Green Technology and Sustainable Development (Volume 2).pdf

GREEN TECHNOLOGY
AND SUSTAINABLE DEVELOPMENT
Volume 2
2012 INTERNATIONAL CONFERENCE ON GREEN TECHNOLOGY
AND SUSTAINABLE DEVELOPMENT
HCMC - VNU PUBLISHING HOUSE
ISO 9001: 2000
University of Technical
Education HCMC, Vietnam
Solar Energy Centre, Ministry of
New and Renewable Energy,
Government of India
National Kaohsiung
University of Applied
Sciences, Taiwan

PREFACE
This Conference Proceedings Contains the accepted papers for the 2012 International
Conference on Green Technology and Sustainable Development (GDST2012) which is co-
organized by University of Technical Education Ho Chi Minh City, Vietnam, National
Kaohsiung University of Applied Sciences, Taiwan and The Solar Energy Center of The
Ministry of New and Renewable Energy, Government of India. The Conference took place at
the beautiful campus of University of Technical Education Ho Chi Minh City, Vietnam from
September 29th
- 30th
2012.
As the supply of traditional source of energy such as coal, oil and gas diminish, the price will
rise thus; renewable energy which is previously uneconomic sources of energy is now a great
alternative to exploit. Green economy and sustainable development are also topics of great
interest in recent years, especially in fast growing countries such as China, India, Vietnam...
just to name a few. This Conference provided a setting for discussing recent development in a
wide variety of topics in the field of green technology and sustainable development. The
Conference has been a good opportunity for participants from Vietnam, Taiwan, India, the
Philippines, Japan, Germany … to present and discuss their respective research.
We would like to thank all participants for their contributions to the Conference program and
for their contributions to these Proceedings. Many thanks go as well to the local organizing
committee at University of Technical Education Ho Chi Minh City for their devoted
assistance in the overall organization of the conference.
We especially acknowledge the financial support from the Ministry of Education and
Training, Vietnam and University of Technical Education Ho Chi Minh City.
General Co-chairs
Assoc. Prof. Dr. Thai Ba Can
Professor Cheng-Hong Yang
Dr. Pradeep Chandra Pant

Steering Committee
Co-Organizations
University of Technical Education Ho Chi Minh City, Vietnam (UTE)
National Kaohsiung University of Applied Sciences, Taiwan (KUAS)
Solar Energy Center, Ministry of New and Renewable Energy, Government of India (SEC)
General Co-chairs
Assoc. Prof. Thai Ba Can, President of University of Technical Education Ho Chi Minh City,
Vietnam
Professor Cheng-Hong Yang, President of National Kaohsiung University of Applied
Sciences, Taiwan
Dr. Pradeep Chandra Pant, Scientist 'E'/Director Solar Energy Centre, Ministry of New and
Renewable Energy, Government of India
Technical Program Committee
Assoc. Prof. Thai Ba Can (UTE)
Assoc. Prof. Do Van Dung (UTE)
Assoc. Prof. Quyen Huy Anh (UTE)
Assoc. Prof. Nguyen Van Suc (UTE)
Assoc. Prof. Nguyen Hoai Son (UTE)
Professor WD Yang (KUAS)
Professor JD Dai (KUAS)
Professor CN Wang (KUAS)
Professor JW Wang (KUAS)
Professor HY Lee (KUAS)
Professor QC Hsu (KUAS)
Professor CH Kuo (KUAS)
Professor Le Chi Hiep (HUT-VN)
Assoc. Prof. Dr. Hoang Ngoc Dong (UD-VN)
Professor Wahid M. Ahmed (NRC-Egypt)
Professor P. Beckers (ULG-Belgium)
Professor Lawrence Berliner (DU-USA)
Professor Nguyen Dang Hung (ULG-Belgium)
Assoc. Prof. Trinh Van Dung (HUT-VN)
Assoc. Prof. Le Quang Toai (HUS-VN)
Local Organizing Committee (UTE)
Assoc. Prof. Do Van Dung
Dr. Lam Mai Long
Dr. Ngo Van Thuyen
Dr. Hoang An Quoc
Assoc. Prof. Nguyen Ngoc Phuong
Assoc. Prof. Quyen Huy Anh
Assoc. Prof. Nguyen Van Suc
Assoc. Prof. Nguyen Hoai Son
Assoc. Prof. Doan Duc Hieu
Dr. Nguyen Van Tuan
Dr. Ngo Anh Tuan
Dr. Vo Thanh Tan
Dr. Tran Dang Thinh
Dr. Dang Truong Son
Mr. Nguyen Tan Quoc
Ms. Nguyen Thi Thanh Nga
Mr. Ho Thanh Cong
Mr. Bui Van Hoc
Mr. Nguyen Anh Duc

The 2012 International Conference on Green Technology and Sustainable Development (GTSD2012)
i
CONTENTS
----VOLUME 2---
1. CHEMICAL AND ENVIRONMENTAL TECHNOLOGY
PROCESS SAFETY AND ITS ROLE IN SUSTAINABLE DEVELOPMENT 1
Ha H. Nguyen, Hai T. M. Le, Suc V. Nguyen, M. Sam Mannan
HIGH PERFORMANCE CO2 GAS SENSOR BASED ON ZNO NANOWIRES FUNCTIONALIZED
WITH LAOCL 7
Le Duc Toan
BIOFILM FORMING BACTERIA ISOLATED FROM WASTEWATER IN VIETNAM 13
Nguyen Quang Huy, Ngo Thi Kim Toan, Trinh Thi Hien, Pham Bao Yen
REPEATED BATCH ETHANOL FERMENTATION OF SUGARCANE AND SWEET SORGHUM
SYRUP UTILIZING A HIGHLY FLOCCULATING STRAIN OF SACCHAROMYCES
CEREVISIAE 19
Ivy Grace U. Pait, Irene G. Pajares and Francisco B. Elegado
SYNTHESIS AND CHARACTERIZATION OF POTENTIAL ENVIRONMENT-FRIENDLY
PIGMENTS BASED ON CEO2-CUO SOLID SOLUTIONS 25
Le Phuc Nguyen, Le Tien Khoa
IMPROVING THE BIOGAS APPLICATION IN THE MEKONG DELTA OF VIETNAM BY USING
AGRICULTURAL WASTE AS AN ADDITIONAL INPUT MATERIAL 31
Nguyen Vo Chau Ngan, Klaus Fricke
CONVERSION OF WASTE PROPYLENE INTO VALUABLE FUEL VIA THERMAL PYROLYSIS 37
Nguyen Thi Le Nhon, Nguyen Thi Hoai Vy, Le Minh Tien, Tran Van Tri, Dang Thanh Tung
RESEARCH ON WASTEWATER TREATMENT BY EXPANDED GRANULAR SLUDGE BED
(EGSB) REACTOR USING POLYVINYL ALCOHOL (PVA) CARRIER 43
Vu Dinh Khang, Nguyen Tan Phong
SOME COMPOUNDS FROM STEM OF TETRASTIGMA ERUBESCENS PLANCH. (VITATEAE) 49
Phan Thi Anh Dao, Tran Le Quan, Nguyen Thi Thanh Mai
BUILDING THE MATHEMATICAL MODEL TO DETERMINE THE TECHNOLOGICAL MODE
FOR THE FREEZING PROCESS OF BASA FILLET IN ĐBSCL OF VIETNAM BY
EXPERIMENTAL METHOD 53
Nguyen Tan Dzung, Le Hoang Du
BUILDING THE METHOD TO DETERMINE THE RATE OF FREEZING WATER IN PENAEUS
MONODON OF THE FREEZING PROCESS 61
Nguyen Tan Dzung, Trinh Van Dzung, Tran Duc Ba
"WASTE TO ENERGY" IN WASTEWATER MANAGEMENT CONCEPT OF NAM DINH CITY -
AN INTERSECTORAL APPROACH – 69
Jörn Kasbohm, Le Thi Lai, Hoang Thi Minh Thao, Le Duc Ngan, Tran Manh Tien, Mario Kokowsky
EVALUATING MODEL FOR THE SOIL ENVIRONMENT IN VIETNAM: A CASE STUDY IN
DAU TIENG DISTRICT, BINH DUONG PROVINCE 75
Che Dinh Ly

ii
COMPARATIVE KINETICS OF THE ETHANOL FERMENTATION OF ZYMOMONAS MOBILIS
WITH SACCHAROMYCES CEREVISIAE USING SUGARCANE AND SWEET SORGHUM
SYRUP 81
Maloles Johnry S, Pajares Irene G and Elegado Francisco B
ELECTRON BEAM CROSSLINKED CARBOXYMETHYL STARCH NANOGEL USED AS A
CARRIER FOR LEAF-SPRAYING FERTILIZER IN AGRICULTURE 87
Doan Binh, Pham Thi Thu Hong, Nguyen Thanh Duoc
POLYLACTIC ACID BIODEGRADABILITY STUDY OF A THERMOPHILIC BACTERIUM
ISOLATED IN VIETNAM 93
Le Hai Van, Pham Bao Yen, Nguyen Quang Huy
EQUILIBRIUM STUDY OF LEAD (II) ADSORPTION FROM AQUEOUS SOLUTION ON
MODIFIED CHITOSAN WITH CITRIC ACID 101
Nguyen Van Suc, Ho Thi Yeu Ly
COPPER (II) ADSORPTION FROM AQUEOUS SOLUTION ONTO MODIFIED CHITOSAN:
OPTIMIZATION, THERMODYNAMIC AND KINETIC STUDIES 109
Ho Thi Yeu Ly, Nguyen Van Suc, Nguyen Mong Sinh
A LESSON LEARNT OF APPLYING GREEN TECHNOLOGY AT LOCAL AREAS. A CASE
STUDY ON IMPLEMENTING COMPOSTING AT SUBURBAN AREAS OF HANOI 117
Minh Hieu Duong, Donald Cameron, Iean Russell
SOME FATTY COMPOUNDS FROM LEAVES OF PSEUDERANTHEMUM CARRUTHERSII VAR.
ATROPURPUREUM 125
Vo Thi Nga,Tran Thi Thanh Nhan, Nguyen Kim Phi Phung, Nguyen Ngoc Suong
PEDIOCIN STRUCTURAL GENES OF BACTERIOCINOGENIC PEDIOCOCCI ISOLATED FROM
INDIGENOUS PHILIPPINE AND VIETNAMESE FOODS 131
Maria Teresa M. Perez, Dame L. T. Apaga, Christopher Jay Robidillo, Francisco B. Elegado
APPLICATION OF BIOAUGMENTATION TECHNIQUES IN COIR PITH COMPOSTING IN
VIETNAM 139
Nguyen Hoai Huong, Nguyen Thi Hoang Oanh, Nguyen Minh Chuong, Tran Kim Dung
PROPOSING SOLUTION FOR SALVAGING CONCENTRATED TREATED WASTEWATER AT
LONG BINH INDUSTRIAL ZONE, DONG NAI PROVINCE 147
Phan Thi Pham, Pham Ngoc Hoa
ADSORPTION STUDY ON THE REMOVAL OF CHROMIUM (VI) ION USING GREEN TEA
WASTE AND ACTIVATED CARBON 153
Vo Hong Thi
NEW METHOD FOR THE SYNTHESIS OF 1-METHYLIMIDAZOLIUM TRIFLUOROACETATE 159
Khan M. Hua, Thach N. Le
SYNTHESIZING METHODS OF MOF-5: INFLUENCE ON CHARACTERISTICS AND
CATALYTIC ACTIVITY IN FRIEDEL-CRAFTS ALKYLATION 165
Tan L. H. Doan, Anh T. Nguyen, Thanh D. Le, Thao N. N. Dinh, Thach N. Le
FAST PREPARATION AND APPLICATION 1,3-DIALKYLIMIDAZOLIUM
TETRAFLUOROBORATE IONIC LIQUIDS FOR FRIEDEL-CRAFTS ACYLATION 173
Tran Hoang Phuong, Tran Ngoc Thu Ha, Le Ngoc Thach

