JOURNAL

ScientificRESEARCH

Volume 5 No. 2

Research Management Institute

ISSN 1675-7009

Dec 2008

SCIENTIFIC RESEARCH JOURNAL

Chief Editor Prof. Dr. Zaiki Awang,

Universiti Teknologi MARA, Malaysia

Managing Editor Assoc. Prof. Dr. Razidah Ismail,

Universiti Teknologi MARA, Malaysia

Editorial Advisory and Review Board Prof. Dr. Ir. Wahyu Kuntjoro, Universiti Teknologi MARA, Malaysia

Assoc. Prof. Dr. Salmiah Kasolang, Universiti Teknologi MARA, Malaysia Assoc. Prof. Ir. Dr. Muhammad Azmi Ayub, Universiti Teknologi MARA, Malaysia

Prof. Dr. Ichsan Setya Putra, Bandung Institue of Technology, Indonesia Prof. Dr. Mohd. Nasir Taib, Universiti Teknologi MARA, Malaysia

Prof. Dr. Ir. Shah Rizam Mohd. Shah Baki, Universiti Teknologi MARA, Malaysia Prof. Dr. Titik Khawa Abd. Rahman, Universiti Teknologi MARA, Malaysia

Prof. Dr. Luciano Boglione, University of Massachusetts Lowell, USA Prof. Dr. K. Ito, Chiba University, Japan

Prof. Dr. Azni Zain Ahmed, Universiti Teknologi MARA, Malaysia Prof. Ir. Dr. Ideris Zakaria, Universiti Malaysia Pahang, Malaysia

Prof. Dr. Abd. Aziz Dato’ Abd. Samad, Universiti Tun Hussein Onn, Malaysia Prof. Sr. Ir. Dr. Suhaimi Abd. Talib, Universiti Teknologi MARA, Malaysia

Assoc. Prof. Ir. Dr. Kartini Kamaruddin, Universiti Teknologi MARA, Malaysia Assoc. Prof. Dr. Hamidah Mohd. Saman, Universiti Teknologi MARA, Malaysia

Dr. Robert Michael Savory, Universiti Teknologi MARA, Malaysia Assoc. Prof. Dr. Mohd Hanapiah Abidin, Universiti Teknologi MARA, Malaysia

Copyright © 2008 Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means; electronics, mechanical, photocopying, recording or otherwise; without prior permission in writing from the Publisher. Scientific Research Journal is jointly published by Research Management Institute (RMI) and University Publication Centre (UPENA), Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia. The views and opinion expressed therein are those of the individual authors and the publication of these statements in the Scientific Research Journal do not imply endorsement by the publisher or the editorial staff. Copyright is vested in Universiti Teknologi MARA. Written permission is required to reproduce any part of this publication.

SCIENTIFIC RESEARCH JOURNAL

Vol. 5 No. 2 December 2008 ISSN 1675-7009

1. Renewable Energy from Biogas Generated by Sewage

Sludge-Relationship Between Sludge Volume and Power Generated Suzana Ramli Aminuddin Baki Muhamad Azmi Ayub Suhaimi Abdul Talib Ramlah Mohd Tajuddin Ismail Atan Jurina Jaafar Nur Aziafwani Abdullah

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2. Temperature Effects on Stripping Performance of Superpave Design Mix Ekarizan Shaffie Juraidah Ahmad Mohd Yusof Abdul Rahman

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3. Mechanical Properties of Rice Husk Ash as a Mineral Addition in Concrete Kartini Kamaruddin Hamidah Mohd Saman

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4.

Arbitration in Construction Industry in Malaysia Nor Azmi Bakhary Azmi Othman

35

5.

Performance Evaluation of AODV, DSR And DYMO Routing Protocol In MANET Siti Rahayu Abdul Aziz Nor Adora Endut Shapina Abdullah Mior Norazman Mior Daud

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Scientific Research Journal

ISSN 1675-7009© 2008 Universiti Teknologi MARA (UiTM), Malaysia.

