalam M. A., Jahan N., Islam M. A. and Hoque M. M.

Preparation and Labeling of Technitium-99M Kit in Pharmaceutical Grade Clean RoomRuhul Amin M., Azizd Haque, Avishek Biswas and Taufiq Hassan Mozumder

Optimization and fabrication of a portable biogas reactorAbuYousuf, SalmaAkhter Iqbal, Niloy Chandra Sarker, Md. Nazmul Hasan and

Mohammad Shahadat Hussain Sarker

Effect of DopingAgent on Elution Profile of TC-99M Generation and Labeling of TC-99M with MDPRuhul Amin M*., Azizul Haque, Hreeshit Kumar and SayemYousuf

Pharmaceutical Waste Water Treatment & Related Economic Aspects for Reusein the Context of BangladeshSadiaAfreen and Smita Paul

Power Generation from Coal-A reviewMridul Sarker, Debasish Chowdhury and Iqbal Hossain*

Design and Fabrication of Membrane Less Microbial Fuel Cell (ML-MFC) using f,'oodIndustries Wastewater for Power GenerationMaksudur R. Khan, M. S. A. Amin, S. Sarker and K. Ferdaus

Study of Hydrate Formation and Inhibition for LPGMridul Sarker, Debasish Chowdhury and Iqbal Hossain

A Comparative study on the photocatalytic degradation of industrial dyes using modifiedcommercial and synthesized TiO2 photocatalystsMohammed Mastabur Rahman, Fatema Akthar Choudhury, Md. Delowar Hossain, Md. NamwarulIslam Chowdhury, Sadia Mohsin, Md. Mehdi Hasan, Md. Fakar Uddin and Niloy Chandra Sarker

Modern Techniques to Analyses Production DataSalmaAkhter Iqbal, Md. Zahidul Islam and Mohammad Shahedul Hossain

Thermal and Mechanical properties of epoxy-jute fiber compositeH. Ahmad, M. A. Islam and M. F. Uddin

Treatment of Textile Dyes by Bio-chemical Process in Stirred Tank SequencingBatch Bioreactor (STSBBR)Pradip saha, M. R. Khan, T. K. Deb, S. Y. Sony and A. C. Baishnab

EditorEngr. Md. Alchtaruzzaman, F/5888

Editoriol boord

Chairman

Vice-chairman

Members

Editor

Editorial Assistance

Engr. Md. Habibur Rahman, F-2452Vice-president (Academic & International), IEB

Dr. Engr. Dil Afroza Begum, F-3522Chairman, Chemical Engineering DivisionalCommittee,IEB

Engr. Md. Abdus Sabur, F-6100Honorary General Secretary, IEB

Engr. Md. Mosaddeque Hossain, F-3994Vice-chairman, Chemical Engineering DivisionalCommittee,IEB

Engr. Mohammad Mahbub Alam, M- 19668General Secretary, Chemical Engineering DivisionalCommittee,IEB

Dr. Engr. Mohammad SabderAli, F-1875

Dr. Engr. A.K.M. Abdul Quader, F.203L

Engr. Kazi Md. Ziaul Haque, M-929 4

Engr. Md. Ak'htartzzaman, F-5888

Dr. Engr. Md. EasirArafat Khan, M-28666LecturerBangladesh University of Engineering and TechnologyDhaka- 1000, Bangladesh

Discloimer

The lnstitution of Engineers. Bonglodesh does not toke ony responsibility of ihe opinions, comments orsuggestion expressed in this journol.

a

Journal of Chemical Engineering, IEBVol. ChE 27,No.2, December, 2012

Optimization and fabrication of a portable biogas reactor

Abu Yousuf*, Salma Akhter Iqbal, Niloy Chandra Sarker, Md. Nazmul Hasan,Mohammad Shahadat Hussain Sarker

Department of Chemical Engineering and Polymer Science, Shahjalal University of Science andTechnolo gy, Sy lhet-3 I I 4, Bangladesh.