iii
SOLVENT FREE PREPARATION OF P-CYMENE FROM LIMONENE USING VIETNAMESE
MONTMORILLONITE 179
Thao Tran Thi Nguyen, Fritz Duus, Thach Ngoc Le
EFFECT OF PARTIAL REPLACEMENT OF FISH MEAL IN PRACTICAL DIETS ON GROWTH
PERFORMANCE AND FEED UTILIZATION OF KOI CARP JUVENILES (CYPRINUS CARPIO L.,
1758) 185
Nguyen Van Nguyen, Tran Van Khanh
RESEARCH ON THE POSSIBILITY OF BREWERY WASTEWATER TREATMENT AFTER
ANAEROBIC PROCESS WITH STICK-BED AND SWIM-BED SYSTEM 193
Nguyen Tan Phong, Dang Minh Son
CHARACTERIZATION OF A RECOMBINANT LIPASE FROM GEOBACILLUS SP., M5 THAT
SHOWS POTENTIAL FOR DEGRADATION OF COOKING OIL WASTE 199
R. E. Arevalo, V. A. Alcantara, I. G. Pajares, A. P. Magtibay, F. Reyes, and J.F. Simbahan
REQUIREMENTS FOR BENEFICIAL USES OF BIOSOLIDS 205
Ho Ngo Anh Dao
ASSESSMENT OF SURFACE WATER RESOURCES IN LAM DONG PROVINCE, VIETNAM
AND RECOMMENDATIONS FOR SOLUTIONS TO MANAGEMENT IN THE DIRECTION OF
SUSTAINABLE DEVELOPMENT 211
Hoang Hung, Pham The Anh, Le Thanh Trung
“THE PERFORMANCES, EXHAUST GAS EMISSIONS OF ETHANOL-GASOLINE BLENDED
WITH HHO ADDITIVE ON A SPAKE IGNITION ENGINE CONTROLLED BY ENGINE
CONTROL UNIT WITHOUT LAMDA SENSOR” 219
Tran ThanhBinh, ImanKartolaksono Reksowardojo, Athol J.Kigour, WinrantoAismunandar
DATA WAREHOUSING OF MICROBIAL INFORMATION DATABASES FOR IN SILICO
MINING OF A BIOACTIVE LIGAND 227
Edwin P. Alcantara, Emmanuel D. Aldea, Marilyn V. Rey, Jelina T. H. Tetangco, Mary Grace C. Dy
Jongco
SOME PROPOSED SOLUTIONS FOR WIDESPREAD APPLICATION OF COMMUNITY - BASED
ENVIRONMENTAL MANAGEMENT APPROACH IN VIETNAM 233
Do Thi Kim Chi
APPLICATION OF FORWARD OSMOSIS ON DEWATERING OF HIGH NUTRIENT SLUDGE 237
Nguyen Cong Nguyen, Hung-Yin Yang, Shiao-Shing Chen
STRUCTURAL CHARACTERIZATION OF ALGINATE ISOLATED FROM SOME SPECIES OF
BROWN SEAWEED IN CENTRAL COASTAL REGION OF VIETNAM 245
Tran Vinh Thien
A NOVEL TREATMENT METHOD FOR ACETAMINOPHEN IN PHARMACEUTICAL
WASTEWATER BY PHOTOCATALYSIS WITH VAIROUS ELECTRON ACCEPTERS 251
Nguyen Cong Nguyen, Bing Lian Lin, Shiao-Shing Chen
DESULPHURIZATION PROCESS IMPORVEMENT IN STEEL MANUFACTURING 257
Chia-Nan Wang, Cao-Khanh Phan, Yao-Lang Chang
EFFECT OF SOME FACTORS ON THE SYNTHESIS OF PECTIN METHYLESTERASE (EC
3.1.1.11) BY ASPERGILLUS NIGER 263
Le Hoang Bao Ngoc, Ly Nguyen Binh

iv
FUNCTIONAL PROPERTIES AND POTENTIAL INDUSTRIAL APPLICATIONS OF A
BIOEMULSIFIER FROM SACCHAROMYCES CEREVISIAE 2031 269
Virgie A. Alcantara, Irene G. Pajares, Jessica F. Simbahan and Marie Christelle D.V. Maranan
ISOLATION AND SCREENING OF RESISTANT LACTIC ACID BACTERIA AGAINST GUAVA
LEAF EXTRACT AND THE HYPOGLYCEMIC EFFECT OF ITS FERMENTATION ON MICE 275
Jennifer D. Saguibo, Blessie T. Jimeno, Marilou R. Calapardo, Maria Teresa M. Perez, Guy A. Ramirez
and Francisco B. Elegado
PHILIPPINE ACTINOMYCETES AGAINST BIOFILM-PRODUCING BACTERIA 283
T. O. Zulaybar, I. A. Papa, and B.C. Mercado
APPLYING INNOVATION APPROACH TO IMPROVE THE SPRAYING ALLOY POWER ON
THE COPPER SURFACE 287
Chia-Nan Wang, Phung Duc Tung, Yao-Lang Chang
SYNTHESIS OF IRON-BASE ADSORBENT FOR LOW-COST TREATMENT OF DRINKING
WATER 297
Nhung T. Tuyet Hoang , Thien Tu Cao, Hung Anh Vu, Thanh T. Thien Tran, The Vinh Nguyen
USE OF ETHANOL TO CONTROL POSTHARVEST DECAY BY PENICILLIUM DIGITATUM
AND PENICILLIUM ITALICUM CONIDIA 303
Dao Thien, Tran Thi Dinh, Tran Thi Lan Huong
INDIGENOUS BACILLUS ISOLATED FROM THE PHILIPPINES AS BIOCONTROL AGENT
AGAINST RALSTONIA SOLANACEARUM 311
Irene A. Papa, Teofila O. Zulaybar, Bernardo C. Mercado, Asuncion K. Raymundo
2. FUNDAMENTAL RESEARCH
THE INFLUENCE OF SILICA COATING ON CRYSTALLINE STRUCTURE OF LANTHANUM
OXIDE NANOPARTICLES SYNTHESIZED BY RESINATE SOL-GEL METHOD 317
Dinh Son Thach, Le Thai Duy, Dau Tran Anh Nguyet
ADAPTIVE FUZZY NARX CONTROLLER FOR MPPT PV SUPPLIED DC PUMP MOTOR 325
Ho Pham Huy Anh, Nguyen Huu Phuc, Tran Thien Huan
TECHNOLOGY AND OPTICAL PROPERTIES OF QDS CDSE FOR APPLICATION IN SOLAR
CELLS 333
Tung Ha Thanh, Quang Vinh Lam, Thai Hoang Nguyen, Thanh Dat Huynh
THE EFFECTS OF DOPING CONCENTRATION ON THE ELECTRICAL PERFORMANCE OF
DC-SPUTTERED P-ZNO/N-SI HETEROJUNCTION 339
Dao Anh Tuan, Bui Khac Hoang, Nguyen Van Hieu, Le Vu Tuan Hung
EFFECT OF PREPARATION METHODS ON THE PHOTOLUMINESCENCE PROPERTIES OF
ZNO THIN FILMS BY DC MAGNETRON SPUTTERING 345
Pham Thi Hong Hanh, Le Vu Tuan Hung
SYNTHETIC STUDY OF ZNO NANOPARTICLES EMBEDDED IN TRIETHANOL AMINE
USING A WET CHEMICAL METHOD 351
Nguyen Van Hien, Tran Quynh, Pham Hai Dinh, Pham Tan Thi, Dinh Son Thach

v
GENETIC ALGORITHM DESIGN OF IN-CORE FUEL RELOADING PATTERNS THAT
MINIMIZE THE POWER PEAKING FACTOR OF NUCLEAR RESEARCH REACTORS 355
Do Quang Binh
CHARACTERISTIC OPTICS OF CDSE QDS, TIO2/CDSE, TIO2/MPA/CDSE FILMS AND
APPLICATION IN SOLAR CELLS 361
Tung Ha Thanh, Quang Vinh Lam, Thai Hoang Nguyen, Thanh Dat Huynh
EFFECT OF SEED LAYER DEPOSITED BY SPRAY PYROLYSIS TECHNIQUE ON THE
NANOROD STRUCRURAL ZNO FILM 367
Lan Anh Luu Thi, Ngoc Minh Le, Duc Hieu Nguyen, Thanh Thai Tran, Phi Hung Pham, Mateus Neto,
Ngoc Trung Nguyen, Thach Son Vo
SYNTHESIS OF ZNO NANORODS ON GRAPHENE 373
Le Quang Toai, Nguyen Doan T. Vinh, Duong Dinh Loc, Ha Hai Yen, Pham Hai Dinh, Dinh Son Thach
FABRICATED ZNO:SB THIN FILMS BY THE SOL – GEL METHOD 379
Dang Vinh Quang, Bui Thi Thu Hang, Tran Tuan, Dinh Son Thach
ENHANCING THE PHOTOCATALYTIC ACTIVITY UNDER VISIBLE LIGHT OF VANADIUM
DOPED TIO2 THIN FILM PREPARED BY SOLGEL METHOD 385
Phung Nguyen Thai Hang, Duong Ai Phuong, Le Vu Tuan Hung
DEVELOPMENT OF GAMMA SPECTROSCOPY NAI(TL) 3INCH X 3INCH 389
Vo Hong Hai, Nguyen Quoc Hung and Bui Tuan Khai
EFFECT OF CU, LA CO-DOPED ON THE ACTIVITY PHOTOCATALYTIC OF TIO2 THIN FILM
PREPARED BY SOL-GEL DIP COATING 395
Tuyet Mai Nguyen Thi, Lan Anh Luu Thi, Xuan Anh Trinh, Dang Chinh Huynh, Ngoc Trung Nguyen,
Thach Son Vo
3. SUSTAINABLE DEVELOPMENT IN ECONOMIC, POLITIC AND SOCIAL AREAS
A STUDY OF THE RELATIONS BETWEEN CUSTOMER SATISFACTION, LOYALTY, AND
PURCHASE INTENTION–IN THE CASE OF CHUNGHWA TELECOM’S MOBILE INTERNET 401
Day Jen-Der, Tsai Ai-Ling
BUSINESS AND ENVIRONMENTAL ETHICS 409
Tran Thuy Ai Phuong
SOME COMMENTS ON GREEN TECHNOLOGY APPLICATION AND SUSTAINABLE
DEVELOPMENT IN THE CRAFT VILLAGES IN VIETNAM 415
Vu Van Thinh, Vu Thi Thu Trang
GREEN BARRIERS TO VIETNAMESE AGRICULTURAL PRODUCTS EXPORTED TO EU:
CHALLENGES AND OPPORTUNITIES 423
Nguyen Thuong Lang
GREEN TECHNOLOGY AND SUSTAINABLE DEVELOPMENT 433
Nguyen Toan
IMPACT OF AQUATIC RESOURCES ON LIVELIHOOD OF THE PEOPLE LOWER MEKONG
BASIN - A CASE STUDY IN PHU LOC, KHANH AN COMMUNES, TAN CHAU, AN PHU
DISTRICT, AN GIANG PROVINCE 439
Pham Xuan Phu, Ngo Thuy Bao Tran, Phan Ngoc Duyen, Thai Huynh Phuong Lan

vi
HUMAN – THE CORE ELEMENT MAKING SUSTAINABLE DEVELOPMENT IN THE STAGES
OF INDUSTRIALIZATION AND AFTER-INDUSTRIALIZATION IN VIETNAM 445
Nguyen Thi Thanh Van, Le Truong Diem Trang, Nguyen Thien Duy
SOLUTIONS FOR SORTING HOUSEHOLD SOLID WASTE AT SOURCE IN HO CHI MINH CITY449
Le Thi Hong Thu
ENVIRONMENTAL MATTER IN LONG DUC INDUSTRIAL PARK IN TRAVINH PROVINCE –
REAL SITUATION AND RECOMMENDATIONS 453
Tran Dang Thinh, Nguyen Van Nguyen
FUNDAMENTAL ISSUES IN THE DEVELOPMENT OF AGRICULTURE ORGANIC
SUBSTRATES 459
Pham The Trinh, Y Ghi Nie
RELATION BETWEEN HUMANS AND NATURE IN “DIALECTICS OF NATURE” 467
Doan Duc Hieu
THINKING ABOUT A GREAT PERSONALITY - NGUYEN AI QUOC–HO CHI MINH’S
REVOLUTIONARY PERSONALITY 471
Truong Thi My Chau
SIGNIFICANCE OF NON-ACTION THOUGHT IN LAO TZU PHILOSOPHY FOR THE
SUSTAINABLE DEVELOPMENT OF SOCIETYIN THE PRESENT PERIOD 475
Dang Thi Minh Tuan, Trinh Thi Thanh
PERSPECTIVE ON SUSTAINABLE DEVELOPMENT OF COMMUNIST PARTY OF VIETNAM
IN THE CAUSE OF INNOVATION 483
Nguyen Dinh Ca, Phung The Anh
ORGANIZING EXTRACURRICULAR ACTIVITIES IN ENVIRONMENTAL EDUCATION FOR
SECONDARY STUDENTS 487
Duong Thi Kim Oanh, Le Na

1
PROCESS SAFETY AND ITS ROLE IN SUSTAINABLE DEVELOPMENT
Ha H. Nguyen2
, Hai T. M. Le2
, Suc V. Nguyen1
, M. Sam Mannan2
1
University of Educational Technology HoChiMinh City, Vietnam
2
Texas A&M University, College Station, USA
ABSTRACT
In developing countries such as Vietnam, major industrial incidents could have severe impact
on society, economy and environment, which are thethree pillars of sustainable development.
Incidents in the past, such as the Bhopal toxic chemical release in India in 1984, have given
valuable lessons about the importance of safety, particularly process safety, to the sustainable
development of developing countries. In this paper, we review the Bhopal disaster, discuss the
importance of an effective process safety program and regulation in sustainable development,
and introduce process safety legislation and education in the United States. These legislation
and education systems could be used as models to improve the effectiveness of the safety
program in Vietnam.
KEYWORDS: Sustainability, developing countries, Bhopal disaster, process safety
1. BHOPAL DISASTER, INDIA, 1984
On the night of December 2nd
1984, at 11
PM, a leak occurred resulting in the release
of large amount toxic chemicals, mainly
methyl isocyanine (MIC) gas and several
others, at a pesticide plant in Bhopal, India
[1]. Several hundred thousand peoples in
towns nearby were exposed to the
chemicals, and approximately 3,800 were
reported dead [1]. Two decades later, the
site of the incident and the surrounding
areas have not yet been cleaned up and
recovered. Many researchers have been
conducted and found high levels of
contamination of toxic organic chemicals
and heavy metals in the soil and water
samples [4]. Many long-term ocular,
respiratory, gastrointestinal, genetic,
psychological, neurobehavioral effects on
human health from the gas leak have been
found, and 15,000 to 20,000 premature
deaths have been reported [3-5].
Investigations into the disaster found that
water entered a tank containing 42 tons of
methyl isocyanine (MIC) which then
reacted exothermically with the entering
water and increased the temperature and
pressure inside the tank, resulting in the
release of approximate 30 metric tons of
MIC into the atmosphere. The combination
of multiple factors including poor
maintenance, the failure of safety systems,
and the substandard operating procedure
has been identified as the underlying causes
of the incident [1]. The disaster is a hard-
learned lesson of catastrophic consequences
from rapid industrialization without proper
attention to safety, which is a major
concern in developing countries [1].
Bhopal disaster and many other incidents
with severe damages to society,
environment and economy show the
importance of an effective process safety
program and pose a challenging question
about the role of safety regulation of highly
hazardous chemicals in developing
countries. This question is even more
critical given that prior to the Bhopal
disaster; the local government in India was
aware of various safety problems at the
plant but failed to intervene for fear of
potential negative effects on the economy
[6].

