Biogas Potential of Co-Substrates in Balinese Biogas Plants.
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Edit or s
Publishing Edit or Wohlbier , T.
Send m ail
105 Springdale Lane, Millersville, USA, PA 17551;
Xu , X.P.
Send m ail
Huaqiao Universit y, Minist ry of Educat ion Engineering Research Cent er for Brit t le Mat erials
Machining; Xiam en, China, 361021;
Edit or ia l Boa r d
Cheng , Y.S.
Send m ail
Harbin I nst it ut e of Technology, School of Mat erials Science and Technology; P.O. Box 435,
Harbin, China, 150001;
Lucas , M.
Universit y of Glasgow, Depart m ent of Mechanical Engineering; Glasgow, Unit ed Kingdom ,
G12 8QQ;
Pa pe r
Tit le Pa ge
Experim ent al I nvest igat ion on t he Use of Secondary Refrigerant in Freezer for Energy
Savings
Aut hors: Aries Prih Har yono, Edi Sukam t o, Sum eru, Farid Nasir Ani
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Abst ract : This st udy present s an experim ent al st udy on a freezer which has sm all cooling
capacit y. Typically a freezer uses prim ary refrigerant ...
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Mirsoheil
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aut om obile engines and t he differences in it s...
239
Flow Charact erist ics around Four Circular Cylinders in Equispaced Arrangem ent near a Plane
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Abst ract : The flow charact erist ics around four circular cylinders in equispaced arrangem ent
locat ed near a plane wall were invest igat ed...
245
Experim ent al St udy on t he Perform ance of I n - Cabin Vent ilat ion Syst em
Aut hors: Abdul Lat iff Zulkarnain, Cheong Weng Soon, Bam bang Supriyo, Mohd Rozi Mohd Perang,
Henry Nasut ion, Azhar Abdul Aziz
Chapt er 1: Energy Conv ersion
Abst ract : Parking a car under t he hot sun wit h all windows closed could increase in - cabin
t em perat ure as high as 70°C. For such sit uat ion, hu m an...
251
Reduct ion of Energy Losses in t he End Wall Junct ion Area t hrough t he Addit ion of Forw ard
Facing St ep Turbulent Generat or
Aut hors: H. Mirm ant o, Sut risno, H. Sasongko, D.Z. Noor
Chapt er 1: Energy Conv ersion
Abst ract : The research is conduct ed in order t o reduce energy losses caused by t he
secondary flow in t he endwall j unct ion. This phenom enon is caused...
256
Biogas Pot ent ial of Co- Subst rat es in Balinese Biogas Plant s
Aut hors: Daniel Net t , I . Nyom an Suprapt a Winaya, I . Made Agus Put rawan, Rolf Wart m ann, Werner
Edelm ann
Chapt er 1: Energy Conv ersion
Abst ract : This research aim s t o give an ov erview on how t o im prov e t he biogas y eild in
Balinese digest er plant s using various co- subst rat es which are...
262
CFD Sim ulat ion of Heat Transfer in Fluidized Bed React or
Aut hors: I . Nyom an Supr apt a Winaya, I . Made Agus Put rawan, I . Nyom an Gede Suj ana, Made Sucipt a
Chapt er 1: Energy Conv ersion
Abst ract : This st udy aim s t o predict heat t ransfer from a heat ed bed in a gas fluidized bed
using Syam lal- OBrien drag coefficient . Discret e part icles...
267
I nfluence of Bioet hanol- Gasoline Blended Fuel on Perform ance and Em issions Charact erist ics
from Port I nj ect ion Sinj ai Engine 650 cc
Aut hors: Bam bang Sudarm ant a, Sudj ud Darsopuspit o, Dj oko Sungkono
Chapt er 1: Energy Conv ersion
Abst ract : Perform ance and em issions charact erist ics from port inj ect ion SI NJAI engine 650
cc operat ing on bioet hanol- gasoline blended fuels of 0% , 5% ,...
273
I m proved Energy Saving for R22 Building Air Condit ioning Ret rofit t ed wit h Hydrocarbon
Refrigerant , St udy Case: Civil Engineering Depart m ent of I TS
Aut hors: Widyast ut i, Ar y Bacht iar Krishna Put ra, Ridho Hant oro, Eky Novianarent i, Arrad Ghani
Safit ra
Chapt er 1: Energy Conv ersion
Abst ract : Sepuluh Novem ber I nst it ut e of Technology ( I TS) encourages t he ECO Cam pus
program . The program enables I TS t o syst em at ically ident ify,...
