High-COD Fine-Chemical Wastewater: Where KLEX-013 Sits Between Pre-Treatment and Biological Polishing

Fine-chemical effluent tends to break the assumptions that ordinary advanced oxidation is built on. The COD is not a few hundred milligrams per litre, it runs into the thousands. The organics are not simple alcohols but benzene rings, heterocycles and halogenated intermediates that shrug off a biological seed. Salinity moves with every batch, and pH can swing several units inside a single shift. Under those conditions a standard silica-alumina medium loses activity within weeks, and the ozone generator ends up burning power for very little COD destruction.

SINOKLE developed KLEX-013 for exactly that corner of the market — high-concentration, high-toxicity fine-chemical streams where the catalyst has to survive as much as it has to perform. The sections below walk through what it does, which parameters matter before you specify it, and what three plants actually measured while running it around the clock.

Why ordinary catalytic ozone stalls on fine-chemical feeds

Three failure modes show up again and again. Oxidation efficiency is the first: with ozone alone, or with a low-activity medium, only a small share of the dosed gas converts into hydroxyl radicals, so most of it leaves in the off-gas. Poisoning is the second — pesticide and dye intermediates adsorb onto the active sites and shut them down. Clogging is the third: resins, colloids and emulsified organics work into the pore structure until the tower has to be opened and cleaned.

KLEX-013 goes at all three at the carrier level. A staged, temperature-controlled sintering route produces a monolithic granule whose connected multi-level micropore network gives a specific surface area above 250 m2/g, carrying manganese, iron and cobalt together with a trace of precious metal. The precious metal and the transition-metal oxides form an electron-synergistic system that lowers the activation energy for ozone decomposition, so ozone cleavage into ·OH happens quickly — measured oxidation efficiency runs 2–5 times that of a conventional catalyst.

Once ·OH is in the water it does not discriminate. It cleaves benzene rings, heterocycles, halohydrocarbons and phenolic structures non-selectively, pushing high-concentration refractory pollutants toward mineralisation instead of merely shifting them into a sludge stream. An atomic-deposition hydrophilic layer on the carrier surface keeps resins, colloids and emulsified impurities from anchoring inside the pores, and because the active components are high-temperature anchored, no heavy metal leaches out over the run.

Specification limits worth checking before you buy

• Form: gray-black spherical granules, standard 2–4 mm, other sizes on request.
• Strength: single-granule compressive strength ≥100 N with annual wear held to ≤0.3%, which matters if the tower runs gas-water backwash.
• Chemical envelope: pH 2–12, and stable in high-chloride matrices up to TDS 60,000 mg/L.
• Ozone conversion: decomposition utilisation ≥98%; high-concentration COD removal ≥70% at incoming COD≥500 mg/L; colour removal ≥98%.
• Life: more than 5 years under standard conditions, with low-cost regeneration once activity decays.
• Duty: rated for 24 h continuous high-load operation.

Three plants, three very different feeds

Pesticide intermediate treated as raw liquid

A pesticide-synthesis line in a fine-chemical park sent raw water at COD 7200 mg/L, loaded with heterocyclic bacteriostatic organics and high chloride salinity, with pH wandering between 3 and 10. Direct biochemistry would not start, and a conventional ozone catalyst managed under 40% degradation. Running ozone at 550 mg/L with 10 g/L catalyst fill and 60 min hydraulic retention, the catalytic unit removed 71% of the COD and brought effluent to 2088 mg/L. Biological inhibition fell from 94% to 7% while the B/C ratio moved from 0.08 to 0.36 — the change that let the downstream anaerobic and aerobic stages run without constant upset.

Fragrance synthesis polished for reuse

Two-stage AO effluent arrived at COD 860 mg/L with residual aromatic-ring organics and a colour of 300-fold, against a park reuse limit of COD≤50 mg/L. At 220 mg/L ozone, 7 g/L catalyst and 40 min retention, COD removal reached 73% and the finished effluent sat at 48 mg/L with colour below 10-fold. Chemical cleaning frequency on the reuse membrane skid dropped by roughly 60%.

Reactive dye intermediate at high salinity

Here the water carried TDS 52,000 mg/L with incoming COD 1350 mg/L and a heavy load of halogenated aromatics. With 180 mg/L ozone, 6 g/L catalyst and 35 min retention, COD removal was 68% and halogenated-organics removal 99%. Across 180 days of continuous high-salinity operation, catalytic activity decayed only 6.8%, and no metal-ion leaching was detected.

Where the process fits, and where it does not

KLEX-013 is not a stand-alone answer. The flowsheet that keeps working in fine-chemical service puts a purely physical stage in front of it: a high-efficiency coalescing oil separator plus CDFU swirl dissolved-air flotation (CDFU) strips floating oil, suspended solids and resinous material before the water ever reaches the catalyst. That keeps the active sites from being covered, and it is the reason the catalytic stage holds its numbers over months rather than weeks. Downstream, the water is detoxified and biodegradable enough for biology, or — in the tail-water variant — clean enough for reuse after primary sedimentation and filtration.

The same package logic covers VOC absorption liquor, pharmaceutical-intermediate streams, coal-chemical and coking deep-processing effluent, dyeing auxiliaries and electroplating rinse water, where the real target is cleaving organic complexing agents so metals can be precipitated and discharged legally.

What the life-cycle cost looks like

The economics rest on four items. Ozone first: because decomposition utilisation stays above 98%, dosing at equal COD removal falls by about 40%, cutting generator capacity and power. Media second — wear of ≤0.3% a year and a life beyond 5 years keep replenishment and hazardous-waste volumes small, and regeneration is nothing more than a water rinse plus low-temperature calcination. Sludge third: with no bulk flocculent or decolorant dosing, chemical sludge falls by more than 70%. Labour last: the skid ships assembled and instrumented for COD, pH, ozone concentration, flow and pressure, so the loop runs unattended and O&M becomes a periodic check rather than a shift position.

Behind the hardware, SINOKLE keeps R&D, process design, commissioning and catalyst regeneration in-house, holds high-tech enterprise and specialised-innovation status with multiple ozone-catalysis invention patents and ISO three-system certification, and supports CDOF ozone-oxidation packages with water testing and field service. For fine-chemical, pesticide, fragrance and dye-intermediate plants fighting high COD at high salinity, that combination is usually the difference between a catalytic stage specified once and one that gets rebuilt every year.