VISVESVARAYA TECHNOLOGICAL UNIVERSITY “Jnana Sangam”, Belgaum-590018 Student Project Programme- 39S_BE_0239 A Project report on “OPTIMISATION OF FOOD-WASTE BASED BIOGAS DIGESTER AND ITS IMPLEMENTATION IN RURAL AREAS” Submitted to the Visvesvaraya Technological University, Belgaum. In partial fulfilment for the award of the degree of BACHELOR OF ENGINEERING IN CIVIL ENGINEERING For the Academic year- 2015-2016 Submitted By MR. BLESSON USN: 4SF12CV020 MR. NIRMITH ASHOK BANGERA USN: 4SF13CV027 MR. KOUSHIK M USN: 4SF13CV056 MR. ARTHIK RAI USN: 4SF13CV022 SPP coordinator Project Guides Dr. Manjappa S. Dr. Prasanna Kumar. C Ms. Rashmishree K. N. Director, Research and Consultancy Sahyadri College of Engineering and Management Associate Professor Department of Electronic and Communication Engineering Assistant Professor Department of Civil Engineering Sahyadri College of Engineering and Management Adyar, Mangalore-575007
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VISVESVARAYA TECHNOLOGICAL UNIVERSITY
“Jnana Sangam”, Belgaum-590018
Student Project Programme- 39S_BE_0239
A Project report on
“OPTIMISATION OF FOOD-WASTE BASED BIOGAS DIGESTER
AND ITS IMPLEMENTATION IN RURAL AREAS”
Submitted to the Visvesvaraya Technological University, Belgaum.
In partial fulfilment for the award of the degree of
BACHELOR OF ENGINEERING IN CIVIL ENGINEERING
For the Academic year- 2015-2016
Submitted By
MR. BLESSON USN: 4SF12CV020
MR. NIRMITH ASHOK BANGERA USN: 4SF13CV027
MR. KOUSHIK M USN: 4SF13CV056
MR. ARTHIK RAI USN: 4SF13CV022
SPP coordinator Project Guides
Dr. Manjappa S. Dr. Prasanna Kumar. C Ms. Rashmishree K. N.
Director, Research and
Consultancy
Sahyadri College of Engineering
and Management
Associate Professor
Department of Electronic
and Communication
Engineering
Assistant Professor
Department of Civil
Engineering
Sahyadri College of Engineering and Management
Adyar, Mangalore-575007
SAHYADRI COLLEGE OF ENGINEERING AND MANAGEMENT
Adyar, Mangalore-575007
DEPARTMENT OF CIVIL ENGINEERING
CERTIFICATE
Certified that the project work entitled “OPTIMISATION OF FOODWASTE BASED
BIOGAS DIGESTER AND ITS IMPLEMENTATION IN RURAL AREAS” carried out
by MR. BLESSON S(4SF12CV020), MR. NIRMITH ASHOK
BANGERA(4SF13CV027), MR KOUSHIK M(4SF13CV056) and MR. ARTHIK
RAI(4SF13CV022) are bonafide students of Department of Civil Engineering,
Sahyadri College of Engineering and Management in partial fulfilment for the award of
Bachelor of Engineering in Civil Engineering of the Visvesvaraya Technological
University, Belgaum during the year 2015-2016. It is certified that all correction/suggestions
indicated for Internal Assessment have been incorporated in the Report deposited in the
department library. The project report has been approved as it satisfies the academic
requirements in respect of Project work prescribed for the said Degree.
Prof. Purushothama C T Dr. U M Bhushi
Head of the Dept. Principal
Dr. Prasanna Kumar. C Ms. Rashmishree. K.N
Project guide Project guide
OPTIMISATION OF BIOGAS PRODUCTION BY THREE STAGED DIGESTER
ACKNOWLEDGEMENT
The gratified feeling that we share at the completion of our project work is the
courtesy of those who were involved in our efforts to bring out a successful project
“OPTIMISATION OF FOODWASTE BASED BIOGAS DIGESTER AND
ITS IMPLEMENTATION IN RURAL AREAS”.
