1. * Corresponding author. Tel.: +977-14492872
E-mail address: jeebanmanab@yahoo.com
International Conference on Mechanical, Industrial and Energy Engineering 2010
23-24 December, 2010, Khulna, BANGLADESH
Innovation of Jeeban’s Model Bioreactor for Organic Municipal Waste Management
Jeeban Shrestha1;*
Amrit Bahadur Karki2
Amrit Science Campus, Tribhuban University. Kathmandu Nepal
Nepal Academy of Science and Technology Lalitpur, Nepal ( Bio-gas Researcher)
ABSTRACT
Production of bio-gas as a renewable source of energy from organic fraction of Municipal
Solid Waste (MSW) is investigated in the present study. A new model of bioreactor 1800 liter capacity, total gas
trapping system in mesophilic type was innovated and successfully tested. The bioreactor was loaded with input of 550
kg of MSW, which was diluted with 550 liter of bio-slurry. The initial pH of substrate was recorded to be 4.90.
Substantial gas production was noted after 16 days of anaerobic fermentation. The bioreactor produced 28.30 liters of
biogas from 1 kg of MSW under ambient temperature. The gas pressure was recorded to be 5.2 kPa to 5.7 kPa. The
digested slurry coming out from bioreactor contained 1.16% Nitrogen, 0.32% Phosphorous, 1.8% Potassium and the pH
of slurry was found to be 7.20.
The present model opens ways and possibilities for further research for production of bio-gas and bio-fertilizer from
organic MSW at large scale to mitigate environmental pollution as well as to decrease greenhouse gas emission.
Keywords: Municipal Solid Waste (MSW); bioreactor, greenhouse gas
1. INTRODUCTION
Improving environmental conditions of urban areas
through effective solid waste management is an urgent
need of the day felt by the Government of Nepal (GoN].
Besides, it is also a matter of great public concern in
localities, specifically Kathmandu city where the
problem of disposal of solid waste is acute. The energy
crisis is equally significant faced by general public since
long which has recently surged up to a high extent.
About 86 percent of the total energy requirement of the
country is being fulfilled by the traditional energy
sources like fuel wood. The high dependence on fuel
wood, agricultural residues and animal wastes gives rise
to various problems among which environmental and
health problems are more prominent. With increased
awareness of the imbalance in rural fuel consumption
pattern, Alternative Energy Promotion Centre (AEPC)
came into being in 1996 under the umbrella of Ministry
of Environment, Science and Technology (MOEST)
with the objective of disseminating and promoting
renewable energy technology (RET) for improving
living standard of rural people, providing the clean
energy and conserving environmental degradation.
Until this date more than 220,000 household-size biogas
plants have been installed in the country covering 75
districts with the support of GoN, German Development
Bank (KfW) and the Netherlands Development
Organization (SNV). However, biogas plants
constructed till date have been using mostly cattle dung
and to some extent, human excreta, as feedstock for the
biogas generation.
Lately, some studies to use alternative feedstock like
poultry waste, kitchen waste, and human faeces,
vegetable and fruit waste (VFW) etc have been carried
out by AEPC with the establishment of pilot plants in
Chitwan, Kathmandu and Lalitpur districts. The results
were found to be very encouraging, while institutional
plants are operational in their full capacity. However, so
far little attention has been given to anaerobically digest
municipal solid waste for the production of fuel and
fertilizer. Appropriate technology to evolve a workable
model that treats solid waste is still overdue.
Environmental problems have been increasing at an
alarming rate in recent years not only in the three cities
of Kathmandu valley (i.e. Kathmandu Metropolitan
City, Lalitpur Sub-Metropolitan City and Bhaktapur
Municipality) but also in other municipalities of Nepal.
This has not only affected the health and the quality of
life of the inhabitants but has also dealt a blow to the
tourism industry of the country.
2. OBJECTIVES
2.1 Main objectives
The principal objective of this study is to test a newly
developed model of bio-reactor with necessary
modification in view of processing Municipal Solid

2. Waste (MSW) for biogas and bio-fertilizer production,
thereby mitigating environmental pollution problem.
2.2 Specific objectives
The specific objectives of this study are as follows:
To survey problematic areas of the
municipality in Kathamandu valley with
respect to Municipal Solid Waste;
To identify and assess the stakeholders
including beneficiaries and assign management
responsibilities for successful operation of
biogas plants;
To select appropriate location for plant
construction based upon criteria;
To install a new model design of bio-reactor
for pilot testing taking into consideration the
availability of feedstock and other
deliberations;
To study various technical parameters
regarding anaerobic digestion of MSW for
biogas production; and
To provide suggestions and
recommendations for installation of
large-scale bio-digesters in Kathmandu
valley and other urban areas of Nepal.
