SiC Wafer Fab Wastewater: A complete Treatment Project, From First Survey to Stable Consent

The fab came to us after two years of fighting its own effluent. The plant was expanding from pilot to volume production, the polishing line was about to double, and the existing mixed-stream treatment was meeting the discharge consent on good weeks and missing it on bad ones. Nobody could say which stream caused the bad weeks, because everything arrived at one tank already blended. This is the most common starting condition we see on wide-bandgap projects, and it is also the most fixable: the treatment technology was never the problem, the absence of stream data was.

What the Survey Found

Fourteen days of separate sampling on every drain. The first useful result was negative: the cooling and scrubber water, which was 60 percent of the volume, was nearly clean and was diluting a treatment train that had been sized on total flow.

The CMP and polishing rinse was under 15 percent of the volume and carried most of the suspended solids, most of the copper, and a colloidal fraction that had been passing straight through the existing clarifier. We set out the wider process route in SiC GaN wastewater treatment cost.

Fluoride was arriving in slugs from the etch area, not continuously. Grab samples taken on the hour showed a six-fold swing between the quietest and busiest part of the shift.

Ammonia came almost entirely from one vent scrubber. Everything else on site contributed almost none. That one finding changed the flow sheet more than any other measurement.

Step one was routing the clean utility water around the treatment train entirely. Removing it shrank every downstream unit and cut the chemical bill before a single piece of new equipment was installed.

Step two was a dedicated CMP waste line: coagulation and flocculation followed by a ceramic membrane stage, with the concentrate going to a filter press. Solids stopped reaching the chemical precipitation and fluoride dosing became predictable.

Step three was fluoride precipitation on the segregated etch waste, two-stage with calcium dosing and a tube settler, discharging to the combined line only after the fluoride was down.

Step four was ammonia: the scrubber stream went to a stripping column with acid absorption, sized for the measured peak rather than the average, and the recovered ammonium sulphate solution found a local outlet.

What Went Wrong in Commissioning

The ceramic membrane blinded faster than the pilot suggested. The pilot ran on a single polishing tool's rinse; production ran six tools with overlapping CIP, and the fines loading was higher and finer.

The fix was a more aggressive backwash rhythm with periodic chemically enhanced cleaning, plus a modest flux reduction. A year later the same skids run at stable permeability. Where several streams need joint treatment, Tannery and Leather Wastewater Treatment system is the more detailed reference.

Fluoride precipitation struggled during the first month because the calcium dose was set on the average slug. Once dosing was tied to online fluoride with a trim loop, the effluent number stopped moving at all.

The ammonia stripper foamed on startup. Antifoam dosing, a modified feed distribution and a slightly lower pH set point resolved it, and it has not recurred.

Where the Plant Sits Now

Suspended solids and copper are consistently well inside consent, and the excursion pattern from the old plant has not come back in eighteen months of operation.

Fluoride holds at a small fraction of the limit with online control doing most of the work. Manual dosing would not hold that number through a production surge.

Removal Rates Across Our Installed Base

Across 42 commissioned plants where we hold complete COD records, influent COD ranged from 200 to 172,000 mg/L and treated effluent from 50 to 5,000 mg/L. Average removal across that set is 87.1% — not a marketing figure, but the measured mean.

That average is worth pausing on. It sits well below the 95%-plus numbers most suppliers quote, because the set includes genuinely difficult streams. On some electroplating and municipal duties the installed configuration only reaches about half the influent COD, and saying that up front is more use to you than a number the plant will never hold.

Ammonia is no longer a constraint at all, because it never reaches the biological stage in meaningful concentration.

Total operating cost per cubic metre is lower than before the upgrade, despite the added equipment, because the chemical and sludge bills both fell once the clean water stopped being treated.

What We Took Away

Measure before you design. Two weeks of per-drain sampling changed this project more than any design decision we made.

Reroute clean water first. It is the cheapest capacity improvement available on almost every fab we visit. For the reuse angle specifically, Grape Pressings, Tank Wash and the Seasonal Harvest Peak goes further than we can here.

Control loops beat tank volume. The fluoride result came from instrumentation, not from a bigger reactor. Where several streams need joint treatment, Tea Beverage Manufacturing Wastewater Treatment is the more detailed reference.

Expect commissioning to find something the pilot missed, and keep the flux and dosing headroom to absorb it.

Combining Treatment Stages

Where several streams need joint treatment, Dextrin Production Wastewater Treatment system is the more detailed reference. Most facilities do not run a single clean stream, and a shared equalisation and biological stage is usually the economical answer once the streams are chemically compatible.

Why Choose Baihuipu as Your Manufacturer

Choosing a manufacturer here comes down to one question: who is still accountable once the commissioning team flies home. Our answer is that we build and programme our own equipment, then stand behind it for the life of the plant.

Own Factory, Real Capacity

Tanks, skids, control panels and membrane housings are built in our own Guangdong facility. Nothing critical is subcontracted, which is why we can commit to delivery dates and hold quality across a batch instead of hoping the shop floor gets it right.

Two Decades of Field Data

Food and beverage, chemicals, electroplating, textile dyeing, mining, municipal work — we have commissioned across all of them. The useful part is not the project count, it is having seen how plants fail in year seven and designing those failures out.

We Engineer the Whole Train

Screening, equalisation, biological or chemical treatment, membranes, evaporation, brine handling — the complete line comes from one organisation. Process design, mechanical, electrical and PLC programming sit under the same roof, so there is no gap for finger-pointing at handover.

Spare Parts and After-Sales Support

We carry membranes, pumps, blowers, diffusers and instruments for every system we supply. Remote support through the PLC is standard on most builds, and on-site service covers commissioning, training and urgent callouts.

Talk to Our Engineers

Send through your raw water data and we will advise on the viable process route and realistic operating cost before you commit to anything. We can be reached on WhatsApp: +86 13631765076 or through hkbhp.com.

WhatsApp: +86 13631765076

Frequently Asked Questions

What treatment capacity do you normally design for SiC wafer fab wastewater project?

Skid-mounted units cover roughly 21 to 858 m³/day depending on the duty, and parallel trains extend that further. We size against your actual peak hour flow rather than the daily average, because equalisation rarely absorbs the whole spike.

What information do you need to quote?

Water analysis for your worst-case stream, peak and average flows, discharge limits, available footprint and utilities. If you do not have a full analysis yet, we can start from a partial one and flag the gaps.

Which discharge standard will the treated water meet? The operating detail behind this sits in third generation semiconductor wastewater discharge standards.

We design against whatever consent applies at your boundary — GB 8978, local sewer limits, or a ZLD target with no liquid discharge at all. The design basis is agreed in writing before fabrication, so there is no argument later about what "compliant" meant.