UTILIZATION OF DONKEY DUNG FOR BIOGAS PRODUCTION IN LAMU

COUNTY.

A RESEARCH PROPOSAL SUBMITED IN PARTIAL FULFILMENT FOR THE AWARD

OF A MASTERS OF SCIENCE IN LIVESTOCK SCIENCE (LIVESTOCK PRODUCTION

SYSTEMS) PWANI UNIVERSITY

BY

NAME: EMMANUEL MAE KARISA

CELL PHONE: 0721863812

REG. NO. A103/PU/2113/13

AUGUST 2014

Supervisors

1. Patterson Semenye

2. Dr Thomas Rewe

DECLERATION

This proposal is my original work and has not been presented for the award of a degree in any

University.

Signature_____________ Date: __________________

KARISA EMMANUEL MAE

Registration Number A103/PU/2113/13

Department of Animal Sciences

This proposal has been submitted for review with my approval as the University Supervisor.

Signature: _______________ Date: _____________

DR. PATTERSON SEMENYE

DEAN SCHOOL OF AGRICULTURE AND ENVIRONMENTAL SCIENCES.

This proposal has been submitted for review with my approval as the University

Supervisor. Signature: _______________ Date: _____________

DR THOMAS REWE

HEAD OF ANIMAL SCIENCE DEPARTMENT

SUMMARY

In recent years the prices of commercial energy sources have increased sharply and there is a

continuous depletion of these scarce resources. In developing countries the need for biomass

energy is not because biomass – based technologies can entirely resolve the nation’s difficulties

with escalating petroleum prices, but because of their urgency of their energy need. Properly

designed biomass conversion technologies could reduce the economic and environmental cost

for cooking and heating and in some cases provide opportunities for economic growth and

employment (Looher, 1984)

Energy is one of the prerequisites for growth of agriculture and industry. The energy

requirements met mainly through commercial energy sources like oil, natural gas etc. In recent

years the prices of these commercial energy sources have increased sharply and there is a

continuous depletion of these scarce resources. Hence there is an urgent need to develop and

exploit the alternative sources of energy.

Biogas is the fourth largest source of energy in the world supplying about 13 %( 55 EJ/YR),

which is equivalent to 25 million barrels of primary energy (Mittal, 1997)

There is therefore a need to study the productivity of biogas from donkey dung which is readily

available and a nuisance to the Lamu residents and also assess the different levels of mixing the

donkey dung with cow dung and biogas productivity.

Biogas from anaerobic digestion can be a solution to current and future energy

needs in Lamu. One option for improving biogas yield of anaerobic digestion of

Organic matter is co-digestion.

Cow dung and donkey manure will be co-digested together. The co-digested experiments were

conducted using flexi bio-digesters at Pwani university farm.

The volume of biogas produced will measured daily by a biogas flow meter.

The five treatments selected for the study will be:

• 25%donkey dung + 75% Cattle dung

• 50%donkey dung + 50% Cattle dung

• 75%donkey dung + 25% Cattle dung

• 100% donkey dung

• 100% cattle dung(control)

A flexi bag digester will be chosen for each substrate combination.

The investigation will be conducted in a completely Randomized Design (CRD) with three

replicates of each treatment.

INTRODUCTION

The world population of equines has been estimated at 44 million donkeys, 15 million mules,

and 65 million horses (Fielding & Pearson, 1991). Population figures for animals are notoriously

difficult to assemble, in many countries they are based on estimates and extrapolations.

However, even allowing for a 20 per cent margin of error, it is clear that these animals represent

a vast power resource (Sims & Kienzle, 2006). It is estimated that 80 per cent of the world’s

equine population, 90 million animals, are found in the developing world, including 97% of all

mules, 96% of donkeys, and 60% of horses (Pritchard et al., 2005; Wilson, 2002). Lamu is the

major island in Coastal Kenya that has the highest number of donkeys used as a means of

transport within the narrow roads in the town. There is a total of 1,832,519 donkey population in

Kenya, 31,916 in coast province and about 6000 in Lamu Island (Kenya National Bureau of

Statistics, 2009 census) .