Abstract

The study was conducted to investigate the production of biogas from kitchen waste (KW) with co-digestion of cowmanure (CM) by using anaerobic digestion process. The experimental protocol was defined to examine the effect oforganic toading rate (OLR), temperature, and NaOH-treatment on the efficiency of the production of biogas. A portable

biogas reactor was fabricated for efficient biogas production which included an agitation and a heating system. The

KW and CM were co-digested at ratios of 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1 and 8:l respectively at loading rates of 50,

100,150, 200,250,300, 350, and 400 {L.The highest degradation rate of 7.96 mUg was obtained from the loading rate

of 200 !L. Furthermore, KW was co-digested at different temperatures 25,35, 40,45, and 500C, maintaining the same

loading rate of 200 {L and the highest degradation rate of Z.gS mUg was inspected at temperatrue 350C. The alkali(NaOH) was used to fteat KW to improve biogas production and four NaOH doses 0.57o, 1.}Vo, l.SVo, and2.0Vo onwetmatter basis of KW were applied. The highest degradation rate l3.ZlmUg was obtained from 1.57o NaOH which was

almost double compared to untreated KW. In addition, 39J4 Vo more biogas could be produced from 1.57o NaOH-treated KW than untreated KW. The results were further verified by scaling up to a semi-continuously-operating pilot-plant reactor co-digesting KW with CM as bacterial seed and confirmed that no negative impact was imposed at

optimized conditions.

1. INTRODUCTION

Disposal of municipal solid waste (MSW) is a majorconcern in large cities of Bangladesh. Kitchen waste,

which is defined as the food residuals generated fromrestaurants, cafeterias, student dormitories, hotels, and

households etc, is a main organic fraction of MSW.Anaerobic digestion of organic waste to producebiogas has been regarded as an attractive technology ofheating waste biomass, for example, agriculture waste,

organic fraction of MSW, as well as organic waste

from food industry. In terms of high biodegradabilityof KW, it is a typical organic waste suitable foranaerobic digestion.Although biodegradable organic matter could be used

as sole feedstock in anaerobic digestion, the digestionprocess tends to fail without the addition of extemalnutrients and buffering agents []. Co-digestion withanimal manure or sewage sludge as base feedstock isan effective way to improve buffer capacity andachieve stable performance [2-5]. On the other hand,

the addition of readily biodegradable organic matterinto animal manure digester could sigrificantlyincrease biogas production due to the changes offeedstock characteristics. According to another report[6], co-digestion of cattle slurry with fruit andvegetable waste obtained more cumulative biogasproduction than the digestion of cattle slurry alone.While co-digestion of KW and CM was expected toachieve better performance due to the advantages ofco-digestion such as more suitable physiochemicalcharacteristics and improved nutrients balance [7].

Corresponding Author: Abu YousufE-mail: ayousut'cep @vahoo.com

The prime object of this work was to investigate theprospect of KW for biogas generation as a renewable

energy sources by means of co-digestion with CM at

different ratio in batch experiment, also investigate the

effects of OLR, temperature and treatment of KW withNaOH. A portable biogas reactor was also fabricated

for efficient biogas production and ultimate goal was

to protect the environment from the bad effect MSW interms of waste to energy.

2. MATERIALS AND METHODS

2.1 Waste collection and processingThe kitchen wastes used in this study were collected

from the student dormitory, residential area ofShahjalal University of Science & Technology. Cowmanures were collected from the village nearby theuniversity. The kitchen waste contains mainlyvegetables, non-used vegetable, cooked rice, etc. Afterremoving the bones, metals, chopsticks, plastic bags

and inorganic residuals, wastes were cut into small size

then they were mashed into pest like substances byusing hopper.

2.2 Experimental DesignA simple lab- scale experiment was designed trsingnine digesters which were made of glass. The volumeof digester was 1 L each and working volume was 0.5

L. Each digester was connected with water chamber(plastic bottles) by a plastic pipe (gas pipe) which was

used to allow the produced gas to flow through it to thewater chamber and hence displaced the same volume

of water from the chamber, which was then used to

L

flow through another plastic pipe (water pipe) to thewater collector. The set up is illustrated in Fig.l.

