International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:14 No:06
39
Effect of Mesosphilic and Thermophilic Temperature
on Floating drum anaerobic bio-digester
S. Sathish1, ª* S. Vivekanandan2, b
1
Research Scholar, Department of Mechanical Engineering, AnnamalaiUniversity, India
Associate Professor, Department of Mechanical Engineering, Annamalai University, India.
Email: [email protected] , [email protected]
2
Abstract--
This work examines the biogas yield and methane
production was performed using swine manure. The anaerobic
digestion process was conducted in floating drum type biodigester with capacity of 1m3 made of fiber material. The codigestion of cow dung+swine manure in the ratio of 1:2
waste/water as 30:60 and waste by volume as 70:30 was added in
the bio-digester. The main purpose of the research is to measure
the biogas production and methane in mesosphilic and
Thermophilic conditions. These results indicated that biogas
yield 420 Liters and 460 Liters in mesosphilic and thermophilic
conditions respectively. The maximum biogas production
reported as 30min in thermophilic condition using inflammable
time.
Here thermophilic anaerobic digestion having high
methane production. It’s found 62.8% and mesosphilic condition
for 59% then pH value also higher for thermophilic condition.
The biogas yield and methane is peak and quick at shorter
retention time in thermophilic temperature 56°c.
Index
Term-Anaerobic Digestion, Floating Drum,
Inflammable time, Thermophilic Condition, Mesophilic
Condition, Retention Time, Fiber material.
1. I NTRODUCTION
The anaerobic fermentation processes mainly used
for organic wastes are eliminating to organic pollutants, and
also eliminate the organic waste volume. So this biogas
generation is very profitable one [1].Biogas is produced by
anaerobic fermentation of organic wastes, manures and
agricultural wastes and energy crops. This biogas is a type of
biofuel [2]. Biogas is mainly based on microorganisms and
other parameters like temperature, acid production (pH), HRT,
Carbon\Nitrogen ratio, etc., [3]. Now a day’s continuously
increases the amount of generated solid waste act to the large
environment as impacts [4]. This anaerobic process is needed
for biogas generation where methanogenic formed on swine
manure (or) animal waste [5]. The composition of biogas
various depending upon the origin of the anaerobic
fermentation process and composition of biogas are 50-70%
Methane (CH4), 30-40% Carbon dioxide (CO2), 0-1%
Hydrogen (H2), 0-10% Nitrogen (N2), 0-3% Hydrogen
Sulphide (H2s), 0-0 Oxygen (O2) [6]. In this process is
commonly used in anaerobic bio digester and most popular
type for floating drum anaerobic bio digester [7]. A possibility
of analyzing and optimizing the biogas generation and both
operating temperature’s from swine manure by serial
fermentation process was studied. The co-digestion of cow
manure + swine manure is creating an environmental benefit
and biogas also used as a fuel in automobile for near future.
It’s one of the renewable energy from biomass and biogas
slurry is used to increase the fertilizer quality of animal waste
[8]. The organic wastes are used to increase the quality of AD
process. It’s mainly depends on good Carbon/Nitrogen ratio
[9]. The swine manure is used mono substrate and low C/N
balance in this condition AD process is Unstable [10]. Fig 1,
illustrates the biogas generation mainly dependence on four
different stages from the anaerobic digestion process.
Conventional Anaerobic digestion (AD) is carried out
at mesophilic temperature, which is 308-310 K. The
composition of organic fraction of MSW is influenced by
several factors, including regional differences, climate, and
collection frequency as well as changes in composition [11].
Environmental LCA studies of AD of pig and cattle manure
(raw or separated fraction) and energy crops such as maize
and ryegrass focused on bio-energy production, greenhouse
gas (GHG) emission reduction potentials, and various biogas
end applications [12]. Main substrates for Anaerobic digestion
include agricultural biomass in the form of animal manures
and energy crops (e.g. Maize), organic residues from the
processing industry (e.g. glycerin, beet tails, and gut and
intestines from slaughtering houses) and other residues such
as, road side grass or forest residues are used in this anaerobic
digestion process of the experiment [13].
The thermophilic conditions resulted in a factor 1.3
higher biogas production rate than under mesophilic
conditions for s.obliquus. The lower results of the digestion of
s.obliquus at a mesophilic temperature can be species related.
