Abstract
Biodegradation has proved over time that it is the cheapest and safest method human
can use to tackle waste and population. The study of biodegradation of
polypropylene revels that Actinomycyte and three other unknown strains are capable
of biodegrading polypropylene (making new functional group) within 3weeks. The
new functional group seen after 3 weeks were ester, cyanide, and ketone. The
microbial community at the Yola waste are a community of diverse organism. Each
with its own unique morphology, and growth pattern. All organisms were gram
positive. This means that they can adapt to high stress and a resist turgor pressure.
Actinomycyte spp was able to biodegrade polypropylene by breaking the carbon to
hydrogen, and breaking down carbon hydrogen bond to make carbon oxygen bonds.
INTRODUCTION
Every year, about 1.3 billion tons of waste is generated globally. By 2025, it is
estimated that this will increase to 2.2 billion tons, with a large sum (2.13
kg/capita/day) from developing countries (Bhada-Tata, &Hoornweg, 2012). The term
waste refers to items or products (organic and inorganic) that are considered useless
or have lost their value (Bhada-Tata, & Hoornweg, 2012). It is a broad term items
such as animal bones, plastic bags and bottles, and used clothes. Waste generation
has been in existence, since the beginning of agricultural revolution, and it can be
traced back to the first human civilization. As a result, waste is inevitable and cannot
simply be avoided, due to urbanization (Muhammad, Huma, Munir, & Atiq, 2015).
Information age, urbanization and industral age has led improve human lifestyle, in
many cities, which is the major cause of increase in solid waste production (Renou,
2008).
With the emergence of the industrial age, and then the information age, urbanization
could not stifled because of the human desire for securing a more comfortable life.
This led to the production of waste products. Urbanization generally brings economic
prosperity, and higher waste production. This is because people living in cities
usually earn more income, and have several options from which they can choose
from (Renou, Givaudan, Poulain, Dirassouyan, & Moulin , 2008).However, urban
settlements are known to be densely populated, leading to greater amount of waste
compared to non-urban areas(Renou, Givaudan, Poulain, Dirassouyan, & Moulin ,
2008).
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Composition of waste in urban areas
On average, urban waste dumps consist of millions of different waste materials
(Bhada-Tata, &Hoornweg, 2012). The composition of a landfill or dumpsite gives an
idea of the physical, chemical, and thermal properties of the waste. There are four
factors that influence the composition of waste in a dumpsite: culture, seasons, laws
guiding waste disposal, and demographics of people living in the area. For example,
in developed countries and in urban areas people tend to consume more processed
foods than unprocessed food. (Bhada-Tata, & Hoornweg, 2012).
Municipal wastes are garbage collected and transported to landfills from households
and industries. Municipal waste in landfills serve as a home and substrate for
microorganisms and provide a unique ecosystem for compositing and anaerobic
digesters.
Fig.(1). Composition of household wastes in the world (Ogola, Chimuka, & Tshivhase,
2011)
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The major challenge in the today’s world is that most of the waste generated are
inorganic, and the rate of degradation is inversely proportional to the amount of it
produced (Pettigrew, Palmisano, & Charles , 1992). In other words, the rate at which
our consumer-driven society utilizes and discards products, especially inorganic
ones, supersedes the time needed for the products to decompose. This situation is
obvious and can be found in the open garbage dumpsites in developed, developing,
and under-developed countries. In developed countries such as United States of
America, 25 million tons of plastics are discarded every year. Most of the plastics are
deposited in landfills where the degradation process may last for decades or
centuries, therefore leading to difficulties in locating new landfill sites (Pettigrew,
Palmisano, & Charles , 1992).
Open landfills are rapidly increasing due to the rate at which the world is producing
and discarding products, which has led to the extension of existing garbage sites into
new lands. New garbage sites are also being created, and this is a threat to agriculture
because it takes up land that could have been used for the cultivation of crops. An
issue with garbage dump sites is that it causes environmental pollution, such as soil
contamination and air pollution, which eventually leads to water contamination and
human health hazards such as diarrhea, respiratory ailments and dengue fever
(Agnieszka Kalwasi?ska, 2012).