We salute our esteemed institution Sahyadri, Adyar which will shape us to
effective engineers of tomorrow. We express our deep sense of gratitude to
department of CIVIL Engineering, which is providing us a homely atmosphere to
develop our all-around skills.
We are grateful to Dr. U M Bhushi, Principal, SCEM, for having extended all
facilities to make this project a grand success.
Our sincere thanks to our respected SPP Coordinator Dr. S Manjappa, Director of
Research and Consultancy, SCEM for his valuable suggestions and providing all
facilities to carry out the project.
We are also grateful to Prof. Purushothama C T, Head of the department, Civil
engineering, and Prof. Umesh S, head of the department, M.Tech Civil, SCEM for
their constant support throughout the project.
We are grateful to Dr. Prasanna Kumar. C, Associate Professor, Department of
E&C Engineering and Ms. Rashmishree K. N., Department of Civil Engineering,
SCEM for their co-operation and guidance at each stage of the project.
Our sincere gratitude to Dr. Gautham P Jeppu, for his guidance and support
throughout the project. His encouragement and inspiration was guiding source
throughout the project work. We are also thankful to Dr. Savitha M, Ms. Sharadha,
(Department of Chemistry, SCEM), Mrs. Ranjini(Headmistress, Govt. School,
Nekkilady), Mrs. Sevrin(Asst. Teacher, Govt. School, Nekkilady) and Edison
Project Team for helping us throughout the project.
Finally we are ever grateful to our parents, teaching and non-
teaching staff members of civil engineering department and
friends for their encouragement, suggestions and help.
OPTIMISATION OF BIOGAS PRODUCTION BY THREE STAGED DIGESTER
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INDEX
Chapters Title Page No. 1. Introduction 3-5 2. Literature Review 6-8
3. Biogas 9-12 4. Design of Digester 13-16 5. Principles for the production of biogas 17-20 6. Tests, observation and results 21-23
7. Conclusion 24 8. Scope for future work 25 9. References 26-27
OPTIMISATION OF BIOGAS PRODUCTION BY THREE STAGED DIGESTER
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CHAPTER-1
INTRODUCTION
1.1 GENERAL
Due to scarcity of supply of petroleum and coal and its threats by emissions
has led to research throughout the world in different corners to get access to the
new sources of energy, like renewable energy resources. Solar energy, wind
energy, different thermal and hydro sources of energy, biogas etc. are all renewable
energy resources. But, biogas is distinct from other renewable energies because of
its characteristics of using, controlling and collecting organic wastes and at the
same time producing fertilizer and water for use in agricultural irrigation. Biogas
neither has any geographical limitations nor does it require any advanced
technology for producing energy. It is very simple to use and apply.
A biogas plant is an anaerobic digester that produces biogas from animal,
food waste or plant waste. Biogas can provide a clean, easily controlled source of
renewable energy from organic waste materials for a small labour input, replacing
firewood or fossil fuels (which are becoming more expensive as supply falls
behind demand). Biogas is generated when bacteria degrade biological material in
the absence of oxygen, in a process known as anaerobic digestion. Since biogas is
a mixture of methane (also known as marsh gas or natural gas, CH4) and carbon
dioxide it is a renewable fuel produced from waste treatment. Food waste is the
best feedstock for biogas production. It is 20times more efficient than conventional
methods of using cow dung and pig wastes.
Biogas does not require any new technology as it is a natural process. But the
optimisation of production can be made by availing proper environment
conditions. Environmental factors temperature, pH, alkalinity, agitation etc. greatly
affect the production of biogas. The mesophilic temperature favours the reaction.
Experiments are made on use of higher temperatures that is thermophilic
temperature for production of biogas and are found effective. Constant stirring
increases the rate of production as the bacteria gets exposed to large area for
decomposing. The pH plays an important role as it should be maintained moderate
for the survival of bacteria.
