The breakdown decomposition degradation or removal of toxic contaminants from the environment is called bioremediation (Aislabie, 2012). Microorganisms are introduced into the contaminated soil to carry out normal functions (Nester, 2001). Microorganisms act on the contaminated soils to neutralize the contaminants. The organisms include bacteria, fungi, and plants to mention a few (Perfumo, 2007).
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The organisms alter the composition of the contaminants by carryout their normal life activities. The waste management technique can be done on the site of contamination or on a neutral waste disposal site. Advanced technologies are employed in the treatment of contaminants (Walworth, 2007). The techniques include bioventing, bioaugmentation, and bioleaching to mention a few. The organisms utilized during bioremediation are called bioremediators.
The organisms are introduced on the site of contamination to degrade the contaminants. Waste management is a necessity because of the effect of the contaminants to human health. These contaminants pose health risk to humans and the environment. A study conducted by Simon revealed that waste managements could reduce the effect of toxic spills by 13 percent (2010).
Reasons for the technology
Environmental studies suggest that oil contaminant causes severe health challenges. This accounts for the rise in toxic related diseases and infant mortality. Bioremediation technology mitigates these contaminants (Walworth, 2007). Observations are ongoing to ascertain the effects of bioremediation on the soil and its effect on human health.
Human beings and Plants suffer similar risk to contamination of the soil. The polluted soil makes it difficult to cultivate crops and grow animals. Contaminants block the passage of soil nutrients and the blockage affects the circulation of soil nutrients. Such situations make the soil infertile and toxic for agriculture.
The contaminants reduce the fertility of the soil. Three important agents are present during bioremediation processes. The agents are; the contaminant, the electron acceptor and a suitable microorganism. The degraded material adds nutrients to the environment. For example, degraded hydrocarbons react with oxygen to cause aerobic respiration. Although these microorganisms have their limits, they combine well under favorable conditions to influence the degradation of various contaminants (Swannell, 2010).
Industrial waste constitutes 65 percent of the world’s toxic materials. The emergence of bioremediation technology is a positive development in curbing the effects of the contaminants. Sveum suggested the use of five microorganisms to reduce the toxicity of industrial contaminants (2008). These microorganisms include; Pseudomonas, Staphylococcus, Aspergillus, Bacillus cereus and aeruginosa. These organisms combine to reduce the toxicity of industrial contaminants.
The effects of industrial waste are so severe that chief executives have careful minimize oil spills. Industrial waste can be recycled using bioremediation to reduce the effect on the environment. Mass protests and demonstrations occur daily because of industrial spillage and soil contamination. A proper management system is the only way of reducing the effects of industrial contamination (Swannell, 2010).
Factors of bioremediation
Bioremediation is a complex process which is controlled by different factors (Walworth, 2007). The factors include: the presence of a suitable organism, the presence of the contaminants, favourable environmental conditions suitable for microbial growth to mention a few.
Microbial populations in bioremediation process
The presence of microorganisms in the contaminants influences bioremediation. The organisms can survive in extreme conditions. The nature of their growth makes them suitable for bioremediation. The organisms can be categorized into four groups.
a. Anaerobic organisms: Anaerobic organisms survive without oxygen. This makes them suitable in the control of biphenyls contaminants and the compounds of chloroform. Composting and land farming techniques favors anaerobic organisms. The compost stimulated the growth of the organisms in extreme temperature.
b. Aerobic organism: They function with oxygen. The microbes include Alcaligenes and Rhodococcus to mention a few.
Methylotrophs microbes: The microbes grow with oxygen and little methane.
Ligninolytic fungi: This group of microorganism can be used to degrade hazardous waste.
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Environmental factors affecting bioremediation
Microorganisms are the principal agents in the bioremediation process. To degrade much contaminant, the population of a suitable microorganism must be balanced (Aislabie, 2012). Thus, microorganisms suitable for bioremediation require favourable environmental conditions to boost their growth.
The nutrients must be available in equal proportions suitable for microbial growth. Microbial organisms require carbon, nitrogen, oxygen, hydrogen, sodium, calcium, chloride to mention a few. Microbial growth and degradation is influenced by the conditions suitable for microbial development.
Bioremediation is influenced by soil moisture, temperature, pH, oxygen level, and temperature, nature of the contaminants, soil type and the nature of heavy metals. The nature of the soil influences the rate of degradation and microbial growth. The presence or absence of oxygen is influenced by the contaminants. The presence of oxygen requires aerobic microorganisms while the absence of oxygen in the soil will require anaerobic bacterial to complete the degradation processes.
The population of the microbes can be simulated by biostimulation techniques (Perfumo, 2007). The addition of oxygen and other favourable nutrients suitable for microbial growth is called biostimulation. The presence of heavy metals affects the growth of microorganisms.
In extreme cases, soil nutrients are introduced in the soil to boost microbial growth. Aerobic organisms will require aerated soils and this can be achieved thorough soil tillage. This will allow easy passage of nutrients suitable for the development of the microorganism.
The nature of the contaminants determines the technique used on the site of contamination. Bioremediation strategies require two broad procedures. In-situ and Ex-situ are two major techniques employed in bioremediation processes. In-situ bioremediation is used when the contaminants are degraded on the contaminated soil.