Gas \Vater

Eigester tr1.afer \{aterChanrber"t collector

Gar collector

Fig.l: Schematic diagram of the lab-scaleexperimental set-up. (Adapted from [8]).

2.3 Anaerobic digester operationLab- scale experiments were operated in batch mode.Firstly we prepared two digesters, D-1.1 and D-1.2 foronly KW and co-digested KW with CM. The digesterswere run at room temperature (28-300C). The substratecomposition of the digesters is shown in the Table-1.

Table-I.: Composition of digester for pre-experimentalstudies

Digester Organic biomass,KW (s)

Bacteria seed,

cM (e)D-1.1 r00 00D-1.2 r00 25

For the subsequent studies, nine digesters were set upas described in the Table-2 maintaing loading rate,mixing ratio and temperature. All digester were putinto water bath to maintain temperature. Retentiontime of digestion was l0- 13 days depending on thegas production. The digestion experiment for eachloading rate was triplicate.

Table-2: Digesters specification

2.4 Pilot-scale

The pilot-scale experiments were operated in semi-continuous mode. According to the lab-scaleexperiment, the loading rate of 200 g/L was carried outin this trial. Subsequently, the total amount of water 3lliters, 6.2 Kg of KW and 1.55 Kg of CM were puuedinto the digester. The agitator was stirred up manually.

3. RESULTS AND DISCUSSION

3.1 Biogas production from KW and co-digestedKW with CMCurrer:rtly, almost all household digesters are usinganimal manure as feedstock to produce biogas.However, manul€ has limited availability in manyplaces particularly in urban areas. Therefbre,alternative feedstocks need to be developed. Biogastechnology have been using mainly in rural area butthere is also a plenty of biomass in urban area.. Themain composition of MSW is KW and it is mostlyunused in all cities of Bangladesh. The biogascomponents and biogas yield depend on a feedmaterial due to the difference of their characteristics-

Digester Mixingratio ofKW to

CM

KW(g)

CM(g)

Loadingl'ate ofKW(eil)

Pal'ameter to

be

optimized

Optirnization of loading rate Loading rate/stL\

D-2.1 0: 00 25 0 0D-2.2 I 25 25 50 50D-2.3 2 50 25 100 r00D-2.4 J 75 25 150 150

D-2.5 4 100 25 200 200D-2.6 5: 1,25 25 250 250D-2.7 6: 150 25 300 300D-2.8 ,7

t'7 5 25 350 350D-2.9 8: 200 25 400 400

Optimization of temperature Temperature/oc)

D-3.1 4 00 25 200 25D-3.2 4: 00 25 200 35D-3.3 4 00 25 200 40D-3.4 4 00 25 200 45D-3.5 4 00 25 200 50

Optimizat cn of alkalinit NaOH (7o)

D-4.1 4 00 25 200 0.sD-4.2 4 00 25 200 1.0

D-4.3 4 00 25 200 1.5

D-4.4 4 00 25 200 2.0

E20o

€rao

hfrCt.E s0

0

910r.112

flfi

T

f,T

tE

Fig.2: Comparisons on biogas production from KW

coldigested^KW & CM at temperattue (35"C) and

loading rate200 gll-.

t D*gradatiofi rate

Kl[q,rrns or b tfftY,$*t

*

Fig.3: Comparisons on degradation rate (mUg)

bJween KW and co-digested KW & CM at

temperature (350C) and loading rate200 gll-'

Fig.3 shows that the digester D-1.2 -(KW and CM)

pr6duced more biogas. The degradation rate for

digester D-1.2 (KW & CM) was 7.96 mVg and that of

D--1.1 was 1.83 mUg. KW contains more readily

biodegradable compositions and it is easily converted

to biogas but it has low buffer capacity and is,easy to

acidiff t9l. So, the co-digestion of KW and CM would

comUine together the positive characteristics of the

both feed stocks and could potentially bring better

digestion performance. The benefits of co-digestion

inJluded improved biogas yield, economic adv,antages

derived from the sharing of equipment and easier

handled of mixed waste etc [10].

