In situ bioremediation technology treats contaminated soil in situ. During the treatment, the soil is not substantially agitated and the most common in situ treatment is biodegradation of the water in the soil. In addition to the addition of nutrients, oxygen sources (mostly H2O2), the ability to introduce microorganisms to enhance biodegradation is also required. Sometimes, digging a set of wells in the contaminated area and injecting the appropriate solution directly, the microorganisms in the water can be introduced into the soil.  

      The technique relies on the characteristics of the repaired object (such as permeability, porosity, etc.), the nature of the contaminant, the amount of oxygen, the pH, the nutrient content, the number of degradable organisms, and so on.

      In-situ bioremediation is actually the process of microbial degradation of organic matter, which generally has three types: aerobic respiration, anaerobic respiration and fermentation. In general, contaminated soil is treated with aerobic treatment. The reasons are that: (1) the aerobic system degrades much faster than the anaerobic system (2) the anaerobic system needs to isolate from the air. It is difficult to achieve this condition for soil treatment, while aerobic systems do not have this special requirement. (3) The final products of the aerobic treatment system are CO2 and H2O, which are harmless to humans. While the products of the anaerobic system are CH4 and H2S, which cause new pollution to the environment. Under aerobic conditions, organic matter enters cells that degrade microorganisms and is degraded by assimilation which is a very complicated process. Simply put, it is:

Organic matter + microbe + O2+ nitrogen source -> CO2 + H2O + by-product + cell body