Many factors are influencing the selection of flocculants in sand-washing wastewater treatment. Different factors such as PH value, temperature, and dosage will affect the flocculation effect of wastewater treatment. The technical department of LZZG chooses and influences flocculants used in sand-washing wastewater treatment. The factors are summarized as follows for the majority of users.
Polyaluminum chloride and polyacrylamide flocculant are mainly used in the treatment of sand-washing sewage. The models of polyaluminum chloride and polyacrylamide are different, the dosage and the sewage treatment effect are also different. Therefore, the sand washing sewage The choice of flocculant for treatment and its influencing factors should be determined according to different water quality at the project site.
1. PH value
The coagulation mechanism of poly aluminum chloride coagulant is related to the pH value of sewage, so the pH of water is one of the main reasons that affect coagulation. When the suspended solids content and alkalinity of the sewage are both low, after adding the coagulant, when the PH value of the water is less than 7, the hydrolyzed product is mainly positively charged and can be coagulated by adsorption and electric neutralization. The best PH value for adding polyaluminum chloride PAC coagulant should be between 6-7. When the alkalinity and suspended solids content of the sewage are high, so that the PH value is still greater than or equal to 7.5 after adding the coagulant, it is necessary to cast a sufficient amount of coagulant, or use polyaluminum chloride, etc. Effect.
2. Dosing amount
The general dosage of polymer flocculant is 0.1-10ppm (0.1-10mg/L). The dosage should be determined according to the nature of the raw water, which can be debugged on the production site or tested in the laboratory beaker depending on the appropriate amount of alum formation. The dosage of sludge sedimentation flocculant: The dosage of sludge dewatering agent is different due to the different sludge content in sewage, so there is no certain standard. Therefore, the types and dosage of sludge dewatering agents are currently determined at home and abroad, and most of them are on site. Or direct laboratory tests to determine.
The temperature affects the addition of polyacrylamide in sewage treatment, and the water temperature decreases, and the coagulation effect of sand washing sewage treatment is correspondingly reduced.
4. Sludge dewatering pretreatment
Generally, polyacrylamide and dosage are used for the treatment of sand-washing wastewater. The solid matter in the sludge of sand washing wastewater is mainly colloidal particles, which have a strong affinity with water. If proper pretreatment is not performed, dehydration will be very difficult. Pretreatment is carried out before sludge dewatering, so that the sludge particles change physical and chemical properties, destroy the colloidal structure of sludge, reduce its affinity with water, and improve its dewatering performance. This process is called sludge conditioning or conditioning. Dosing conditioning is to coagulate the sludge and improve the dehydration performance by adding coagulants and flocculants to the sludge. When the box-type filter press is used for sewage treatment in the sand washing plant, the amount of medicine used is relatively small, while the belt-type filter press requires a larger amount of medicine for the second dosing.
To sum up: Under normal circumstances, for most of the sand washing wastewater treatment, the amount of polyaluminum chloride is about 70-150 kg of solid products per 100 tons of sewage, and the amount of polyacrylamide is about 1-2 kg of solid products per 100 tons of sewage. Product (depending on the mud content). If you need to understand the selection and influencing factors of flocculants for sand washing sewage treatment, you can call or leave a message and we will reply to you in time.
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