In-Depth Breakdown: How CDOF's Four-Fold Catalytic Oxidation + Flotation + Activated Carbon Achieves High-Efficiency COD Degradation
New-energy battery-material wastewater is difficult to treat because it has the dual attributes of "high COD concentration + extremely low biodegradability." Ternary precursor mother liquor, lithium-battery recycling leachate, and nickel-cobalt-manganese metallurgical wash water — the dissolved organics in these wastewaters are mostly nitrogen-containing heterocycles, organic solvents and their degradation products, with stable chemical structures that leave microorganisms no way in. Conventional Fenton relies on ferrous ions to catalyze hydrogen peroxide to generate ·OH free radicals that forcibly break chemical bonds — effective but costly; while conventional ozone catalytic oxidation faces bottlenecks such as low ozone solubility, slow mass transfer, and easy catalyst deactivation. SINOKLE's CDOF breakthrough lies in not relying on a single oxidation method, but building a four-tier, progressive catalytic-oxidation system.
Four-Fold Catalytic Oxidation: Each Plays Its Role, Synergistically Enhancing Efficiency
Layer 1 — Homogeneous catalysis: Dissolved transition-metal ions are introduced into the liquid phase, and their valence changes catalyze ozone decomposition to produce ·OH free radicals. The advantage of homogeneous catalysis is ion-level dispersion, achieving molecular-level contact with organics in the wastewater and leaving no mass-transfer dead zones. However, using homogeneous catalysis alone makes metal-ion recovery difficult; CDOF solves this synchronously through the subsequent flotation + activated-carbon steps.
Layer 2 — Heterogeneous catalysis: CDOF's core component is a dedicated solid catalyst — an active metal-oxide substrate loaded with noble-metal catalytic components, its surface modified to be super-hydrophilic. This design solves three problems at once: ① High specific surface area provides abundant active sites, accelerating ozone adsorption and decomposition on the catalyst surface; ② Super-hydrophilic modification lets water molecules occupy the surface first, repelling hydrophobic pollutant deposition and achieving self-anti-fouling; ③ Noble-metal components lower the activation energy of ozone decomposition, raising ·OH free-radical yield.
Layer 3 — Hydrodynamic cavitation catalysis: When high-pressure fluid passes through a specially designed Venturi structure it creates localized negative pressure, forming many micron-scale bubbles. The bubbles collapse violently the instant pressure recovers, releasing "hot spots" with localized temperatures as high as 5000K and pressures of hundreds of atmospheres. This extreme microenvironment is sufficient to directly cleave some organic molecules, while promoting ozone decomposition and ·OH generation. Hydrodynamic cavitation requires no extra energy input — it exploits the system's own pressure energy.
Layer 4 — Pressurized catalysis: The entire high-pressure reaction section operates under pressure (effective retention < 15 min); by Henry's law the increased pressure directly raises ozone's equilibrium solubility in water and extends gas-liquid contact time. The combined effect of pressurization + catalysis raises ozone mass-transfer efficiency several-fold versus atmospheric conditions; this is what enables CDOF to press the ozone dosing ratio down to 0.5–1.2.
Comparison Table: Every Row Hides a Technical Rationale
| Comparison item | Fenton + Flocculation-Sedimentation | SINOKLE CDOF + Activated Carbon | Root technical cause |
|---|---|---|---|
| COD removal | High but unstable, prone to re-coloration | High and stable, no re-coloration | CDOF oxidizes thoroughly; activated carbon as final adsorption safeguard |
| Reaction time | ≥60 min | ≤25 min | Four-fold catalysis + pressurized + synchronous flotation, no series waiting |
| Cost per ton of water | ≥25 yuan | ≤15 yuan | Ozone utilization 99.98%+; no iron salt + unattended |
| Sludge volume | 4 kg/t | 0.1 kg/t | CDOF adds no iron salt, generates no iron sludge |
| Decolorization | Poor, prone to re-coloration | >90%, no re-coloration | ·OH free radicals thoroughly destroy chromophores |
| Ozone dosing ratio | 1.5–4 | 0.5–1.2 | Four-fold catalysis raises effective ozone utilization |
| Automation | Low, manual operation | Fully automatic | Multi-parameter real-time monitoring + adaptive control |
| Safety & environmental protection | Not sealed | Fully sealed, zero leakage | Pressure sealing + tail-gas destructor + deodorization system |
| Footprint | Large | Only 1/5, compact skid-integrated design | — |
Case Data: Three Gradients Validate Process Robustness
Case 1 (medium concentration + low dosing ratio): COD 1215→285 mg/L, removal rate 76.5%, ozone dosing only 300 mg/L (dosing ratio approx. 0.25:1). Total phosphorus completely removed from 11 mg/L. This validates CDOF's effectiveness at low ozone dosing and its simultaneous total-phosphorus removal capability.
Case 2 (high requirement + economical dosing ratio): COD 1200→below 98 mg/L, removal rate >91.8%, dosing ratio 0.85:1. This gives the best effluent quality of the three cases, proving that near the theoretical dosing ratio CDOF can achieve advanced treatment (COD < 100 mg/L).
Case 3 (high concentration + upper-limit dosing ratio): COD 1200→150–300 mg/L, the highest removal rate 87.5%, dosing ratio 1.26:1. Even at a slightly higher dosing ratio, it still far outperforms the traditional process's 1.5–4 range, with stable effluent.
The ozone dosing ratios of the three cases are distributed across the 0.25–1.26 interval, with COD removal rates all above 75% — sufficient to prove CDOF's broad adaptability to different water-quality conditions and tunable parameters.