2
2. THE IMPORTANCE OF AN
EFFECTIVE PROCESS SAFETY
PROGRAM IN SUSTAINABLE
DEVELOPMENT
To understand the importance of an
effective safety program in sustainable
development, it is essential to revisit the
concept of sustainability. The main
components of sustainability, as defined by
the United Nation on the resolution at the
World Summit in 2005, are [7]:“… the
three components of sustainable
development – economic development,
social development and environmental
protection – as interdependent and
mutually reinforcing pillars. Poverty
eradication, changing unsustainable
patterns of production and consumption
and protecting and managing the natural
resource base of economic and social
development are overarching objectives of
essential requirements for sustainable
development.”
Figure 1 further elaborates the concept of
sustainability and its constituents as
following: the globe of sustainable
development is supported by three pillars:
i) economic development, ii) social
development and iii) environmental
protection. These three pillars are
interdependent and mutually reinforcing to
balance and support the globe of
sustainable development. Without any one
pillar, the balance will be upset and the
sustainable development globe will be lost.
For developing countries such as Vietnam,
maintaining the delicate balance of those
three pillars is a great challenge. While the
pressure of economic development requires
a rapid expansion and investment into the
industry sector, a thorough understanding
and awareness of safety are not at the same
pace. In 2009, reports from the Vietnam
Ministry of Labor, War Invalids and Social
Affairs showed that there were 6,250
workplace incidents resulted in a total of
1,771 fatalities and serious injuries [8].
Table 1 and Figure 2 summarize the
workplace incident statistics from 1999 to
2010 in Vietnam using data published by
the Vietnam Ministry of Labor, War
Invalids and Social Affairs [9-10]. The
increase in the number of work related
incidents from 1999 to 2009 indicates that
efforts by Vietnamese government to
reduce industrial incidents have been
insufficient.
Figure 1. The interdependent and mutually
reinforcing three pillars of sustainable
development: economic development, social
development and environmental protection.
Industrial incidents cause severe damages
to the society, economy and environment of
a country. In some cases, the grave
consequences of a single incident similar to
the Bhopal disaster can completely destroy
the economy and environment of a region,
causing a negative long term effect on the
society. Having a robust safety regulation
and an effective safety program is critical
to prevent such incidents, and protect the
three elements of sustainable development.
It is important to understand that, for
safety, relying on technology alone is never
considered sufficient to prevent incidents
from occurring. Having the commitment
and accountability in all levels, from
national to organization level, is more
critical since the occurring of most
incidents is not from the failure of a single
event, but more often from the failure of a
series of events/barriers which is illustrated
by Figure 3.

3
Table 1. Workplace incident statistics from
1999 – 2010 in Vietnam (Data from the
Vietnam Ministry of Labors, War Invalids and
Social Affairs [9-10])
Year
Number of
Workplace
incidents
Number
of
Victims
Number of
Fatalities
1999 2611 2813 399
2000 3405 3530 403
2001 3601 3748 395
2002 4298 4521 514
2003 3896 4089 513
2004 6026 6186 575
2005 4050 4164 473
2006 5881 6088 536
2007 5951 6337 621
2008 5836 6047 573
2009 6250 6421 550
2010 5125 5307 601
Figure 2. Statistics of workplace incidents in
Vietnam from 1999 to 2010
Figure 3. The Swiss cheese model (Adapted
from [11])
3. PROCESS SAFETY LEGISL -
ATION AND EDUCATION IN THE
UNITED STATES
In developed countries such as the United
States, Japan, European countries, various
safety programs and regulations have been
implemented to prevent and mitigate
industrial incidents. For examples, the U.S.
Occupational Safety and Health
Administration (OSHA) has established
and implemented a regulation called
Process Safety Management of Highly
Hazardous Chemicals to prevent
andminimize the consequences of releases
of toxic, reactive, flammable, or explosive
chemicals [12]. Table 2 presents the 14 keys
elements of the Process Safety Management
regulation issued by OSHA.
Table 2. The 14 element of the Process Safety
Management for highly hazardous chemical
[15]
-Process Safety
Information
-Process Hazard
Analysis
-Operating Procedures
-Employee
Participation
-Training
-Contractors
-Pre-Startup Safety
Review
-Mechanical Integrity
-Hot Work Permit
-Management of
Change
-Incident
Investigation
-Emergency Planning
and Response
-Compliance Audits
-Trade Secrets
Similar regulations such as the Risk
Management Plan issued by the U.S
Environmental Protection Agency [13], the
IEC 61511 standard: Functional Safety -
Safety Instrumented Systems for the
Process Industry Sector of the International
Electro-technical Commission [14], have
been accredited for greatly reduce the
number of workplace incidents, especially
in the highly hazardous chemical process
industry.

4
Table 3. Safety courses available or under
development at the Mary Kay O’Connor
Process Safety Center [17]
Incident Investigation
Process Hazard
Analysis
Safety Instrumented
Systems
Systematic
Assessment of
Reactive Chemicals
Management of
Change
Hazard Evaluation
Process Safety
Management
Risk Based Design
System Safety
Engineering
Relief System Design
Behavioral Safety
Alarm Management
Ergonomics
Fire Protection
Industrial Hygiene
Process Safety
Engineering
Product Safety
Industrial Ventilation
Chemical Reactivity
LNG and LPG Safety
Quantitative Risk
Assessment
Human Factors and
Improvement of
Human Performance
Inherently Safer
Design
Fire Protection and
Fire Risk Analysis
Emergency Planning
Together with regulations, the educational
system in the U.S has been also updated to
further enhance the understanding and
awareness of process safety, noticeably at
undergraduate level. For example, the
America Institute of Chemical Engineering
recently proposed the inclusion of chemical
safety education in the undergraduate
curriculum of the U.S college system
[16]:“...to address the management of all
chemical process hazards, not just reactive
hazard.”
The Texas A&M University system is one
of the first to have chemical safety
education incorporated into undergraduate
chemical engineering curriculum. The
Mary Kay O’Connor Process Safety Center
(MKOPSC) at the Artie McFerrin
Department of Chemical Engineering [17]
has been recognized as an international
leader in educating and promoting process
safety engineering in industry. The
MKOPSC is also a model of the effective
partnership among academia, industry and
government for the purpose of developing a
workforce with valuable process safety
knowledge to meet current and future needs
of industry. Table 3 lists the courses
currently available or under development at
the MKOPSC.
In summary, we discuss the importance of
process safety and safety regulation in
sustainable development for developing
countries. In order to achieve sustainable
development, it is crucial to havea strong
safety program/regulation and commitment
from the government as well as the
industry. By learning from lessons and
experiences of other countries, Vietnam
could greatly benefit in its sustainable
development program.
4. REFERENCES
[1] Broughton E., The Bhopal disaster and
its aftermath: a review, Environ.
Health, 2005, 4(6).
[2] Sharma DC., Bhopal: 20 Years
On, Lancet, 2005, 365, 111–112.
[3] www.bhopal.org.
[4] Dhara VR, Dhara R., The Union
Carbide disaster in Bhopal: a review of
health effects, Arch. Environ.
Health, 2002, 57, 391–404.
[5] Misra UK, Kalita J.,A study of
cognitive functions in methyl-iso-
cyanate victims one year after Bhopal
accident, Neurotoxicology, 1997,18,
381–386.
[6] Shrivastava P., Bhopal: Anatomy of a
Crisis, Cambridge, MA, Ballinger
Publishing, 1987, p.184.
[7] Resolution adopted by the General
Assembly, United Nation,
2005.http://data.unaids.org/Topics/Uni
versalAccess/worldsummitoutcome_re
solution_24oct2005_en.pdf.

5
[8] http://vietnewsonline.vn/News/Society/
_12811/Industrial-accidents-kill-550-
last-year.htm.
[9] The Vietnam Ministry of Labors, War
Invalids and Social Affairs.
www.molisa.gov.vn.
[10]Workplace incident statistic in
Vietnam 1999-2010,
website:www.antoanlaodong.gov.vn.
[11]Reason J., Human error: models and
management, British Medical
Journal, 2000, 320(7237), 768–770.
[12]United States Occupational Safety and
Health Administration. www.osha.gov.
[13]Occupational Safety and Health,
Administration publication
3132.www.osha.gov/Publications/osha
3132.pdf.
[14]United States Environmental
protection Agency, www.epa.gov.
[15]International Electrotechnical
commission,
www.iec.ch/functionalsafety/
[16]http://www.csb.gov/newsroom/_detail.
aspx?nid=411.
[17]The Mary Kay O’Connor Process
Safety Center. http://psc.tamu.edu
Contact:
Email: nvsuc@hcmute.edu.vn

6

7
HIGH PERFORMANCE CO2 GAS SENSOR BASED ON ZnO NANOWIRES
FUNCTIONALIZED WITH LaOCL
Le Duc Toan
Phu Yen University
ABSTRACT
In this paper, a high performance CO2 sensors based on the ZnO functionalized with LaOCl
was developed. The sensor was fabricated by drop-coating ZnO nanowires on Pt interdigitated
electrodes and subsequently dropping LaCl3 aqueous solution. Before gas-sensing
characterizations, as-fabricated sensors were heat-treated in air at temperatures of 600o
C to
convert LaCl3 to LaOCl and to stabilize the sensor resistance. The LaOCl coating increased
the gas response (Ra/Rg) to CO2 gas. The Ra/Rg value of LaOCl-coated ZnO nanowires to 4000
ppm CO2 was as high as 4.1 at 400o
C, while the response of the sensor to other gases such as
CO (100 ppm), C2H5OH (50 ppm), H2 (25ppm), NO2 (5 ppm) and NH3 (25 ppm) was lower
(1.4-2.1). The selective detection of CO2 and enhancement of the gas response were attributed
to the p-type characters and good catalyst active of LaOCl.
KEYWORDS: CO2, ZnO NWs, gas sensor
1. INTRODUCTION
CO2 is a toxic gas produced from different
sources such as the coal, volcano, and
natural gas industries. The control of CO2
concentration is important in many
applications. Non-expensive and robust
detection systems are required for air
quality, food control and for early fire
detection. To date, optical and
electrochemical sensors have been used,
but the high cost of the former and the
unreliability of the latter are current
disadvantages. Solid-state gas sensors
based on nanostructured semiconductor
metal oxide such as ZnO nanowires (NWs),
SnO2 NWs may be a promising alternative,
since they offer good sensing properties
and can be easily mass-production.
Recently, LaOCl material has been
demonstrated as a new CO2 gas sensing
material [1-4]. The selectivity and
sensitivity of ZnO NWs sensors can be
enhanced either by doping with other oxide
materials [5-7] or by functionalizing with
catalytically active materials [8-10]. Oxide
materials are usually doped by the thermal
evaporation of a mixed source material [5-
7]. Noble catalyst materials are generally
deposited by vapor deposition [8, 9] or
sputtering [10] next to the growth of ZnO
NWs. A source material for doping with an
appropriate vapor pressure is indispensable
for the thermal evaporation of mixed
materials and there is a limitation in the
precise control of the dopant concentration.
Moreover, the deposition of catalyst
materials after the growth of NWs is
relative complex and not cost-effective.
Accordingly, a convenient approach to
form a functional layer on ZnO NWs is
essential for enhancing the selectivity and
sensitivity, as well as for achieving a simple
process at low cost. In this study, ZnO NWs
were grown by thermal evaporation and the
ZnO NWs sensors were functionalized with
LaOCl by dropping a LaCl3 solution at
optimum concentration. The sensing
characteristics to CO2 of the ZnO NWs
sensors without and with the
functionalizing LaOCl were compared.
Besides, the selective characteristics of the
sensors were checked with variety of gases
like CO, Ethanol, H2, LPG, NO2, and NH3.
The main focus was placed on the role of
LaOCl in enhancing the sensitivity to CO2,
the selective detection of CO2 in the
presence of interference gases such as CO,

