1. The Problem: What Is Tempered Glass Washing Wastewater?
During the production of tempered glass, washing and cooling processes generate large volumes of wastewater. This water mainly contains:
- Fine glass powder (SiO₂) – suspended solids (SS) can reach several hundred to thousands of mg/L.
- Small amounts of grinding fluid, polishing powder, or cutting oil – contributing to chemical oxygen demand (COD) and turbidity.
- Occasional surfactants – from cleaning agents used before tempering.
If discharged directly, this wastewater causes severe turbidity, harms aquatic life, and violates environmental regulations. On the other hand, simply settling the water in tanks takes too long and still leaves a milky appearance, making reuse impossible.
2. Why PAM Powder?
Polyacrylamide (PAM) powder is a water-soluble polymer widely used as a flocculant in industrial wastewater treatment. For glass washing wastewater, the right PAM grade (typically anionic PAM with medium to high molecular weight) offers:
- Rapid bridging and charge neutralization – capturing fine glass particles that sedimentation alone cannot remove.
- Large, dense floc formation – accelerating settling speed by 5–10 times compared to natural sedimentation.
- Clear supernatant – allowing water to be reused directly for washing or cooling, reducing fresh water intake by up to 80%.
- Low dosage – typically only 2–10 ppm based on wastewater characteristics, making it cost-effective.
3. Laboratory Beaker Test: Visual Proof
Laboratory beaker test conditions:
- pH = 7
- PAC (polyaluminum chloride, 5% solution) added: 0.1 mL per sample (additional test for A623 with increased PAC)
- PAM (polyacrylamide, 0.1% solution) dosage: 0.05 mL per 30 mL wastewater
- PAM grades tested: HRFLOC C8040, HRFLOC A613, HRFLOC A623, HRFLOC A678, HRFLOC A606 (all anionic)
Under identical PAC (0.1 mL) and PAM dosage, grade A613 demonstrated the best overall performance – achieving the clearest supernatant (<8 NTU), lowest residual SS (<15 mg/L), and fastest settling time (<3 minutes).
For grade A623, similarly excellent results can be achieved by slightly increasing the PAC dosage, offering flexibility for plants with adjustable coagulant feed.
4. Recommended Process Flow for Glass Washing Wastewater
For a typical glass processing plant, a simple but effective treatment system includes:
- Collection tank – to equalize flow and concentration.
- PAM dosing unit – dry PAM powder is pre-dissolved into 0.1–0.2% stock solution, then metered into the wastewater.
- Mixing flocculation tank – slow mixing to grow flocs (no high shear).
- Inclined tube or lamella settler – for rapid solid-liquid separation.
- Reclaimed water tank – clean water is pumped back to glass washing machines.
- Sludge dewatering – settled glass sludge can be collected, dried, and sold as a byproduct (e.g., for construction materials).
5. Key Advantages for Glass Manufacturers
- Zero discharge compliance – meets local EPA limits for SS and COD.
- Water cost reduction – recycle up to 90% of process water.
- Minimal maintenance – no complicated membranes or biological stages.
- Recoverable glass powder – settled solids are often reusable or saleable.
6. How to Select the Right PAM Powder
Not all PAM powders work equally. For cleaning tempered glass wastewater, we recommend:
- Ionic type: Anionic PAM (negative charge) – because glass powder is slightly positively charged in neutral pH water.
- Molecular weight: 10–18 million (medium to high) – for optimal bridging of fine particles.
- Dissolution time: ≤40 minutes in room-temperature water.
- Solid content: ≥90% – ensuring high activity.
We provide free jar test recommendations based on your customer’s actual water sample.
7. Conclusion
Tempered glass washing wastewater is no longer a disposal problem – it is a recycling opportunity. With properly selected anionic PAM powder, glass processors can:
- Turn milky wastewater into clear reusable water.
- Reduce environmental fines and fresh water bills.
- Improve plant sustainability profile.
Contact us today for technical support, free lab beaker testing, or bulk sample requests.
