Application and research of Polyferric Sulfate (PFS) in water treatment

Abstract

Polyferric Sulfate (PFS) is a highly effective inorganic polymer flocculant that is widely used for its excellent properties in water treatment. In this paper, the physical and chemical properties, main functions, application methods and applicability of polyferric sulfate in different water treatment environments are discussed in detail, and its practical application effect and prospect are analyzed by examples.

1. Introduction

With the rapid development of industrialization and urbanization, water pollution is becoming more and more serious. Effective water treatment technology has become an important means to ensure water quality safety and environmental protection. As an efficient flocculant, polyferric sulfate occupies an important position in the field of water treatment due to its excellent ability of removing turbidity, decolorization, deodorization, organic matter and heavy metal ions. This paper aims to introduce the characteristics, application and important role of polyferric sulfate in water treatment.

2. Physical and chemical properties of polyferric sulfate

Polyferric sulfate is a kind of inorganic macromolecular compound, which is mainly produced by hydrolysis and polymerization of ferric sulfate. The former is usually expressed as \ [\ text {[Fe} 2 (\ text {OH}) _n (\ text {SO} _4) {3 – n / 2} \ text} {] _m ], where n and m said polymerization degree. Depending on the preparation process, polyferric sulfate can appear as a yellow to reddish-brown liquid or solid powder. Its main physical and chemical properties are as follows:

• Molecular weight: varies widely, depending on the degree of polymerization
• pH value: 3.0-3.5 (10% aqueous solution)
• Density: 1.4-1.5 g/cm³ (liquid)
• Solubility: easily soluble in water, forming a colloidal solution after dissolution

The excellent properties of polyferric sulfate mainly come from its polymer structure and large specific surface area, which makes it have strong adsorption and bridging capabilities, and can effectively condense suspended matter and pollutants in water.

3. The main function of polyferric sulfate

3.1 Turbidity removal

Polyferric sulfate can effectively remove suspended matter and turbidity in water. Its polymer structure provides a large number of active sites, which can condense fine suspended particles into larger alum flowers by adsorption and bridging, and then remove them by precipitation separation.

3.2 Decolorization

Polyferric sulfate has a good removal effect on organic dyes and inorganic pigments. Through adsorption, bridging and precipitation, the chromaticity material in water is condensed into insoluble particles to achieve the purpose of decolorization.

3.3 Deodorization

Polyferric sulfate can reduce the organic content of the water, thus reducing the odor of the water. It reduces the concentration of dissolved organic matter in water by reacting with organic matter to form insoluble compounds.

3.4 Removing organic Matter

Polyferric sulfate can significantly reduce the chemical oxygen demand (COD) and biological oxygen demand (BOD) in water. Through flocculation and precipitation, the dissolved and suspended organic matter is removed and the water quality is improved.

3.5 Heavy Metal Removal

Polyferric sulfate has remarkable removal effect on heavy metal ions such as lead, cadmium and chromium in water. It converts heavy metal ions into insoluble compounds through chemical precipitation and adsorption, thereby removing heavy metal pollution in water.

4. Use of polyferric sulfate

4.1 Preparing for use

Polyferric sulfate can be supplied in solid or liquid form. Solid polyferric sulfate should be dissolved into a liquid before use. Generally, it is mixed with water according to the mass ratio of 1:3-1:5 until it is completely dissolved. It is recommended to prepare an aqueous solution of 10%-20% and adjust it according to the water quality of the treatment.

4.2 Method of dosing

1. ** Dosing equipment ** : Use a metering pump or other dosing equipment to evenly add the prepared polyferric sulfate solution to the water to be treated.
2. ** Dosage ** : The general dosage is 10-50 mg/L, and the specific dosage is adjusted according to the water quality. The optimum dosage can be determined by small trials.
3. ** Coagulation reaction ** : After adding the drug, it is necessary to stir fully to make the agent fully contact with the suspended matter and pollutants in the water to form a larger alum flower. The stirring time is usually 5-10 minutes.
4. ** Precipitation separation ** : After coagulation reaction, stand and precipitate for 30-60 minutes to make the alum fully settle. Solid-liquid separation can be carried out by sedimentation tanks or mechanical filtration equipment.

