This project belongs to the field of Environmental Science and Technology - Water Pollution Prevention and Control Engineering. With the improvement of emission standards in China, traditional biological treatment processes are no longer sufficient, and advanced wastewater treatment technologies for deep treatment are imperative. Advanced oxidation methods are the most promising deep treatment technologies, but there are few types and a lack of engineering practice. The Fenton process (also known as 'Fenton's reagent') is the most well-known advanced oxidation method with a history of over a hundred years, occupying an important position in the fields of chemistry and environmental science. However, its large-scale application in wastewater deep treatment has only been about ten years, and there have been issues in practice: 1. The Fenton reaction conditions are highly acidic and oxidizing, which cause severe corrosion to equipment; 2. The Fenton process produces a large amount of sludge, which is 3 to 5 times that of traditional biological methods, and has no calorific value, making it difficult to handle with thermal treatment. The cost of iron mud treatment is often greater than that of wastewater treatment, becoming a bottleneck issue for the promotion and application of the Fenton process. Under the tight schedule of upgrading tasks at the largest industrial wastewater treatment plant in the country, combined with the National Science and Technology Support Plan topic 'Research and Industrialization of Iron-Based Composite Water Treatment Materials' (2013BAC01B001), the project team conducted theoretical basis and process condition research: 1. Experimental studies have shown that the homogeneous catalytic reaction rate of the Fenton process is extremely fast, and the lifetime of the generated active species ·OH is very short. Based on this characteristic, a strong turbulence is provided by using a static pipe mixer to design a Fenton process pipeline reactor, thereby improving the reaction efficiency and significantly reducing the volume of the reactor. By advanced oxidation mechanism: First, ·OH activates to generate organic radicals, Molecules of O2 then oxidize and degrade organic matter, thus oxygenation can enhance the oxidation reaction. Therefore, a new type of Fenton combined reaction system was developed—'Pipeline Reactor + Air Floatation Separation'. Utilizing the existing air flotation tank as the subsequent unit to the pipeline reactor, on one hand, it continues the advanced oxidation reaction during the dissolved oxygen release process, compensating for the insufficient residence time of the pipeline reactor; on the other hand, it maintains the original separation function of the air flotation tank. After adjusting the operating parameters and local equipment, the air flotation tank is more suitable for the separation of high-concentration fine particle iron sludge. 2. A comprehensive study on the formation process of iron sludge was conducted, revealing that during the oxidation stage of the Fenton reaction, schwertmannite is formed, while during the neutralization stage, goethite is formed. Both gradually transform into stable lepidocrocite and hematite; through material characterization methods, changes in the composition and crystal structure of iron sludge were studied. Reveal the transformation laws of iron mud throughout the entire Fenton process. Based on this, resource utilization pathways for iron mud were developed, leading to technical routes such as a catalyst for catalyzing ozone, an adsorbent for phosphorus in water bodies, and raw material for cement production. Achievements include: 1) Using a static mixer as the Fenton reactor has reduced the hydraulic retention time of the typical Fenton reactor from more than 15 minutes to about 15 seconds. The original gas flotation tank is used as a combined unit in the Fenton process, with an optimized dosing system for various chemicals, and the engineering scale reaches 600,000 tons per day. Over the past three years, savings in transformation investment and sewage treatment costs totaled 123.63 million yuan (excluding savings in sludge treatment costs). 2) A new large-scale resource utilization pathway for iron mud from the Fenton process has been opened—producing high-quality cement raw materials with a scale of about 1000 tons per day (with an moisture content of 80%). By making all the iron sludge into valuable industrial raw materials, a new added value of 160.51 million yuan has been generated over the past three years, saving a total of 190.6 million yuan in costs for sludge treatment and iron ore mining. During the research process, 16 authorized patents were formed, including 10 invention patents; 11 papers were published in SCI/EI journals. The 'Horizontal Search Report' confirms that the scale of wastewater treatment using advanced oxidation as a new process, as well as the scale of resource utilization of solid waste as industrial raw materials, far exceeds and is superior to other similar engineering levels. The evaluation institution's 'Achievement Evaluation Certificate' believes that the first item has reached an international leading level, and the second item has reached an international advanced level.