Polyaluminum chloride: PAC for short, also known as basic aluminum chloride or hydroxyl aluminum chloride.
Principle: through the hydrolysis product of polyaluminum chloride or polyaluminum chloride, the colloidal precipitation in sewage or sludge is rapidly formed, which is easy to separate the large particles of precipitate. Performance: The appearance and performance of PAC are related to alkalinity, preparation method, impurity composition and alumina content.
1, when the alkalinity of pure liquid polyaluminum chloride is within the range of 40%~60%, it is a light yellow transparent liquid. When the alkalinity is more than 60%, it gradually becomes a colorless transparent liquid.
2, when the alkalinity is less than 30%, solid polyaluminum chloride is a lens.
3, when the alkalinity is within the range of 30%~60%, it is a colloidal material.
4, when the alkalinity is greater than 60%, it gradually becomes glass or resin.Solid polyaluminum chloride made of bauxite or clay mineral is yellow or brown.
Product illustration
Common classification
22-24% content: drum drying process production, without plate and frame filtering, water insoluble material is higher, is the current market price of industrial products, mainly used for industrial wastewater treatment.
26% content: drum drying process production, without plate and frame filtering, water insoluble material is lower than 22-24%, this product is the national standard of industrial grade, the price is slightly higher, mainly used in industrial wastewater treatment.
28% content: this has two kinds of process of drum drying and spray drying, liquid through plate frame filter, water insoluble than the first two low, belong to PAC high-grade products, can be used for low turbidity sewage treatment and tap water plant pretreatment.
30% content: there are two kinds of drum drying and spray drying, mother liquid through plate frame filter, belong to high-grade PAC products, mainly used in tap water plant and low turbidity of domestic water treatment.
32% content: this is made by spray drying, is different from other products, this PAC appearance is white, is high purity non-ferrous polyaluminum chloride, mainly used in fine chemical industry and cosmetics manufacturing, belong to food grade.
Polyacrylamide: called PA M, commonly known as flocculant or coagulant
Principle: PAM molecular chain and dispersed phase through a variety of mechanical, physical, chemical and other effects, the dispersed phase linked together, forming a network, thus enhancing the role.
Performance: PAM is white powder, soluble in water, almost insoluble in benzene, ether, lipids, acetone and other general organic solvents, polyacrylamide aqueous solution is almost transparent viscous liquid, is a non-dangerous goods, non-toxic, non-corrosive, solid PAM has hygroscopicity, hygroscopicity increases with the increase of ionic degree.
Product illustration
Common classification
PAM according to its characteristics of the dissociable group is divided into anionic polyacrylamide, cationic polyacrylamide and non-ionic polyacrylamide. Ionic polyacrylamide.
Cationic PAM: activated sludge produced by biochemical method
Anionic PAM: sewage and sludge with positive charge, such as steel plant, electroplating plant, metallurgy, coal washing, dust removal and other sewage, have better effect
Nonionic PAM: for cationic and anionic have good effect, but the unit price is very expensive, generally not commonly used
Both added to use instructions
What is flocculation?After adding coagulant to the raw water, fully mixing with the water body, most of the colloid impurities in the water lose stability, and the unstable colloid particles collide and condense with each other in the flocculation pool, and then form the floc that can be removed by precipitation method.
The influencing factors of flocculation
The process of floc growth is the process of contact and collision of small particles.
The quality of flocculation effect depends on the following two factors:
1 the ability of polymer complexes formed by coagulant hydrolysis to form adsorption frame bridge, which is determined by the properties of coagulants
2 the probability of collision of small particles and how to control them for reasonable and effective collision.Water treatment engineering disciplines believe that in order to increase the probability of collision, the speed gradient must be increased, and the energy consumption of water body must be increased by increasing the speed gradient, that is, increasing the flow velocity of the flocculation pool (addendum: if the particles aggregate and grow too fast in flocculation, they will be destroyed. There are two problems: 1 floc growth too fast its strength is weakened, in the flow process encountered strong shear will make the adsorption frame bridge is cut off, the cut off adsorption frame bridge is difficult to continue up, so the flocculation process is also a limited process, with the growth of floc, flow velocity should be reduced, so that the formed floc is not easy to be broken; 2 some floc too fast growth will make the water floc specific surface area sharply reduced, some reaction is not perfect small particles lost reaction conditions, these small particles and large particles collision probability sharply reduced, it is difficult to grow up again, these particles can not only for the sedimentation tank retained, it is also difficult to retain for the filter.)
Add requirements
In the early stage of the reaction of adding coagulant, it is necessary to increase the chance of contact with sewage as much as possible, increase the mixing or flow rate.Depending on the collision of water flow and folding plate and the flow of water between folding plate to increase the speed, so that the water particles collision opportunity increases, so that the floc condensation.And to the late reaction, in order to reduce the speed gradient, can get better flocculation, precipitation effect.
Adding equipment: drug container, drug storage tank, dosing stirrer, dosing pump and metering equipment. Equipped with the use of methods
PAC, PAM dispensing concentration (taken out from the drug packaging bag and added to the dissolution tank)PAC and PAM dispensing concentration According to experience: PAC dissolution pool concentration of 5%-10%, PAM concentration of 0.1%-0.3%, the above data in proportion to the quality, that is, every cubic water PAC 50-100kg, PAM 1-3kg.This concentration is relatively high, PAM dissolution capacity is limited, need to stir fully stirring medium speed to completely dissolved.In summer, PAM dissolution concentration can be properly increased to 0.3-0.5%.Take PAC dissolution concentration of 10%, PAM dissolution concentration of 0.5%, then every cubic water dissolved PAC100kg, PAM5kg, adjust the diaphragm flow meter pump flow, according to 1 cubic meter /24 hours calculation, that is, Q = 42 liters / hour, can achieve the ideal sewage treatment flocculation effect. PAC, PAM sewage treatment agent dosage (dissolved in the original water)Sewage treatment agent dosage is generally PAC 50-100ppm, PAM 2-5ppm, ppm unit is one millionth, so converted into 50-100 grams of PAC per ton of sewage, 2-5 grams of PAM, it is recommended that generally according to this dosage trial.If the daily sewage treatment capacity is 2000 cubic meters, PAC dosage concentration according to 50ppm, PAM dosage concentration according to 2ppm calculation, then every day PAC dosage is 100kg, PAM dosage is 4kg.The above dosage is calculated according to general experience, the specific dosage and dosage concentration need to be based on the specific experiment of water quality. Calculate the set value in the dosing pump flow meter
After adding the agent to the sewage or sludge, it should be effectively mixed. The mixing time is generally 10-30 seconds, generally no more than 2 minutes. The specific dosage of the agent and the concentration of colloidal particles, suspended solids in sewage or sludge, the nature and treatment equipment have a great relationship, sludge treatment dosage to some, the best dosage are obtained through a large number of experiments.According to the best dosage concentration (ppm1 to add concentration) and water flow (t/h) and the configuration of the solution concentration (ppm2 preparation concentration), can be calculated on the dosing pump flowmeter display value (LPM).The display value of the dosing pump flowmeter (LPM) = water flow (t/h)/60×PPM1 to add concentration /PPM2 preparation concentration.
Note: ppm is one millionth;dosing pump flowmeter value units, LPM is liters/minute;GPM is gallons/minute
Post time: Feb-19-2024
