The Science Behind Flocculants: Enhancing Water Treatment Efficiency

Table of Contents


Combining the current development of flocculants in water pollution treatment and our own experience in water pollution prevention and management, this paper analyzes the characteristics and types of flocculants in water pollution treatment. Based on this, the application status and research direction of flocculants in water pollution treatment are discussed, hoping to provide some help for the future promotion and application of flocculants.


 water pollution treatment; flocculants; research trends; flocculant classification; flocculant properties

With the increasing prominence of water pollution problems worldwide, China faces more severe water pollution issues due to its large population. The water environment is deteriorating, and industrial and domestic wastewater discharge remains uncontrolled, ultimately leading to a serious shortage of water resources and difficulty in maintaining the rapid development of enterprises. In this context, a large amount of research has focused on water treatment technologies to remove harmful substances in water using various methods, such as physical, chemical, and combined physical-chemical methods. Among them, flocculation sedimentation, which is low-cost and easy to operate, has been widely applied. With the continuous development of technology, water treatment flocculants are gradually transitioning from traditional single-component organic and inorganic flocculants to composite and microbial flocculants. This paper focuses on the flocculants involved in wastewater treatment, drawing from practical work experience.

Characteristics and Types of Flocculants in Water Pollution Treatment

Main Characteristics of Flocculants

In the process of water pollution analysis, flocculants enable the solutes and suspended particles in water solutions to form flocculent precipitates through specific reactions or treatments. If two or more substances are involved in the process, it is referred to as a composite flocculant. The main purpose of flocculants is to accelerate the sedimentation process of fine particles in the liquid.

Main Types of Flocculants

Considering the practical applications and characteristics of flocculants, they are widely used in various fields, particularly in river water purification, application water purification, and industrial wastewater treatment. The most prominent types of flocculants are inorganic flocculants and organic polymer flocculants. Organic polymer flocculants were proposed in the 1960s and, compared to other types, have lower dosages, faster flocculation speeds, and are less affected by coexisting salts and temperature. In application, attention should be paid to the input amount, molecular weight, and stability of organic polymer flocculants. The main types include natural modified polymer flocculants and synthetic organic polymer flocculants.

Inorganic flocculants are mainly applied in the fields of industrial wastewater purification and drinking water treatment, with the primary types being iron and aluminum salts. Traditional inorganic flocculants consist of low-molecular-weight aluminum and iron salts, which mainly function through double-layer adsorption. In general, aluminum sulfate flocculants exhibit better effects. However, they are greatly affected by temperature, and their main advantages lie in their simplicity, reliability, and cost-effectiveness.

Application Status and Research Directions of Flocculants in Water Pollution Treatment

Application Status of Flocculants in Water Pollution Treatment

In the context of increasingly severe water pollution problems, the proper use of flocculants in water pollution treatment can effectively remove fine particles and colloidal substances from polluted water, reducing the COD value of the wastewater, and simultaneously eliminating viruses and bacteria.

Combining the application of flocculants in wastewater treatment, it mainly reflects the application of high molecular weight flocculants and low molecular weight flocculants, which are the two most common types of flocculants. In practical applications, polyferric sulfate flocculant belongs to the category of high molecular weight flocculants. It plays an irreplaceable role in domestic and industrial water use, reflecting fast settling speed and strong coagulation properties. By utilizing relevant reactions, it can effectively remove BOD and COD, solving the problem of heavy metal pollution in water. For example, when using 210ml/L of polyferric sulfate, it can effectively reduce the nickel ion content in wastewater to 0.88 mg/L and control COD below 136 mg/L, thus meeting the corresponding wastewater discharge standards.

At the same time, low molecular weight flocculants like ferrous sulfate are suitable for wastewater treatment with high alkalinity and turbidity. In specific application scenarios, oxidation and aeration methods can be used to achieve the oxidation of iron ions, achieving the desired treatment goals. Moreover, ferric chloride flocculants have a wide range of applications in practice. They can quickly dissolve in water, making them a high-performance flocculant and precipitant. They are less affected by pH and water temperature, making them suitable for the treatment of hard-to-degrade organic matter under certain operating conditions. It is particularly important to determine the iron ion dosage based on actual conditions, effectively reduce the CODcr content in the mixed liquid, achieve the expected wastewater treatment effect, and effectively control membrane fouling issues.

Research Directions of Flocculants in Water Pollution Treatment

As analyzed above, current flocculants have good effects on water pollution issues. However, with the rapid development of new technologies, China is gradually increasing its investment in research and development in this area, making some progress. Microbial flocculants are the future development direction. They not only possess the characteristics of traditional flocculants but also take full advantage of the unique properties brought by microbial degradation. In wastewater treatment, the main principle is to use extracellular biopolymers produced by the microorganisms themselves, which can meet the relevant wastewater treatment requirements. These biopolymers have a molecular weight of over 105 and possess biodegradable and non-toxic properties. Therefore, microbial flocculants represent the future development direction and deserve close attention for better adaptation to wastewater treatment environments.


In conclusion, considering the current situation of water pollution in China, research on flocculants for water pollution should not only focus on theoretical studies but also practical applications. Strengthening the practical application of flocculants and ensuring a close combination of theory and practice will help meet the expected goals of wastewater treatment and promote the development of water pollution prevention and control in China. This will lay a solid foundation for the rapid development of China’s economy.

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