Introduction

Our environment is polluted by various organic and inorganic compounds, primarily anthropogenic in origin. These pollutants are released from various industries like automobiles, smelting, tanneries, mining, pesticides, and many more. Heavy metals such as lead, chromium, mercury, cadmium, copper, nickel, arsenic, zinc selenium, and uranium are emitted from such sources. As well as organic substances such as lignin and polyaromatic hydrocarbon, polychlorinated biphenyl, naphthalene. Such pollutants modify the physical and chemical properties of soil and water. Here comes the need for Bioremedtiaon. So, let us read further to know about the principles of bioremediation.

Treating or remediating such contaminants by conventional methods requires high cost and energy. To deal with the problem of high cost, and remediate pollutants simultaneously we require some promising approach, which is bioremediation. In this process, we use microorganisms that are either aerobic or anaerobic to treat the polluted site and remove the environment’s pollutants. We can apply this both in-situ or ex-situ environments and work effectively.

Bioremediation is sub-categorized into two categories microbial bioremediation and phytoremediation. In Microbial bioremediation, different kinds of microbes (bacteria or fungi) are used with different techniques to remediate the contaminated site effectively. While in the phytoremediation technique, different types of plant species are used, which can degrade the pollutant and accumulate inside the body.

Principles of Bioremediation

Bioremediation can be broadly categorized into two categories i.e namely Microbial bioremediation and Phytoremediation. Let us read in detail about them.

Microbial Bioremediation

1. Natural Attenuation:- It is the in-situ process of bioremediation. It can be applied when proper nutrients, moisture, microbes, and temperature are available naturally. This helps reduce the mass of pollutants significantly in soil or groundwater without any human intervention. This process needs to be monitored until the remediation process occurs entirely or up to an acceptable level.
2. Biostimulation:- It is one of the method remediation processes used in an in-situ environment by stimulating the growth of the native microbes by adding nutrients in the contaminated site (soil or water). This method effectively works for the removal of metals or hydrocarbons.
3. Bioaugmentation:- Another type of in-situ remediation process is when native, non-native, or genetically modified microbes are added to the contaminated site to speed up biodegradation and make the site cleaner. This technique is majorly implemented for municipal wastewater treatment and soil pollutants with chlorinated and aromatic hydrocarbon. Sometimes introducing non-native microbes will compete with native microbes and eliminate them, changing the soil microbiology so that site needs proper management.

Phytoremediation

1. Phytovolatilization:- In this method, we use plants to remove the contaminant from the site. Majorly heavy metal like mercury is removed by the phytovolatilization process. The inorganic mercury is degraded and accumulated into the above body part. Still, some elemental mercury is remitted back to the atmosphere via transpiration and causes pollution, which is the drawback of the process.
2. Rhizofiltration:- We can use this method for contaminated groundwater treatment instead of polluted soil. In this process, the plant’s roots pick up the contaminant and then absorb on the root surface or inside the root and accumulate it. It is used for the removal of organic and heavy metal pollutants. To employ this process, the plant required acclimatization before being used to the actual site. When plants get saturated with contaminants, they are disposed of safely. The process is repeated until all the contaminant is removed.

3. Phytostabilization: In this method, pollutants mobility is reduced or restricted by using plants, which makes stable complexes in the contaminated site and precipitates there that prevent entry further.
4. Phytoextraction: This remediation method is similar to Rhizofilteration and can be employed in contaminated soil or water. Plants uptake the pollutants and convert them into less or non-harmful substances from harmful substances.
5. Rhizodegradation:- It is also another kind of phytoremediation mechanism in which biodegradation of pollutants occurs in soil or water in the root zone. This harbors the microbes and helps in the degradation of organic pollutants.

Now you must be clear about the principles of bioremediation.

Factors Affecting Bioremediation

1. Biodegradation depends on the biomass of microbes, diversity, enzymatic and metabolic activity.
2. Pollutant’s physicochemical characteristics and load on the site and energy sources.
3. Environmental parameters like pH, temperature, carbon content, humidity or moisture presence, and aerobic or anaerobic environment.
4. Apart from the above technical factors, some non-technical factors can influence the biodegradation process, such as research, regulatory, human resources, liability, and economic factors.