4.3 Precautions

1. **pH adjustment ** : The best working pH range of polyferric sulfate is 4-11, it is recommended to adjust the pH value of the water to be treated before use to achieve the best treatment effect.
2. ** Storage conditions ** : Should be stored in a cool and dry place, away from direct sunlight. Liquid polyferric sulfate may crystallize at low temperatures and should be heated to dissolve before use.
3. ** Safety protection ** : Wear protective gloves and goggles during operation to avoid contact with skin and eyes. In case of contact, rinse immediately with plenty of water.

5. Applicable environment and scenario of polyferric sulfate

5.1 Municipal Water supply treatment

In municipal water supply treatment, polyferric sulfate is widely used in raw water purification treatment. Its efficient flocculation and precipitation capacity can effectively remove suspended solids, colloids and microorganisms in water, improving the quality of drinking water. Generally, the dosage is controlled at 20-30 mg/L, which is adjusted according to the water quality of the source.

5.2 Industrial wastewater treatment

Polyferric sulfate is also widely used in industrial wastewater treatment. For example, in the treatment of printing and dyeing wastewater, polyferric sulfate can significantly remove dyes and organic matter in the wastewater through coagulation and precipitation, and the dosage is generally 30-50 mg/L. After treatment, the chroma and COD in wastewater decreased significantly and reached the discharge standard.

5.3 Sewage treatment plant

In the municipal sewage treatment plant, polyferric sulfate can be used for secondary treatment and advanced treatment, through coagulation precipitation and chemical precipitation, significantly reduce the concentration of suspended matter and organic matter in the water, improve the effluent quality. The dosage is generally 10-30 mg/L.

5.4 Paper and textile industry

In the paper and textile industry, polyferric sulfate is used in wastewater treatment, which can effectively remove the chroma, suspended matter and organic matter in the water, reduce the COD and BOD content in the water, and the dosage is generally 20-50 mg/L.

5.5 Food processing

In the food processing process, polyferric sulfate is used for water treatment, which can effectively remove suspended matter and organic matter in the water, and ensure the clean and safe production water. The dosage is generally 10-30 mg/L.

6. Example application analysis

6.1 Cases of municipal water supply treatment

In a municipal water supply treatment plant, raw water with high turbidity was treated with polyferric sulfate. The optimal dosage was determined to be 25 mg/L. In actual operation, after adding polyferric sulfate, the suspended matter and turbidity in the water were significantly reduced, and the effluent quality reached the national drinking water standard.

6.2 Industrial wastewater treatment cases

In the wastewater treatment of a printing and dyeing plant, the color and COD of the wastewater are high, and polyferric sulfate is used to treat the wastewater. The optimum dosage was 40 mg/L. In the actual operation, the chroma and COD in the wastewater are significantly reduced, and the wastewater has reached the discharge standard after treatment.

6.3 Sewage Treatment plant cases

Polyferric sulfate was used for secondary treatment in a municipal sewage treatment plant. The optimal dosage was determined to be 15 mg/L. In actual operation, the concentration of suspended matter and organic matter in sewage is significantly reduced, and the effluent quality is obviously improved.

6.4 Paper industry wastewater treatment cases

In the wastewater treatment of a paper mill

The wastewater color and suspended matter are high, and polyferric sulfate is used for treatment. The optimum dosage was 35 mg/L. In actual operation, the chromaticity and suspended matter in the wastewater were significantly reduced, and the wastewater reached the discharge standard after treatment.

7. Research progress of polyferric sulfate

With the increasing demand of water treatment, the research of polyferric sulfate is also deepening. The main research areas include:

1. Improve the preparation process: By optimizing the preparation process of polyferric sulfate, improve its stability and flocculation effect.
2. Composite flocculant: polyferric sulfate is used in combination with other flocculants to further improve its treatment effect.
3. Application expansion: Explore the application of polyferric sulfate in different water quality and different treatment conditions, and expand its scope of application.
4. Environmental impact assessment: Study the environmental impact and ecological toxicity of polyferric sulfate to ensure its safety during use.
5. Conclusion

As a highly efficient inorganic polymer flocculant, Polyferric Sulfate (PFS) is widely used in municipal water supply, industrial wastewater, sewage treatment and other fields due to its excellent flocculation and precipitation ability. Through reasonable use method and scientific dosage control, polyferric sulfate can significantly improve the efficiency and effect of water treatment, and achieve the dual purpose of cost saving and environmental protection. In the future, with the deepening of research, polyferric sulfate will play a greater role in the field of water treatment, help solve the problem of water pollution, and ensure the safety of water quality.