Technological Innovation in Oily Wastewater Treatment for the New Energy Industry: Engineering Practice from Fenton to Ozone Catalytic Oxidation
With the transformation of the global energy structure, the production capacity of lithium battery ternary precursors and cathode materials has expanded rapidly. In hydrometallurgy, extraction, and equipment cleaning processes, large amounts of oily wastewater are inevitably generated. This wastewater typically contains high-concentration emulsified and dispersed oil, with complex composition and extremely strong stability, belonging to the typical difficult-to-treat industrial wastewater.
For a long time,“Fentonoxidation+coagulation-sedimentation”has been the mainstream process in the industry for treating such wastewater. However, in practical engineering applications, this process has gradually exposed problems such as high operating costs, difficult sludge disposal, and unstable effluent quality. This article will combine engineering practice to analyze the pain points of existing processes and explore the development and application of a new generation of treatment technologies centered on ozone catalytic oxidation.
1. TraditionalFentonProcess Engineering Application Bottlenecks
FentonThe oxidation method usesFe²⁺catalysisH₂O₂to generate hydroxyl radicals (·OH) to oxidize organic matter. Although the mechanism is mature, when facing the specific oily wastewater of the new energy industry, it faces the following engineering challenges:
1. Large chemical dosing and poor operating economy
FentonThe reaction needs to take place inpH 3–4a strongly acidic environment, and the dosing ratio forH₂O₂andFe²⁺must be strictly controlled. To maintain oxidation efficiency, chemicals usually need to be dosed in excess, which not only raises the per-tonne water cost but also increases the acid-base consumption of the subsequent neutralization step.
2. Large production of iron-containing sludge and high hazardous-waste disposal pressure
The iron sludge generated during the reaction contains residual heavy metals and oil pollutants and is usually defined as hazardous waste. Engineering data shows that in the traditional process, for every1tonne of wastewater treated, the chemical sludge generated can reach3–4 kg. The high hazardous-waste disposal cost has become a major burden for enterprises.
3. Poor demulsification of emulsified oil, and effluent prone to yellowing
The emulsified oil in new-energy wastewater forms a stable oil-water interfacial film due to the presence of surfactants.Fentonoxidation has limited ability to destroy this physicochemical stability, leading to large fluctuations in oil removal rate. At the same time, the residualFe²⁺/Fe³⁺is highly prone to oxidative discoloration, causing the effluent chromaticity to yellow and affecting the stability of compliance.
2. Mechanism Analysis of Ozone Catalytic Oxidation Flotation Technology
To address the above problems, the physical–-chemical coupling technology based on ozone advanced oxidation has gradually become a research hotspot. TakingCDOFCyclonic Dissolved Ozone Flotation(Ozone Advanced Oxidation Flotation integrated unit) technology as an example, this technology achieves efficient removal of emulsified oil by optimizing reaction conditions.
1. Hydroxyl Radical Chain Reaction under Multi-Catalysis
Different from conventional ozone oxidation, this technology builds a homogeneous-heterogeneous synergistic catalytic environment inside the reactor and combines it with the hydrodynamic cavitation effect, significantly increasing the ozone decomposition rate. As a result, high-concentration hydroxyl radicals are generated in water, whose redox potential is as high as2.8 V, and can rapidly attack the emulsifier molecules at the oil-water interface, destroying the emulsification balance.
2. Physical Demulsification and Oil Droplet Coalescence
The hydrodynamic conditions inside the reactor promote the physical rupture and coalescence of the interfacial film. Under specific flow regimes, tiny bubbles collide with oil droplets, using impact force to destroy the electric double-layer structure on the oil droplet surface and reduce theZetapotential, causing the tiny emulsified oil droplets to coalesce into large oil beads, thereby achieving oil-water separation.
3. Micro-Nano Flotation for Efficient Solid-Liquid Separation
The system adopts the cyclonic dissolved air flotation principle, generating bubbles with a diameter of5–30μmmicro-nano bubbles. These bubbles have a huge specific surface area and strong adsorption, can efficiently attach to destabilized oil droplets and suspended solids, and float to the water surface at extremely fast speed to be scraped off. Compared with traditional gravity sedimentation, the rate and efficiency of flotation separation are significantly improved.
3. Process Performance Comparison and Engineering Verification
4. Conclusion and Outlook
The rapid development of the new energy industry puts forward higher requirements for environmental governance. Although the traditional chemical oxidation process played a role in the past, under the“dual-carbon”background, its drawbacks of high energy consumption, high material consumption, and high hazardous-waste production have become increasingly prominent.
CDOFThe flotation technology centered on ozone catalytic oxidation, by enhancing mass-transfer efficiency and oxidation selectivity, achieves efficient removal of emulsified oil. This“approach, which mainly relies on physical demulsification supplemented by chemical oxidation,”not only reduces chemical dependence but also solves the problem of hazardous-waste generation at the source.
In the future, with the improvement of ozone generator energy efficiency and the extension of catalyst life,CDOFozone catalytic oxidation technology is expected to play a greater role in the advanced treatment and reuse of new-energy wastewater, promoting the industry's continuous development toward a green and low-carbon direction.