3. METHODOLOGY
3.1 Desk study and literature review
The researcher carried out necessary desk study and
consulted relevant literature regarding the design of bio-
reactors and appropriate technology on the production
of biogas and manure from MSW. To collect required
information, the researcher visited libraries, websites
and also interacted with knowledgeable experts in this
field.
3.2 Finalization of design of innovating bio-
reactor
Based upon the research carried out by the Researcher
proceeded to prepare detailed engineering drawing for
the proposed bioreactor, which is depicted in following
photograph. The manufacturing detail of this innovative
model has been presented in fig. No. 1.
Innovative model tested by Jeeban Shrestha
Figure 1: Sketch of 1.8 m3
bio-reactor
Figure 1 shows that there are two slurry chambers
connected to the bioreactor which has following
dimensions:
a. Dimension of Bioreactor
L =1.22 m
B =1.22m
H =1.22m
Volume of bioreactor = 1.8 m
Capacity =1800 liters
b. Dimension of Slurry Chamber
L =0.61m
B =0.61m
H =1.06 m
Volume of slurry chamber = 0.3972
m3
Capacity =397.2
liters
3.3 Construction and installation of innovative
bio-reactor
After finalization of the site selection and in agreement
with AEPC, the researcher fabricated the experimental
bio-reactor as per the approved engineering drawings.

3. The new model bio-reactor was manufactured in Rajan
Iron work Company located at Samakhushi,
Kathmandu. First of all, 4 ft x 4ft mild iron sheet of 14
mm gauze was joined with each other with electric
wielding. Topmost part of the reactor was kept open
with dimension of 30" x 30 " to connect centre inlet.
The centre inlet size of 30" x 30" length and breadth and
4 ft height was fixed to the bioreactor. After completion,
the reactor was painted with metallic primer, then with
rubber seal paint to protect the reactor from rusting.
Thereafter the reactor was filled with water for leakage
test. Some leakage was detected and again it was
corrected by wielding. The gas outlet was fixed at the
topmost of the reactor of size 3 ft height and i/2 "G.I.
pipe. At the one side of reactor to the bottom 2
"diameter, 6 inch long G.I nipple was fixed for slurry
outlet flow. Slurry outlet having 2 ft length, 2 ft breadth
and 4.5 ft height was fabricated with iron sheet of 14
gauze thickness. After fabrication, iron sheet was
painted with metallic primer and then with rubber seal
paint and 2 inch nipple was fixed to the bottom of its
one side and connected with the help of 2" size Union to
the reactor (see photographs below).
Jeeban checks quality of welding Welding in progress
UN Volunteer Henna visits bioreactor Jeeban
explain functioning of
reactor to Prof. J.N.Shrestha
After the completion, the reactor was fixed to the
project area on 4 pillar constructed with brick and
cement. Thereafter gas pipe line was laid underground
with ITPF polypore. Pipe line to kitchen was connected
with help of ½ " G.I. pipe. Further connection to the
burner was done by means of rubber hose pipe.
All necessary equipments like burner, gas flow meter,
pressure gauze, desulphrizer, water drain etc were fixed
to gas pipe line for recording the necessary data. To
protect the water drain a chamber containing 1.5 '
length, 1.5 ' breadth and 2.5 ' depth was constructed
with brick cement close to the bioreactor.
Constructing water drain chamber
Stirring section was fixed to the inlet of the reactor and
for total gas trapping system special plastic was
procured and secondary gas outlet was made in the
system. To facilitate loading of feeding materials a
metallic ladder was fixed to the reactor. Ultimately,
bioreactor was insulated with glass wool and plastic
sheet.
4. RESULTS AND DISCUSSIONS
Following technical parameters were recorded regularly
during the experimental period:
4.1 Nature and quantity waste fed to the bio-
reactor
Table 1 depicts the nature of the ingredients quantity of
bio-waste collected from various sources for this
research. It shows that among the various sources.
All these wastes were collected from Amrit Science
College where this research was carried out.
Table 1: Nature and quantity of bio-waste
S.N Nature of waste
(ingredients)
Quantity
(kg)
1 Meat shop waste 18
2 Tea shop waste 35
3 Fruit shop waste 49
4 Restaurant waste 79
5 Vegetable shop waste 112
6 Kitchen waste 257
Total 550
4.2 Waste loading rate
All the collected wastes were loaded to the bioreactor
from 1 to 5 days as shown in Table 2. Thus batch

4. system was followed for experimentation contrary to
continuous feeding system adopted for cow dung plant.
