1. The problem of fluoride in high salt wastewater
Fluoride removal from high salt wastewater - adsorption+process: With the rapid growth of industrial economy, a large amount of industrial wastewater has been generated, some of which contain a large amount of salt (such as F -, Cl -, SO42- plasma) and belong to high salt wastewater.
High salt wastewater is one of the most difficult types of wastewater to treat. Currently, the main methods for treating salt containing wastewater include biological, physical, and physicochemical methods.
At present, the use of evaporation and incineration technology to treat high salt wastewater has shown good treatment effects. However, there are also drawbacks in the treatment process, such as the increasingly prominent problem of equipment corrosion, and many equipment's actual lifespan cannot reach the design lifespan. Therefore, the issue of high salt wastewater treatment equipment has also been taken seriously.
The commonly used industrial equipment is made of stainless steel, which is inexpensive and well formed. However, due to the high chlorine content and strong corrosiveness of high salt wastewater, there are anti-corrosion requirements for equipment materials. In order to prevent equipment corrosion, alternative materials with better anti-corrosion performance, such as titanium metal materials and titanium metal alloys, are being considered.
Titanium metal materials and titanium metal alloys have the advantages of good corrosion resistance, light weight, and long service life, and have been widely used in evaporation and incineration treatment in recent years.
Unfortunately, the good times did not last long. Many titanium and titanium alloy equipment found that corrosion still occurred after several years or even shorter periods of use. Through analysis and investigation of the cause, it was ultimately confirmed that the corrosion of the equipment was caused by fluoride ions contained in the wastewater.
Due to the formation of a stable and strong adhesion oxide film on the surface of titanium, titanium alloys have excellent corrosion resistance in alkaline solutions, most organic acid solutions, inorganic salt solutions, and oxidizing media.
However, in reducing acid solutions, fluoride easily combines with hydrogen ions to form hydrogen fluoride, which preferentially adsorbs on the surface oxide film of titanium materials, displacing oxygen atoms and causing soluble fluoride to form a passive film on the surface of titanium alloys, leading to corrosion and destruction. Among them, HF solution has the strongest corrosion effect on titanium metal.
At the beginning, the fluorine content was very low and did not cause equipment corrosion. However, as the processing time increased, the fluorine content continued to rise through concentration and enrichment, exceeding the corrosion resistance of titanium metal materials, ultimately leading to fluorine corrosion.
Therefore, there are two ways to prevent fluoride corrosion in chemical production: one is to reduce the fluoride content in industrial fluorine-containing wastewater, and the other is to solve the problem of fluoride corrosion in titanium equipment. Therefore, it is urgent to develop a low-cost and high-efficiency deep defluorination technology for deep defluorination, improve the equipment usage environment, extend its service life, reduce the cost of high salt wastewater treatment, reduce the risk of wastewater treatment accidents, and promote chemical safety production.
2. Demand for fluoride removal from high salt wastewater
In summary, the treatment needs of high salt wastewater generating enterprise customers include the following six points:
Implement relevant environmental regulations to ensure that all effluent indicators meet the requirements of national and local water quality standards;
Choose a relatively mature processing technology that is simple, reliable, safe, and easy to operate, while minimizing operating costs and investment expenses;
Choose a treatment process that is short, feasible, impact resistant, and has stable treatment effects;
Convenient operation management and easy maintenance;
The construction site and land use should fully consider the existing conditions of the users, designate the site and land use according to the requirements of the factory, and consider the reasonable layout of the pipeline network;
Try to avoid secondary pollution during the treatment process and improve the treatment effect.
3. Haipu adsorption+process introduction:
Jiangsu Haipu Functional Materials, relying on core adsorption+processes, has developed a targeted wastewater standard HAP process, which is well suited for defluorination of high salt wastewater and can achieve treatment effects.
The core principle of the Haipu adsorption+process is to use our company's developed special adsorption materials to selectively adsorb the components or substances to be removed. When the adsorption is saturated, a specific desorption agent is used to desorb the adsorption material, allowing it to regenerate. This process is continuously repeated. The conventional process for treating wastewater by adsorption method is shown in the following figure.
The wastewater is pre filtered to remove suspended and particulate matter, and then enters the adsorption tower for adsorption. The special adsorption material filled in the adsorption tower selectively adsorbs and enriches fluorine in the wastewater, reducing the fluoride concentration in the adsorbed water.
4. Process treatment effect:
Using adsorption technology to treat fluorine-containing wastewater, 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:
After adsorption treatment, the experimental treatment effect of wastewater from a certain enterprise in Ningbo showed that the fluoride removal rate in the wastewater reached over 97% using adsorption treatment. While ensuring compliance with customer requirements, a certain safety margin was left, which can effectively prevent water quality fluctuations in the incoming wastewater from causing the effluent to fail to meet standards.
From the above figure and table, it can be seen that the raw water and effluent are colorless and transparent, and the fluoride in the wastewater is almost completely removed. Experiments have shown that using special adsorbents for adsorption can effectively reduce the fluoride concentration in wastewater.
5. The core advantages of adsorption+(HAP) process:
At present, the treatment methods for fluorine-containing wastewater have their own shortcomings in terms of treatment effectiveness and operating costs. However, the adsorption+(HAP) process can effectively remove fluoride from wastewater below the emission limit, making it an economical and effective method for treating fluorine-containing wastewater. Its advantages include the following points.
(1) Stable compliance with emission standards or returning to production lines can effectively alleviate the environmental pressure on enterprises;
(2) Conduct experiments on sampling samples of wastewater generated on-site by enterprises, based on technology and experiments to design adsorption processes with high compatibility between wastewater and processes;
(3) The equipment occupies less land, has a compact structure, and requires less investment in civil engineering and equipment; The desorption agent is applied multiple times and concentrated step by step, resulting in high drug utilization and low operating costs;
(4) It can be implemented in module component form, flexibly adjusted according to production capacity, and easy to install;
(5) Advanced and mature technology, no secondary pollution, strong technical strength and rich engineering application experience.
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