281
The Evaluat ion of a Rigid Sail of Ship Using Wind Tunnel Test
Aut hors: Aries Suliset yono
Chapt er 1: Energy Conv ersion
Abst ract : This paper described t he evaluat ion of rigid sail perform ances by using t he wind
t unnel t est . The rigid sail m odels were dev eloped in t he...
287
Applied Mechanics and Materials Vol. 493 (2014) pp 262-266
© (2014) Trans Tech Publications, Switzerland
doi:10.4028/www.scientific.net/AMM.493.262
Biogas Potential of Co-Substrates in Balinese Biogas Plants
Daniel Nett 1,a, I Nyoman Suprapta Winaya2,b, I Made Agus Putrawan3,c,
Rolf Wartmann4,d and Werner Edelmann5,e
1
Management Center Innsbruck, Environmental and Process Engineering, 6020 Innsbruck, Austria
2
3
Mechanical Engineering Department, Udayana University, Bali-Indonesia
Magister Program of Mechanical Engineering, Udayana University, Bali-Indonesia
4
Life sciences and facility management, Einsiedlerstr. 29, 8820 Wädenswil, Switzerland
5
Arbeitsgemeinschaft Bioenergie, arbi GmbH,Baar, Lättichstr. 8, 6340 Baar, Switzerland
a
[email protected] , [email protected], [email protected],
d
[email protected], [email protected]
Keywords: co-substrate, biogas, anaerobic, digestion, biogas yield, Indonesia, improvement
Abstract
This research aims to give an overview on how to improve the biogas yeild in Balinese digester plants
using various co-substrates which are available in Bali. A series testing on the digestibility of
substrates were set up either in the field or in the biogas laboratory. In-field analyses like testing the
CO2-content and taking samples from digested manure were undertaken. Analyses such as dry matter
(DM) and organic dry matter (oDM) determination, pH measurement and FOS/TAC were handled in
the biogas laboratory. The huge number of different fruits in Bali gives a good opportunity to use their
wastes like Durian hulls and Banana peelings, which can not be used anymore, as co-substrates in
biogas plants. The results of these investigations allow to estimate the additional biogas yield, when
adding co-substrates to a cow manure biogas plant.
Introduction
The majorities of small scale biogas plants in Bali are built by the “SIMANTRI” Project and
mostly follow the Chinese type. The biogas reactor is constructed from cement, pebble, brick, sand
and waterproof coating material [2]. The biogas plant has an open inlet, a digester (with around 6 m3
volume) and an open outlet (Figure 1). A small pipe with 1 cm diameter leads to a gas-flow-meter and
further to a U-turn pipe where the pressure is measured. A valve on the head of the reactor can be
opened and closed for taking gas samples e.g. for CO2-content testing purpose. The manure is stored
next to the stall and biogas plant and in most cases not protect from sun and precipitation. The biogas
plant is fed in non-continuous intervals mainly ranging between three to six days.
Figure 1: SIMANTRI 258 biogas plant
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP,
www.ttp.net. (ID: 36.86.237.235-08/01/14,05:27:22)
Applied Mechanics and Materials Vol. 493
263
This preliminary study aims to give an overview about the current development of biogas and is
concentrated in the area of Southern Bali and the city of Ubud. Through the “SIMANTRI” Project,
launched in 2009 by the Governor of Bali, till now more than 350 farmer groups run small cattle
biogas plants. This “SIMANTRI” Project uses synergy effects from organic farming and animal
husbandry, mainly cows. The cow manure is utilized for producing biogas for small cocking devices
as well as light [1]. Also some small self made biogas plants, fed with cow and pig manure, are run by
local farmers. For this study two “SIMANTRI” biogas plants (SIMANTRI 258 and 260) and one self
made biogas plants are observed.
Methodology
To analyze and evaluate the performance of existing agricultural biogas plants a biogas laboratory
has to be build up located at Technique Campus of Udayana University in Jimbaran / Bali. In-field
analyses like testing the CO2-content and taking samples from digested manure are undertaken.
Analyses such as dry matter (DM) and organic dry matter (oDM) determination, pH measurement
and FOS/TAC are handled in the biogas laboratory. The laboratory offers the possibility to digest
available substrates from Bali. The results of these first tests allow to estimate the additional biogas
yield, when adding co-substrates to a cow manure biogas plant. Two series for testing the digestibility
of substrates are set up. Whereas results of biogas yield for the first series are presented in this paper.
