The core mechanism of the technology is   “Oxygen,” as the most critical electron acceptor, drives the transformation of matter and the flow of energy throughout the entire ecosystem. Its mechanism of action and the evolution process of the ecosystem are illustrated in the figure below:

 

Phase 1: Chemical Oxidation (Rapid Odor Removal, Preliminary Blackness Elimination)

In the early stages of reoxygenation, oxygen first rapidly reacts with strongly reducing substances on the surface of water and sediment. Non-biological chemical oxidation reaction 。

 

1) Oxidation of hydrogen sulfide (H₂S): Rapid odor removal

Reaction The primary source of the foul odor, H₂S, is rapidly oxidized by oxygen.

Critical path ：

2H₂S + O₂ → 2S (elemental sulfur, pale yellow) + 2H₂O Partial oxidation

H₂S + 2O₂ → SO₄²⁻ (sulfate, colorless and odorless) + 2H⁺ Complete oxidation

2) Oxidation of ferrous sulfide (FeS): Initial blackening removal

Reaction ： The primary coloring substance in black bottom sediment is FeS. Oxygen attacks and damages it.

Critical path ：

4FeS + 3O₂ + 6H₂O → 4FeOOH (ferric hydroxide, yellow-brown) + 4S

4FeS + 9O₂ + 4H₂O → 4FeOOH + 4SO₄²⁻

FeS is converted into yellow-brown FeOOH (the main component of rust). The sediment has changed from “black” to “yellowish-brown.”  。

Phase 2: Aerobic Biodegradation (Stabilization and Purification, Reduction of Pollution Load)

Once the strongly reducing substances have been consumed, the dissolved oxygen level stabilizes and begins to rise, creating favorable living conditions for aerobic microorganisms, and the remediation process enters a phase characterized by... Biological reaction A new stage led by the principal.

 

1) Complete mineralization of organic matter: Purifying water bodies

Process Aerobic heterotrophic bacteria (such as Bacillus and Pseudomonas) utilize dissolved oxygen in water to completely oxidize small-molecule organic acids, alcohols—products of anaerobic fermentation—as well as residual organic matter.

Key reaction Organic matter + O₂ → CO₂ + H₂O + Energy (microbial growth)

Significantly reduce the water body's Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD) Organic matter is mineralized, and water transparency increases.

2) Nitrification: Removal of ammonia nitrogen

Process In anaerobic environments, nitrogen-containing organic matter decomposes to produce ammonium nitrogen (NH₄⁺/NH₃), which is the primary culprit behind toxicity and eutrophication. After reoxygenation, nitrifying bacteria (including nitrite-oxidizing bacteria and nitrate-oxidizing bacteria) oxidize it further.

Key reaction ：

Nitritation: NH₄⁺ + 1.5O₂ → NO₂⁻ + 2H⁺ + H₂O

Nitrification: NO₂⁻ + 0.5O₂ → NO₃⁻

Convert the more toxic ammonia nitrogen into less toxic nitrate nitrogen, thereby rendering the nitrogen harmless.

Phase 3: Ecosystem Reconstruction and Sediment Stabilization (Long-term Maintenance)

Continuous reoxygenation alters the structure and function of the entire ecosystem, enabling long-term management.

 

1) Microbial community succession

Process : Ecosystem from   “Anaerobic bacteria dominate”   ( Methanogens, sulfate-reducing bacteria) transformed into   “Aerobic bacteria-dominated”   (Aerobic heterotrophic bacteria, nitrifying bacteria); the system’s function has shifted from “generating pollution” to “degrading pollution,” establishing a positive feedback microecological cycle.

2) Changes in sediment structure and formation of the oxidation layer

Process Oxygen continuously penetrates the surface layer of the sediment (from a few millimeters to a few centimeters), forming a yellow-brown, dense layer. Aerobic oxidation layer This layer of material consists primarily of iron and aluminum hydroxides and stable organic-inorganic complexes. This oxide layer creates a triple-barrier effect:

① Physical barrier It prevents odorous gases (such as CH₄ and H₂S) generated in the lower anaerobic zone from being released into the water body.

② Chemical barrier Trivalent iron (Fe³⁺) can strongly fix phosphorus in sediment, forming insoluble iron phosphate precipitates. Effectively inhibits the release of phosphorus from sediment. To prevent eutrophication of water bodies.

③ Biological barrier Aerobic bacteria active within the oxidation layer continuously decompose organic pollutants that have diffused upward from the lower layers.

In summary:

Organic matter reduction Through aerobic biodegradation, the easily degradable substances in the sediment that cause black and odorous conditions are broken down. Organic component (Proteins, fats, carbohydrates, and others) are consumed by microbial respiration and converted into CO₂ and H₂O, resulting in a significant decrease in total quantity.

Relative increase and transformation of inorganic substances : Sediment of the bottom Inorganic framework (The relative proportion of iron-aluminum oxides/hydroxides, such as FeOOH, increases and becomes the primary component and coloring agent of the sediment, causing it to appear...) Yellow-brown At this point, the sediment tends to become stabilized and inert.