More than half of the human population is dependent on the power provided by draft animals. A

study on the use of donkeys in Limuru (Kenya)IIII, where 43 per cent of households own

donkeys and an additional 20 per cent of households use them through a hiring scheme, indicated

that the use of donkey carts is an essential component of the farming system, In addition, in areas

where non-farm employment is becoming a critical factor in the economies of rural households,

donkeys are often owned for providing transport services (Njenga 1993). There are few

motorized vehicles on Lamu, only a couple of tractors, one ambulance and a handful

motorcycles. There is a clear consensus that more cars or motor vehicles are not desired on the

Island, among all groups such as farmers, employed by tourist industry, local governance and

tourists (Kombo, 2011). Instead of cars for overland transports there are donkeys, around 5000 of

them. Since they eat almost anything; fruit peels, other organic waste or corrugated paper (which

seem to be a favorite) they are actually part of the waste management of the island. The problem

is however not solved since the dung coming out the other end of the donkeys need to be taken

care of.

The main perceived environmental issue on Lamu, by both residents and tourists, is waste;

plastic bags, bottles and donkey dung, lying on the beach and other open surfaces.(Kombo,

2011), Dung, primarily available from donkeys, is not used today and ends up on the dumpsites.

It has value as organic fertilizer and an energy potential if used in Anaerobic Digestion to

produce biogas. Since there over 5000 donkeys on the island the volume of dung is substantial, if

each donkey produces two kilograms of dung per day the resource base would be over 3000 tons

per year. However, it is only realistic to make use of dung from the hard made streets of Lamu

Town and Shella. Infrastructure to collect donkey dung is already in place by Lamu Safi and

SERG. Daily around five 20 kg wheelbarrows of waste; dung mixed with sand and other waste,

are collected from Lamu Town and Shella.( Ali, Abdala, et al. 2012.)

Donkeys play a vital role in rural economies through the provision of draught power and

transport. Compared to other equids species, donkeys contribute the major proportion of readily

available transport needs of poor women and men living in hostile environments, enabling them

integrate into social and economic processes (Fernando and Starkey 1996). Donkeys are

preferred to other equine because of their affordability, survivability, docility and ease of training

and handling. The ability of donkeys to thrive on poor quality minimally supplemented feeds has

also made them popular in environments where feed shortages can seasonally become a critical

problem. Donkeys have been reported to survive better under drought condition than any

livestock species due to their small body size and low dry matter intake requirements minimizing

their water and maintenance needs in arid and semi-arid areas (NRC 1984).

Donkeys play a vital role in Lamu town residents economies through the provision of draught

power and transport compared to other regions in the country. With this increasing population

comes with a lot of waste from donkey dung littering the town posing health risk to the residents

for example the risk of infection with tetanus. Biogas is one of the good and promising source of

alternative energy. This energy can be harnessed successfully to meet the existing as well as

future needs of the rural areas. Biogas is the fourth largest source of energy in the world

supplying about 13% (55EJ/YR), which is equivalent to 25 million barrels of primary

energy(Mittal, 1997). Only one study of biogas yield from donkey dung has been found and is

shows that a batch 75 liter digester of 10 percent dry content gives a total of around 240 liter of

biogas with around 55 percent methane content after full digestion (The study also noted benefit

of co-digestion with poultry manure) ( Kannan, N. 2003). Assuming 50 percent dry content in

collected dung the overall potential would be 1600 m3 of biogas per year equivalent of 10,500

kWh or 730 kg of LPG worth ksh 180,000. This is a conservative estimation since it assume only

3.5 percent of all dung is collected.