It has been reported that the strain can grow at temperatures
up to 35°C optimized [14].
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International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:14 No:06
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The main problem of thermophilic digestion (as a
compared to the mesophilic digestion) include energy
requirement and highly pollutant supernatant, all of which
prevent this technique from being widely used and
commercialized [17]. Generally biodigester can be operated in
the temperature ranges a) Psychrophiles below 28°c
b) Mesophilic medium temperature at 29°c to 45°c
c) Thermophilic at 50 to 56°c [18]. Basically Mesophilic
condition is more stable than thermophilic condition in
anaerobic digestion process [19]. Pig manure and cow dung,
the cheap and abundant animal wastes in Tamil nadu, so this
experiment investigated to be applied as a raw material for the
bio-energy production. In this research mainly focus on
performance of the floating drum anaerobic biodigester in
treating swine manure + cow manure. The biogas generation
using two different temperature ‘s and then compared pH
range ,biogas composition from both temperature ranges in
four different stages like, hydrolysis, acidogenesis,
acetogenesis and methanogenesis [20].
2. METHODS AND M ATERIAL
In this experiment were conducted using floating
drum anaerobic bio- digester. The cow dung + swine manure
feed as a bio-digester and it is one of the batch process and it’s
used
in
two
different
temperatures
mesophilic
temperature(36°c) and thermophilic temperature(56°c) here
cow dung is used as a inoculums’. The composition of biogas
was carried out with a help of gas chromatography GA45.
Then pH was measured weekly using pH redox meter and
cumulative gas was measured with help of gas meter. The
daily gas production was measured inflammation time using
gas burner.
Fig. 1. Different stages of anaerobic digestion process
Separating the acidogenic and methanogenic steps in
the anaerobic digestion process, provides enhanced stability to
the different groups of microorganisms and better process
control for the digestion process [15]. The effect of various
parameters in general and total ammonia (free ammonia and
ammonia – N) accumulation in particular upon thermophilic
dry anaerobic digestion systems here ammonia – N and
were accumulation in particular upon thermophilic dry
anaerobic digestion system, which can affect the overall CH4
[16].
3. EXPERIMENTAL AND METHODS
Fig 2.shows the schematic view of the Experimental
setup while Fig 3. Illustrate the Photo graphic view of the
Experimental setup. The bio-digester with a capacity of 1m3
made up of fiber material floating drum type. The raw
material cow dung and Fresh swine manure as taken from
rural areas near Chidambaram town and this feeds are dried 1
week in sun light and crushed mechanically.
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International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:14 No:06
41
GAS PILLOR
PRESSURE GAUGE
VALU
700 LITRES GAS COLLELTING
GAS HOLDER
BIOGAS
GAS OUTLET
BIOGAS DOME
BURNER
INLET PH PROBE
HEATER WATRER TANK
FEED STOCK INLET
GAS FLOW
METER
STIRRER
PUMP
BIOGAS MEASUREMENT BY
INFLAMMABLE TIME
HOT WATER ( THERMO PHILLIC CONDITION )
(SLURY) FEEDSTOCIC
PH OUTLET PROBE
700 LITRES GAS COLLELTING
GAS HOLDER
FEET STOCK OUTLET
Fig. 2. Schematic view of the experimental setup
Fig. 3. Photographic view of the experimental setup
Then feed to cow dung swine manure mixed in the
ratio of 1:2 waste/water as 30:60 and waste by volume as
70:30 was added in the same quantity of water added in the
bio-digester. The bio digester was operated in two temperature
ranges mesophilic temperature range 36°c and thermophilic
temperature range 56°c. Hot water is used to the thermophilic
condition with the help of water jacket. The produced biogas
is collected in airbag then composition was analyzed using gas
chromatography GA45. Biogas production is monitored
weekly one day. Pneumatic stirrer was used to agitate digester
slurry and digested slurry was collected from inside bio
digester then we used as an organic fertilizer here waste is
convert to useful energy. Here both temperature conditions
were measured using thermocouples device monitored daily.