OPTIMISATION OF BIOGAS PRODUCTION BY THREE STAGED DIGESTER
Sahyadri College of Engineering and Management Page 4
Considering all these factors a new technique digester designed to optimise
the biogas production. Three staged digester improves agitation process. The pH
was regulated and temperature was monitored to influence bacterial fermentation.
Three staged digester not only provides complete utilisation of food waste. But
also provides stirring effect.
1.2 AIM OF THE STUDY
The main objective of the project was to design a prototype and to study the
efficiency on using a three staged digester for production of biogas with food waste
and also to study the feasibility of implementation in rural areas as a community
reactor.
The project intended in comparing the production of normal digester with the
three staged digester. The aim was to develop a design of biogas digester for a
school in rural area, a community reactor to propose a disposal management
system for food waste.
1.3 OBJECTIVES
The objectives of our project are listed below-
To design two prototype biogas digesters and test them for biogas
production from food waste.
To study the production of biogas with normal digester and a three staged
digester.
To quantify the biogas produced with both normal and three staged digester
and thus obtaining the biogas yield at constant percentage of feedstock for
both prototypes.
To optimize the production of biogas using higher temperature with heat
exchanger.
To regulate the pH of slurry in the digester and thus promoting bacterial
activity.
To obtain the efficiency of using a three staged digester over normal
digester.
To survey a rural area and develop a design a biogas digester design by
considering yield and food waste produced.
OPTIMISATION OF BIOGAS PRODUCTION BY THREE STAGED DIGESTER
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1.4 METHODOLOGY
1. A normal biogas digester was designed and it was fed with constant
feedstock of 0.2% the size of the digester.
2. The gas produced was quantified daily and the conditions like pH and
temperature were regulated.
3. The yield per 100L size of the digester was calculated.
4. A new technique three-staged digester was designed and even that was fed
constantly with 0.2% the size of the digester.
5. The yield produced was quantified daily and yield for 100litre size of the
digester were calculated.
6. From the results the optimisation by using the three staged digester were
studied.
7. A survey was made on quantity of food waste produced in Nekkilady
village, near Uppinangady.
8. The quantity of LPG cylinders used and the waste produced in college were
studied.
9. Based on the results a digester was designed for the school which would
replace the use of LPG completely.
1.5 SOURCES OF INFORMATION
ARTI
GOOGLE
HANDBOOK OF BIOGAS UTILIZATION.
ENCYCLOPEDIA OF PHYSICAL SCIENCE AND TECHNOLOGY.
BIOGAS THESIS
JOURNALS
DOCUMENTS FROM OFFICE OF THE SCHOOL.
OPTIMISATION OF BIOGAS PRODUCTION BY THREE STAGED DIGESTER
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CHAPTER-2
LITERATURE REVIEW
2.1 INTRODUCTION
Food waste is a very good feedstock for biogas production. It is 20 times
more efficient than the conventional methods of using cow dung. Multi-stage
anaerobic digestion has the advantage of achieving superior performance compared
with single-stage conventional digestion. The multi-stage process is capable of a
higher volatile solids (VS) reduction with shorter residence times, production of
biogas of higher quality, and elimination of foaming. The purpose of stirring is to
distribute the nutrients in the biogas digester uniformly, to form a suspension of
liquid and solid parts, to avoid sedimentation of particles, to ensure uniform heat
distribution, to prevent foam formation and to enable gas lift from the fermentation
substrate at high dry matter (DM) contents.