The process of biogas production takes place in anaerobic conditions and in different

temperature diapasons. There are psychrophilic (temperature diapason 10-250C), mesophilic (25-

400C) and thermophilic (50-550C) regimes of bioconversion. Biogas reactors, working in a

thermophilic regime, can be introduced in agricultural farms where the number of livestock

exceeds 5. Biogas produced on such farms can be used not only for cooking and heating water,

but for dairy production as well. Anaerobic digestion (AD) can be defined as the conversion of

biodegradable material to biogas which comprises of about 60% methane and 40% carbon

dioxide. The process is performed by the activity of several different groups of micro-organisms

in the absence of oxygen Biogas technology involves the use of biogas digesters that are

constructed vessel in which animal waste and other bio-degradable materials are broken down by

bacteria in complete absence of oxygen to produce biogas. The biogas digester is free from theft

risks as compared to solar installations. Biogas consists of different component gases, mainly

methane (CH4), carbon dioxide (CO2), with traces of hydrogen sulphide (H2S) and hydrogen

(H2) gas (Bajracharya et al., 2010). Biogas is also a waste management technique because the

anaerobic treatment process eliminates the harmful micro-organisms. It is a heap source of

energy due to the feed stock is usually waste materials. The technology ensures energy

independence as a unit can meet the need of a family or community.

The digester slurry is a good fertilizer. Most of the pathogens are destroyed in the process of

anaerobic digestion (FAO 1996).However, the state of hygienisation of the effluent slurry of

biogas digesters strongly depends on the influent concentration in pathogenic microorganism, the

retention time and the temperature. High temperatures and long retention times are more

hygienic (SASSE 1988). If more than 55°C are achieved for one to a few days, inactivation can

be considered as efficient (SCHOENNING & STENSTROEM 2004).

The energy content of biogas is 9.8 kWh/m3 (Thours 2007). The anaerobic digestion process is

divided into four steps, hydrolysis, acidogenesis, acetogenesis and methanogenesis (Davidsson

2007; Leksell 2005). Studies done elsewhere show optimization of methane content of biogas

through co-digestion. Cow dung yield the highest biogas with methane content of 67.9%. Cow

pea yielded 56.2% methane content. The lowest methane content was produced by cassava

peelings with 51.4%.( Ukpai, P. A.2012). Donkey manure and cow dung were used as co-

substrates in the study. For co-digestion of cow dung and donkey manure gas production was

highest between 18-26 days. From 30 days and above biogas production decreased until it

became negligible because all the food in the digester had been consumed and there was no

supply of food for the methanogens. For cow dung, gas production increased as between 16-28

days(P Mukumba, G Makaka, S Mamphweli).

Co-digestion of donkey manure and cow dung is highly desirable for increasing methane yield (P

Mukumba. poultry droppings and donkey-dung combination as feed material can generate on an

average a total gas of 11352 l with an average methane content of 61.52% 0.5 m3 floating drum

type biogas plant yielding digested slurry, which contains an average of 2.42%, 0.84% and

0.70% of nitrogen, phosphorous and potassium, respectively(N Kannan, T Guruswamy, V

Kumar, 2003) A study has shown that anaerobic co-digestion of a mixing ratio of 25% cow

dung and 25% donkey dung co-digested with 25% goat dung and 25% horse dung produced the

biogas yield with the highest methane yield of 75% than the other mixing ratios(P. Mukumba,

…..)

Highest biogas yield was obtained from a mixing ratio of 50% cow dung to 50% donkey manure,

(Makumba et al)

PROBLEM STATEMENT

There is a high population of donkeys In Lamu county IIII. They litter the streets with their dung

as they transport merchandise from one point to another. The dung puts the residents at a risk of

getting infected with tetanus and the odor causes air pollution.

Most residents lack access to commercial energy sources which are costly.

The main perceived environmental issue on Lamu, by both residents and tourists, is waste;

donkey dung, lying on the beach and other open surfaces.(Kombo, 2011), Dung, primarily

available from donkeys, is not used today and ends up on the dumpsites. Since there over 5000

donkeys on the island the volume of dung is substantial, if each donkey produces two kilograms

of dung per day the resource base would be over 3000 tons per year posing environmental

pollution.

JUSTIFICATION

Energy is one of the prerequisites for growth of agriculture and industry. Its requirements are met

mainly through commercial energy sources whose prices in the recent years have increased

sharply and are continuously getting depleted.

Hence the urgent need to develop and exploit the alternative sources of energy such as biogas

obtained from donkey’s dung which Is readily available a nuisance in Lamu county.

As in the rest of Kenya, main cooking fuels for Lamu residents are traditional biomass as

agricultural waste; coconut shells, dung or maize stems, firewood; IIII mostly easily collected

branches or sticks and charcoal. Though cheap and renewable these fuels have issues.