FOS/TAC- and pH-measurement are undertaken, after sampling the fresh digested inoculum, in the
biogas laboratory. Each FOS/TAC- and pH-average value consists of three single measured test. The
pH-value is measured during the FOS/TAC-measurement.
The term FOS/TAC refers to the proportion between organic volatile (FOS) acids and the total
alkaline carbonates (TAC) [3]. This methode is used to measure the performance of the biogas plants
mentioned above.
The FOS/TAC is calculated by the following formula:
/
=
,
, ,
,
/ ,
,
/ ,
,
(1)
Formula explication:
- The factor of 1,66 (numerator) refers to the amount of substrate used by the Prof. Weiland
(20g) and the molar mass of sulphuric acid used in the titration (0,05 molar, 0,1 N).
- The factor of 0,15 (numerator) corrects the CO2 contained in the sample
- The numbers (numerator) and 250 (denominator) are factors oft he multiplication oft he
empiric formula.
- X,X is the measured start pH at each FOS/TAC testing.
An option to increase the biogas yield of biogas plants fed only with cow manure is to add
co-substrates to the digestion process. Therefore ten different co-substrates are tested on dry matter
(DM) using Eq. 2 and organic dry matter (oDM) using Eq. 3 [4].
% =
(2)
% =1−
( 3)
Results and Discussion
Measuring the CO2-content is done during the visits of the biogas plants. The observed
CO2-contests range between 35% of CO2 in selfmade and 50% of CO2 in SIMANTRI 260 biogas
plant as seen in Fig. 2.
264
Advances in Applied Mechanics and Materials
Fig. 2. Measured CO2-contents in the observed biogas plants
The left three bundles of columns show SIMANTRI 258, the middle SIMANTRI 260 and the right
columns show the selfmade biogas plant in Fig. 2 above. This means the composition methane gas in
selfmade digester is better than the Simantri 258 and 260.
Table 1. FOS/TAC-measurement
name of biogas plant date FOS/TAC average
SIMANTRI 258
15.04.13
0,23
29.04.13
0,26
27.04.13
0,39
SIMANTRI 260
15.04.13
0,93
29.04.13
2,08
27.04.13
1,19
SELFMADE
15.04.13
0,24
29.04.13
0,27
27.04.13
0,17
The performance between the three biogas plants vary a lot as seen in Table 1. As SIMANTRI 258
is hungry and balanced feeded, SIMANTRI 260 is always overfeeded. In Opposite the selfmade
biogas plant could use more feed to work much better.
In the first series of anaerobic digestion, Banana peeling, Durian hulls, Orange peeling and Snake
fruit / Salak are chosen as the four substrates to determine.
This list below can be used to get an idea, when the biogas plant is hungry, balanced or overfeeded:
> 0,6
overfeeded; reduce feeding rapidly
0,5 – 0,6 danger of overfeeding; reduce feeding
0,3 – 0,5 balanced feeding; stay at feeding level
0,2 – 0,3 hungry; increase feeding
< 0,2
very hungry; increase feeding rapidly
The pH-level should range between a minimum of 7,2 and 7,8 pH to have ideal digestion with
microorganism. SIMANTRI 258 is within this toleranze, whereas SIMANTRI 260 is below and the
selfmade biogas plant above this limit (Table 2).
Applied Mechanics and Materials Vol. 493
265
Table 2. pH-measurement
name of biogas plant
SIMANTRI 258
SIMANTRI 260
SELFMADE
date
15.04.13
29.04.13
27.04.13
15.04.13
29.04.13
27.04.13
15.04.13
29.04.13
27.04.13
pH average
7,75
7,76
7,80
6,94
6,52
7,06
8,01
7,92
8,10
Table 3. DM and oDM determination of co-substrates
Material
Avocado hull
Banana peeling
Corn
Durian hull
Manggo hull
Nangka hull
Orange peeling
Pineapple peeling
Rice straw
Snake fruit / Salak
DM [%]
24,43
13,42
18,90
14,22
19,99
16,60
13,19
9,99
37,46
17,93
oDM [%]
96,40
76,02
96,29
91,73
95,00
92,77
95,39
91,07
74,87
92,71
After calculating the dry matter using Eq. 2 and organic dry matter uding Eq. 3, a certain amount of
co-substrate; 20 g +- 5% of fresh material are put into laboratory scaled digesters. The total volume of
these digesters are 1090 ml. They are filled with 100 ml of fresh inoculum straight from the biogas
plants, the co-substrate and with fresh water to a 300 ml mark. Afterwards filled with nitrogen gas and
closed gastight with a rubber stopper. A small needle is but through the rubber stopper and connected
to a gastight three-way-valve. There the pressure can be measured.