3.2. Effect of organic loading rateOne of the main objectives of this study was to

determine the performance of the anaerobic digestion

process when operated at different loading rates'

therefore, it was important to evaluate process

performance in term of biogas production or

iegradation rates. To optimize the loading rate, several

baiches were run at ambient temperature and at 350C'

Fig.4: Degraclation rate (ml/g) of KW at temperature

tr4)J

i<i

: ,!Q

Hl

g1ffi

Effi

tniu^l*11.i

t+ |

6ll i

!Ef.l-Iii i

Et'

Ij

0 ",1*---

t

fr*E

Er

I

Fig.5: Degradation rate (mUg) of KW at room

temperature for various loading rates

Fig.4 represented the biogas production-f^or per gram of

ffr auring the digester's operation at differentloading

rates. The" degraJation rates were 'l'92, 7'96' 6'48'

1 .g 6, 7 .5, 7.08; 7'08 & 7.00 respectively conesponding

loading rate of 50, 100, 150, 200,250,300, 350' & 400

etL.Tiedegradation rate KW for 200 g/L and 100 g/L

ir".. ,utn" and higher than other loading rate'

According to Fig.5, when digestion were carried out at

.oorn ,"rip"ratuie, the degraclation rates were 5'48'

5,.42, 5.06, 5.55, 4.84, 4.81, 5.26 and 5'39 mVg

respectively corresponding to same loading rates' In

tort .ot"., maximum biogas was produced when the

reactor was loaded at the rate of 200 g/L of KW'

However, manure has limited availability in many

places particularly in urban areas' Therefore' it was

i.i.d to tne maximum amount of KW and minimum

amount of CM.

3.3 Effect of temPeratureBiogas production from organic substrates is.strongly

affe-ctedby the temperature where anaerobic digestion

takes placl. The process of organic material anaerobic

digestion takes place in three main temperature ranges:

frJm 10-25'C (psychrophilic conditions), from 30-

37"C( mesophilii conditions) and from 48-55"C (

thermophilic conditions). The majority of methanogens

(the microorganisms that form methane from organic

.,f;3f;388ff8- I-tndiugl'ilrt(gm r) "f

I

matter) belong to the mesophilic. They grow quickly inthis temperature range and exhibit high degrees ofconversion. In practice, this has direct implications inthe design of biogas plants as they are the most stableoperating plants. The stability and growth conditions inthe digester at mesophilic conditions make the process

more balanced, more resistant to chemicals that inhibitdigestion (e.g. ammonia) and capable of treatingefficiently a great variety of different types of biomassand waste. The effect of temperature was studied withmaintaining sarne loading rate of 200 gll-.

Fig.6: Daily biogas production from KW for loadingrate of 200 g/L at different temperature.

. Degradation rat0

3.4 Eff'ect of addition of NaOHSodium hydroxide (NaOH) was added with KW inliquid state at 35"C temperature to intprovebiodegradability and anaerobic biogas production.

Forrr NaOH doses of 0.57o, 1.0Vc, l.Sc/o, and 27o on

wet matter basis of KW were applied. The raw and

NaOH-added KW were then anaerobically digested at

900

s00

700

Bor:5oo.!ooL900

*oo*ooX, N

? onY4 6

Fig.S: Daily biogas production from KW with treated

by various percentages NaOH in loading rate of 200g/L at temperature 350C.

Fig.9: Degradation rate Orllg of KW treated bydifferent percentages of NaOH for loading rate of2OOgfi, at iemperature 350C.

From Fig.8 and 9, it was detected that for 0.57o, 1.07o,

l.5%o and 2.0Vo of NaOH the daily biogas productionand degradation rates (mUg) were 12.63, 11.36, 13.21

and7.76 respectively. It also found that first two (0.5Vo

&. l.\Vo) digesters took retention time 6 days and nexttwo (1.5%o & 2.0Vo) digesters took retention time 8

days. Although, retention time was longer for 1.57o ofNaOH but biogas production or degradation rate was

also higher than others. Therefore, KW incorporatedby l.5Vo NaOH was optimum in this experiment.