8
Ethanol, H2, LPG, NO2, and NH3.
2. EXPERIMENTAL
The ZnO NWs were synthesized as similar
as the previous works [11- 12]. In brief,
ZnO NWs were synthesized on Au-coated
Si substrates by a simple thermal
evaporation of ZnO powder and graphit
with ratio of 1:1. The source material was
loaded in an alumina boat, which was
placed at the center of a quartz tube in a
horizontal-type furnace. The furnace was
heated to 950 ◦C and maintained for 30 min
during the synthesis of the nanowires. The
pressure in the quartz tube was controlled
between 10-2
Torr using Ar and O2 gas with
flow rates of 50 sccm and 1 sccm. The as-
synthesized ZnO NWs were analyzed by
field emission scanning electron
microscopy (FE-SEM, 4800, Hitachi,
Japan), transmission electron microscopy
(TEM, JEM-100CX), and Raman and X-
Ray diffraction (XRD, Philips Xpert Pro)
with CuK  radiation generated at a voltage
of 40 kV as source. To fabricate ZnO NWs
gas sensors, as-obtained ZnO NWs was
dispersed in a mixture of deionized water
(50%) and isopropyl alcohol (50%) by
ultrasonication. The slurry contained ZnO
NWs was dropped on Pt interdugiated
electrode by using micropipette. Number of
droplets and the NWs density were
optimized to give the best performance of
the sensor. After drying of the sensor at
120o
C for 5 min, a droplet of aqueous 24
mM LaCl3 solution was dropped onto the
ZnO NWs layer. This concentration was
already optimized to give the best
performance of the sensors. Subsequently,
the sensor was heat-treated at temperature
of 600 o
C for 5 hours in order to convert
LaCl3 to LaOCl. The gas sensing
characteristics of the ZnO NWs
functionalized with LaOCl and pure ZnO
NWs sensors were measured under the
same identical experimental conditions.
The CO2 gas concentrations controlled by
changing the flow rate of CO2 gas and dry
synthetic air are in the range 250-8000
ppm. Additionally, the sensors was tested
with various gas such as 100 ppm CO, 50
ppm C2H5OH, 25 ppm H2, 250 ppm LPG, 5
ppm NO2, and 25 ppm NH3 on order to
investigate the selectivity of the sensors. A
flow-through technique with a constant
flow rate of 200 sccm was used with home-
made system as previously described in
[12].
3. RESULTS AND DISSCUSION
Figurre 1. FE-SEM, TEM and XRD
characterizations ZnO NWs and LaOCl-coated
ZnO NWs: (a) FE-SEM image of ZnO NWs;
(b)FE- SEM image of LaOCl-coated ZnO NWs;
(c) TEM image of LaOCl-coated ZnO NWs;
and (d) XRD pattern of as-synthesized ZnO
NWs
Fig. 1 shows the morphology of the as-
prepared ZnO NWs before and after coating
LaOCl. Before coating, uniform ZnO NWs
with homogeneous entanglement were
produced on a large area (2 cm × 3 cm).
The diameter of the ZnO NWs ranged from
100 nm and the lengths ranged from several
tens to hundreds of micrometers. All the
NWs were smooth and uniform along the
fiber axis. The XRD patterns of the as-
synthesized ZnO NWs (Fig. 1d) were
indexed to the tetragonal rutile structure,
which agrees well with JCPDS No 05-
0664.
(a) (b)
(d)
(c)

9
Figure 2. XRD pattern of LaOCl coated ZnO
NWs heat-treated at temperatures of 500, 600,
and 700 o
C
After coating, the morphology of ZnO
NWs functionalized with LaOCl using a 24
mM LaCl3 solution and subsequent heat-
treated at 600 o
C for 5 hours was shown in
Fig. 1b. The LaOCl-coated ZnO NWs were
uniformly coated on the Pt electrode and
surface of the NWs becomes rough,
probably due to the surface functionalizing
with LaOCl. TEM image of LaOCl-coated
ZnO NWs clearly indicated that the rough
surfaces were attributed to the attachment
of LaOCl nanoparticles on the NWs.
The minor phase of LaOCl-coated ZnO
NWs was identified by XRD. We have
characterized the ZnO NWs functionalized
with LaOCl uisng LaCl3 solution after heat-
treatment at temperatures of 500 o
C, 600 o
C
and 700 o
C and the XRD patterns are
shown in Fig. 2. It can be seen that most of
LaCl3 converted to LaOCl at heat-treated
temperature of 600 o
C, when the heat
treated temperature increased up to 700 o
C,
the LaCl3 also converted to the La2O3.
Therefore, the heat-treated temperature of
600 o
C was selected to convert large among
of LaCl3 to LaOCl for the ZnO NWs sensor
functionalization. This observation is
similar with that of previous work [1, 14].
Fig. 3 shows the responses at 400 o
C to
CO2 at the different concentrations from
500 ppm to 8000 ppm in four cases: ZnO
NWs, LaOCl-coated ZnO NWs using a 24
mM M LaCl3 aqueous solution at the heat-
treated temperatures of 500 o
C, 600 o
C and
700 o
C. It can be seen that the resistance of
the ZnO NWs and LaOCl-coated ZnO NWs
sensors decreased up exposure to CO2,
which corresponds to the n-type
semiconductor behavior. It has been noted
that the LaOCl is p-type semiconductor.
This indicated that the the ZnO NWs still
main contributed to electrical properties of
LaOCl-coated ZnO NWs sensors.
From Fig. 4, we can be also seen that the
LaOCl coating enhanced the response
(Ra/Ra) of ZnO NWs sensor. Additionally,
the LaOCl-coated ZnO NWs sensor was
heat-treated at temperature of 600 o
C
showed the best performance to CO2 gas.
The response (S=Ra/Rg) to CO2 at 4000
ppm (this concentration begins to be
harmful to the human health [12] was 4.1.
This response is higher than that for the
pure ZnO NWs sensor (S = 1.9 at 4000
ppm CO2). It was observed the LaOCl-
coated ZnO NWs sensor has response to
500 ppm to be 2.2, which indicates that the
LaOCl-coated ZnO NWs are promising
materials platform to detect trace
concentration of CO2.
The response values were plotted as a
function of CO2 concentration in Fig. 4. It
can be seen that the response increased
with increases of CO2 concentration, and it
tends to be saturation at concentration
higher than 4000 ppm. We have compared
our sensor response to CO2 to previous
works [1-4, 7] and found that our sensors
have much better performance.

10
Figure 3. The gas responses to CO2 (500 – 8000 ppm) at operating temperature of 400◦C for ZnO
NWs sensor (a), LaOCl-coated ZnO NWs at the heat-treated temperatures of 500 0
C (b), 600 0
C (c)
and 700 0
C (d)
One important is issue of CO2 gas sensor is
its selectivity. Therefore, in this work, we
have examined the response of LaOCl-
coated ZnO NWs sensors to six different
toxic gases in the environment such as CO
(100 ppm), Ethanol (50 ppm), H2 (100
ppm), LPG (100 ppm), NO2 (10 ppm), and
NH3 (25 ppm). The obtained responses
Figure 4. Gas response (Ra/Rg) to CO2 at
operating temperature of 400 o
C of pure ZnO
NWs and LaOCl-coated ZnO NWs heat-treated at
500, 600 and 700o
C.
Figure 5. Gas responses of pure ZnO NWs and
LaOCl-coated ZnO NWs to CO2 (4000 ppm), CO
(100 ppm), Ethanol(50 ppm), H2(100 ppm),
LPG(100 ppm) NO2 (10 ppm ) and
NH3(25PPM).

11
were shown in Fig. 5 for pure ZnO NWs
sensor (red bars) and LaOCl-coated SnO2
NWs sensor (green bars). It can be seen
that the response of pure ZnO NWs sensor
to 4000 ppm CO2 is comparable with the
responses of the sensor to CO, Ethanol, H2,
LPG, NO2, and NH3. Thus, the selective
detection of CO2 in the presence of these
gases is difficult in pure ZnO NWs sensor.
In contract, the LaOCl-coated ZnO NWs
sensor showed a significant change in gas
sensing characteristics. The response value
to 4000 ppm of this sensor were 4.1, it was
higher than those to CO, Ethanol, H2, LPG,
NO2, and NH3 (1.4-2.1). Thus, highly
selective of CO2 can be realized by the
LaOCl-coated ZnO NWs sensor.
When exposed to reducing gases such as H2
and CO, the p-type LaOCl increases the
resistance whereas the n-type SnO2
decreases the resistance. Thus, the simple
mixture between ZnO and LaOCl does not
greatly change the sensor resistance. The
extension of the electron depletion layer
near the p–n junction may explain the
enhancement of the response of the LaOCl-
coated ZnO NWs sensor upon gas
exposure. However, specially high
enhancement of the sensor response to CO2
in comparison with the other gases was
attributed to the use of LaOCl, which has
been reported strong reaction with CO2 gas
[1, 4]. Beside the O2
-
charged species
adsorbs on the surface of LaOCl, there is
addition of the OH-
charged species that
still adsorbs to LaOCl up to temperature of
350o
C [5]. The latter species can react with
CO2 and release of electron to p-n junction,
contributing to the variation in sensor
resistance [4].
4. CONCLUSION
A new CO2 gas sensor based on ZnO NWs
functionalized with LaOCl by solution
coating method was demonstrated. The
CO2 gas sensing characteristics were
investigated. The LaOCl-coated ZnO NWs
sensor increased the gas response to CO2
up to 4.1-fold, thereby enhancing the
selectivity towards CO2 over various
environmental gases such as CO2, CO,
Ethanol, H2, LPG, NO2, and NH3. The
enhancement of CO2 sensing performance
of the sensor was attributed to the
formation of p-n junction from LaOCl-
ZnO NWs and the strong adsorption of OH-
on surface of LaOCl at high temperatures.
The deposition of LaOCl via the solution
route, provides an effective and convenient
route for accomplishing both high
sensitivity and high selectivity to CO2
sensor.
5. ACKNOWLEDGMENTS
This work was supported by Phu Yen
University for basic studies.
6. REFERENCES
[1] A. Marsal, G. Dezanneau, A. Cornet,
J.R. Morante, A new CO2 gas sensing
material, Sens. Actuators B 95 (2003)
266-270.
[2] D.H. Kim, J.Y. Yoon, H.C. Park, K.H.
Kim, CO2 sensing characteristics of
SnO2 thick film by coating lanthanum
oxide, Sens. Actuators B 62 (2000) 61–
66.
[3] N. Mizuno, T. Yoshioka, K. Kato, M.
Iwamoto, CO2 sensing characteristics
of SnO2 element modified by La2O3,
Sens. Actuators B 13–14 (1993) 473–
475.
[4] A. Marsal, M.A. Centenob, J.A.
Odriozolab, A. Cornet, J.R. Morante,
DRIFTS analysis of the CO2 detection
mechanisms using LaOCl sensing
material, Sens. Actuators B 108 (2005)
484–489.
[5] Q.Wan, T.H.Wang, Single-crystalline
Sb-doped SnO2 nanowires: synthesis
and gas sensor application, Chem.
Commun. (2005) 3841–3843.
[6] X.Y. Xue, Y.J. Chen, Y.G. Liu, S.L.
Shi, Y.G.Wang, T.H.Wang, Synthesis
and ethanol sensing properties of
indium-doped tin oxide nanowires,
Appl. Phys. Lett.88 (2006) 201907-3.
[7] N.S. Ramgir, I.S. Mulla, K.P.

12
Vijayamohanan, A room temperature
nitric oxide sensor actualized from Ru-
doped SnO2 nanowires, Sens.
Actuators B 107 (2005) 708–715.
[8] A. Kolmakov, D.O. Klenov, Y. Lilach,
S. Stemmer, M. Moskovits, Enhanced
gas sensing by individual SnO2
nanowires and nanobelts
functionalized with Pd catalyst
particles, Nano Lett. 5 (2005) 667–673.
[9] L.H. Qian, K. Wang, Y. Li, H.T. Fang,
Q.H. Lu, X.L. Ma, CO sensor based on
Au-decorated SnO2 nanobelt, Mater.
Chem. Phys. 100 (2006) 82–84.
[10]H.T. Wang, B.S. Kang, R. Ren, L.C.
Tien, P.W. Sadik, D.P. Norton, S.J.
Pearton, Hydrogen-selective sensing at
room temperature with ZnO nanorods,
Appl. Phys. Lett, 86 (2005) 243503.
[11]N.V. Hieu, N.D. Chien, Low-
temperature growth and ethanol-
sensing characteristics of quasi-one-
dimensional ZnO nanostructures,
Physica B: Condensed Matter, 403
(2008) 50-56.
[12]Nguyen Van Hieu*, Dang Thi Thanh
Le, Le Thi Ngoc Loan, A comparative
study on the NH3 gas-sensing
properties of ZnO, SnO2, and WO3
nanowires, Int. J. Nanotechnology, 8
(2011) 174-187.
[13]L.V. Thong, L.T.N. Loan, N.V. Hieu,
Comparative study of gas sensor
performance of SnO2 nanowires and
their hierarchical nanostructures.
Sensors and Actuators B 112 (2010)
112-119.
[14]A. Marsal, E. Rossinyol, F. Bimbela,
C. Tellez, J. Coronas, A. Cornet, J.R.
Morante, Characterisation of LaOCl
sensing materials using CO2-TPD,
XRD, TEM and XPS, Sens. Actuators
B 109 (2005) 38–43.
[15]N. Yamazoe, Toward innovations of
gas sensor technology, Sens. Actuators
B 108 (2005) 2-14.
Contact: Name of author: Le Duc Toan
Tel: (+84) 1072632110
Employ: Nanomaterials
Email:toanvatlieu@gmail.com