After 30 days the experiment is finished. Within these 30 days the pressure has to be measured,
depending on the high of pressure, daily or every second / third day. After each measurement the gas
has to be released and at the end a sum of all pressures has to be calculated. The experiment is carried
out under real conditions, like they appear in the nature. So the average temperature over these days is
29,0 °C. The result can be plot as Fig. 3, showing the curve of increase in pressure when adding
co-substrate to pure manure inoculum [4].
The norm volume of biogas is calculated with Equation below:
=
ℎ
273,15 +
273
1,013
(Eq. 4)
266
Advances in Applied Mechanics and Materials
1000.000
Norm volume [ml]
800.000
600.000
Inoculum + Cellulose
Banana peeling
Durian hull
Orange peeling
Snake fruit / Salak
400.000
200.000
0.000
Days
Fig. 3. Biogas yield with additional co-substrates
It is seen from Fig. 3, Banana peeling and Durian hulls show a very good performance and increase
the biogas yield very much. Orange peeling and Snake fruit show at the beginning good improvement
of biogas yield but it decreases afterwards. Possible reasons could be the acidity of both fruits or the
essential oils within them. Those might influence the bacteria so they can not digest the substrates.
Further investigations have to be carried out to give more detailed information about adequate
co-substrates for improving the performance of existing biogas plants.
Summary
So far all known biogas plants in Bali are only fed with mainly cattle manure and sometimes with pig
or a mixture of cattle and pig manure. The huge number of different fruits in Bali gives a good
opportunity to use their wastes like hulls and peelings, which can not be used anymore, as
co-substrates in biogas plants. It was found using co-substrate such as Banana peeling and Durian
hulls could increase the production of biogas.
References
[1] Agung Suryawan Wiranatha, Island Economy towards a Low-Carbon Economy (A Case Study
of Bali Province, Indonesia), Udayana University, Bali – Indonesia, pp. 10-11 (2009).
[2] T. W. Widodo, A. Asari, Ana N., Elita R., Design and development of biogas reactor for farmer
group scale, Indonesian Journal of Agriculture 2(2), pp. 121-128 (2009).
[3] D. Moerschner, Instructions to carry out FOS/TAC analysis by titration, Fermenter – Doktor,
(2012).
[4] Moisture in Peat, (967.03) Official Methods of Analysis, Association of Official Analytical
Chemists, 15th Edition, 1990, http://www.foragetesting.org/lab_procedure /sectionB /2.2/part2.2.2.2.
htm (2013).
[5] S. Baum, H. Zweifel, Gasbildung (GB21) Messung des Biogaspotentials, Insitut für
Biotechnologie, zhaw Züricher Hochschule für angewandte Wissenschaften, Zürich, Schweiz (2007).
Applie d M e cha nics a nd M a t e r ia ls
I SSN :
1662- 7482
Abou t :
Applied Mechanics and Mat erials publishes only com plet e volum es on given t opics,
proceedings and com plet e special t opic volum es. Thus, we are not able to publish stand-alone
papers.
Applied Mechanics and Mat erials specializes in t he rapid publicat ion of proceedings of
int ernat ional conferences, w orkshops and sym posia as well as st at e- of- t he- art volum es on
t opics of current int erest in all areas of m ech anics and t opics relat ed t o m at erials science.
Aut hors ret ain t he right t o publish an ext ended, significant ly updat ed version in anot her
periodical.
I n de x in g: I ndex ed by Elsevier: SCOPUS w ww.scopus.com and Ei Com pendex ( CPX)
www.ei.org/ . Cam bridge Scient ific Abst ract s ( CSA) www.csa.com , Chem ical Abst ract s ( CA)
www.cas.org, Google and Google Scholar google.com , I SI ( I STP, CPCI , Web of Science)
www.isinet .com , I nst it ut ion of Elect rical Engineers ( I EE) www.iee.org, et c.