2.2 ARTI
Appropriate Rural Technology of India, Pune (2003) has developed a
compact biogas reactor which uses waste food rather than any cow dung as
feedstock, to supply biogas for cooking. Dr. Anand Karve (ARTI) developed a
compact biogas system that uses starchy or sugary feedstock (waste grain flour,
spoilt grain, overripe or misshapen fruit, nonedible seeds, fruits and rhizomes,
green leaves, kitchen waste, leftover food, etc.). Just 2 kg of such feedstock
produces about 500 g of methane, and the reaction is completed with 24 hours. The
conventional biogas systems of cattle dung, sewerage, etc. use about 40 kg of
feedstock to produce the same quantity of methane and it requires about 40 days
for completing the reaction. Thus, from the point of view of conversion of
feedstock into methane, the system developed by Dr. Anand Karve is 20 times as
efficient as the conventional system, and from the point of view of reaction time, it
is 40 times as efficient. Thus, overall, the new system is 800 times as efficient as
the conventional biogas system.
2.3 SHALINI SINGH
Shalini Singh (2000) studied the increased biogas production using microbial
stimulants. They studied the effect of microbial stimulant aquasan and teresan on
biogas yield from cattle dung and combined residue of cattle dung and kitchen
waste respectively. The result shows that dual addition of aquasan to cattle dung on
OPTIMISATION OF BIOGAS PRODUCTION BY THREE STAGED DIGESTER
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day 1 and day 15 increased the gas production by 55% over unamended cattle dung
and addition of teresan to cattle dung kitchen waste (1:1) mixed residue 15%
increased gas production.
2.4 WASTEWATER INNOVATION- TDS-BIO-06-2015
Anaerobic digestion, a widely used biological process for treating wastewater
solids, refers to the process of converting organic matter into methane and carbon
dioxide through the help of anaerobic bacteria. There are three distinct steps during
anaerobic digestion, with each performed by a different group of microorganisms:
Hydrolysis,
Volatile acid fermentation
Methane formation.
Temperature and the amount of time the process is allowed to react define the
efficiency of each step. Multi-stage anaerobic digestion systems can be utilized for
all wastewater treatment systems, either new installations or retrofits. The only
requirement needed would be that the solids delivered to the system should be of
acceptable levels of concentration. For most wastewater solids and for all loading
rates, multi-stage anaerobic digestion has the advantage of achieving superior
performance compared with single-stage conventional digestion. The performance
increase is achieved even with smaller digester volumes because of the higher
loading rates that can be achieved with multi-stage digesters. The multi-stage
process is capable of a higher volatile solids (VS) reduction with shorter residence
times, production of biogas of higher quality, and elimination of foaming.
2.5 LISSENS
Lissens (2004) completed a study on a biogas operation to increase the total
biogas yield from 50% available biogas to 90% using several treatments including:
a mesophilic laboratory scale continuously stirred tank reactor, an up flow biofilm
reactor, a fiber liquefaction reactor releasing the bacteria Fibrobacter succinogenes
and a system that adds water during the process. These methods were sufficient in
bringing about large increases to the total yield. However, the study was under a
very controlled method, which leaves room for error when used under varying
conditions.
2.6 HANS–JOACHIM NAGELE, JANA SONDERMAN
A unique probe sampling system has been developed that allows probe
sampling from the top of the concrete roof into different parts and heights of the
digester. The samples were then analysed in the laboratory for natural fatty acids
concentrations. Three different agitation setups were chosen for evaluation at
continuous stirring and feeding procedures. The results showed that the analysis
OPTIMISATION OF BIOGAS PRODUCTION BY THREE STAGED DIGESTER
Sahyadri College of Engineering and Management Page 8
approach for agitator optimization through direct measurement of the nutrients
distribution in the digester is promising. The type of the agitators and the agitation
regime showed significant differences on local concentrations of organic acids,
which are not correlated to the dry matter content. Simultaneous measurements on
electric energy consumption of the different agitator types verify that by using the
slow-moving incline agitator with large propeller diameters in favour of the fast-
moving submersible mixer with smaller propeller diameters, the savings potential
rises up to 70% by maintaining the mixing quality.