13
BIOFILM FORMING BACTERIA ISOLATED FROM WASTEWATER IN
VIETNAM
Nguyen Quang Huy, Ngo Thi Kim Toan, Trinh Thi Hien, Pham Bao Yen
Hanoi University of Science, VNU
ABSTRACT
Biofilm-associated microorganisms play crucial roles in terrestrial and aquatic nutrient
cycling and in the biodegradation of pollutants. Biofilm formation ability was determined for
a total of 52 bacterial isolates obtained from the wastewater in Thanh Hoa province, Vietnam.
Among these, three showed strong biofilm-forming capacity. Their phylogenetic affiliation
was determined through 16S rDNA sequencing, morphological and biochemical
characteristics. The results grouped the isolates into three bacterial species: Pseudomonas
pseudoalcaligenes, Bacillus licheniformis and Bacillus amyloliquefaciens. Interestingly,
during the cultivation time of these three strains, nitrogen was degraded. After 30 days of
cultivation, strain B. licheniformis degraded more than 99.86% of ammonia supplemented
while B. amyloliquefaciens and P. pseudoalcaligenes converted the added nitride to nitrate
with the rates of 99.87% and 99.14%, respectively.
KEYWORDS: Biofilm forming, wastewater treatment, bacterial, isolates, nitrogen removed
1. INTRODUCTION
Biofilms are defined as consortia of
microorganisms that attach to a biotic or
abiotic surface. Microbial attachment to the
surfaces and the development of biofilms
are known to occur in many environments
[1]. Biofilm formation occurs gradually,
including steps such as conditioning layer
formation, bacterial adhesion, bacterial
growth and biofilm expansion. Biofilm can
form on all types of surfaces such as plastic,
metal, glass, soil particles, etc… [2].
Biofilm-forming microorganisms play
crucial roles in terrestrial and aquatic
nutrient cycling and in the biodegradation
of environmental pollutants [2]. Compared
with planktonic bacteria, biofilm bacteria
are more resistant to several antimicrobial
agents or other environmental stresses. It
has been postulated that large amounts of
biofilm formed by these microorganisms
play an important role in the degradation
and transformation of pollutants in the
increasingly polluted soil and water
environment [3, 4]. Understanding the
microbial spatial communities in terms of
mixed species biofilms present in the
polluted sites, and reintroducing these
cooperative and inedible biofilms including
pollutant-degrading bacteria to the polluted
sites would be crucial to render
bioremediation, especially
bioaugmentation, a more effective and
practical technology with fewer
environmental impacts [4].
The aim of this study was to evaluate the
synergistic interactions that occur during
multispecies biofilm formation in
wastewater isolated from Vietnam.
2. MATERIALS AND METHODS
2.1 Isolation of biofilm-forming bacteria
from wastewater
The samples used for isolation were
collected from wastewater of biogas tanks
at Vinh Yen, Vinh Loc, and Thanh Hoa
provinces. The samples were transported to
the laboratory in plastic bags or bottles and
analyzed within 24 hours.
2.2 Culture media
Luria (L-) broth, containing 10 g Bacto
tryptone (Difco), 5 g yeast extract (Difco)

14
and 10 g NaCl per liter was used for general
cultivation of bacteria. Minimal salt
medium (MSM) contained 1 g K2HPO4, 0.5
g MgSO4.7H2O, 0.4 g FeSO4.7H2O, 2 g
NaCl and trace CaCO3 per liter. Nitrogen
sources added in the media contained 2 g
(NH4)2SO4 or 1 g NaNO2, 1 liter distilled
water. The pH of all media ranged from 6.8
to 7.1. Culture media were sterilized at
121°C for 20 min.
2.3 Biofilm assay
To visualize biofilm formation and its
adherence to a surface, the general method
of O’Toole and Kolter was used [5].
Briefly, cells were pre-grown overnight in
LB broth and then 100 µl was used to
inoculated 0.7 ml LB medium in 1.5 ml
polypropylene tubes; these cultures were
incubated overnight at 37 o
C without
shaking. After discarding the medium and
rinsing the tubes with water, adhering cells
were stained with 1% w/v crystal violet.
After washing with distilled water, the
crystal violet attached to the biofilm was
solubilized in 1ml ethanol 70%, and
quantitated by measuring its absorbance at
570 nm.
2.4 Identification of the isolated bacteria
Phenotypic tests included Gram staining,
aerobic heat-stable spore formation, nitrate
reduction, gelatin hydrolysis using API kit
(Bioméreus). The phylogenetic affiliation
of the isolates showing high biofilm-
forming capacity was further characterized
using 16S rDNA analyses. The
phylogenetic affiliation of bacterial strains
was determined by comparing the obtained
sequences to the Gene Bank database.
2.5 Scanning electron microscopy (SEM)
Biofilm from all growth conditions were
prepared for SEM using a fixation method
described by Birdsell et al [6], and were
done in the Centre of Materials Science,
Faculty of Physics, Hanoi University of
Science.
2.6 Ammonium or nitride etabolization
Nitrogen metabolized from the culture
media was determined by standard method
for the examination of water and
wastewater [7].
3. RESULTS AND DISCUSSIONS
3.1 Isolation and characterization of
biofilm-forming bacteria
After 1 week of enrichments, cultivable
bacteria were collected from wastewater.
Plural from 52 bacterial strains were
different from each other in morphological
characteristics such as color, shape, size and
surface properties on agar plate. By the
method of staining with crystal violet, we
initially assessed their ability to form
biofilms. Only a few strains were capable of
forming strong biofilm. Among the strains
isolated, strains B1.11, B1.10 and B3.2
could grow and create biofilm stronger than
the others (Fig 1). Compare these results
with those reported by T.T. Hang, three
strains had higher activity [8], thus we
selected them for further experiments.
0
0.5
1
1.5
2
2.5
3
OD
value
Isolated strains
OD 620nm
OD 570nm
Figure 1. Biofilm formation from isolated
strains from wastewater
Under scanning electron microscope
(²5000), the typical biofilm structure of
the three selected strains clearly showed
two components: a network of extracellular
compounds and bacterial cells which
located into micro-colonies in order to
create 3-dimensional structure of biofilm
(Fig 2). However, biofilm formation was
different for each strain. Strain B1.11
biofilm was thick, very long and formed
uneven coating on the surface. Strain B1.10

15
biofilm was relatively homogeneous, had
complex three-dimensional, multi-layer coil
into each other, the biofilm was more
susceptibly chopped. Strain B3.2 biofilm
formation was very thin, transparent, rough,
and less tough. These biofilms were created
in the culture media (Fig 3).
3.2 Ability to metabolize ammonia and
nitrite from the isolates
Nitrogen pollution in wastewater is very
popular. High nitrogen content is toxic to
living organisms in the water and caused
eutrophication which reduces the amount of
oxygen [9]. Thus we tested the ability to
metabolize ammonia and nitrite of the three
isolated strains.
After 5 days of culture with shaking, two
strains, B3.2 and B1.10, showed high
activity for nitride degradation. With the
initial concentration of nitride
approximately 85 mg/l, after 5 days, the
concentration of nitride remaining in the
media culture of strain B1.10 was 21 mg/l
or 75.58% of nitride was metabolised
compared to 23 mg/l or 72.29% for strain
B3.2.
After 10 days, strain B1.11 started to show
nitride metabolism. By the 15th
day, the
strain B1.11 showed very slow metabolism
and the transformation could be considered
stalled on the 30th
day. The metabolism of
two strains, B3.2 and B1.10, continued at a
slower rate and after 30 days, most of
nitride in the environment was converted to
nitrate, with 99.87% and 99.14% efficiency
for strains B1.10 and B3.2, respectively
(Fig 4).
Figure 2. SEM of biofilm of isolated strains attached on organic medium B3.2 (left), B1.10 (middle)
and B1.11 (right)
Figure 3. Biofilm formation in the culture media of isolated strains B3.2 (left), B1.10 (middle) and
B1.11 (right)
Two strains, B1.10 and B3.2, showed
almost no ability to metabolize ammonia.
After 30 days, NH4
+
concentration in the
culture medium of these strains was not
changed. However, for strain B1.11, from
an initial ammonium concentration of 432
mg/l, after 5 days of culture, the remaining
concentration of NH4
+
was 177 mg/l (or
59.01% of NH4
+
was metabolized). After 30
days, almost all NH4
+
in the culture medium
was metabolized with 99.86% efficiency
(Fig 5).

16
Figure 4. Nitride active metabolism from
isolated strains
Figure 5. The activity of ammonia metabolism
from isolated strains
3.3 Identification of three selected
bacterial strains isolated form
wastewater
All bacterial strains isolated were
biochemically characterized based on the
API test kit (data not shown). However, to
confirm the identity of the isolated strains,
we conducted 16S rDNA sequencing and
compared with Gene bank database.
16S rDNA gene sequence similarities of
strain B1.10 were 99.8% (1397/1400 bp)
with the 16S of Bacillus amyloliquefaciens
AB255669. 16S rDNA gene sequence
similarities of strain B3.2 were 97.8%
(1370/1401 bp) with the 16S rDNA gene of
Pseudomonas pseudoalcaligenes_Z76666.
16S rDNA gene sequence similarities of
strain B1.11 were 99.9% (1399/1400 bp)
with the 16S rDNA gene of Bacillus
licheniformis_X68416 in Gene bank
database.
Other studies showed that the genus
Bacillus and Pseudomonas genus are
capable of creating biofilm with high
activity and are applied in the study of
water pollution [9]. The initial classification
results showed that our isolates were
capable of application in wastewater
treatment for the water that contains high
nitrogen concentration.
4. CONCLUSION
From wastewater, we isolated 52 bacterial
strains which showed biofilm forming
ability. Base on morphology, biochemistry
and 16S rDNA sequencing, we concluded
that B1.11 and B1.10 strains belong to
Bacillus genus and B3.2 belongs to
Pseudomonas genus.
After 30 days of cultivation, strain B.
licheniformis (B1.11) degraded more than
99.86% of ammonia supplemented in the
medium while strain B. amyloliquefaciens
(B1.10) and strain P. pseudoalcaligenes
(B3.2) converted nitride added in the
culture to nitrate with the percentages of
99.87% and 99.14%, respectively.
5. ACKNOWLEDGEMENTS
This research was financially supported by
the Ministry of Industry and Trade of
Vietnam. We also appreciate financial
assistance from Vietnam National
University, Hanoi (VNU) for grant code
QG 11-16.

17
Figure 6. Phylogenetic tree based on the 16S
rDNA gene sequence of isolated strains The
scale bar shows 0.01 nucleotide substitution
per site
6. REFERENCES
[1] G. O’Toole, H.B. Kaplan and R.
Kolter, Biofilm formation as microbial
development. Annu. Rev. Microbiol.
54, 2000, pp. 49-79
[2] M.E. Davey and G. O’Toole,
Microbial biofilms: From ecology to
molecular genetics. Microbiol. Mol.
Biol. Rev. 64, 2000, pp. 847-867.
[3] M. Morikwa, Beneficial biofilm
formation by industrial bacteria
Bacillus subtilis and related species. J.
Bioscien. Bioeng. 101, 2006, pp. 1-8.
[4] C.R. Kokare, S. Chakraborty, A.N.
Khopade, and K.R. Mahadik, Biofilm:
Importance and applications. Ind. J.
Biotechnol. 8, 2009, pp. 159-168.
[5] G.A. O'toole and R. Kolter, Flagellar
and twitching motility are necessary
for Pseudomonas aeruginosa biofilm
development. Mol. Microbiol. 30,
1998, pp. 295-304.
[6] D.C. Birdsell, R.J. Doyle and M.
Morgensten, Organization of teichoic
acid in the cell wall of Bacillus
subtilis. J. Bacteriol. 121, 1975, pp.
726-734.
[7] APHA/ AWWA/ WEF, Standard
methods for the examination of water
and wastewater, 20th
ed 1998,
Washington, DC, American Public
Health Association.
[8] T.T. Hang and N.Q. Huy, Isolation of
biofilm-forming Bacillus strains from
contamination site in trade villages in
Vietnam. J. Science VNU 27 (2S),
2011, pp. 157-162.
[9] V. Lazarova and J. Manem, Biofilm
characterization and activity analysis
in water and wastewater treatment.
Wat. Res. 29, 1995, pp. 2227-2245.
Contact: Nguyen Quang Huy, PhD.
Faculty of Biology, Hanoi University of
Science
334 Nguyen Trai, Thanh Xuan, Hanoi.
Tel: 0904263388
Email: huynq17@gmail.com
Azorhizophilus paspali_AJ308318
Azotobacter beijerinckii_AJ308319
Azotobacter chroococcum_AB175653
Pseudomonas aeruginosa_X06684
Pseudomonas otitidis AY953147
Pseudomonas resinovorans_Z76668
73
Serpens flexibilis_GU269546
Pseudomonas tuomuerensis_DQ868767
Pseudomonas stutzeri_AF094748
Pseudomonas xanthomarina_AB176954
Pseudomonas oleovorans lubricanti_DQ842018
Pseudomonas alcalophila AB030583
Pseudomonas pseudoalcaligenes_Z76666
100
Pseudomonas mendocina_D84016
Strain B3.2
66
76
71
50
100
57
92
68
93
89
0.01
Staphylococcus aureus_X68417
Bacillus aerophilus AJ831844
Bacillus stratosphericus_AJ831841
Bacillus altitudinis AJ831842
99
Bacillus pumilus AY876289
Bacillus safensis AF234854
99
100
Bacillus aerius AJ831843
Bacillus licheniformis_X68416
Bacillus sonorensis_AF302118
100
Bacillus atrophaeus AB021181
Bacillus mojavensis AB021191
Bacillus subtilis spizizenii AF074970
Bacillus subtilis AB042061
77
Bacillus vallismortis AB021198
Bacillus amyloliquefaciens_AB255669
Bacillus siamensis GQ281299
Bacillus methylotrophicus EU194897
Strain B1.10
80
89
79
68
80
100
97
10
99
0.01
Staphylococcus aureus X68417
Bacillus aerophilus_AJ831844
Bacillus stratosphericus AJ831841
Bacillus altitudinis AJ831842
99
Bacillus pumilus_AY876289
Bacillus safensis AF234854
99
100
Bacillus aerius_AJ831843
Bacillus licheniformis_X68416
Strain B1.11
100
Bacillus sonorensis_AF302118
63
Bacillus atrophaeus AB021181
Bacillus siamensis GQ281299
Bacillus amyloliquefaciens_AB255669
Bacillus methylotrophicus EU194897
57
Bacillus vallismortis AB021198
Bacillus mojavensis_AB021191
Bacillus subtilis AB042061
Bacillus subtilis subsp spizizenii_AF
65
78
88
52
81
100
97
100
99
0.01