Publishing edit or: Thom as Wohlbier, TTP USA, t .wohlbier@t t p.net
Su bscr ipt ion :
I rregular: approx. 80- 100 volum es per y ear.
The
subscript ion
rat e
for web
access
is
EUR
St anding order price: 20% discount off list price
I SSN print 1660- 9336 I SSN cd 1660- 9336 I SSN web 1662- 7482
1089.00
per
year.
Pe r iodica l:
APPLI ED M ECH AN I CS AN D M ATERI ALS
I SSN : 1 6 6 2 - 7 4 8 2
Edit or ia l boa r d:
Edit or s
Publishing Edit or Wohlbier , T.
Send m ail
105 Springdale Lane, Millersville, USA, PA 17551;
Xu , X.P.
Send m ail
Huaqiao Universit y, Minist ry of Educat ion Engineering Research Cent er for Brit t le Mat erials
Machining; Xiam en, China, 361021;
Edit or ia l Boa r d
Cheng , Y.S.
Send m ail
Harbin I nst it ut e of Technology, School of Mat erials Science and Technology; P.O. Box 435,
Harbin, China, 150001;
Lucas , M.
Universit y of Glasgow, Depart m ent of Mechanical Engineering; Glasgow, Unit ed Kingdom ,
G12 8QQ;
Pa pe r
Tit le Pa ge
Experim ent al I nvest igat ion on t he Use of Secondary Refrigerant in Freezer for Energy
Savings
Aut hors: Aries Prih Har yono, Edi Sukam t o, Sum eru, Farid Nasir Ani
Chapt er 1: Energy Conv ersion
Abst ract : This st udy present s an experim ent al st udy on a freezer which has sm all cooling
capacit y. Typically a freezer uses prim ary refrigerant ...
233
I nv est igat ion of Nat ural Gas Com posit ion Effect s on Knock Phenom enon in SI Gas Engines
Using Det ailed Chem ist ry
Aut hors: Ahm ad Javaheri, Vahid Esfahanian, Ali Salavat i- Zadeh, Mehdi Darzi, Seyyed Moj t aba
Mirsoheil
Chapt er 1: Energy Conv ersion
Abst ract : Considering t he growing role of nat ural gas as an alt ernat ive fuel in st at ionary and
aut om obile engines and t he differences in it s...
239
Flow Charact erist ics around Four Circular Cylinders in Equispaced Arrangem ent near a Plane
Wall
Aut hors: A.Grum m y Wailanduw, Triyogi Yuwono, Wawan Aries Widodo
Chapt er 1: Energy Conv ersion
Abst ract : The flow charact erist ics around four circular cylinders in equispaced arrangem ent
locat ed near a plane wall were invest igat ed...
245
Experim ent al St udy on t he Perform ance of I n - Cabin Vent ilat ion Syst em
Aut hors: Abdul Lat iff Zulkarnain, Cheong Weng Soon, Bam bang Supriyo, Mohd Rozi Mohd Perang,
Henry Nasut ion, Azhar Abdul Aziz
Chapt er 1: Energy Conv ersion
Abst ract : Parking a car under t he hot sun wit h all windows closed could increase in - cabin
t em perat ure as high as 70°C. For such sit uat ion, hu m an...
251
Reduct ion of Energy Losses in t he End Wall Junct ion Area t hrough t he Addit ion of Forw ard
Facing St ep Turbulent Generat or
Aut hors: H. Mirm ant o, Sut risno, H. Sasongko, D.Z. Noor
Chapt er 1: Energy Conv ersion
Abst ract : The research is conduct ed in order t o reduce energy losses caused by t he
secondary flow in t he endwall j unct ion. This phenom enon is caused...
256
Biogas Pot ent ial of Co- Subst rat es in Balinese Biogas Plant s
Aut hors: Daniel Net t , I . Nyom an Suprapt a Winaya, I . Made Agus Put rawan, Rolf Wart m ann, Werner
Edelm ann
Chapt er 1: Energy Conv ersion
Abst ract : This research aim s t o give an ov erview on how t o im prov e t he biogas y eild in
Balinese digest er plant s using various co- subst rat es which are...
