Solar Ultrapure Water System Process Flow for Photovoltaic High-Concentration Acidic and Alkaline Wastewater Treatment

As solar photovoltaic (PV) manufacturing grows, the need to treat its high-concentration acidic and alkaline wastewater has become crucial to meet environmental standards. This article explores the ultrapure water system process flow designed for solar PV applications and the specific treatment requirements for complex wastewater with high levels of organic content, fluoride, and phosphorus.

In solar PV manufacturing, the wastewater generated is categorized into acidic and alkaline streams, with a general composition ratio of 6:4. The chemical oxygen demand (COD) for alkaline and acidic wastewaters is approximately 7,550 mg/L and 8,100 mg/L, respectively. Primary materials involved in this wastewater include ultrapure water, sodium hydroxide, hydrochloric acid, hydrofluoric acid, ethanol, propylene glycol, and silicon.

Upon mixing the acidic and alkaline wastewaters to achieve a pH balance around 7, the COD typically reduces to about 6,300 mg/L. After the treatment, the effluent goals are set to COD <100 mg/L, BOD <20 mg/L, color <40 times, and pH between 6-8.

Primary Process Flow for Acidic and Alkaline Wastewater Treatment:

1. Aeration: Pre-treatment aeration promotes initial organic breakdown.
2. pH Adjustment: Acidic and alkaline wastewaters are mixed to neutralize the pH to approximately 7.
3. Anaerobic Reactor: Organic compounds are broken down in an oxygen-free environment, reducing COD and BOD levels.
4. Oxidación por contacto biológico: The wastewater undergoes a biological oxidation process, further reducing organic content.
5. Aerobic Reactor: Oxygen is introduced to enhance the microbial decomposition of organic pollutants.
6. Sedimentation Tank: Solids settle out, clarifying the water.
7. Chemical Dosing: Chemicals are added to remove any remaining impurities.
8. Sand Filtration: Final polishing of the effluent occurs through a sand filter, preparing it for compliant discharge.

This process flow effectively reduces pollutant concentrations, enabling safe wastewater disposal that meets stringent environmental regulations.

Wastewater in solar PV manufacturing often contains excessively high levels of fluoride ions, with recorded levels reaching over 1,600 mg/L, far exceeding the national limit of 10 mg/L. The treatment of fluoride- and phosphorus-laden wastewater requires advanced neutralization and sedimentation processes, given the complexity of removing these contaminants effectively.

Main Equipment and Structures for Fluoride and Phosphorus Wastewater Treatment:

• Collection Sump: Wastewater initially collects in a sump to ensure consistent inflow.
• Primary Acid-Resistant Pump: A specially designed pump transports wastewater to the next stage.
• Equalization Tank: Balances pH fluctuations before further treatment.
• Secondary Acid-Resistant Pump: Moves water to the next phase withstanding high acidity.
• Neutralization Reactor: Acidic or basic compounds are added to adjust the pH to optimal levels.
• Adjustment Reactor: Fine-tuning of pH and contaminant concentration.
• Precipitation Reactor: Key step for solidifying pollutants, allowing them to settle out.
• Buffer Tank: Stabilizes flow and contaminant concentration.
• Centrifugal Reactor: Enhances separation of suspended solids.
• Vertical Sedimentation Tank: Solids are removed from the treated water, achieving further clarity.
• Milk of Lime and Coagulant Systems: Milk of lime and coagulants are introduced to aid in the precipitation of contaminants.

Process Flow for Fluoride and Phosphorus-Contaminated Wastewater:

1. Wastewater Collection: Initial collection in the sump.
2. Pumping to Equalization Tank: Levels out pH variations.
3. Chemical Dosing and Neutralization: Addition of chemicals to balance pH and precipitate contaminants.
4. Adjusting Reaction and Precipitation: Fine-tuning of chemical reactions to maximize pollutant removal.
5. Centrifugal Reaction & Vertical Sedimentation: Ensures further contaminant separation.
6. Sludge Removal: Collected sludge is treated separately in a shared organic wastewater sludge treatment system.
7. Neutralization Pool and Discharge: Final pH adjustments ensure compliance before safe discharge.

• Efficient Removal of Pollutants: The systems are designed to handle high concentrations of COD, BOD, fluoride, and phosphorus.
• Environmentally Friendly: Reduces environmental impact by neutralizing pH levels and removing hazardous materials from wastewater.
• Compliance with Stringent Standards: Achieves safe disposal levels for effluents, supporting clean production standards in solar PV manufacturing.
• Cost-Effective and Scalable: The system is adaptable for various capacities, making it suitable for different plant sizes and future upgrades.
• Minimizes Chemical Usage: Advanced pH adjustment and filtration reduce reliance on chemical additives, lowering operating costs and environmental footprint.

The solar ultrapure water system process flow effectively addresses the challenges of high-concentration acidic and alkaline wastewater, as well as fluoride- and phosphorus-laden wastewater, generated in solar PV manufacturing. With tailored treatment methods, these systems enable compliance with environmental standards, supporting the solar industry’s commitment to sustainable production.

Xian CHIWATEC Water Treatment Technology es una empresa de alta tecnología especializada en varios dispositivos de procesamiento de agua. Aparte de estos productos individuales, que cubren una serie de tipos y series, también podemos ayudar con proyectos de ingeniería integrales relacionados. Gracias a nuestro arduo trabajo y dedicación desde nuestra fundación, ahora somos uno de los fabricantes de equipos de tratamiento de agua de más rápido desarrollo en el oeste de China.

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