Fluoride Removal from Wastewater in the Photovoltaic Industry-Adsorption+Process

Fluoride removal from wastewater in the photovoltaic industry - adsorption+process: The photovoltaic and semiconductor industries have developed rapidly in recent years and are a sunrise industry. However, this is also a high energy consuming, high polluting, and water consuming industry. Taking the IOMff polycrystalline silicon production line as an example, the daily water consumption is about 1500 tons, and hydrogen fluoride containing wastewater accounts for about 70% of the total wastewater generated.

At present, the typical treatment method for fluorine-containing wastewater in wastewater treatment systems used in the photovoltaic and semiconductor industries is the precipitation method. The chemical precipitation method involves adding chemicals such as calcium salts to fluorine-containing wastewater to form fluoride precipitates or adsorb fluoride onto the formed calcium salt precipitates, thereby promoting the co precipitation of fluoride and calcium salts. This method is simple, easy to treat, and cost-effective.

However, calcium salts have low solubility and can only be added in the form of emulsions. The resulting precipitate is wrapped around the surface of the particles, resulting in a low utilization rate and a large amount of usage. Moreover, the fluoride content in the wastewater treated by this chemical precipitation method can generally only be reduced to 15mg/L, making it difficult to meet the national standard for discharge.

Moreover, the entire Yiyi process also has drawbacks such as slow sedimentation of sludge, difficulty in dewatering, long processing cycle for large flow discharge, and inability to continuously process and discharge.

Therefore, the traditional chemical precipitation method for treating fluorine-containing wastewater in the photovoltaic industry belongs to the first level of defluorination precipitation, with unstable effluent quality, large sludge volume, large land area, high treatment cost, and easy waste of resources.

Haipu adsorption+process (HAP process)

The principle of Hap adsorption+process (HAP) is to use the special adsorption material developed by our company to selectively adsorb the components or substances to be removed.

When the adsorption is saturated, a specific desorption agent is used to desorb the adsorbent material, allowing it to regenerate. This process is continuously repeated, and the conventional process for treating wastewater by adsorption is shown in the following figure.

Case analysis

The newly built defluorination wastewater treatment facility adopts the Haipu adsorption+(HAP) process, with a total designed wastewater treatment capacity of 600m³/d. The adsorption process is used to treat fluorine-containing wastewater, and experiments have shown that the use of special adsorbents can effectively reduce the fluoride concentration in wastewater. The specific treatment data is shown in the table below:

From the above figure and table, it can be seen that the filtered water of the raw water is treated with a special adsorbent and the effluent is colorless. The fluoride in the wastewater is almost completely removed. The experiment proves that using a special adsorbent for adsorption can effectively reduce the fluoride concentration in the wastewater.

At the same time, the Haipu adsorption+(HAP) process also has impressive performance in deep fluoride removal. A company produces 100 tons/day of wastewater with a pH of 9.5 and a fluoride content of 10.5mg/L during the production process, with a treatment requirement of ≤ 1mg/L.

The fluorine content significantly decreased after treatment using the Haipu process, which meets the customer's processing requirements for this indicator.