262
CFD Sim ulat ion of Heat Transfer in Fluidized Bed React or
Aut hors: I . Nyom an Supr apt a Winaya, I . Made Agus Put rawan, I . Nyom an Gede Suj ana, Made Sucipt a
Chapt er 1: Energy Conv ersion
Abst ract : This st udy aim s t o predict heat t ransfer from a heat ed bed in a gas fluidized bed
using Syam lal- OBrien drag coefficient . Discret e part icles...
267
I nfluence of Bioet hanol- Gasoline Blended Fuel on Perform ance and Em issions Charact erist ics
from Port I nj ect ion Sinj ai Engine 650 cc
Aut hors: Bam bang Sudarm ant a, Sudj ud Darsopuspit o, Dj oko Sungkono
Chapt er 1: Energy Conv ersion
Abst ract : Perform ance and em issions charact erist ics from port inj ect ion SI NJAI engine 650
cc operat ing on bioet hanol- gasoline blended fuels of 0% , 5% ,...
273
I m proved Energy Saving for R22 Building Air Condit ioning Ret rofit t ed wit h Hydrocarbon
Refrigerant , St udy Case: Civil Engineering Depart m ent of I TS
Aut hors: Widyast ut i, Ar y Bacht iar Krishna Put ra, Ridho Hant oro, Eky Novianarent i, Arrad Ghani
Safit ra
Chapt er 1: Energy Conv ersion
Abst ract : Sepuluh Novem ber I nst it ut e of Technology ( I TS) encourages t he ECO Cam pus
program . The program enables I TS t o syst em at ically ident ify,...
281
The Evaluat ion of a Rigid Sail of Ship Using Wind Tunnel Test
Aut hors: Aries Suliset yono
Chapt er 1: Energy Conv ersion
Abst ract : This paper described t he evaluat ion of rigid sail perform ances by using t he wind
t unnel t est . The rigid sail m odels were dev eloped in t he...
287
Applied Mechanics and Materials Vol. 493 (2014) pp 262-266
© (2014) Trans Tech Publications, Switzerland
doi:10.4028/www.scientific.net/AMM.493.262
Biogas Potential of Co-Substrates in Balinese Biogas Plants
Daniel Nett 1,a, I Nyoman Suprapta Winaya2,b, I Made Agus Putrawan3,c,
Rolf Wartmann4,d and Werner Edelmann5,e
1
Management Center Innsbruck, Environmental and Process Engineering, 6020 Innsbruck, Austria
2
3
Mechanical Engineering Department, Udayana University, Bali-Indonesia
Magister Program of Mechanical Engineering, Udayana University, Bali-Indonesia
4
Life sciences and facility management, Einsiedlerstr. 29, 8820 Wädenswil, Switzerland
5
Arbeitsgemeinschaft Bioenergie, arbi GmbH,Baar, Lättichstr. 8, 6340 Baar, Switzerland
a
[email protected] , [email protected], [email protected],
d
[email protected], [email protected]
Keywords: co-substrate, biogas, anaerobic, digestion, biogas yield, Indonesia, improvement
Abstract
This research aims to give an overview on how to improve the biogas yeild in Balinese digester plants
using various co-substrates which are available in Bali. A series testing on the digestibility of
substrates were set up either in the field or in the biogas laboratory. In-field analyses like testing the
CO2-content and taking samples from digested manure were undertaken. Analyses such as dry matter
(DM) and organic dry matter (oDM) determination, pH measurement and FOS/TAC were handled in
the biogas laboratory. The huge number of different fruits in Bali gives a good opportunity to use their
wastes like Durian hulls and Banana peelings, which can not be used anymore, as co-substrates in
biogas plants. The results of these investigations allow to estimate the additional biogas yield, when
adding co-substrates to a cow manure biogas plant.
Introduction
The majorities of small scale biogas plants in Bali are built by the “SIMANTRI” Project and
mostly follow the Chinese type. The biogas reactor is constructed from cement, pebble, brick, sand
and waterproof coating material [2]. The biogas plant has an open inlet, a digester (with around 6 m3
volume) and an open outlet (Figure 1). A small pipe with 1 cm diameter leads to a gas-flow-meter and
further to a U-turn pipe where the pressure is measured. A valve on the head of the reactor can be
opened and closed for taking gas samples e.g. for CO2-content testing purpose. The manure is stored
next to the stall and biogas plant and in most cases not protect from sun and precipitation. The biogas
plant is fed in non-continuous intervals mainly ranging between three to six days.