Vol. 5 No. 2, 1-9, 2008

Renewable Energy from BiogasGenerated by Sewage Sludge –Relationship between SludgeVolume and Power Generated

Suzana Ramli1,3, Aminuddin Mohd Baki1, Muhamad Azmi Ayub2,Suhaimi Abdul Talib1, Ramlah Mohd Tajuddin1, Ismail Atan1,

Jurina Jaafar1 & Nur Aziafwani Abdullah1

Institute for Infrastructure Engineering andSustainable Management (IIESM)

1Faculty of Civil EngineeringUniversiti Teknologi MARA (UiTM), Malaysia

2Faculty of Mechanical EngineeringUniversiti Teknologi MARA (UiTM), Malaysia

3Email: suzana_ramli@yahoo.com

ABSTRACT

Biogas is a product of decomposition of organic matter during the process ofanaerobic digestion (AD). The main components are methane and carbondioxide. The methane content in the biogas enables it to be used as fuel whichcan be converted to heat and electricity. The biogas generated by the anaerobicdigesters has the potential to be redirected from the flaring facilities torenewable energy (RE) facilities. The biogas may then be used to generateelectricity, which in turn can operate the sewage treatment plant (STP) itself.However, feedbacks from the sewerage industry indicated that heavyinvestments are needed for any RE initiatives on biogas generated by sewagesludge. In order to find the cost effective way of generating energy from biogas,fundamental relationships are necessary to enable development of prototypein the future. Thus, this paper presents a study to establish the relationshipbetween the volume of sludge and the amount of power and energy that can begenerated.

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Keywords: Anaerobic digestion, biogas, methane, renewable energy, sewagesludge, sludge volume to power ratio

Introduction

In response to the rapid development and industrialisation that had takenplace over the last 15 years, the energy consumption in this country hasincrease drastically. To cope with the increase in demand much of thenatural hydrocarbon fuel had been utilised, resulting in pollution of theenvironment and increase in hydrocarbon fuel prices. To overcome this,alternate fuels are being sought worldwide. In Malaysia, work has alreadybegun to identify potential source of RE since 1999. The Governmenthad embarked on efforts to raise awareness on the benefits of RE andthe viability of such projects [1]. In October 2002, Pusat Tenaga Malaysia(PTM) was appointed as the agency to implement the Biomass-basedPower Generation and Cogeneration in the Malaysian Palm Oil MillsIndustry project (BioGen), where empty fruit bunches that is usuallydisposed as waste will be used to generate power [1]. Following thisinitiatives, the government announced the Fifth Fuel Policy to include REas alternative fuel resources. The Eight Malaysia Plan contains provisionson the use of biomass for power generation with a specific target that by2005 five percent of the power supplied to the national grid should comefrom RE [1].

Biogas is created during the process of AD. The main componentsof the biogas are methane and carbon dioxide. Methane content in thebiogas enables it to be used as fuel which can be converted to heat andelectricity. The biogas generated within the anaerobic digesters has thepotential to be redirected from the flaring facilities to RE facilities. Thebiogas may then be used to generate electricity, which in turn can operatethe STP itself. The use of biogas generated during the AD of sewagesludge has been reported in many parts of the world.

Biogas production from sewage sludge treatment is already a well-established means of generating energy in the UK. Over 10 billion litresof sewage are produced everyday in England and Wales. AD of sludgeproduces a mixture of methane (60 – 65 %), CO2 (35 – 40 %) andtraced gases. Impurities, such as hydrogen sulphide and water, areremoved and the resulting biogas is then used in boilers or combined heatand power (CHP) systems. Biogas may also be used for other applications,such as vehicle fuel, if CO2 is also removed [2]. In addition to this, reports

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Renewable Energy from Biogas Generated by Sewage Sludge

on studies in Yorkshire and Humberside region have been made [3].There are 610 STP with a total equivalent population of over 6,000,000.The total biogas resource from this population, assuming 0.028 m3 perhead per day is approximately 390 GWh per year.

In China, biogas is used by about 25 million people for cooking andlighting for 8-10 months a year. China also has reliable experience ofrunning diesel and gasoline engines with biogas [4]. Bangkok, Thailand,with about 10 million people, is expected to produce up to 63,000 tons/year of sewage sludge by 2010 [4]. The amount of biogas generatedduring AD of sewage and brewery sludge at different mixing ratios canbe determined [4]. It was found that the maximum quantity of biogaswas generated at a mixing ratio of 25:75 (optimum). Table 1 shows theelectricity generation using biogas is quite common around the world.

