What is flocculant?
First, the definition of flocculant
At present, there is no unified concept of flocculant. A relatively accurate view is that all substances used to produce flocculent precipitation of solute, colloid or suspended particles in aqueous solution are called flocculants. No matter the inorganic or organic matter is added, as long as the flocculent precipitation process can occur, it can be called flocculant. If a flocculant contains two or more substances to flocculate, the flocculant is called compound flocculant. At present, polyacrylamide is the most widely used flocculant material.
Two, the role of flocculant
(1) Influence on chemical oxygen consumption (COD).
Flocculant plays an important role in solid-liquid separation of water and wastewater treatment. The use of coagulation or flocculation to remove fine particles from water has long been noted. The reduction of colloidal substances is closely related to the reduction of COD value in water, that is, the flocculant can simply and effectively remove 80% ~95% suspended substances and 65% ~95% colloidal substances, so it has an important role in reducing the COD value in water.
(2) the role of disinfection and sterilization.
Flocculant has a stable effect on removing bacteria and viruses in water. Through flocculation purification, more than 90% of microorganisms and viruses in water can be brought into sludge, making it easier to further disinfect and kill bacteria in water treatment process.
(3) phosphorus removal and decolorization.
The problems such as eutrophication of water body and decolorization of wastewater, which are paid more and more attention, can be improved by adopting inorganic flocculant. Inorganic flocculant has the effect of phosphorus removal and decolorization, which is better than biological phosphorus removal and decolorization.
(4) Improve sludge dehydration.
Sludge dewatering is the main problem of wastewater treatment nowadays. At present, the most effective method is to improve the sludge shape by adding appropriate inorganic chemical agents and cationic polymer flocculant, so that the next mechanical dehydration is convenient for treatment.