18

19
REPEATED BATCH ETHANOL FERMENTATION OF SUGARCANE AND
SWEET SORGHUM SYRUP UTILIZING A HIGHLY FLOCCULATING
STRAIN OF SACCHAROMYCES CEREVISIAE
Ivy Grace U. Pait, Irene G. Pajares, Francisco B. Elegado
University of the Philippines Los Baños, Philippines
ABSTRACT
A locally isolated highly flocculating Saccharomyces cerevisiae strain (coded 5N1), the top
strain screened for ethanol fermentation of sugarcane and sweet sorghum juices, was
successfully used to carry out ten batches of fermentation at 30°C using 23-25% total sugars
(TS) of unsterile nutrient-supplemented diluted sugarcane syrup using a 5-L bioreactor. High
cell concentrations (108
-109
cells/ml) were achieved per batch, yielding ethanol contents of
up to 11-15% (v/v) after 12-14 hours. The average volumetric ethanol productivity ranged
from 5-6 g/L-hr which is 2-3 folds compared to conventional batch process. On the other
hand, only seven (7) rounds of repeated batch fermentation was implemented for sweet
sorghum syrup feed diluted to contain 23% TS because industrial requirements of 8-9% v/v
ethanol was only attained for batches 1-3 and decreased thereafter.
KEYWORDS: Ethanol, Saccharomyces cerevisiae, flocculating yeast, repeated-batch
fermentation
1. INTRODUCTION
In recent years, bioethanol has gained
acceptance as gasoline replacement due to
dwindling reserve and increasing prices of
fossil fuel. Philippines had enacted a law,
the Biofuels Act of 2006 that mandates 5%
(v/v) blending of locally-produced ethanol
into gasoline for the first 5 years and then
10% (v/v) since 2011. However, local
supply of bioethanol is inadequate and oil
companies have to import anhydrous
ethanol. Existing local ethanol distillers
mostly cater for the alcoholic beverage
industry, utilizing blackstrap molasses as
substrate and operating by traditional batch
process or yeast recycling after acid
washing and centrifugation. Sugarcane
and sweet sorghum are two of the main
biofuel crops being considered by the
country that can help supply the immediate
need for feedstock materials.
High cell density fermentation using highly
flocculating yeast strains can increase
fermentation efficiency and productivity
while reducing capital and operating costs.
Ethanol formation is growth-associated and
specific productivity, Qp, is related to
product yield (Yp/x) and biomass by the
equation:
where µ is the specific growth rate.
Previously, we screened for flocculation
abilities from a pool of high ethanol
producing yeast isolates and initially tested
them using sugarcane and sweet sorghum
juices as substrate [1]. In here, we are
reporting on the performance of the
selected highly flocculating yeast strain,
5N1, in a 5-L bioreactor repeated batch
ethanol fermentation system using nutrient-
supplemented unsterile sugarcane and
sweet sorghum syrups diluted to contain
23-25% total sugars.
2. MATERIALS AND METHODS
2.1 Yeast strain and culture medium
Saccharomyces cerevisiae 5N1, a high
ethanol-producing and highly flocculating
yeast strain, was grown on yeast extract
peptone dextrose (YEPD) agar slants
containing (in g/L): yeast extract, 10;

20
bactopeptone, 20; glucose, 20; and agar, 20.
It was maintained at 4°C.
2.2 Preparation of yeast inoculum
Yeast was grown on YEPD slant at ambient
temperature (~30° C) for 24 hr and then
subsequently grown with shaking for 20 hr
in 50 mL of sugarcane or sweet sorghum
syrup diluted to contain 50 g/L total sugars
(TS) containing (g/L): KH2PO4, 0.14;
MgSO4, 0.25; and (NH4)2SO4, 0.1, and pH
adjusted to 4.5 by adding 85% H3PO4.
2.3 Inoculum build-up and initial batch
fermentation.
Three (3) successive flask cultures at
increasing TS concentrations (5%, 10% and
15%) of sugarcane or sweet sorghum syrup,
supplemented with nutrients as mentioned
above and pH adjusted to 4.5, were
employed to attain the desired biomass
count of 108
cells/mL in the bioreactor. The
cells were collected via flocculation and
transferred at 20% inoculation rate to
nutrient supplemented sugarcane or sweet
sorghum media (23% TS) contained in a 5-
LBiostat Sartorius Aplus bioreactor. Corn
oil was added (0.5% v/v) as antifoam. To
promote cell growth, aeration (1 vvm) and
Figure 1. Repeated batch fermentation agitations (300 rpm) were done for the first 2 hr. The
anaerobic fermentation was then made to proceed at decreased agitation rate (100 rpm) at 30 °C

21
2.4 Repeated-batch fermentation
Up to 10 rounds of high cell density
repeated-batch trials with cell reuse by
flocculation was implemented using
unsterile nutrient-supplemented sugarcane
or sweet sorghum media with 23% TS (230
g/L) for the first 5 rounds and 25% TS
thereafter. When the residual sugar content
reached 50 g/L (10-11 ºbrix), agitation was
stopped for 30 min for complete cell
flocculation. The beer supernatant was
withdrawn from the reactor using a
peristaltic pump (Masterflex) leaving 0.5 L
of yeast flocs for the next round of
fermentation. Two liters of fresh media was
added to restart batch fermentation (Fig.1).
Sampling was done every 2 hrs for 24 hrs
and every 4 hrs thereafter, for the analysis
of ethanol, residual sugar and viable cell
count.
2.5 Analytical Methods
Ethanol was determined by gas
chromatography. The total sugar content
was analyzed by Phenol-sulfuric acid
method [2] while the residual sugar content
by Dinitrosalicylic acid method [3]. Viable
cell count was estimated by plating.
3. RESULTS AND DISCUSSION
3.1 Unsterile batch fermentation
Figures 2 & 3, show batch fermentation
profiles of unsterile nutrient supplemented
diluted sugarcane and sweet sorghum
syrup, respectively. For sugarcane syrup,
ethanol concentrations were 11.6 and 13.6
% (v/v) after 24 and 36 hrs, respectively
(Fig. 2). On the other hand, only 9.9 %
(v/v) was obtained after 24 hrs for sweet
sorghum syrup and increment was quite
minimal thereafter (Fig. 3). The end of
batch fermentation wherein the residual
sugar content reached 5% (w/v) was around
18 to 20 hrs that were consecutively used
for the repeated batch fermentation runs.
3.2 Unsterile repeated batch
fermentation
Figure 2. batch fermentation profile of
nutrient-supplemented SUGARCANE SYRUP
Figure 3. Batch fermentation profile of
nutrient-supplemented sweet sorghum syrup
Repeated-batch fermentation of unsterile
nutrient-supplemented sugarcane medium
utilizing highly dense flocculating yeast cell
yielded high ethanol ranging from 11.1 to
16.6% (v/v) (Table 1). Due to an increase in
cell density as the batch fermentation is
repeated, there was a remarkable increased
ethanol with corresponding decreased
fermentation time, thus leading to increased
productivity.

22
Table 1. Ethanol yield and productivity of
repeated batch ethanol fermentation of
sugarcane molasses
*Batch
Number
Time
(h)
EtOH
Conc.
(% v/v)
Product-
ivity
(g/l-h)
1 18 11.1 4.01
2 16 12.2 4.65
3 14 13.6 5.95
4 12 13.4 5.67
5 12 13.3 6.17
6 14.5 14.3 5.38
7 14 15.9 6.51
8 14 15.8 6.50
9 15 15.7 5.35
10 13 16.6 7.26
*Total sugar of feed is 23 % (w/v) for batch
numbers 1-5 and 25% (w/v) for batch
numbers 6-10.
For nutrient-supplemented sweet sorghum
values meeting industrial requirements (~8-
9% v/v ethanol) were only achieved for
batches 1-3. Thus, only 7 rounds of cell
reuse were implemented. Low ethanol
content from batches 4-7 indicates that the
strain was already sluggish due to a
possible negative effect of the accumulation
of inhibitory components (Table 2).
Table 2. Ethanol yield and productivity of
repeated batch ethanol fermentation of sweet
sorghum syrup
Batch
Number
Time
(h)
EtOH
Conc.
(% v/v)
Product-
ivity
(g/l-h)
1 20 9.4 3.12
2 20 10.0 3.03
3 20 8.04 3.08
4 22 7.7 2.31
5 17 6.8 3.00
6 21 7.7 2.17
7 17 7.2 2.69
Firgure 3. Variations of ethanol and residual sugar concentrations for each bacth in a repeated-batch
fermentation unsterilized sugarcane syrups at pH 4.5 and 300
C. Arrow indicate feeding stages. Value
plotted represents the average of two assays

23
Figure 4. yeast cell concentration profiles in
the repeated batch fermentation of sugarcane
syrup
The fast sugar utilization (Fig. 3) and high
cell concentration (Fig. 4) achieved in the
bioreactor during sugarcane syrup
fermentation was made possible by the
flocculating ability of strain 5N1 as well as
the acclimatization to the media. Cell
density increased as the number of batches
increased, reaching as high as
2.56x109
cells/mL at the end of the 8th
batch.
Strain 5N1 also proved to be a very robust
strain which can tolerate high sugar
concentrations (up to 25% w/v) and high
ethanol contents (up to 16% v/v). High
osmotolerance and ethanol tolerance are
also traits that a good industrial strain must
possess. According to Zhao and Bai [4],
yeast flocs are generally more resistant to
toxic substances and adverse environmental
conditions, probably because most of the
cell’s surface is bound to that of the other
cells and therefore remain unexposed to
extreme environmental stress. Yeast cell
viability in a repeated batch setup is very
crucial especially at high cell
concentrations to maintain long-term
activity, it is important that the floc size be
as large as possible so that the separation
time is as brief as possible, since this is
when the cells are exposed to the maximum
concentration of ethanol [5]. Only 10
batches were successfully implemented for
sugarcane media, but strain 5N1 still
formed viable colonies after the 10th
batch
and its ethanol production has not yet
declined, indicating a possibility of being
able to handle more fermentation runs.
Multiple batch runs can be extended to
determine the strain’s maximum residence
time if this system is to be industrially
adapted.
4. CONCLUSION
Saccharomyces cerevisiae 5N1 strain was
successfully used to carry out ten (10)
batches of repeated fermentation at 30°C
using 23-25% (230-250 g/L) TS unsterile
nutrient-supplemented sugarcane syrup
media with cell reuse. High cell
concentrations (108
-109
cells/ml) were
achieved per batch yielding ethanol
contents (11-16 %w/v) at a shorter
fermentation time (12-14 hr). This
improved the average volumetric ethanol
productivity of the process by 3-4 folds
over conventional batch systems. On the
other hand, only 7 rounds of repeated batch
fermentation was implemented for sweet
sorghum feed containing 23% (230 g/L) TS
because industrial requirements of 8-9% v/v
ethanol per batch was only attained for
batches 1 to 3 and ethanol contents for
succeeding cycles are approximately 7
%v/v (55 g/L) ethanol only. Nevertheless,
high cell concentrations (108
-109
cells/ml)
were still achieved per batch but volumetric
ethanol productivity was not significantly
improved because a shorter fermentation
time was not experienced. This may
indicate the presence of inhibitory
components in the sweet sorghum syrup
which could be addressed by a thorough
analysis of the media, or a more suitable
strain for this process is yet to be
discovered or developed.
5. ACKNOWLEDGEMENT
The authors wish to thank Philippine
Council for Industry, Energy and Emerging
Technology Research and Development
(PCIEERD), Department of Science and
Technology for the research grant.

24
6. REFERENCES
[1] I.G.U. Pait, I.G. Pajares and F.B.
Elegado. 5N1 superyeast: fulfillinf
every distiller’s dream. Proceedings of
the 6th
Asia-Pacific Biotechnology
Congress and 40th
PSM Annual
Convention. May 10-14, 2011.
Manila.p. 49.
[2] M.K. DuBois, A.J. Gilles, K.
P. Hamilton, P. A. Reber and F. Smith.
Colorimetric method for determination
of sugars and related substances. Anal.
Chem., 28 (3), 1956, pp 350–356.
[3] G. L. Miller. Use of dinitrosalicylic
acid reagent for determination of
reducing sugar. Anal. Chem. 31 (3),
1959, pp. 426–428.
[4] X.Q. Zhao and F.W. Bai. Yeast
flocculation: new story in fuel ethanol
production. Biotechnol. Advances, 27
2009, pp. 849-856.
[5] N. Hawgood, S. Evans and P.F.
Greenfield. Enhanced ethanol
production in multiple batch
fermentations with an auto-flocculating
yeast strain. Biomass 1985, pp. 261-
278.
Contact: Francisco B. Elegado
Tel: 6349-536-0547
Employer: BIOTECH, Univ. Philippines
Los Banos
Email: fbelegado@hotmail.com

