Introduction

Biostimulation is one of the aspects of the bioremediation technique, which is eco-friendly, highly efficient, and cost-effective. This remediation method introduces rate-limiting nutrient elements like nitrogen, phosphorus, and oxygen at the heavily polluted site. The addition of nutrients to the site acts as a stimulant to the native bacteria and helps degrade harmful, toxic, or hazardous pollutants.

Mechanism of Biostimulation

This biostimulation method is the most effective method for hydrocarbon biodegradation, basically for petroleum products and their derivatives. The introduction of rate-limiting nutrients effectively upgrades and increases the biodegradation process pollutant by the microbes of a contaminated site. The contaminated site by hydrocarbon lacks rate-limiting nutrients, limiting the bacterial population, while the addition of nutrient elements (organic matter) causes an increase in bacterial population and increases the degradation process of pollutants extensively. In a study, the use of rare limiting nutrients extracted from the inorganic fertilizer and sewage rich in nitrogen and phosphorus accelerates the disintegration of petroleum-based hydrocarbons by about 96%.

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Factor Influencing Biostimulation

This bioremediation aspect is impacted by some physical factors of the environment like temperature, moisture content, pH, etc. Apart from these parameters, the existing environmental physiology affects the biostimulation rate. For example, the rate of bioremediation in the marine environment is meager because the microbial number is less to act on the pollutant, and pollutants get diluted due to wave action, making it hard to degrade the pollutant. Adding nutrients to the soil does not always favor the biostimulation process; for example, eutrophication occurs due to an excessive load of nitrogen and phosphorus in water and kills all aquatic life. This technique needs balance with the environment to achieve the desired results.

Application of Biostimulation

1. This technique is best for removing complex hydrocarbons like petroleum products, sulphate, polyester, and polyurethanes.
2. The sulphate pollutant in groundwater is treated with the biostimulation method, which needs an electron donor, which increases sulphate reduction and remediates it.
3. Polyurethane is the varied group of artificial polymer that is used on a large scale in commercial and industrial applications like packaging, insulating, fabrics, and many more; the bonds present in their structure are similar or analogous to biopolymer and show microbial degradation due to bond similarities like ester or urethane linkage on which microbe act on it.
4. Sewage sludge and animal manure are used to degrade the atrazine and alachlor.
5. Cornmeal, ryegrass, and poultry litter are used to remove the cyanazine and fluometuron.
6. Maize straw is used to remove the methabenzthiazuron.
7. Mannitol nutrient is used to remediate atrazine.