As for dilution of the substrate, equal amount of liquid
bio-slurry collected from previous research was mixed
with the waste instead of water. The bio-slurry provided
sufficient inoculum for introducing methanogenenic
bacteria capable of producing biogas within a short
time.
Table 3: Waste loading rate
S.N Loading schedule Quantity
(kg)
1 1st day 98
2 2nd day 102
3 3rd day 92
4 4th day 93
5 5th day 165
Total 550
4.3 Gas Yield
The gas started to produce after 4th week after which
the measurement of gas was done by Gas Low Meter as
well as noting down of burning hour of gas unto 24th
week. The data are presented in Table 4.
Table 4: Record of daily gas production and burning
hour time
Week Daily average gas
produced
(litre)
Average gas
burning period
(Minutes)
1st
110.29 8.22
2nd 133.27 13.45
3rd
145.08 15.33
4th
159.22 20.22
5th
159.00 20.00
6th
162.23 25.00
7th
169.23 27.00
8th
170.33 29.00
9th
172.35 32.00
10th 172.00 32.00
11th 162.00 31.00
12th 160.00 30.00
13th 158.43 20.00
14th 155.00 20.00
15th 143.00 18.00
16th 110.00 8.27
17th 111.00 9.00
18th 103.00 8.00
19th 90.00 7.00
20th 67.00 5.56
21th 45.00 3.39
22th 20.00 2.01
23th 10.00 1,2
24th 7.00 0.47
Table 4 and Figure 2 shows that the production of gas
increased from Ist week unto the 10th week. But after
10th week it started decreasing and after 18th week the
decrease in gas was remarkable and by 24th week the
production of gas was almost exhausted. This indicated
that after this period, the bioreactor needs to be emptied
and recharged again with fresh biodegradable materials.
The total gas production within this experimental period
is calculated as 15,568 litres; hence one kg of bio-waste
is capable of generating 28.30 litres of biogas).
Comparison of methane and carbon di-oxide
The percentage of methane content in biogas was
determined by Biogas Analyzer Gas Board-3200P
which was procured from BSP-Nepal. It has an inlet and
an outlet valves for gas passing respectively. It shows
the percentage of CH4 and CO2 directly.
Biogas Analyzer Gas Board-3200P
The percentage of methane content and carbon dioxide
found in biogas in different period is shown in Table 5
below:
Table 5: Composition of methane and carbon
dioxide found in biogas
Week1
Percentage of
CH4
Percentage of CO2
1st
48.22 39.78

5. 2nd 49.56 38.44
3rd
51.38 37.54
4th
52.16 35.23
5th
53.00 34.68
6th
53.23 34.29
7th
54.58 32.46
8th
55.07 32.16
9th
55.12 32.06
10th 55.33 33.22
11th 55.23 33.12
12th 55.21 33.29
13th 55.62 33.28
14th 55.68 33.29
15th 55.28 34.58
16th 54.11 34.08
17th 55.22 33.28
18th 55.23 32.07
19th 55.29 34.09
20th 55.23 33.68
21th 55.44 32.09
22nd 55.81 33.67
23rd
55.68 33.00
24th
55.38 32.00
Table 5 and Figure 3 shows that initially the
percentage of CH4 was 48.22 and of CO2 was 39.78. But
in function of time period the percentage of CH4 started
augmenting and reached a value of 55.38 after 24
weeks. In case of CO2, decreasing trend started slowly
unto 9th week and increased somewhat unto 17th weeks
after which it remained more or less constant. The final
values of CH4 and CO2 noted by the end of 24 weeks
were 55.38% and 32.00% respectively.
Figure 3: Percentage of CH4 and CO2 in function of
weeks
4.4 Record of Pressure Gauze Reading
The pertaining data on pressure reading of bio-reactor
has been recorded by means of pressure gauze and is
presented in Table 6.
Table 6: Pressure meter reading of bioreactor at
different periods
Week Pressure meter reading
1st 2.7
2nd 3.0
3rd 3.8
4th 3.9
5th 4.1
6th 4.2
7th 4.3
8th 5.2
9th 5.5
10th
5.7
11th
5.3
12th
5.0
13th
4.9
14th
4.5
15th
4.1
16th
4.1
17th
3.1
18th
2.6
19th
2.0
20th
1.6
21th 1.0
22th 0.06
23th 0.3
24th
0.1
By installing pressure meter, one can easily guess as to
how much quantity of gas is available in the biogas
plant in a given time. In the beginning of this
experimentation, (Ist week) the pressure reading was 2.7
which gradually increased to 5.7 in the 9th week. This is
a good indication. Thereafter as the quantity of gas was
decreased, the pressure gauze reading started falling
down with result that by the end of experimentation (i.e.
