Bio -Remediation:

• Bio -Remediation is the use of microorganisms to break down environmental contaminants into less dangerous forms. The microorganisms may be indigenous to the contaminated area, or they may have been isolated elsewhere and brought to the contaminated site.
• The Oxidation Reduction Potential, or redox, in soil and groundwater, together with pH, temperature, oxygen content, electron acceptor/donor concentrations, and breakdown product concentrations, can indirectly monitor the Bio -Remediation process (e.g. carbon dioxide).
• Bio -Remediation can be effective only when the environmental conditions allow for microbial growth and activity.

Bio -Remediation Strategies:

• Bio -Remediation strategies mainly include in-situ Bio -Remediation techniques and ex-situ Bio -Remediation techniques.
• In situ Bio -Remediation Techniques
• In situ Bio -Remediation is the use of on-site decontamination technologies to remediate polluted soil or groundwater while causing minimal damage to the soil structure.
• Because excavation processes are avoided, these Bio -Remediation methods are less expensive.
• The cost of building and installing complicated equipment to boost biotic activity in Bio -Remediation, on the other hand, is a considerable concern.
• In situ Bio -Remediation techniques have been used to detoxify chlorinated solvents, dyes, nutrients, heavy metals, and organic waste sites.
• In situ, Bio -Remediation techniques include bioventing, biosparging, and bioaugmentation.

Bioventing:

• Bioventing is an in situ Bio -Remediation technique that promotes aerobic decomposition.
• It boosts the innate potential of indigenous microorganisms to break down organic contaminants adsorbed to the soil by supplying oxygen into an unsaturated zone.
• Air is fed directly into the contaminated zone using vertical and horizontal wells.
• In this technique, only the amount of air required for degradation is utilized. Pollutant volatilization and discharge into the environment are also reduced.
• Bioventing was one of the first large-scale technologies to be developed in the 1990s, and it is now widely used in commercial applications.
• Bioventing can be performed actively or passively.
• In passive bioventing, gas exchange from vent wells is merely affected by atmospheric pressure, whereas in active bioventing, the air is forced into the ground by a blower, sometimes in conjunction with vacuum extraction of the gas.

Biosparging:

• The method of injecting pressurised air or gas into a contaminated area to increase in-situ aerobic biological activity is known as biosparging.
• This approach targets chemical substances that can be biodegraded under aerobic circumstances, such as mineral oils and benzene, toluene, ethylbenzene, xylene, and naphthalene (BTEXN), and is used to remediate soluble and residual pollutants in the saturation zone.
• The injection of air (and gaseous nutrients if needed) encourages the development of the aerobic microbial population and so increases the bioavailability of contaminants by providing oxygen to the microorganisms and enhancing the interactions between air, water, and the aquifer.
• A sparging system aims to promote pollutant biodegradation while reducing volatile and semi-volatile organic compound volatilization.
• The flow rate of air injection is set to provide the amount of oxygen required to promote bacterial contamination degradation.
• However, depending on the operation mode and design chosen, some volatilization may occur, needing air capture and treatment.

Bioaugmentation:

• It entails investigating local indigenous varieties to determine whether biostimulation is feasible.
• Bioaugmentation refers to adding more archaea or bacterial cultures to increase pollutant breakdown, whereas biostimulation refers to providing nutritional supplements to increase bacterial metabolism.
• If the indigenous bacteria detected in the area are capable of metabolizing the pollutants, more indigenous bacterial cultures will be introduced into the area to hasten the breakdown of the contaminants.
• If the indigenous species lack the metabolic ability to heal itself, exogenous microorganisms with such sophisticated pathways are introduced.
• Industrial wastes that contain inhibiting or harmful constituents that can be addressed using bioaugmentation products include acetone, acrylic acid, ammonia, nitrite, furfural, phenolic compounds, and methyl ethylamine.

Ex-situ Bio -Remediation Techniques:

• Ex-situ Bio -Remediation is a biological approach in which excavated soil is placed in a lined above-ground treatment area and then aerated to assist the indigenous microbial population in degrading organic contaminants.
• Under aerobic conditions, organic pollutants such as petroleum hydrocarbon mixtures, polycyclic aromatic hydrocarbons (PAH), phenols, cresols, and some pesticides can be used as a source of carbon and energy by specific microbes and then degraded to carbon dioxide and water.
• Although adding microbial communities is uncommon, it is usual to need to assess nutrient requirements and supplement the soil’s basic nutrients and organic substrate if any of these elements are insufficient or lacking.
• Oxygen (via the introduction of air) is essential to allow the microbial population to form cultures capable of sustaining degradation.
• Ex-situ, Bio -Remediation techniques include Landfarming, Biopiles, Bioreactors, Composting.

Landfarming:

• Land farming is the most fundamental kind of Bio -Remediation.
• Before being tilled into the ground, contaminated soils are combined with soil additives such as bulking agents and fertilisers.
• Inland farming, they are excavated and spread them in layers of around 0.3m thickness on a lined treatment area.
• Bio -Remediation can be aided by regular bed flipping and the addition of nutrients.
• Contaminants are degraded, converted, and immobilized by microbiological and oxidative processes.
• Controlling soil conditions optimizes the rate of pollutant breakdown.
• Moisture content, aeration frequency, and pH are all modifiable variables.
• Landfarming techniques require huge areas and are often not feasible for small sites due to the restricting thickness of soil layers (0.3m), yet they can be the most cost-effective type of Bio -Remediation.

Biopiles:

• A Biopile is a sort of ex-situ treatment that employs biological processes to convert pollutants into non-hazardous byproducts.
• It is frequently used to reduce petroleum component concentrations in soils through the Bio -Remediation process. Biopiles are a form of remediation technology that is only employed for a limited duration.
• Excavated soil or silt is placed over an impermeable base or pad with aeration to increase and manage the rate of biodegradation.
• Pads are frequently provided with a cover and adequate drainage to manage precipitation exposure, as well as probes to measure temperature, moisture content, and pollutant concentrations.
• Optional equipment may include a moisture addition system, leachate collection system, and off-gas treatment, depending on the site’s attributes and regulatory needs.

Benefits of Bio –Remediation:

• The most notable advantage of using Bio -Remediation technology is the favorable environmental impact. In Bio -Remediation, nature is used to repair nature.
• When performed properly by competent employees using specialized Bio -Remediation equipment, this is the safest and least invasive soil and groundwater treatment.
• Bio -Remediation can treat organic pathogens, arsenic, fluoride, nitrate, volatile organic compounds, metals, and a number of other pollutants like ammonia and phosphates.
• It effectively removes pesticides and herbicides from aquifers, as well as seawater intrusion.
• There is no transportation risk: The majority of work is done on-site, reducing transportation concerns.
• Other than a few particular parts, very little equipment is necessary.
• Maintenance and input expenses are both minimal.
• Because poisons are less likely to escape, liability is minimized.
• Compared to incineration and landfilling, there is very little energy consumed.
• Disadvantages of Bio -Remediation
• The main limitation of the Bio -Remediation technique is that it can only treat biodegradable pollutants.
• Researchers have also discovered that the new product formed as a result of biodegradation is sometimes more damaging to the environment than the original component.
• Finally, the technique takes time, especially ex-situ Bio -Remediation, which requires excavation and pumping.