Deforestation because of charring is a very urgent issue in Lamu district, population density is

not very high, though if all charcoal consumed on Lamu were produced there the island would

have large problem with deforestation. Alternative energy sources will decelerate environmental

degradation through pollution and deforestation.

OBJECTIVES

To assess donkey’s dung biogas productivity

To determine the presence of N, P and K in the donkey slurry from the bio digester for crop

fertilization.

To assess the presence of Clostridium tetani in the donkey dung before and after passing through

the Flexi bio digester

To compare quantity and quality of biogas produced from different levels of the two types of

animal dung

General Objectives:

To determine the amount of gas emitted from combination of cow dung and donkey dung

To evaluate donkey dung as a potential substrate for biogas production

Specific Objectives:

1. To compare the amount of gas produced from combinations of cow dung and donkey

dung.

2. To determine a mixing ratio of the feed stock and water that gives maximum amount of

biogas from combined feed stock( cow dung and donkey dung).

3. To determine the effect of feed stock substrate mixing ratios

4. To establish the presence of N, P, K in the sludge for crop fertilization.

Hypothesis.

1. Slurry from the bio – digester contains N, P, K. restate as below

2. Mixing ratio of substrate and water affects the amount of gas produced from each

substrate

3. Substrate mixing rations affect the amount of biogas produced.

4. 75% donkey dung and 25% cow dung level of combination produces the maximum

amount of biogas.

Can the hypothesis be stated in the Null format eg The slurry from the biodigester will

have the same N, P, K levels as those in the raw dung

Materials and methods

Raw materials and equipment:

Freshly voided donkey, and cattle wastes were collected from Lamu and Pwani University

respectively

The feedstock materials mainly donkey dung, cattle dung will be tested for biogas productivity in

twelve digesters for a retention period of 56 days under batch fed system and their performance

evaluated

The five treatments selected for the study will be:

• 25%donkey dung + 75% Cattle dung

• 50%donkey dung + 50% Cattle dung

• 75%donkey dung + 25% Cattle dung

• 100%donkey dung

• 100% cattle dung(control)

• A flexi bag digester will be chosen for each substrate combination.

• 15 identical flexi bag digester units will be used as experimental units.

• The investigation will be conducted in a completely Randomized Design (CRD) with

three replicates of each treatment.

Comparison between the two types will be carried out using the Analysis Of Variance tables

(ANOVA) Expand this statement to be more descriptive.

Experimentation:

The experiment will be conducted using a Randomized Complete Block Design (RCBD)

research design with 5 bio – digester as the blocks and 5 treatment levels. Samples of fresh

donkey dung will be ferried from Lamu while cow dug will be collected from Pwani university

farm. Prior to loading into the digester, stones, leaves, waste feed, sticks, and other foreign

matter were carefully picked from the wastes which were then properly stirred to break the

lumps into finer particles. A 25 kg charge (30%TS) of each waste type was measured and mixed

with 25 kg of water in a mixing tank; and stirred for about 20 minutes to ensure sufficient

dispersal of the waste particles and achieve slurry of regular consistency. The mixed slurry was

then poured into the digester tank and sealed properly to ensure air-tightness. Two other

concentrations of ratios 2:1 (50 kg of waste mixed with 25 kg of water) and 3:1 (75 kg of waste

mixed with 25 kg of water) were loaded. Three replicates were used for each experiment. All the

experiments were subjected to a retention period of 30 days each. All were exposed to ambient

temperatures which were within the mesophilic range and none was artificially heated.The whole

arrangements were fully set up on the experimental site, free of any shade to ensure maximum

reception of solar radiation. The ambient temperatures of the site were continually monitored and

measured daily. The arrangement was vigorously shaken twice daily, at 7.00am in the morning

and 7.00pm in the evening and biogas production was measured at 12.00 noon throughout the

30-day retention period used for every experiment. In each batch 3kg of each animal dung

combination will be weighed and placed in the digester unit then mixed with water at a ratio of

1:1 The gas holder will then be placed on the digester with the gas outlet sealed by the rubber

tube. The produced gas will then be discarded at intervals each time when the level in one of the

digesters reach 21 cm. At each discarding event the produced gas will be tested to examine the

presence of methane by ignition.