25
SYNTHESIS AND CHARACTERIZATION OF POTENTIAL
ENVIRONMENT-FRIENDLY PIGMENTS BASED ON CeO2-CuO SOLID
SOLUTIONS
Le Phuc Nguyen1
, Le Tien Khoa2
1
Petrovietnam Research and Development Center for Petroleum Processing, VPI
2
Ho Chi Minh University of Sciences
ABSTRACT
New inorganic pigments based on CeO2–CuO solid solutions were synthesized and their color
properties were assessed from the view point of potential environmentally benign nontoxic
brown-yellow pigments. A wide range of compositions, nCuO/nCeO2 = x (x ranges from 0 to 1)
were prepared and characterized by powder X-ray diffraction, lattice parameter
measurements, L*, a*, b* color measurements. The thermal and chemical stabilities of the
pigments have also been examined. Among the various colorants prepared, Cu doped
pigments having x<0.2 are found to be promising candidates as ecological pigments because
of their high chemical stabilities towards strong acid and base media. L*, a*, b* values of
these brown-yellow colorants are stables and there is no Cu leaching problem observable.
KEYWORDS: Environment-friendly; Non-toxic pigment; Rare earth; Copper; CeO2
1. INTRODUCTION
Inorganic pigments are used in various
applications such as paints, ceramics, inks,
plastics, rubbers, glasses... [1,2]. The use of
these pigments is not only because of their
coloristic properties but also to protect the
coating from the effects of solar light (UV
as well as visible and infrared light). In
order to be suitable in a wide variety of
applications, they need to have high
temperature stability and high color
stability. The majority of the inorganic
pigments, which are currently employed on
an industrial scale, generally, comprise
toxic metals, such as Cd, Pb, Cr, Se, Co,
Ni...[3, 4], which are harmful not only to
our health but also to the environment. The
use of the above pigments is becoming
increasingly strictly controlled, indeed
banned, by government legislation and
regulations in many countries due to their
reputedly high toxicity. Nowadays,
practical applications for the coating
materials also require pigments that are
resistant to acid rain and corrosive gases
such as NOx, SO2. Thus, the development
of substituting inorganic pigments which
possess high chemical resistance to prevent
the metal leaching and color change are
necessary.
Recently, CeO2 and its related pigments
have been attracted recently because they
have high thermal and chemical stability [5,
6]. Furthermore, there are a number of
processes to prepare and modify CeO2 fine
particles [7,8]. It is reported that we can
control the color hue of the pigments by the
incorporation of another element into the
CeO2 lattice, because the coloring
mechanism is based on the charge transfer
transition from O2p to Ce4f in the CeO2 band
structure, which can be modified by the
introduction of an additional electronic
level between the anionic O2p valence band
and the cationic Ce4f conduction band [4].
Thus, the present paper is focused on the
synthesis of a novel class of potential
environment-friendly brown-yellow
pigments based on CeO2 and CuO by co-
precipitation method, which has not
developed yet in the literature. The new
pigments have been synthesized with the
nCuO/nCeO2 ratio ranging from 0.01 to 0.4.
The composition of the pigments has been

26
optimized and their color properties have
been characterized from the viewpoint of
possible ecological inorganic pigments.
Moreover, the chemical stabilities and Cu
leaching problem have also been studied on
the samples in order to evaluate the
potential environmental impacts.
2. EXPERIMENTAL
2.1 Pigments preparation
Several compositions based on different
nCuO/nCeO2 (x) ratios were prepared by co-
precipitation method. Cerium (III) nitrate,
Ce(NO3)3.6H2O (from Yurui (China); extra
pure grade 99.99%) and copper (II) nitrate,
Cu(NO3)2.3H2O (from Merck (Germany),
extra pure grade 99.9 %) were used as
precursors for pigment synthesis. NH3
solution (25 %, technical grade) was used
to establish basic media during the
preparation. All chemicals were used in this
study as received without further
purification. Distilled water was used in all
the experiments. In this method, cerium
(III) nitrate and copper (II) nitrate were
respectively dissolved in water and then
mixed in the proper stoichiometric
compositions under constant stirring. NH3
was regularly added in the solution up to
pH = 10 in order to co-precipitate the two
corresponding hydroxides: cerium
hydroxide and copper hydroxide. These
hydroxides were then filtered, washed in
distilled water and calcined in an electric
furnace at 800°C for 5 hours. The resulting
powders were then ground in an agate
mortar to refine and homogenize the
particle size. A CeO2 sample without Cu-
doping was also prepared by the
precipitation of Ce(NO3)3.6H2O in the basic
medium in order to compare with
CeO2:CuO samples.
2.2 Pigments characterization
The powder X-ray diffraction (XRD
patterns obtained on a Bruker AXS D8 X-
ray diffractometer using Cu Kα radiation (λ
= 1.5406 Å) were used to investigate
crystallite structures and phase
compositions of pigment samples. The
acceleration voltage and the applied current
were 40 kV and 40 mA, respectively. Data
were collected by a step scanning from 20°
to 70° (2 θ) with a step size of 0.03° and a
step time of 0.8 s.
Colorimetric coordinates including the
luminosity of the as-synthesized pigments
were measured in the 400 and 700 nm
range, using a chromameter Konica Minolta
CR-300 equipped with a standard type D65
(daylight) light source, following the CIE
L*a*b* colorimetric method recommended
by the CIE (Commission Internationale de
l’Eclairage) [9].
The acidic/alkali resistance of all samples
was characterized by immersing them (with
an exact quantity) in a HCl (technical
grade) solution (2 mol.L-1
) and NaOH
(technical grade) solution (2 mol.L-1
) under
magnetic stirring for 24 hours at room
temperature.. Then, the pigment was
filtered, washed with water, dried and re-
weighed. Their colorimetric properties were
then remeasured using the chromameter
Konica Minolta CR-300. This condition is
considered as an "extreme condition"
compared with the literature [1,3].
Moreover, the Cu leaching problem in acid
and base media was also examined. After
the acidic/alkali resistance test, the filtration
was performed. The Cu2+
concentration of
filtered solutions was determined by
measuring their absorbance at 620 nm with
a SP-300 Optima spectrophotometer.
3. RESULT AND DISCUSSION
Table 1 shows the composition with
different copper content (Cu/Ce atomic
ratio) and the notation of 8 samples
prepared in this study in order to evaluate
the effect of this parameter on the optical
properties of the final pigments. The visual
color of the calcined powders varied from
yellow-white to yellow-brown and dark-
brown on increasing of copper content
(Figure 1). On the other hand, a progressive
decrease of luminosity at higher copper
content was also observed.

27
Table 1. Composition and nomination of the Cu-doped CeO2 samples prepared by co-precipitation
and calcined at 800°C
Sample CeO2
x = nCu : nCe
CuO
0.01 0.02 0.05 0.1 0.2 0.4
Notation D0 D1 D2 D3 D4 D5 D6 D7
D0 D1 D2 D3
D4 D5 D6 D7
Figure 1. Photographs of the naked CeO2 (D0) and Cu-doped CeO2 pigment samples (D1, D2, D3,
D4, D5, D6 and D7)
Table 2. The color coordinates (L*a*b*) of the naked CeO2 and Cu-doped CeO2 samples calcined at
800° before and after chemical resistance test with NaOH 2M (24h) (presented as Lb*, ab* and bb*).
∆E* = [(∆L*)2
+ (∆a*)2
+ (∆b*)2
]1/2
Sample L* a* b* Lb* ab* bb* ∆E* Result
D0 91.25 -2.92 12.44 89,87 0,02 13,40 3.35 Stable
D1 75.64 -4.36 13.70 76,58 -2,60 12,19 2.31 Stable
D2 68.95 -4.91 18.05 67,95 -2,23 18,28 2.86 Stable
D3 46.80 -0.15 9.13 45,30 2,02 7,13 3.30 Stable
D4 46.63 0.22 7.53 45,52 1,98 5,54 2.90 Stable
D5 40.13 1.32 1.84 39,52 1,82 0,30 1.73 Stable
D6 36.87 -0.55 -1.01 35,47 1,26 -1,80 2.40 Stable
D7 36.75 -0.14 -0.75 35,39 1,08 -1,72 1.98 Stable
Table 3. The color coordinates (L*a*b*) of the naked CeO2 and Cu-doped CeO2 samples calcined at
800° before and after chemical resistance test with HCl 2M (24h) (presented as La*, aa* and ba*). ∆E*
= [(∆L*)2
+ (∆a*)2
+ (∆b*)2
]1/2
Sample L* a* b* La* aa* ba* ∆E* Result
D0 91.25 -2.92 12.44 91.10 -1.59 12.62 1.35 Stable
D1 75.64 -4.36 13.70 76.49 -4.52 13.74 0.80 Stable
D2 68.95 -4.91 18.05 70.47 -4.20 17.24 1.80 Stable
D3 46.80 -0.15 9.13 46.04 0.56 8.28 1.98 Stable
D4 46.63 0.22 7.53 46.47 0.69 6.54 1.10 Stable
D5 40.13 1.32 1.84 44.98 0.94 3.27 5.07 Not stable
D6 36.87 -0.55 -1.01 39.63 0.39 1.04 3.56 Not stable
D7 36.75 -0.14 -0.75 78.73 -18.60 0.51 45.9 Not stable

28
3.1 Color characterization
The color measurements performed on all
powders showed systematic changes in the
CIE-Lab 1976 color scales directly
correlated with the variation of copper in
the system. The L*, a*, and b* parameters
of the pigment samples were listed in table
2. The increase of copper content would
have induced a darkening of the samples,
with demonstrated decrease of the
parameter lightness (L*). In opposition, the
result showed no systematic change in the
color parameters a* (green- red parameter).
The most interesting observation was the
variation of parameter b* (blue-yellow
parameter). The addition of small amount
of copper (x = 0.01 and 0.02) slightly
improved b* (from 12.44 up to 13.7 (x-
0.01) and 18.05 (x = 0.02), respectively.
However, the higher copper content
(x>0.02) showed smaller b* values which
means the decrease in yellow component.
However, to become an environmentally
benign nontoxic pigments, the powders
obtained must present chemical stability
and resistance toward metal leaching
problem.
3.2 Powder X-ray diffraction analysis
XRD was used to study the effects of Cu-
doping on the crystallite structures and
phase compositions of powder samples.
Figure 2 shows the XRD patterns of naked
CeO2 and Cu-doped CeO2 samples. The
Rietveld refinement was carried out using
the Fullprof 2009 structure refinement
software [10]. The cell parameters are
summarized in the Table 3. Naked CeO2
consists of a CaF2-type structure (space
group Fm3m, JCPDS N°34-0394) identified
with the XRD peaks at 2θ = 28.50° ((111)
line), 2θ = 33.02° ((200) line) and 2θ =
47.52° ((220) line). This sample shows the
lattice parameter a = 5.421 Ǻ.
For CeO2-CuO samples, when x varies
from 0.01 to 0.2, no additional phase is
detected, indicating that the Cu-doping in
this range does not modify the phase
composition of CeO2. However, the
Rietveld refinement shows a decrease of
lattice parameter a* with higher copper
content. This confirms the formation of
solid solution between CeO2 and CuO
oxides. Kumar et al. [11] reported that the
Co-doping decreases the lattice parameter a
of CeO2, which is attributed to the
substitution of bigger Ce4+
ions (radii of
0.97 Ǻ) by the smaller Co2+
ions (radii of
0.72 Ǻ). The decrease of lattice parameter
a* in our samples should be also related to
the presence of smaller Cu2+
ions (radii of
0.83 Ǻ) in the Ce4+
sites of CeO2 structure.
Secondary phase, CuO (space group C2/c,
JCPDS N°48-1548), identified with the
XRD peaks at 2θ = 35.54° ((002) line), 2θ =
38.74° ((111) line) and 2θ = 48.55° ((-202)
line), is only found along with the major
fluorite phase of CeO2 in the sample with x
= 0.4. The absence of CuO phase in most of
samples (x<0.4) indicates that CuO could
be highly dispersed in CeO2 lattice to form
a solid solution with Cu2+
ions substituting
Ce4+
ions, which is consistent with the
literature [12, 13].
Figure 2. XRD patterns of naked CeO2 (D0)
and CeO2-CuO samples (D2, D5 and D6)

29
Table 3. Unit cell parameters of naked CeO2
and Ce1-xCuxO2 samples
Samples
Unit cell parameters
CeO2 CuO
D0
a =b = c =
5.4207 Å
α = β = γ =
90.00°
D2
a = b = c =
5.4107 Å
α = β = γ =
90.00°
D5
a = b = c =
5.4046 Å
α = β = γ =
90.00°
D6
a = b = c =
5.4130 Å
α = β = γ =
90.00°
a = 4.7011 Å
b = 3.4500 Å
c = 5.1224 Å
α = γ = 90.00°;
β = 99.86°
3.3 Chemical stability studies of the
pigments
A pre-weighed quantity of the pigment was
treated with acid/alkali and soaked for 24
hours with constant stirring using a
magnetic stirrer. The pigment powder was
then filtered, washed with water, dried and
weighed. Negligible weight loss of pigment
was noticed for all the acid and alkali
tested. The color coordinates of the typical
pigments were remeasured after acid/alkali
treatment. The total color difference ∆E* of
all the pigments after alkali resistance test
were found to be negligible (∆E*<3.5 is
considered negligible [9]) (Table 2). This
indicates that the typical Cu-CeO2 pigment
exhibits high resistance towards NaOH in
extreme condition. However, in acidic
resistance test, only samples having ratio
nCu:nCe x<0.2 were stables (Table 3). This
result was well correlated with XRD
analysis which indicated that Cu could only
be totally in a solid solution with CeO2
when x is smaller than 0.2. At higher x, all
the Cu2+
could not be completely inserted
into the CeO2 lattice. Thus, some amount of
Cu could be dissolved by HCl and causes
the color change.
Moreover, the Cu leaching problem in acid
and base media was also examined. There
was no Cu2+
in the filtered solutions with all
the pigments. In acid media, the Cu2+
leaching problem was only observed on the
samples with x>0.2. As the results, these
pigment samples could be used in order to
protect the coatings from the effects of
weather (acid rain) or the corrosive gas
such as NOx, SO2.
4. CONCLUSION
In summary, new inorganic pigments based
on CeO2–CuO solid solutions have been
successfully synthesized by inserting
copper into ceria lattice. Their color
depends on the composition, and can vary
from yellow-white to yellow-brown and
dark-brown with increasing of Cu content.
The developed pigments CeO2–CuO with
the ratio nCu:nCe<0.2 are found to be
chemically stable and also do not have
metal leaching problem in "extreme
condition" which potential environment-
friendly. Thus, the present pigments may
find potential alternative to the classical
toxic yellow-brown inorganic pigments for
various applications such as paints,
coatings, cosmetics, plastics and glass
enamels.
5. REFERENCES
[1] P. Prabhakar Rao, M.L.P. Reddy,
Synthesis and characterisation of
(BiRE)2O3 (RE: Y, Ce) pigments, Dyes and
Pigments, 63, 2004, pppp. 169-174.
[2] M. Jansen, H.P. Letschert, Inorganic
yellow-red pigments without toxic metals,
Nature, 404, 2000, pp. 980-982.
[3] P. Prabhakar Rao, M.L.P. Reddy,
(TiO2)1(CeO2)1−x(RE2O3)x – novel
environmental secure pigments, Dyes and
Pigments, 73, 2007, pp. 292-297.
[4] S. Furukawa, T. Masui, N. Imanaka,
New environment-friendly yellow pigments
based on CeO2–ZrO2 solid solutions,
Journal of Alloys and Compounds, 451,
2008, pp. 640-643.