Figure 1: SIMANTRI 258 biogas plant
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Applied Mechanics and Materials Vol. 493
263
This preliminary study aims to give an overview about the current development of biogas and is
concentrated in the area of Southern Bali and the city of Ubud. Through the “SIMANTRI” Project,
launched in 2009 by the Governor of Bali, till now more than 350 farmer groups run small cattle
biogas plants. This “SIMANTRI” Project uses synergy effects from organic farming and animal
husbandry, mainly cows. The cow manure is utilized for producing biogas for small cocking devices
as well as light [1]. Also some small self made biogas plants, fed with cow and pig manure, are run by
local farmers. For this study two “SIMANTRI” biogas plants (SIMANTRI 258 and 260) and one self
made biogas plants are observed.
Methodology
To analyze and evaluate the performance of existing agricultural biogas plants a biogas laboratory
has to be build up located at Technique Campus of Udayana University in Jimbaran / Bali. In-field
analyses like testing the CO2-content and taking samples from digested manure are undertaken.
Analyses such as dry matter (DM) and organic dry matter (oDM) determination, pH measurement
and FOS/TAC are handled in the biogas laboratory. The laboratory offers the possibility to digest
available substrates from Bali. The results of these first tests allow to estimate the additional biogas
yield, when adding co-substrates to a cow manure biogas plant. Two series for testing the digestibility
of substrates are set up. Whereas results of biogas yield for the first series are presented in this paper.
FOS/TAC- and pH-measurement are undertaken, after sampling the fresh digested inoculum, in the
biogas laboratory. Each FOS/TAC- and pH-average value consists of three single measured test. The
pH-value is measured during the FOS/TAC-measurement.
The term FOS/TAC refers to the proportion between organic volatile (FOS) acids and the total
alkaline carbonates (TAC) [3]. This methode is used to measure the performance of the biogas plants
mentioned above.
The FOS/TAC is calculated by the following formula:
/
=
,
, ,
,
/ ,
,
/ ,
,
(1)
Formula explication:
- The factor of 1,66 (numerator) refers to the amount of substrate used by the Prof. Weiland
(20g) and the molar mass of sulphuric acid used in the titration (0,05 molar, 0,1 N).
- The factor of 0,15 (numerator) corrects the CO2 contained in the sample
- The numbers (numerator) and 250 (denominator) are factors oft he multiplication oft he
empiric formula.
- X,X is the measured start pH at each FOS/TAC testing.
An option to increase the biogas yield of biogas plants fed only with cow manure is to add
co-substrates to the digestion process. Therefore ten different co-substrates are tested on dry matter
(DM) using Eq. 2 and organic dry matter (oDM) using Eq. 3 [4].
% =
(2)
% =1−
( 3)
Results and Discussion
Measuring the CO2-content is done during the visits of the biogas plants. The observed
CO2-contests range between 35% of CO2 in selfmade and 50% of CO2 in SIMANTRI 260 biogas
plant as seen in Fig. 2.
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Advances in Applied Mechanics and Materials
Fig. 2. Measured CO2-contents in the observed biogas plants
The left three bundles of columns show SIMANTRI 258, the middle SIMANTRI 260 and the right
columns show the selfmade biogas plant in Fig. 2 above. This means the composition methane gas in
selfmade digester is better than the Simantri 258 and 260.
Table 1. FOS/TAC-measurement
name of biogas plant date FOS/TAC average
SIMANTRI 258
15.04.13
0,23
29.04.13
0,26
27.04.13
0,39
SIMANTRI 260
15.04.13
0,93
29.04.13
2,08
27.04.13
1,19
SELFMADE
15.04.13
0,24
29.04.13
0,27
27.04.13
0,17
The performance between the three biogas plants vary a lot as seen in Table 1. As SIMANTRI 258
is hungry and balanced feeded, SIMANTRI 260 is always overfeeded. In Opposite the selfmade
biogas plant could use more feed to work much better.
In the first series of anaerobic digestion, Banana peeling, Durian hulls, Orange peeling and Snake
fruit / Salak are chosen as the four substrates to determine.
This list below can be used to get an idea, when the biogas plant is hungry, balanced or overfeeded:
> 0,6
overfeeded; reduce feeding rapidly
0,5 – 0,6 danger of overfeeding; reduce feeding
0,3 – 0,5 balanced feeding; stay at feeding level
0,2 – 0,3 hungry; increase feeding
< 0,2
very hungry; increase feeding rapidly
The pH-level should range between a minimum of 7,2 and 7,8 pH to have ideal digestion with
microorganism. SIMANTRI 258 is within this toleranze, whereas SIMANTRI 260 is below and the
selfmade biogas plant above this limit (Table 2).