Try to insert experiment 1, 2 3 and 4 as per the objectives describing each in details of what will

be carried out.

PROPOSED BUDGET FOR DONKEY BIOGAS PROJECT

ITEM QUANTIT

Y

UNIT

COST

FREQUENCY TOTAL

SURVEY AND DATA COLLECTION

ENUMERATORS (MAN

DAYS)

5 2500 5 62500

DATA ANALYSIS 5 1000 1 5000

VALIDATION OF THE

DUNG MENACE(DAYS)

2 10,000 1 20000

STATIONARY 3 2500 3 22500

DUNG COLLECTION AND

TRANSPORTATION

0

FLEXI - BIODIGETER 15 30,000 1 450000

MIXING BUCKETS 15 500 1 7500

DUNG COLLECTOR FOR

TWO MONTHS

2 5000 2 20000

DUNG TRANSPORTATION 3 20,000 1 60000

TOTAL 647500

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MATERIALS AND METHODS

livestock farms at the Institute of Agricultural Research

and Training (IAR&T), Moor Plantation, Ibadan, Nigeria.

Nine 220-litre black-coated, batch type, sheet metal

digesters which incorporated a water tank as well as

iron sponge and saw dust sealed in a separate cylinder

were used in this 3x3 factorial experiment.

Biogas

samples were obtained at the beginning, and towards

the end of the detention period. Biogas quality was

measured using a gas detector. Volume measurements

of biogas produced were done by water displacement.

The experiment reported in this present study

is part of a wider set of biogas production experiments

which were conducted in the months of February to

May, 2008. Energy to run the experiments came

entirely from solar radiation. According to Fagbenle

(1991), the monthly average daily extraterrestrial solar

radiation for Ibadan, Nigeria is as shown in Table 1.

Table 1:

Monthly average daily extraterrestrial solar radiation on horizontal surface (KJ/m

2

) for Ibadan, Nigeria (Lat

7.43

0

N, Long 3.80

0

were well stirred and digested in a 3x3 factorial experiment using a retention period of 30 days and within

the mesophilic temperature range. The waste: water mixing ratios of slurry used were 1:1, 2:1 and 3:1 by

mass. Three replicates were used for each ratio. Two hundred gram samples of each animal waste type

were obtained before and after experimentation and analysed for chemical constitution. All the readings of

the biogas yield were analysed using the Duncan Multiple Range Test (DMRT). Biogas yield was

significantly (p < 0.05) influenced by the various factors of animal waste (F=86.40, P< 0.05), different water

mixing rates (F=212.76, P< 0.05) and the interactions of both factors (F=45.91, P< 0.05). Therefore, biogas

yield was influenced by variations in the mixing ratios as well as the waste types used. The 1:1 mixing ratio

of slurry resulted in biogas productions of 20.8, 28.1, and 15.6 l/kgTS for poultry, piggery and cattle wastes

respectively. The 2:1 ratio resulted in 40.3, 61.2 and 35.0l/kgTS while the 3:1 ratio produced 131.9, 117.0

and 29.8l/kgTS of biogas respectively. Therefore an increasing trend was observed in biogas production as

mixing ratio changed from 1:1 to 3:1. For cattle waste however, production decreased from ratio 2:1 to ratio

3:1. The N, P, K values were highest for poultry waste (3.6, 2.1, and 1.4% respectively) and least for cattle

waste (2.2, 0.6, 0.5% respectively). Organic carbon was highest for cattle waste (53.9%) and least for

poultry waste (38.9%). Reduction in C/N ratio for each experiment ranged from 1.1 to 1.9%.

Conclusion and application of findings

: This study found that for poultry and piggery wastes, slurries mixed

in ratios 3:1 waste:water produced more biogas than those of 2:1 and 1:1 ratios. For cattle waste, the 2:1

mixing ratio produced the most biogas. This paper therefore recommends a livestock wastes: water mixing

ratio of 3:1 for poultry and piggery slurries, and 2:1 for cattle slurry for maximum biogas production from

methane-generating systems, given 30% TS content.