2.7 JANTSCH AND MATTIASSON
Jantsch and Mattiasson (2004) discuss how anaerobic digestion is a suitable
method for the treatment of wastewater and organic wastes, yielding biogas as a
useful by-product. However, due to instabilities in start-up and operation it is often
not considered. A common way of preventing instability problems and avoiding
acidification in anaerobic digesters is to keep the organic load of the digester far
below its maximum capacity. There are a large number of factors which affect
biogas production efficiency including: environmental conditions such as pH,
temperature, type and quality of substrate; mixing; high organic loading; formation
of high volatile fatty acids; and inadequate alkalinity.
2.8 TALEGHANI AND KIA
Taleghani and Kia, (2005) outlined the economic, and social benefits of
biogas production.
The economic benefits were as follows:
1. Treatment of solid waste without long-term follow-up cots usually due to soil
and water pollution.
2. Increased local distribution of fertilizer, chemical herbicides, and pesticide
demand. Generation of income through compost and energy sales
(biogas/electricity/heat) to the public grid.
3. Improved soil/agriculture productivity through long-term effects on soil
structure and fertility through compost use.
4. Reduction of landfill space and consequently land costs.
The social and health effects associated with biogas include:
1. Creation of employment in biogas sector.
2. Improvement of the general condition of farmers due to the local availability of
soil improving fertilizer.
3. Decreased smell and scavenger rodents and birds.
OPTIMISATION OF BIOGAS PRODUCTION BY THREE STAGED DIGESTER
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CHAPTER- 3
BIOGAS
3.1 COMPOSITION OF BIOGAS
BIOGAS is produced by bacteria through the bio-degradation of organic
material under anaerobic conditions. Natural generation of biogas is an important
part of bio-geochemical carbon cycle. It can be used both in rural and urban areas.
Table 3.1- Composition of biogas.
Component Concentration (by volume)
Methane (CH4) 55-60 %
Carbon dioxide (CO2) 35-40 %
Water (H2O) 2-7 %
Hydrogen sulphide (H2S) 20-20,000 ppm (2%)
Ammonia (NH3) 0-0.05 %
Nitrogen (N) 0-2 %
Oxygen (O2) 0-2 %
Hydrogen (H) 0-1 %
3.2 CHARACTERISTICS OF BIOGAS
Composition of biogas depends upon feed material also. Biogas is about 20%
lighter than air has an ignition temperature in range of 650 to 750 °C. Biogas is an
odorless & colorless gas that burns with blue flame similar to LP gas. Its calorific
value is 22 Mega Joules (MJ) /m3 and it usually burns with 60% efficiency in a
conventional biogas stove. Biogas digester systems provides a residue organic
waste, after its anaerobic digestion(AD) that has superior nutrient qualities over
normal organic fertilizer, as it is in the form of ammonia and can be used as
manure. Anaerobic biogas digesters also function as waste disposal systems,
particularly for human wastes, and can, therefore, prevent potential sources of
environmental contamination and the spread of pathogens and disease causing
bacteria. Biogas technology is particularly valuable in agricultural residual
treatment of animal excreta and kitchen refuse (residuals).
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3.3 FACTORS AFFECTING YIELD AND PRODUCTION OF BIOGAS
Many factors affecting the fermentation process of organic substances under
anaerobic condition are,
The quantity and nature of organic matter
The temperature
Acidity and alkalinity (pH value) of substrate
The flow and dilution of material
Table 3.2 GENERAL FEATURES OF BIOGAS
Energy Content 6-6.5 kWh/ m3
Fuel Equivalent 0.6-0.65 l oil/ m3 biogas
Explosion Limits 6-12 % biogas in air
Ignition Temperature 650-750 °C
Critical Pressure 75-89 bar
Critical temperature -82.5 °C
Normal Density 1.2 kg/ m3
Smell Bad eggs
3.4 PROPERTIES OF BIOGAS
1. Change in volume as a function of temperature and pressure.
2. Change in calorific value as function of temperature, pressure and water vapor
content.
3. Change in water vapor as a function of temperature and pressure.