There are about 9,500 STP (public and private) and over 1 millionsindividual septic tanks in Malaysia. These sewerage facilities generatedabout 6.5 millions tons of sewage sludge annually [6]. Reviews weremade on the need for RE, such as those obtained through the use ofbiogas from sewage sludge to generate energy in terms of electricity orheating [6]. It was found that evaluation of potential use of biogas from

Table 1: Use of Biogas Generated for Electricity or Heating [5]

Plant Capacity Sludge Biogas BiosolidsTons of Dry Type Utilisation UtilisationSolids/ year

Oxley Creek Municipal, mixture Electricity Dewatered cakeWWTP, Brisbane, 10,800 of primary and generation and for agriculture

Australia secondary plant heating

Kapusciska 7,650 Municipal mixture Electricity Dewatered cakeWWTP, of primary and generation, for agriculturePoland secondary plant heating

and distributedheating

Bruxelles Nord 18,800 Municipal, mixture Stream BiosolidsWWTP, of primary and production destroyedBelgium secondary (thermal in ATHOS

hydrolysis &ATHOS)

Niigata WWTP, 1,200 Municipal, mixture Test Plant Test PlantJapan of primary and

secondary

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sewage sludge in Malaysia shows that it is technically feasible but thereare logistics factors that may cause limitations.

Based on success of biogas utilisation around the world, the totalvolume of sewage generated in Malaysia is more than sufficient for REgeneration. Reviews were made on four regional STP equipped withanaerobic digesters, which are currently operating in Malaysia. It wasfound that these four plants are viable for any RE initiatives. However,there was no great effort for the renewable energy project due to lack ofexpertise and technology locally. Feedbacks from the sewerage industryalso indicate that substantial cost and effort are needed for any REinitiatives on biogas generated by sewage sludge. Therefore, this paperwill study the potential of implementing an effective method of REgeneration from biogas from sludge by developing the relationshipsbetween the critical parameters. One of the most basic and importantrelationships is the ratio between sludge volume to power generated.This ratio enables both the economic and technical feasibility of a REfacility constructed to be evaluated.

Development of Methodology

A laboratory based study, utilising bench-scale reactors will be designedas the first stage of the study. The experimental set-up to establish thesludge volume to power ratio will be made. At the end of the study, thesludge volume to power ratio can be applied for utilising biogas for energygeneration. The research consists of six samples and three cycles as inFigure 3. In this research, there were two type of sludge involved whichwas pure sludge and sludge mix with wastewater. These two types ofsludge give difference rate of volume of biogas in 40 days.

Batch Digestion Tests

Digestion tests will be performed in a reactor at ambient temperature.The total volume of reactors used is 1L. 500 mL of sampled sludge willbe fermented in the reactor for a few days. The produced biogas will becollected in a cylinder (gas collector), which is equipped with a gasregulator.

Figure 1 shows the apparatus for biogas collection and measurement.The apparatus consists of a reactor which has tubes connected to thethermometer and cylinder. The thermometer will monitor the temperature

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Renewable Energy from Biogas Generated by Sewage Sludge

of sludge in the reactor. The biogas generated will be collected in acylinder. The cylinder then will be equipped with a gas regulator.

Electrical Energy Transformation

The resulting biogas normally consists of 50 to 60 percent methane, 30 to40 percent carbon dioxide and small quantities of residues. The gas iscompressed and purified if it contains larger amounts of contaminants,and stored temporarily in a gasometer from which it is fed to a CHP unitat constant pressure. A gas engine transforms the energy stored in thebiogas into mechanical and thermal energy. It also powers a synchronousgenerator, which in turn generates electrical energy for the operation ofthe STP. The field transformation of sewage sludge into biogas, which inturns generates electrical energy, is illustrated in Figure 2 [7].

Results and Analysis

i. Analysis of First TestThe reading of 150 ml sample during primary test was increasedfrom 0.98 to 2.00 in a day. It later become constant for some day

Figure 2: The Field Transformation of Sewage Sludge into Biogas,which in Turn Generates Electrical Energy [7]

Heatconsumer

Heat exchanger

Exhaust gas

Electricalenergy

Gaspurifier

GasometerGascompressor

Sewage gas

Sewage sludge, agriculturalutilization possible

Digester

Sewagesludge

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before the reading dropped drastically and become inconstant untilthe test cycle being ended. However, it can be seen through thegraph that the methane production was decreased slowly at the endof the day. The reading of 200 ml, 250 ml, 300 ml and 350 ml ofsamples during primary test was somehow constant throughout the40 days.

ii. Analysis of Second TestThe readings of all samples were much unrelated to another. All ofthe reading started with high value and started to increased anddecreased from time to time. The only similarity of them was that itall decreased estimated around 20 days of the experiment.

From the second test also, it can be observed as the amount ofthe sample may not contribute much to the finding if the gaps are notobvious. This is because that the higher the amount does not necessarygive higher value of methane. This finding was the result of theamount of methane from 200 ml sample was still available until day28 whereas the amount of methane from 250 ml sample had stoppedat day 18. The same approved by amount of methane from 300 mlthat still available until 38 days even though the 350 ml sample wasalready finished the production of its methane at day 30.

iii. Analysis of Third TestThe readings of all samples were not much related to another. All ofthe reading started somewhere at the average values and started toproduce anomalous pattern from time to time. The readings however,were not changed with significant values.