Applied Mechanics and Materials Vol. 493
265
Table 2. pH-measurement
name of biogas plant
SIMANTRI 258
SIMANTRI 260
SELFMADE
date
15.04.13
29.04.13
27.04.13
15.04.13
29.04.13
27.04.13
15.04.13
29.04.13
27.04.13
pH average
7,75
7,76
7,80
6,94
6,52
7,06
8,01
7,92
8,10
Table 3. DM and oDM determination of co-substrates
Material
Avocado hull
Banana peeling
Corn
Durian hull
Manggo hull
Nangka hull
Orange peeling
Pineapple peeling
Rice straw
Snake fruit / Salak
DM [%]
24,43
13,42
18,90
14,22
19,99
16,60
13,19
9,99
37,46
17,93
oDM [%]
96,40
76,02
96,29
91,73
95,00
92,77
95,39
91,07
74,87
92,71
After calculating the dry matter using Eq. 2 and organic dry matter uding Eq. 3, a certain amount of
co-substrate; 20 g +- 5% of fresh material are put into laboratory scaled digesters. The total volume of
these digesters are 1090 ml. They are filled with 100 ml of fresh inoculum straight from the biogas
plants, the co-substrate and with fresh water to a 300 ml mark. Afterwards filled with nitrogen gas and
closed gastight with a rubber stopper. A small needle is but through the rubber stopper and connected
to a gastight three-way-valve. There the pressure can be measured.
After 30 days the experiment is finished. Within these 30 days the pressure has to be measured,
depending on the high of pressure, daily or every second / third day. After each measurement the gas
has to be released and at the end a sum of all pressures has to be calculated. The experiment is carried
out under real conditions, like they appear in the nature. So the average temperature over these days is
29,0 °C. The result can be plot as Fig. 3, showing the curve of increase in pressure when adding
co-substrate to pure manure inoculum [4].
The norm volume of biogas is calculated with Equation below:
=
ℎ
273,15 +
273
1,013
(Eq. 4)
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Advances in Applied Mechanics and Materials
1000.000
Norm volume [ml]
800.000
600.000
Inoculum + Cellulose
Banana peeling
Durian hull
Orange peeling
Snake fruit / Salak
400.000
200.000
0.000
Days
Fig. 3. Biogas yield with additional co-substrates
It is seen from Fig. 3, Banana peeling and Durian hulls show a very good performance and increase
the biogas yield very much. Orange peeling and Snake fruit show at the beginning good improvement
of biogas yield but it decreases afterwards. Possible reasons could be the acidity of both fruits or the
essential oils within them. Those might influence the bacteria so they can not digest the substrates.
Further investigations have to be carried out to give more detailed information about adequate
co-substrates for improving the performance of existing biogas plants.
Summary
So far all known biogas plants in Bali are only fed with mainly cattle manure and sometimes with pig
or a mixture of cattle and pig manure. The huge number of different fruits in Bali gives a good
opportunity to use their wastes like hulls and peelings, which can not be used anymore, as
co-substrates in biogas plants. It was found using co-substrate such as Banana peeling and Durian
hulls could increase the production of biogas.
References
[1] Agung Suryawan Wiranatha, Island Economy towards a Low-Carbon Economy (A Case Study
of Bali Province, Indonesia), Udayana University, Bali – Indonesia, pp. 10-11 (2009).
[2] T. W. Widodo, A. Asari, Ana N., Elita R., Design and development of biogas reactor for farmer
group scale, Indonesian Journal of Agriculture 2(2), pp. 121-128 (2009).
[3] D. Moerschner, Instructions to carry out FOS/TAC analysis by titration, Fermenter – Doktor,
(2012).
[4] Moisture in Peat, (967.03) Official Methods of Analysis, Association of Official Analytical
Chemists, 15th Edition, 1990, http://www.foragetesting.org/lab_procedure /sectionB /2.2/part2.2.2.2.
htm (2013).
[5] S. Baum, H. Zweifel, Gasbildung (GB21) Messung des Biogaspotentials, Insitut für
Biotechnologie, zhaw Züricher Hochschule für angewandte Wissenschaften, Zürich, Schweiz (2007).