Bioremediation serves as a promising approach to address the environmental challenges posed by the intensification of agriculture and manufacturing industries
By Safdar Gazi
The intensification of agriculture and manufacturing industries has resulted in an increased release of a wide range of xenobiotic compounds into the environment. This excessive loading of hazardous waste has led to a scarcity of clean water and disturbances in soil, thereby limiting crop production. Harnessing Microorganisms to Clean up the Environment
Bioremediation, a technology that utilizes biological agents primarily consisting of microorganisms such as yeast, fungi, or bacteria, is employed to clean up contaminated soil and water. This innovative approach relies on promoting the growth of specific microflora or microbial consortia that are native to the contaminated sites and capable of carrying out desired activities.
The establishment of such microbial consortia can be achieved through various methods, such as promoting growth by adding nutrients, introducing terminal electron acceptors, or controlling moisture and temperature conditions. In bioremediation processes, microorganisms utilize the contaminants as nutrients or energy sources.
The global population explosion has resulted in an increase in the area of polluted soil and water. As the number of people continues to grow, it brings along a mounting pressure on our natural resources, including air, water, and land. The rapid expansion of industries, food production, healthcare, and transportation further exacerbates this strain on the environment.
However, maintaining a high quality of life amidst these new developments, which often prove detrimental to the environment, requires proper management. While nature has various fungi, bacteria, and microorganisms constantly at work breaking down organic compounds, the question arises: who will clean up when pollution occurs?
Recognizing the inextricable link between the quality of life and the overall quality of the environment, global attention has focused on finding ways to sustain and preserve our surroundings. Biotechnology plays a crucial role in this endeavor. Environmental biotechnology investigators specialize in addressing various types of contaminants, including chlorinated solvents, petroleum hydrocarbons, ketones, and TNT, through the application of microorganisms in bioremediation processes, yielding encouraging results.
There are different strategies employed in bioremediation, such as in-situ and ex-situ techniques. In-situ bioremediation involves treating the contaminated material at the site itself. Bioventing, for instance, supplies air and nutrients through wells to contaminated soil, stimulating the growth of indigenous bacteria. This method is suitable for simple hydrocarbons and can be employed when contamination is deep below the surface. Biosparging, on the other hand, involves injecting pressurized air below the water table to increase groundwater oxygen concentration and enhance the rate of biological degradation of contaminants by naturally occurring bacteria. Another technique, bioaugmentation, entails introducing microorganisms to the contaminated site to enhance the degradation process.
Ex-situ bioremediation techniques involve the removal of contaminated material to be treated elsewhere. Land-farming, for example, involves excavating contaminated soil and spreading it over a prepared bed, periodically tilling it until pollutants are degraded. The goal is to stimulate the indigenous biodegradative microorganisms and facilitate their aerobic degradation of contaminants. Biopiles, a hybrid of land farming and composting, construct engineered cells as aerated composted piles, typically used for treating surface contamination with petroleum hydrocarbons. Bioreactors, on the other hand, process contaminated solid materials such as soil, sediment, sludge, or water through an engineered containment system.
Composting is another bioremediation technique that has been effectively utilized. TERI has developed a mixture of bacteria called oil-zapper, which degrades pollutants in oil-contaminated sites, leaving behind no harmful residues. This technique not only proves environmentally friendly but also highly cost-effective.
Additionally, genetic engineering approaches have been employed in bioremediation. Phytoremediation, for instance, utilizes plants to remove contaminants from soil and water. There are various types of phytoremediation, including phytoextraction/phytoaccumulation, which involves plants accumulating contaminants in their roots and above-ground shoots or leaves. Phytotransformation or phytodegradation refers to the uptake of organic contaminants from soil, sediments, or water, transforming them into more stable, less toxic, and less mobile forms. Phytostabilization is a technique in which plants reduce the mobility and migration of contaminated soil by adsorbing and binding leachable constituents into their structures, preventing re-entry of contaminants into the environment. Rhizodegradation involves the breakdown of contaminants through the activity of proteins and enzymes present in the rhizosphere, produced by plants or soil organisms such as bacteria, yeast, and fungi.
Nature, with its millions of years of fine-tuning bioremediation methods, serves as the ultimate expert in this field. We now have the opportunity to learn from its wisdom, as stated by Aubaid Akhoon.
Bioremediation offers several advantages, including the complete destruction of a wide variety of contaminants, the possibility of completely eradicating target pollutants, and its cost-effectiveness while being environmentally friendly.
However, bioremediation also has its limitations. It is only applicable to compounds that are biodegradable, and not all compounds are susceptible to rapid and complete degradation. Biological processes in bioremediation are often highly specific, and the process itself tends to take longer than other treatment methods.