In ancient times, when mankind relied on foraging for survival, waste management
was not a major issue because the small human population produced little waste
compared to that which we produce in tons daily (Giusti, 2009). The wastes we
produce are poorly managed globally, especially in developing countries, which is
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causing serious environmental pollution (Giusti, 2009). The impact of improper
waste disposal can be seen in developing countries around the world.
Waste management in developing countries
Composition, waste generation, and the waste management practices in use vary
from one geographical area to another in both developed and developing countries
(Vaibhav, & Sultan, 2014). Due to the pollution caused by poor waste management
practices, there has been concern about control practices, inadequate legislation, and
the environmental and human health impacts of waste.
As a result, some countries have made efforts to enact laws that control unsustainable
Fig. (2). Waste collection data for different countries
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waste management. However, in developing countries globally, waste may be
dumped in open landfills, without adhering to the recommended rules by the
municipal authorities. Landfills are lands where solid waste is disposed. They are
usually located at the outskirts of urban centers. Landfills are usually the final site for
waste disposal in many developing countries. This is because open-dump sites are
cheap and affordable for any nation (Vaibhav, & Sultan, 2014). However, in
developing countries, few data exist about open waste dumps, and this could be a
reason for continuous environmental pollution. . In developed countries on the other
hand, efforts have been made in reducing the amount of municipal wastes littered in
the environment. Developed countries have made modern waste management
models. These models include modern recycling, incineration, and anaerobic
digestion has been developed. In addition, countries have begun investigating a
natural form of waste clean-up: bioremediation.
Bioremediation
Bioremediation is a naturally occurring process whereby micro-organisms convert
harmful products to less toxic products (Arvanitoyannis,&Thassitou,
2001).Municipal waste acts as substrate for many microorganisms. These microorganisms provide a unique ecosystem for composting and anaerobic digesters. Each
layer of a landfills provide a conducive environment for microorganisms (Palmisano
& Barlaz, 1996).
The upper layer has the most nutrients because of the adequate moisture and
temperature present. A typical waste dump consists of polymeric substances, such as
paper, yard waste, and food. Therefore, waste dumps act as substrates for microbe ,
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and these substrate will include cellulose, starch, protein, and hemicellulose. The
microbial organisms in landfills include digesters, composters, anaerobic digesters
(hydrolytic and fermentative bacteria), acetogen, methanogens and sulphate reducers.
Other micro-organisms present include such bacterial species as Bacillus spp.,
Escherichia coli, Klebsiellaspp., Proteus spp., Pseudomonasspp.,
Staphylococcusspp., and Streptococcus spp. On the other hand, fungi such as
Aspergillus, Fusarium, Mucor, Penicillium, and Saccharomyces are capable of
biodegrading waste materials (plastics). All these microbes work together to
breakdown waste as part of the bioremediation process.
Bioremediation has been found to be the most sustainable way for water and soil
remediation. This is because it does not pose a threat to the environment or human
health, and it is inexpensive (Arvanitoyannis, & Thassitou, 2001). Bioremediation
processes for the treatment of contaminated soil and water are divided into four
categories: inoculation, stimulation, use of immobilized enzymes, and use of plants.
The methods used are composting, landfarming, use of bioreactors, and intrinsic
bioremediation (Arvanitoyannis,& Thassitou, 2001).There are different types of
bioremediation that help restore polluted sites. The total number of organisms found
in a polluted area, gives an insight on how efficient the wastes can be degraded over
time. In addition, the method implore for the biodegradation also count to how fast
the waste is degraded over time. These methods includes gravimetric method and the
ohimic technology. The gravimetric method is an old method of degrading waste.
However, advanced technologies, such as the ohmic technology, have helped in
overcoming the limitations associated with characterisation of wastes for
biodegradation (Azubuike, Chikere, & Okpokwasili, 2016)