Microorganisms are introduced at the site of contamination (Swannell, 2010). Large contaminations will require excavation of the contaminants to another site for treatment, which is called Ex-situ bioremediation. The introduction of suitable microorganisms in the soil is called bioaugmentation. Bioaugmentation is affected by two factors.
a. The introduced organism may not adapt with the indigenous microbes in the soil. Thus, population growth may be limited.
b. Indigenous microbes have potentials to carry out bioremediation processes.
The degradation of contaminants at the site of contamination is called In-situ bioremediation. It is a cheap technique compared to the excavation of contaminated soil to a new facility. Its disadvantage is caused by the soil type. The soil type influences the level of degradation. Aerated soils degrade faster and biostimulation is easy. In-situ bioremediation can be achieved in different ways.
Bioventing: It involves the supply of nutrients and oxygen in equal amounts through wells. The quantity of oxygen is controlled to produce stable growth of the microorganism.
Biodegradation: Gaseous solutions are supplied on the site of contamination to circulate the nutrient requirements suitable for microbial growth. The procedure requires the use of groundwater to distribute oxygen and microbial nutrients on the contaminated site.
Bioaugmentation: The supply of internal or external microorganisms into the site of contamination is called bioaugmentation. One disadvantage of exogenous microbe is the performance ratio. Exogenous microorganisms may not grow in extreme temperature. Extreme temperature will limit the population of the microorganism.
Biosparging: The site of contamination is pressurized to induce the availability of oxygen. The injection of pressurized air alters the concentration of groundwater at the contaminated site.
The techniques include land farming, composting, biopiles and bioreactors.
Land farming: The process requires the excavation of the contaminated soil to a prepared facility suitable for degradation. The microbes are stimulated with oxygen and microbial nutrients to increase its population (Walworth, 2007).
Compost: The combination of the contaminated soil with manure or agricultural products is called composting. The manure stimulates microbial growth and facilitates the development of ingenious microorganisms. The temperature of the soil is controlled to influence the production of anaerobic organisms.
Biopiles: The combination of land farming and compost is called biopiles. Engineered organisms are used to degrade contaminants. The technique is suitable for aerobic and anaerobic microbes.
Bioreactors: The use of treated vessels to decontaminate the soil is another bioremediation technique. The contaminants are transported to an engineered facility. The process is monitored under a controlled temperature (Nester, 2001).
Advantages of bioremediation
1. Bioremediation is a natural process and the residues do not pose a health risk.
2. Bioremediation is useful in the degradation of heavy metals and other toxic waste.
3. Contaminants can be destroyed or neutralized at the site of contamination. The procedure reduces the risk of transporting hazardous waste from the site of contamination to a free zone.
4. Except in extreme cases, the process of bioremediation does not disrupt the ecological system of the contaminated site.
5. Bioremediation is a cheap method of decontamination compared with various decontamination techniques.
Disadvantages of bioremediation
1. The decontamination of the soil is a limited process. Most contaminations cannot be degraded by microorganisms.
2. The introduction of microorganisms may cause severe damage to the ecological system.
3. The chances of success are slim because of the absence of microbial population. It is difficult to estimate the quantity of microbial organisms required for the decontamination process.
4. The process requires time. The evacuation and transportation of the contaminated soil to the treated facility lengthens the time of biodegradation.
5. The processes of bioremediation cannot be justified. The extent of damage cannot be determined.
The treatment of industrial waste requires bioremediation. Unlike other methods of waste managements, bioremediation mitigates these contaminants. Bioremediation benefits man and the environment. Oil spills and heavy metals, which are major soil contaminants are treated with suitable microorganisms.
A combination of two or more microorganisms can create an atmosphere suitable for the degradation of contaminants. Although the treatment is cost-effective, it reduces the effects of toxic wastes on the environment. A practical approach must be used to degrade contaminants in large quantity.
The process is suitable for degradation of contaminated sites. The cost of the procedure makes it suitable for large decontamination. The risk associated with the process cannot be ascertained; however the process provides the best technique for decontamination.
I will recommend further studies to determine the extent of damage during the cleanup. Regulatory agencies must reduce the occurrence of oil spillage and soil contamination.
Aislabie, J. (2012). Bioremediation of hydrocarbon-contaminated soils. USA, New York: McGraw-Hill.
Nester, E. (2001). Microbiology: A human perspective and approach. USA, New York: McGraw-Hill.
Perfumo, A. (2007). Thermal enhanced approaches for bioremediation of hydrocarbons. USA, New York: McGraw-Hill.
Simon, M. (2010). Evaluation of bioaugmentation for remediation of petroleum in a wetland. USA, New York: McGraw-Hill.
Sveum, P. (2008). Hydrocarbon bioremediation and its benefits. Sydney, Australia: Ibex Press.
Swannell, R. (2010). The use of bioremediation to treat an oiled shoreline. Sydney, Australia: Maxon Press.
Walworth, J. (2010). Fine tuning soil nitrogen to maximize petroleum bioremediation. South Melbourne, Australia: Maxon Press.