1. Functional agents and auxiliary agents
1.1 Functional agents remove specific pollutants, while other agents prevent scaling, defoaming and cleaning. Common functional agents in sewage treatment processes include ammonia nitrogen removers, phosphorus removers, heavy metal capture agents, decolorizers, defoamers, etc.
1.1.1 Decolorizers: In the process of industrial sewage treatment, sewage decolorizers are substances commonly used to improve water quality, remove suspended matter and reduce turbidity. They can remove impurities such as organic matter, heavy metal ions, suspended matter and colloids in water, so that the water quality can be effectively purified.
1.1.2 Defoamers: Foam problems are often encountered in sewage treatment. Defoamers can inhibit and eliminate bubbles. The principle is to react chemically with the foaming agent to generate water-insoluble substances, thereby reducing the concentration of surfactants in the liquid film and promoting the rupture of foams. Commonly used defoamers can be divided into silicone (resin), surfactants, paraffins and mineral oils according to their ingredients.
1.1.3 Phosphorus removal agent: Phosphorus removal agent mainly uses flocculation and sedimentation to remove phosphorus. After adding phosphorus removal agent to wastewater, the phosphorus removal agent quickly neutralizes the negative charge on the surface of colloidal particles in water, and easily combines with phosphorus ions in water to produce precipitates. Then, through sedimentation tanks or filtration processes, it can ensure that the phosphorus in wastewater meets the discharge standards. It is commonly used for phosphorus removal in domestic sewage treatment plants, pharmaceuticals, papermaking, pesticides, fertilizer plants and other wastewater treatment.
1.1.4 Ammonia nitrogen removal agent: Ammonia nitrogen removal agent is mainly used to remove ammonia nitrogen in wastewater. After addition, the ammonia nitrogen in the wastewater is partially generated into water-insoluble nitrogen, carbon dioxide and water, and has auxiliary removal of COD and decolorization effects. It reacts quickly, has no residue, no pollution, and has a high removal rate. It is suitable for the treatment of pharmaceutical factories, circuit board factories, coking plants and domestic sewage.
1.1.5 Heavy metal scavenger: It is a chemical agent that strongly chelates heavy metal ions. Using the grafting synthesis process, the chelating groups on the branch chain can chelate heavy metals to form stable insoluble substances and precipitate. The reaction can not only be carried out at room temperature and a wide range of pH conditions, but also is not affected by the concentration of heavy metal ions. Even if the treated wastewater contains complex components, it can precipitate various heavy metal ions in the wastewater so that the wastewater meets the discharge standards.
1.2.1 Scale inhibitors, also known as anti-scaling agents, refer to a class of chemicals that can inhibit the formation of scale by scale-forming salts such as calcium and magnesium in water. There are natural scale inhibitors such as tannins, lignin derivatives, etc.; inorganic scale inhibitors such as sodium hexametaphosphate, sodium tripolyphosphate, etc.; organic and polymer scale inhibitors, among which polymer scale inhibitors have the best effect and have a promising future.
1.2.2 Bactericides: kill or inhibit the growth of microorganisms in water to prevent biological contamination. Common types: chlorine-based bactericides: such as sodium hypochlorite (NaClO). Non-oxidizing bactericides: such as quaternary ammonium salts and isothiazolinones.
1.2.3 Demulsifiers are used to treat wastewater containing emulsified oil. They achieve oil-water separation by destroying the stability of oil droplets and are often used in the pretreatment stage.