3.5 Fabrication of portable biogas reactorPortable biogas reactor was fabricated and run out insemi-continuous system. The digester volume was

about 62 liters. Fig.l0 illustrates the experimental set-

Lrp. The biogas plant could be constructed over earth

*4e*0.5 %NaOH

**1.0.%NaOlf

"';l '1.5?iNa0Fl

ti

cLl

Iln

.9b

t i1

F-l

o-l

tsr,'lbal:i719a.lEq. l

d41

!irlEol* r j

0 r." tfi45 500c)

Fig.7: Degradation rate (ml-lg) of KW for loading rateof 200 gll- at different temperature.

When temperature dropped down microbial activitydecreased, as a result biogas production or degradationrate was also decreased. On the other hand with theincreased of temperature some microorganisms begunto die, once again the production of biogas ordegradation rate gradually decreased. From the Fig.6and 7, it was observed that at 35'C the biodegradabilitywas high and biogas production was maximum. So, the

optimum temperature of biogas production was

recorded at 35oC.

)qn

225

2003 rrr{a 150

E 12s

E 100

Et5a50Elt 4J

.3nco

-{*Ar zS"C

-fi*Ar 35"C

,*rmi**At 40"C

**s.-At 45"C

"-+*AtsC"C

0 r ? 3 4 5 6 fl.r8 91011121314

E ncor.ldaliflrl

surface or underground. In Bangladesh, undergroundbiogas plants are mostly used in rural areas.

Bangladesh is a flood prone country and large parts ofBangladesh have experience of flood almost everyyear. So, entering of flood water into the digester willbreak down its operational capacity. Temperature is

another importaot factor for biogas production. Butwrderground biogas plant has low temperature as a

result they can not run with full efficiency to produce

biogas. Homogeneous mixing of slurry in the

underground digester is not maintained. This digester

is not user friendly as it is not carried out one place to

another. This type of plant is mostly used in rural areas

but not used in urban areas.

The portable biogas plant prepared in our study, easy

to carry from one place to another, it will not affected

by flood water, temperature also can be maintained at

desire condition. Heating system can easily be

installed. Even heat can be supplied to the system

when it is needed (e.g. in winter). For homogeneousmixing of biomass, agitator can be used in plant. Thistype of digester or plant can be widely used in bothurban and rural areas, and even in multi storied

building.

(Hot wattr 1tr)

-I.+{}lotwatffsrt)I

Fig.10: A portable biogas digester set-up.

4. CONCLUSIONS

Anaerobic digestion is promising process for reducingthe amounts of biodegradable waste in MSW stream

and is also an energy producer from renewable

resources. Considering the characteristics of the high-moisture solid waste, anaerobic digestion represents a

feasible and effective method to convert the waste to

biogas fuel. Maximum biogas (l3.2lmUg) was

produced under the conditions- temperature 350C,

OLR 200g/L and treated with l.S%o NaOH. When KWwas treated by l.5%o NaOH, it could be achieved39.74Vo more biogas production. Finally a portable

biogas digester was fabricated and it was workingefficiently under the optimum conditions. The reactor

was mainly designed for use in the top of multistoriedbuilding. Successful implementation of anaerobic

digestion as the method of waste treatment leads to the

regional utilization of renewable energy resources, as

well as the disposal of high moistening content of KW'

Acknowledgement: The authors are grateful forthe financial support of this research from Research

Center, Shahjalal University of Science and

Technology, Sylhet-3 I 14, Bangladesh.

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Adsorption of acid dyes on to granular activatedcarbon in hxed beds, Wat. Res.31(8): 2093-2101.

2. Tzan,Y.L. and Yang, Y. M. (2001), On the criteriaof nucleate pool boiling enhancement by surfactantaddition to water, Trans IChemE, 79 PartA: 409-415.

3. Kwon, O. K., and Pletcher, R. H. (1981), Prediction of theIncompressible Flow Over a Rearward-Facing Step,

Technical Report HTL-26, CFD-4, Iowa State Univ.,Ames, IA.

4. Lee, Y., Korpela, S. A., and Home, R. N. (1982),Structwe of Multi-Cellular Natural Convection in a Ta11

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