Figure 3: Sludge Volume versus Time

S lu d g e V o lu m e v s T im e

0

0 . 2

0 . 4

0 . 6

0 . 8

1

1 . 2

1 . 4

0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5

T i m e ( d a y )

Slu

dg

e V

olu

me

F ir s t C y c le - R a ws lu d g e ( in je c t w it h n i t r o g e ng a s )S e c o n d C y c le - S lu d g e m ixe dw it h w a s t e w a t e r ( 1 d a yf e r m e n t a t io n )T h ir d C y c le - S lu d g e m ixe dw it h w a s t e w a t e r ( 7 d a y sf e r m e n t a t io n )

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Renewable Energy from Biogas Generated by Sewage Sludge

Figure 4: Results of Biogas Production versus Sludge Volume

Reading of Methane vs Volume during First Test

day 1

day 10

day 21

day 30day 35

day 1 day 10 day 21 day 30 day 35day 1 day 10 day 21 day 30 day 35day 1 day 10 day 21 day 30 day 35day 1 day 10 day 21 day 30 day 35

0.00

0.50

1.00

1.50

2.00

2.50

Volume (ml)

Met

hane

Dat

ecto

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eadi

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) 150ml200ml250ml300ml350ml

Reading of Methane vs Volume during Second Test

1.91

0.65

0.210.00 0.00

0.260.00 0.00 0.00

0.86

0.02 0.00 0.000.38 0.24

0.000.26 0.23

0.00 0.00

0.80

2.00

1.85

-0.50

0.00

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1.50

2.00

2.50

Volume (ml)

Met

hane

Det

ecto

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eadi

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(%)

200ml250ml300ml350ml400ml

Reading of M ethane vs Volume during Third Test

0.590.31

0.00 0.02 0.00

1.11

1.62

0.190.02 0.00

0.490.78

0.350.18

0.00

0.780.63

0.11 0.09 0.00

0.41 0.41 0.320.09 0.00

-0.50

0.00

0.50

1.00

1.50

2.00

Volume (ml)

Met

hane

Det

ecto

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eadi

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250ml300ml350ml400ml450ml

(a)

(b)

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Concluding Remarks

In conclusion, the use of biogas to generate electricity has been provenworldwide with many successful implementations. In Malaysia, evaluationof the four STP with digesters facilities shows that there is good prospectof utilising biogas for energy generation. The research shows that theconstituent of methane in the biogas are not necessarily become higheror lower in parallel with the amount of the sewage sludge. There may beseveral factors that can probably affect the readings as well. There arethe type of sewage sludge (raw sludge or treated), the method that beingused (injecting nitrogen or natural fermenting) and the time duration.

Acknowledgement

The research team would like to acknowledge the Ministry of HigherEducation Malaysia for the fundamental research grant (FRGS-1193)for this study.

References

[1] PTM, 2004. Energysmart,http://www.ptm.org.my/division/download/Energy_Smart/es%20(14).pdf. Accessed on 13rd Sept. 2007.

[2] Parliamentary Offices. 2007. Energy and sewage. Available:http://www.parliamentary.uk/parliamentary_offices/post/pubd2007.cfm. Accessed on 15th August 2007.

[3] Hawley, R. J. 2001. Energy from sewage sludge in the Yorkshireand Humberside region. Available: http://crestdl.lboro.ac.uk/support/dissertations/2001/ richardhawley.pdf/. Accessed on 15th

August 2007.

[4] Babel, S., Parkpian, P. and Sae-Tang, J. 2005. Alternative energygeneration from waste sludge by anaerobic co-digestion. Journalof Environmental Management, 69, pp.15-24.

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[5] Cambi. 2000. Sludge Treatment. Available: http://www.cambi.no/References/sludge/, accessed on 16 September 2007.

[6] Baki, A., Abdul-Talib, S., Abdul Hamid, M. H. and Khor, B. C.2005. Energy from sewage sludge: Potential application in Malaysia.3rd Workshop on Regional Network Formation for EnhancingResearch and Education on Green Energy Technologies, BatuFerringhi, Penang, Malaysia.

[7] General Electric Company. 1997. Biogases. Available:http://www.ge-nergy.com/prod_serv/products/recip_engines/en/gas_types/biogas landfill.html, Accessed on 15 August 2007.