24th week), the pressure recorded was found as low as
0.1.
4.5 Analysis of Bio-slurry
The anaerobically digested slurry has been proved to be
of high quality organic fertilizer which has various
benefits for plant growth and soil condition. It is rich in
organic matter, major plant nutrients such as Nitrogen
(N), phosphorus (P) and potassium (K) and also
contains micronutrients. Therefore it is of paramount
importance to analyze the bio-slurry to assess its
physico-chemical values.
4.5.1 pH
pH is one of the necessary conditions for the production
of biogas by methanogenic bacteria in the absence of
oxygen. The methanogens flourish only if the pH of the
media lies in slightly alkaline range i.e. around pH 7.
The pH of fermenting media was detected by using
special pH paper starting from first week unto the
period of 7 weeks.

6. Researcher detects pH of bio-slurry
The result presented in Table 7 shows that initially the
pH was found to be in acidic range i.e. 5.8 and then in
function of time it started increasing and reached 7.0 in
4 week's time. Then it remains buffered in the range of
7.1 to 7.3 from 5th week onwards. As there was no
further change in pH the measurement was stopped after
7th week.
Table 7: Detection of pH in function of time
Period pH
1st week. 5.8
2nd week. 6.5
3rd week. 6.9
4th week 7.0
5th week 7.2
6th week 7.1
7th week 7.3
4.5.2 Major plant nutrient present in bio-slurry
An attempt was made to assess the major plant nutrients
in the bio-slurry under the experimental conditions.
The analysis was done in different three periods as
given in Table 8 below.
Table 8: Major plant nutrients present in bio-slurry
Frequency of
test
N P K
First Test 1.25 0.39 1.8
Second Test 1.16 0.42 1.7
Third Test 1.32 0.38 1.6
Table 8 shows that the content of N and P was found
higher than traditionally prepared FYM or improved
compost. However, K content was found somewhat
lower than N and P.
4.6 Utilization of biogas and bio-slurry
The gas produced from this bioreactor is used to run the
canteen for making tea and breakfast for the teachers.
The bio-slurry is used to fertilize garden plants. It is also
planned to prepare high quality compost out of the bio-
slurry and sell it to the interested people to generate
income so as to create an example.
Maximum flame produced Prof. J.N
Making tea in ASCOL canteen
Cooking vegetables in Ascol canteen
4.7 Economic benefits
Mr. Bal Krishna Raut, the user of this bioreactor has
been using LPG gas for cooking. According to him he
was able to save 1.5 cylinder during the period of this
experimentation which lasted for five month.
Considering the current price of one cylinder of LPG to
be 1,250 he was very happy to be able to save Rs 1,875
by using biogas, which other could be spent .
6. RECOMMENDATIONS AND
CONCLUSIONS
6.1 Recommendations

7. Having successfully experimented the Innovative Model
of bioreactor, the researcher would like to put forth
following recommendations to AEPC for consideration:
AEPC should consider propagating such
innovative bioreactor tested in this project in
suitable locations of this country so as to
process various types of available bio-waste
for the production of biogas and bio-fertilizer.
It is strongly recommended that GoN should
encourage and provide necessary financial
support for promoting such innovative model
in large scale in view of mitigating
environmental pollution caused due to ill-
management of solid waste.
AEPC should launch an awareness
programme about the benefits for "turning the
waste into wealth".
6.2 Conclusions
This innovative model was successfully tested as will be
revealed from the result of experimentation carried out
by the researcher. This model is highly suitable to
process available biodegradable waste generated from
household and commercial sources so as to produce
biogas as reliable fuel and bio-fertilizer as high quality
organic manure. Based upon this research, it is high
time now to establish large scale bio-reactor in different
parts of this country for treating the bio-waste, thereby
mitigating environmental pollution.
7. REFERENCES
[1] Karki, A.B., Shrestha, J.N., Bajgain, S. and
Sharma, I. (2009) Biogas as renewable source
of energy in Nepal: Theory and Development,
BSP-Nepal
[2] Lungkhimba, H.M., (2010) Biogas production
from anaerobic digestion of biodegradable
household wastes. A Master's Thesis, CDES,
T.U., Kirtipur.
[3] YSD (2006) Installation of a pilot
institutional biogas plant by utilizing kitchen
and other biodegradable waste. AEPC.
[4] YSD (2006) Physico-chemical analysis of bio-
slurry and farm yard manure for cosmparison
of nutrient contents and other benefits so as
to better promote bio-slurry. BSP--Nepal.
[5] YSD (2008) Study and installation of the
vegetable and fruit waste biogas plant in
Kathmandu Valley. AEPC.