ABSTRACT
This study was carried out to examine the effects of Single
Super Phosphate with Wood ash on the production of biogas from Cow Dung and
Chicken Droppings mixed with Digitaria Smuts II. An existing
digester design was adopted (3 in 1 floating drums) and fabricated using
locally available materials to digest Cow Dung from Kawo Abattoir, Chicken
Droppings from Salma Farms and Digitaria Smuts II (Woolly Finger Grass)
from NAPRI respectively. The study was carried out in eight (8) identical
reactors to enable variation of the catalyst combination and were labelled A1,
B1, C1, D1, A2 B2 C2 and D2. The research showed that using SSP and wood ash
could reduce the lag phase in anaerobic digestion. The controls A1 and A2 had
the longest lag phase of 7.5 and 8.9 days as compared to 5.5 and 7.9 days with
(200gSSP/100gWood ash). At the end of the digestion period, there was
significant difference in volume of biogas produced across the digesters which
ranged from 0.0893m3 (no additives) to 0.1188m3
(200gSSP/100gwood ash) for cow dung, while that of chicken droppings mixed with
grass is from 0.0647m3 (no additives) to 0.1088m3
(200gSSP/100gWood ash), indicating 20.6% and 40.6% increment respectively. The
Modified Gompertz equation was applied to describe the cumulative biogas
generation. The biogas production kinetic constants estimated by the linear
regression method using the solver function in Microsoft Excel as well as other
characteristics obtained for the eight digesters were 0.0037m3/day
0.0036m3/day 0.0045m3/day, 0.0056m3/day,
0.0025m3/day, 0.0028m3/day, 0.0031m3/day, and
0.0046m3/day for Biogas Production Rate and 0.0893m3, 0.0841m3,
0.0977m3. 0.1188m3, 0.0647m3, 0.0737m3,
0.0808m3 and 0.108 8m3 for Biogas Production Potential.
The average temperatures of the digesters recorded were 35.20 0C,
35.30 0C, 35.17 0C, 35.18 0C 35.25 0C,
35.28 0C, 35.30 0C, and 35.40 0C respectively
while the average ambient temperature observed during the study was 36 0C
which were within the mesophilic range. The results obtain indicated that the
additives used influenced biogas production.
CHAPTER
ONE
INTRODUCTION
1.1 Background
of Study
Environmental pollution is a major problem in the world
today, it affect humans, animals and other forms of living organisms including
plants. This pollution is mostly as a result of man activities, either in the
process of producing his food, shelter, transportation, or the quest to improve
his economy. Thakur (2006), stated that economic growth and heavy consumption
of natural resources are responsible for global warming, acid rain and
destruction of the ozone layer.
Energy is an essential tool for development. Africa and
other developing countries are faced with energy challenge. Less than 10% of
the population of 21 Sub-Sahara African countries have access to electricity,
Mshandete and Parawira, (2009). These countries however produce tremendous
amount of waste which if channeled towards energy production can meet the
energy need of the region. In Nigeria for instance, aside from the large amount
of waste and manure generation, Adaramola and Ovewola (2011) opined that, the
country is endowed with huge resources of conventional energy resources (hydrocarbon)
and reasonable amount of renewable energy resources (e.g. hydro, wind, solar
and biomass).
The Organization of Petroleum Exporting Countries (OPEC)
annual statistical bulletin 2009 in buttressing these facts revealed that
Nigeria proven crude oil reserves and natural gas are 37.2 billion barrels and
5,292 trillion standard cubic meters, respectively. In addition, the estimated
reserve of tar sands and proven reserves of coals are about 30 billion barrels
of oil equivalent and 639 million tons (with inferred reserves of about 2.75
billion tons), respectively (Adaramola and
Oyewola, 2011). According to (Iwayemi, 2008), the region has
biomass reserve of 144 million tons per year
Despite all these abundant energy resources, Nigerian Bureau
of Statistics (NBS) revealed that, Nigeria as at 2006 had a total of about
28,900,492 households. 79.6% of these households still depend on wood fuel for
cooking as at 2008. In some states like Adamawa, Nasarawa, Zamfara, and Sokoto,
there is over 90% dependency on fuel wood (NBS, 2009).
