Photovoltaic Industry

Advanced Treatment of Acidic and Fluoride-Containing Wastewater

The photovoltaic manufacturing process produces wastewater containing hydrofluoric acid (HF), nitric acid (HNO₃), phosphoric acid (H₃PO₄), and alkaline cleaning agents, along with silica fines and heavy metals from wafer texturing, etching, and polishing operations.
These waste streams are highly corrosive, chemically unstable, and vary significantly across different process lines, which makes conventional treatment difficult to operate reliably.

Deepflow provides modular, integrated treatment systems specifically designed for the solar wafer, cell, and module manufacturing industry.
Our solutions combine RaeX chemical-physical neutralization, Seltra membrane filtration, and Aevya or PFET evaporation to ensure efficient removal of fluorides, suspended solids, and heavy metals, while minimizing chemical consumption and maintenance effort.
For large volumes of rinsing water, the PFET polymer-film evaporator offers excellent anti-scaling performance, low energy use, and stable long-term operation.

Reliable and Sustainable Treatment for HF-Containing Wastewater

In the final concentration stage, Vorkx crystallizers and RedGan dryers can be integrated to recover salts such as sodium fluoride (NaF) and to reduce the total solid waste volume.
These combined systems enable Zero Liquid Discharge (ZLD) operation while allowing partial reuse of purified water in rinsing or cleaning steps.
All Deepflow systems can be built using Titanium Grade 2 or Super Duplex 2507, ensuring resistance to strong acids, alkalis, and mixed corrosive compounds commonly found in PV production.

Typical Wastewater Sources

Wafer texturing and etching wastewater
Polishing and cleaning wastewater
Acidic and alkaline rinsing water
Cutting and slurry recovery wastewater
Module cleaning and surface preparation wastewater

Process Flow

1. Equalization and buffering → flow homogenization and load balancing

2. RaeX neutralization and precipitation → removal of fluoride and heavy metals

3. Seltra membrane filtration → ultrafiltration and RO for suspended solids and ions

4. Aevya / PFET evaporation → concentration of mixed salts and removal of residual pollutants

5. Vorkx crystallization → sodium fluoride and mixed-salt recovery

6. RedGan drying (DYS) → solid drying and waste minimization

7. Distillate reuse → clean water return to rinsing or washing lines

Your Advantages at a Glance

Effective removal of fluoride, silicon, and heavy metals
PFET system optimized for high-volume rinsing wastewater with minimal scaling
Recovery of NaF and mixed salts through Vorkx crystallization
RedGan DYS dryers ensure ZLD and solid waste minimization
Resistant to HF, HNO₃, NaOH, and mixed acid-alkaline environments
Modular design allows easy scaling and integration into existing PV production lines
Optional Titanium Gr.2 / Super Duplex 2507 construction for superior corrosion resistance

Recommended products

DEH – Single-effect, heat pump
DES – Single-effect, steam/waste heat
DE2H – Multi-effect, heat pump
DE2S – Multi-effect, steam/waste heat
DEP – PFET polymer film evaporator
DUF-Ultrafiltration (UF) systems
DRO-Reverse Osmosis (RO) systems
DJY – Chemical dosing skid
DPFR – Pipe flocculation reactor skid
DYS – Horizontal dryer with scraper, steam/hot water

Q&A

Q

Can RaeX automatically adjust chemical dosing based on real-time water changes?

A

Yes. Advanced RaeX systems use pH, conductivity, and turbidity sensors with PLC control to adjust reagent dosing dynamically.

Q

How is clarification efficiency evaluated?

A

It is assessed through turbidity, total suspended solids (TSS), floc quality, and retention time — by comparing inlet and outlet performance.
Q

How should flocculant or reagent solutions be stored to maintain stability?

A

They should be kept in sealed containers, at stable temperature, away from light, and at consistent concentration to prevent degradation.

Q

How often should deep chemical cleaning be performed compared to routine CIP?

A

When standard CIP cannot restore performance or solids removal efficiency, a stronger chemical regeneration should be carried out.
Q

How should polymers be mixed to optimize particle binding?

A

Begin with vigorous mixing to disperse the polymer, followed by gentle agitation to promote floc growth — the “bridging” principle.

Q

How does temperature influence floc formation?

A

Higher temperature accelerates reaction kinetics but may reduce floc stability and adsorption performance.