A digital Redox pH meter was used to determine the pH of the
bio digester. The initial pH was adjusted to the optimum limit
for the digester. In this case gas burner provided to measure
using inflammation time with both condition of the
experiment. Initial and final Pressure was measured using
pressure gauge. Biogas production was calculated weekly
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from by gas flow meter. The digester inside temperature was
maintained in electric heater which circulate the hot water in
bio-digester and it is observed by the digester slurry in this
process water jacket used as a heat exchanger. The final
digested slurry was collected and used as an organic fertilizer.
4. RESULTS AND DISCUSSION
Fig. 6. Cumulative Biogas production in seven weeks of digestion
Fig. 4. Biogas production in seven weeks of digestion
In Fig.6.Shows the productions of cumulative biogas
in mesophilic and thermophilic condition was measured
during seven weeks of digestion. The cumulative biogas
production at different time interval for both temperature
ranges. The cumulative biogas production in mesophilic
condition at 49th day was 1770 liters and maximum
cumulative biogas produced in thermophilic condition at 49th
day was 2400 liters achieved, then retention time for
cowdung+swine manure is last 15 days best for maximum
production of biogas.
Fig.4. Shows the productions of biogas yield in
mesophilic and thermophilic condition was measured during
seven-weeks of digestion. In thermophilic condition after fifth
week of digestion gas production tends to increase then drops
in the seventh week and mesophilic condition the gas
formation was lower than thermophilic condition. The high
quantity of biogas yield was produced in thermophilic
temperature in sixth week of digestion. Major difference
between the mesophilic and thermophilic condition biogas
production occurs in last ten days of the experiment.
Fig. 7. Acid production in 7weeks of digestion
Fig. 5. Quantity of Biogas with inflammable time
Fig.5. shows the digester performance of cow dung +
swine manure was investigated under mesophilic and
thermophilic condition based on the inflammable time of the
Gas production. It was observed that biogas production was
actually slow at starting and the end of observation. It’s
observed that the maximum gas production reported as 30min
in thermophilic condition. The peak value of daily gas
production differs for both temperature conditions.
The acid production mainly based on acetogenesis
and methogenesis process. Here Fig.7.shows the acid
production (pH) in mesophilic and thermophilic temperature
from cowdung + swine manure, the pH tends to increase then
drops from 7.5 to 7.4 in thermophilic condition and
mesophilic condition where maximum pH formation occur at
seventh week of digestion. The optimum pH for the
production of biogas was found to be 7.4 to 7.5 in
thermophilic temperature. This means pH tents to increase on
the 35th day of digestion. Then the production of biogas
reduced and process stopped at some point.
Table I
Biogas composition of co-digestion process
Mesophilic temperature
CH4
59%
CO2
32.%
O2
0.30%
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Thermophilic temperature
CH4
62.8%
CO2
37.50%
O2
0.50%
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International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:14 No:06
[6]
[7]
[8]
[9]
[10]
[11]
[12]
Fig. 8. Biogas composition in mesophilic and thermophilic condition
Fig.8.shows the biogas composition (CH4, CO2 & O2)
was analyzed in course of the seven weeks of digestion with
gas analyzed GA45.Table 1 represent the biogas composition
of cowdung + swine manure in mesophilic and thermophilic
temperature range. The average methane content ranged from
59% and 32% of CO2 content in mesophilic temperature
range. The maximum level of CH4 was 62.8% and 37.50% of
CO2 obtained in the seventh of digestion in thermophilic
condition. Then the oxygen was under 1% of digestion in both
conditions. The high quantity of biogas (methane) is generated
in thermophilic temperature range is compare to mesophilic
temperature range.
5. CONCLUSION
The results show that the optimum temperature
observed from experiment is at thermophilic range 56°c was
achieving a higher biogas yield and high methane content
compare to mesophilic temperature range and maximum
burning time of gas production was 30min. The biogas yields
ranged between 420 and 460 liters in mesophilic and
thermophilic anaerobic digestion has operated at constant
temperature 36°c and 56°c. The percentage of CH4 in biogas
produced in thermophilic range is higher on mesophilic range.
Generally the generation of biogas from anaerobic digestion
process is dependent on the amount of acid formation and
temperature. Thermophilic condition of energy plant at 56°c is
truly more economical one.
[1]
[2]
[3]
[4]
[5]
[13]
[14]
[15]
[16]
[17]
[18]
[19]
[20]
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