30
[5] P. Šulcová, M. Trojan, The synthesis of
the Ce0.95−yPr0.05LayO2-y/2 pigments, Dyes
and Pigments, 44, 2000, pp. 165-168.
[6] P. Šulcová, M. Trojan, The synthesis
and analysis of Ce0.95−yPr0.05SmyO2−y/2
pigments, Dyes and Pigments, 58, 2003, pp.
59-63.
[7] T. Masui, S. Furukawa, N. Imanaka,
Synthesis and Characterization of CeO2-
ZrO2-Bi2O3 Solid Solutions for
Environment-friendly Yellow Pigments,
Chemistry Letters, 35, 2006, pp. 1032-
1033.
[8] G.-y. Adachi, N. Imanaka, The Binary
Rare Earth Oxides, Chemical Reviews, 98,
1998, pp. 1479-1514.
[9] U. Hempelmann, G. Buxbaum, H.G.
Völz, Introduction, in: Industrial Inorganic
Pigments, Wiley-VCH Verlag GmbH &
Co. KGaA, 2005, pp. 1-50.
[10] J. Rodriguez-Carvajal, Commission of
Powder Diffraction, IUCr Newsletter, 26,
2001, all pages.
[11] S. Kumar, Y.J. Kim, B.H. Koo, H.
Choi, C.G. Lee, Structural and Magnetic
Properties of Co Doped CeO Nano-
Particles, Magnetics, IEEE Transactions on
Magnetic, 45, 2009, pp. 3-8.
[12] D. Delimaris, T. Ioannides, VOC
oxidation over CuO–CeO2 catalysts
prepared by a combustion method, Applied
Catalysis B: Environmental, 89, 2009, pp.
295-302.
[13] G. Avgouropoulos, T. Ioannides, H.
Matralis, Influence of the preparation
method on the performance of CuO–CeO2
catalysts for the selective oxidation of CO,
Applied Catalysis B: Environmental, 56,
2005, pp. 87-93.
Contact:
1. Le Phuc Nguyen, PhD
Petrovietnam Research and Development
Center for Petroleum Processing (PVPro), 4
Nguyen Thong, Ho Chi Minh city
Tel: 0084 (0)902666482
Email: nguyenlp@pvpro.com.vn
2. Le Tien Khoa, PhD
Department of Inorganic and Applied
Chemistry – Ho Chi Minh University of
Sciences, 227 Nguyen Van Cu, Ho Chi
Minh City
Tel: 0084 (0)937293251
Email: tienkhoale@gmail.com

31
IMPROVING THE BIOGAS APPLICATION IN THE MEKONG DELTA OF
VIETNAM BY USING AGRICULTURAL WASTE AS AN ADDITIONAL
INPUT MATERIAL
Nguyen Vo Chau Ngan1, 2
, Klaus Fricke2
1
College of Environment & Natural Resources, Cantho University, Vietnam
2
Technical University of Braunschweig, Germany
ABSTRACT
This investigation studied the co-digestion between pig manure (PM) and spent mushroom
compost (SMC) to produce biogas in lab-scale. The batch and semi-continuous anaerobic
digesters were applied to co-digest PM+SMC with different mixing ratios based on organic
dry matter values. The result of the 35 continuous day batch treatment showed that the more
percentage of SMC contained in the mixing ratio of PM+SMC, the less biogas was produced
but it was not significantly different between the treatments of 100%PM+0%SMC, of
75%PM+25%SMC, of 50%PM+50%SMC and of 25%PM + 75%SMC. The semi-continuous
testing in 90 continuous days of 75%PM+25%SMC showed the relatively stable operation of
the treatment. The outcomes indicated that farmers in the Mekong Delta can apply SMC as an
additional feeding material to biogas digesters in case pig manure is short.
KEYWORDS: Batch anaerobic process, semi-continuous anaerobic process, spent mushroom
compost, the Mekong Delta
1. INTRODUCTION
1.1 Background
In the Mekong Delta of Vietnam, biogas
plants are strongly confirmed as an
optimum treatment way for livestock waste
and biogas supply for household cooking,
lighting, etc. The output from biogas plants
can be used to feed fish in a VACB farming
system. According to Tran et al. (2009) [1],
more than 90% of the biogas users apply
PM as the sole input material to their
biogas plants. Any negative progress of the
pig market will directly affect the operation
of biogas plants and make the investment in
installation of biogas digesters wasted. This
is considered as one of primary limits to the
promotion of widespread application of
biogas digesters, weakening the potentials
of favorable conditions of the Mekong
Delta for biogas application and having an
impact on the environmental pollution
prevention in the area.
Looking into the real conditions of the
Mekong Delta, among the possible uses,
SMC could be potentially used as an
additional input material for biogas plants.
As the residue from rice straw mushroom
cultivation, SMC has already been partly
degradable, helping shorten the duration of
anaerobic process. However, there has been
no research on the application of SMC in
biogas production in the Mekong Delta.
1.2 Research objectives
This study is expected to contribute
locality-based evidence supporting the
encouragement of the local owners of
biogas digesters to take into account the
usage of SMC as potentially additional
input materials for their biogas digesters,
especially when animal manure is in short
supply. Two types of experiments were
processed to give answers to the questions
of:
- The influence of differential mixing
ratios of SMC with PM on gas
production by batch digester.
- The stability of the semi-continuous
anaerobic co-digestion of SMC to PM.

32
2. METHODOLOGY
2.1 Material preparation
The input materials loaded to the digesters
were prepared as follows:
- PM collected from the piggeries at Hoa
An Center was air-dried out at ambient
temperature (25 ± 4°C) for one week
before coming into use, then the dried
PM was manually mashed and mixed up
until it became a homogenous form.
- SMC was collected from the farmers’
households producing straw mushroom
around Hoa An ward. The SMC was
manually cut into approximate 1.0 ÷ 2.0
cm long pieces. The chopped SMC was
air-dried at ambient temperature up to
unchanged weight, and then manually
mixed up completely.
- Inoculums: to shorten the time of gas
production, the seeding material which
was the effluent taken from an existing
active biogas plant was used. This is a
100 m3
activated biogas plant at Hoa An
Center.
2.2 Experimental set-up
For batch treatments, 17.5 L inoculum was
mixed together with 665 g mixture of PM
and SMC (based on organic dry matter
(ODM) values). Five co-digestion batches
of PM and SMC were set up to evaluate the
influence of various mixing ratios on gas
production. Each of the treatments was in
triplicate. All of the batch treatments were
allowed to be fermented for 28 days and
were mixed up by shaking the digesters
manually once a day so as to increase the
gas production.
- SMC0: 100%PM + 0%SMC
- SMC1: 75%PM + 25%SMC
- SMC2: 50%PM + 50%SMC
- SMC3: 25%PM + 75%SMC
- SMC4: 0%PM + 100%SMC
A semi-continuous treatment 75%PM+
25%SMC was set up in triplicate. The
digesters were fed at the same time every
day during the experiment time. In this
treatment, only the action of feeding the
digesters helped stir the substrate inside the
digesters. The semi-continuous treatments
were conducted for a 90 consecutive day
period.
SMC5: 17.5 L inoculums and 23.75 g
ODM mixture of PM and SMC were added
as starting materials. From the 2nd
day, the
daily feeding rate included 875 mL
inoculums and 17.81 g ODM of PM plus
5.94 g ODM of SMC.
There were 18 sets of airtight digestion
apparatus installed of which 15 digesters
for batch fermentation and 3 digesters for
semi-continuous fermentation. To minimize
the development of algae population that
creates oxygen inside the digesters, all
digesters were covered by black nylon bags
throughout the testing period.
Figure 1. Treatments on batch (above) and
semi-continuous experiments (below)
(1) the air-valve; (2) the gas pipe
2.3 Analytical methods
The substrates before and after the
experiments were taken and analyzed for
pH, carbon (C), total Kjeldahl nitrogen (N),
dry matter (DM), ODM, alkalinity
according to methods of APHA (1995) [2].
The gas production was recorded daily by
the Ritter gas-meter, and the biogas

33
components were monitored weekly by the
GA94 gas analyzer.
All of the experiments and analyses were
conducted at the Environmental
Engineering Laboratory - College of
Environment and Natural Resources,
Cantho University, Vietnam.
3. RESULTS AND DISCUSSIONS
3.1 Results on feeding materials
Table 1. The physical and chemical analysis of
the input materials
Material DM (%) ODM (%) C/N
PM 76.36 36.60 9.59
SMC 81.28 76.49 24.56
(*): ODM calculated based on DM value
The mixing ratio of input materials in this
study was calculated according to their
ODM. Eder & Schulz (2007) [3] suggested
that the optimal input should be 1 ÷ 4 kg
ODM day-1
.m-3
for an anaerobic digester.
Based on this suggestion, the input quantity
was chosen to be 1.25 g ODM day-1
.L-1
.
Table 2. Mixing ratios on dry weight basis
Treatments PM SMC Total
Batch treatments
100%PM+0%SMC 2380 0 2380
75%PM+25%SMC 1785 268 2053
50%PM+50%SMC 1190 535 1725
25%PM+75%SMC 595 803 1398
0%PM+100%SMC 0 1070 1070
Semi-continuous
75%PM+25%SMC 64.00 9.55 73.55
The relationship between the amount of
carbon and nitrogen available in organic
materials is represented by the C/N ratio.
Microorganism generally utilizes carbon
and nitrogen in the ratio of 25/1 ÷ 32/1
(Bouallagui et al. 2003) [4]. Because the
C/N ratio in PM is low while it is high in
SMC, the co-digestion PM+SMC can help
adjust the C/N ratio closer to the optimum
value.
In this study, the C/N ratio of the input
materials ranged from 9 to 25. The C/N of
input materials can be significantly affected
by the factors such as biomass varieties,
cultivation system, soil condition, applied
fertilizers, etc.
3.2 Results of produced biogas from
batch treatments
The daily gas production from the
PM+SMC treatments was taken after two
day operation and recorded for 28
continuous fermentation days. However, at
the day 28th
, the material contained in the
substrate was still in the original form but
not much degradable. Then the treatments
were kept for fermentation in 35 days.
Figure 2. Substrate after 28 fermented days
The recorded results showed that the biogas
volume of the treatments reached
maximum values around the end of the 1st
week. In the 2nd
week, the peak value of
biogas volume fell down and then slightly
declined until the end of the testing period.
At the end of the 5th
week, the daily
produced biogas volume only accounted for
1.02%, 1.24%, 1.45%, 1.66% and 2.28% of
the total biogas in the %PM+%SMC
treatments of 100+0, of 75+25, of 50+50,
of 25+75, and of 0+100, respectively.
The higher biogas production recorded in
the later period of treatments with higher
SMC percent was possibly caused by high
lignin content remaining in SMC. Study on
methane production from rice straw by Lei
et al. (2010) [5] showed that the first peak
of gas happened after 20 ÷ 30 operation
days, and the second peak presented after
60 ÷ 80 days, but the second peak was
always greater than the first peak. Because

34
the fermentation time in this study lasted
only 35 days, only PM and part of SMC
were decomposed. As a result, just the first
peak of produced gas occurred in this
study.
In respect with the various mixtures of
SMC and PM, the treatments with a larger
percentage of SMC generated lower biogas
volume. Nevertheless, the generated biogas
volumes between the testing treatments
were not significantly different except the
treatment of 0%PM+100%SMC. The
letters a and b in Figure 3 displayed the
difference in the total gas produced in the
PM+SMC treatments. The results showed
that SMC could apply as co-digestion with
PM up to the mixing ratio of
25%PM+75%SMC without affecting the
biogas production.
Figure 3. Accumulative biogas volume
Calculation on biogas yield for each
treatment was based on the weekly biogas
production and the fermented ODM value.
The results indicated that higher biogas
yield was present in the treatments with
lower percentage of SMC in the mixture
ratio (Figure 4).
The variation on biogas production
between the treatments was caused by the
difference in pH and alkalinity values
resulted by the various mixing ratios of PM
and SMC. In this study, the SMC substrate
was the most acidic while the PM substrate
was the most alkaline. It was observed that
the SMC was high lignin content that
exhibited a multi-stage gas production
pattern. In fact, after the peak gas
production in the PM+SMC treatments,
there were other small “peak” values (on
the day of 12th
, 22nd
, 27th
, 29th
and 33rd
). It
is believed there would be re-fermentation
process to occur in anaerobic digestion in
order to complete the gasification of SMC.
Figure 4. The biogas yield of treatments
Figure 5. Control parameters of treatments
Before the fermentation, the alkalinity
value of the treatments decreased due to
higher percentage of SMC in the mixture.
The alkalinity is the result of the release of
amino groups (-NH2) and production of
ammonia (NH3) as the proteinaceous
wastes are degraded (Gerardi, 2003) [6]. By
that fact, the treatments containing high
percentage of SMC could not maintain the
optimum alkalinity. After the experiment,
the alkalinity of the treatments tended to
increase more than that of the input
substrate. The alkalinity variation was the
greatest in the treatment of 0%PM+100%

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