Key words:

Anaerobic digestion, biogas, cattle waste, piggery waste, poultry waste.

Journal of Applied Biosciences 22: 1333 - 1343

ISSN 1997–5902

Adelekan & Bamgboye.

....................................

J. Appl. Biosci. 2009. Biogas production with farm waste

1334

INTRODUCTION

Scientific interest and efforts in researching into

biogas production technology are still relevant

because of the often very high costs of energy

supply worldwide. Another reason for their

relevance is the fact that the rampant use of

firewood for domestic cooking in low income

countries invariably results in the destruction of

forests which is harmful to the environment. Also,

the use of firewood, kerosene and charcoal in

households has adverse effects on human health

(Adelekan & Adelekan, 2004). Furthermore, using

waste biomass to produce energy can reduce the

use of fossil fuels, reduce greenhouse gas

emissions and reduce pollution and waste

management problems (Vetter

et al.,

1990;

Marshall, 2007; Inderwildi and King, 2009). EEA

(2006) pointed out that by 2020, the equivalent of

19 million tonnes of oil will be available from

biomass, of which 46% will be from biowastes

mainly municipal solid wastes, agricultural

residues, farm waste and other biodegradable

waste streams.

The objective of the research work being

reported in this paper was to investigate the effect

of mixing ratio of slurry on biogas productivity of

wastes from poultry birds, pigs and cattle. Biomass

represents a continuously renewable potential

source of methane and thus offers a partial

solution to the eventual prospects of fossil fuel

depletion. In addition, biomass can be

economically converted to biogas at a variety of

scales and thus can be tailored to supply local,

regional and nationwide biogas needs.

It has been discovered that, under aerobic

conditions, living plants also produce methane

which is significantly larger in volume than that

produced by dead plants. Although this does not

increase global warming because of the carbon

cycle (Keppler

et al.,

2006), it is not readily

recoverable for economic purposes. However, the

methane which is recoverable for the direct

production of energy is from dead plants and other

dead biomass under anaerobic conditions. Biogas

is a flammable gas produced by microbes when

organic materials are fermented in a certain range

of temperatures, moisture contents, and acidities,

under air–tight conditions. Anaerobic digestion is a

process through which organic materials are

decomposed by bacteria in the absence of air to

produce biogas. The digestion process itself starts

with the bacterial hydrolysis of the biomass so as

to break down carbohydrates and other insoluble

organic polymers. After the chemical break down,

various kinds of bacteria convert the materials into

different gases and organic acids in several stages

(Ciborowski, 2004). Methanogenic bacteria finally

convert these products into methane and carbon

dioxide (Fergusen and Mah, 2006; Anaerobic

Digestion Reference Sheet, 2007). UNDP (1997)

stated that anaerobic digestion facilities constitute

one of the most useful decentralized sources of

energy supply and they are less capital intensive

than conventional power plants.

Many publications have pointed out that

simple, home and farm-based anaerobic digestion

systems have the potential for supplying cheap,

low cost energy for cooking and lighting in

developing countries (Doelle, 2001; Friends of the

Earth, 2004; Cardiff University, 2005). Many

developing nations meet significant amounts of

their energy needs through biogas particularly in

the rural areas. The biogas support program in

Nepal has installed over 150,000 biogas plants in

the rural areas (AEPCNEPAL, 2009) while the

biogas program in Vietnam has led to the

installation of more than 20,000 plants throughout

the country (SNV, 2009). Also, in Rwanda, the

Kigali Institute of Science and Technology has

developed and installed several large-scale biogas

plants at prisons to treat sewage and provide

biogas for cooking (KIST, 2009). Even in

developed countries, significant potential for

biogas use still exists. For example in the United

Kingdom, biogas is estimated to have the potential

to replace about 17% of vehicle fuel (Claverton

Energy Conference, 2008). In Sweden, a biogas-

powered train has been in service since 2005

(Svenskbiogas, 2005).

Options for biomass exploitation include

plant materials and livestock wastes mostly.

Several researchers have reported biogas

production from various materials including pigeon

Adelekan & Bamgboye.

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