Over dependency on fossil fuel in most part of the urban
area is also a major problem, which often results in the accumulation of carbon
dioxide in the atmosphere. As human development continues to increase and fossil
fuels continue to be depleted, it is undeniable that sustainable, alternative
energy sources must replace fossil fuels in order for society to maintain its
quality of life (Igboro, 2011).
Energy is central to nearly every major challenge and
opportunity the world faces today. Be it for jobs, security, climate change,
food production or increasing incomes, access to energy for all is essential
SDG (2015). Part of the United Nations Sustainable Development Goal is to
harness the potential of other sources of energy other than fossil fuel which
is clean and sustainable. Sustainable energy is opportunity, it transforms
lives, economies and the planet. At the UN conference held in France, December
2015 on climate action, the following were revealed;
i.
One in five people still lacks
access to modern electricity
ii.
Three billion people rely on wood
coal, charcoal or wood fuel for cooking
iii.
Energy is the dominant contributor
to climate change, accounting for around 60 percent of total global greenhouse
gas emissions
There is a great deal of environmental pressure in many
parts of the world to ascertain how livestock and poultry waste can best be
handled. These wastes like cow dung and poultry droppings in the absence of
appropriate disposal methods can cause adverse environmental and health
problems such as pathogen contamination, greenhouse gases, air borne ammonia
and odor. Anaerobic digestion has been considered as waste to energy
technology, and is widely used in the treatment of different organic wastes,
for example, organic fraction of municipal solid waste, sewage, sludge, food
waste, animal manure among others. Anaerobic treatment comprises of decomposition
of organic material in the absence of oxygen resulting in the production of
methane, carbon dioxide, ammonia and traces of other gases.
Biogas refers to a mixture of different gasses produced by
the breakdown of organic matter in the absence of oxygen. Agricultural waste,
sewage, food waste, municipal waste, plant material and manure are some of the
raw materials used to produce biogas. Biogas can be produced by anaerobic
digestion with anaerobic bacteria, which digest material inside a closed
system, or fermentation of biodegradable materials. Biogas is primarily methane
(CH4) and carbon dioxide (CO2) and may have small amount of hydrogen sulphide
(H2S) and traces of other gasses. The gasses methane, hydrogen, and carbon
monoxide can be combusted or oxidized with oxygen. This energy released allowed
biogas to be used as a fuel for heating or in some cases are used to generate
electricity. Typical composition of biogas are; Methane (CH4) 50 – 75%, Carbon
Dioxide (CO2) 25 – 50%, Nitrogen (N2) 0 – 10%, Hydrogen (H2) 0 – 1%, Hydrogen
Sulphide (H2S) 0 – 3%, (www.lowimpact.org/factsheetbiogas.pdf, 2012).
Environmental quality has been largely affected as a result
of petroleum base fuels. The detrimental consequences of the fossil based fuels
and the depleting supplies of crude oil products have prompted and triggered
the search for renewable alternative energy.
Biofuel should meet peculiar criteria such as providing net
energy gain, positive favorable environmental effect and benefits, be
economically cost effective and competitive.
It is important to note that in biogas production, the
substrates which are basically waste from municipalities helps in environmental
cleanup, it produces lower CO2 emissions compared to fossil fuels. The sources
of Anaerobic Digestion can be classified as either industrial waste and waste
water, Sewage sludge, Farm waste, Municipal solid waste, or Green waste. (Alfa,
2013).
Recently, large volume of cow dung and chicken dropping
generated from feedlot and poultry farming increase annually, most of which are
disposed into landfills or are applied to the land without treatment. Anaerobic
digestion provides an alternative option for energy recovery and waste
treatment.
Over the years, a lot of research has been made to produce
gas from various bio degradable materials. In this study, the effect of
catalyst on biogas production using cow dung and chicken droppings with grass
will be assessed. The effectiveness of SSP (Single Super Phosphate) and Ash to
accelerate the rate of digestion to produce biogas in batch operation will be
determined.
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