The role of polyacrylamide flocculant in the treatment of municipal sewage, the selection of the flocculant, and the influencing factors.

- Aug 24, 2019-

QUANSEN PAM application industries include: steel mill waste water, electroplating waste water, coal washing, coating, ore dressing, sand washing, metallurgy, paper making waste water, pharmaceutical waste water, municipal waste water, liquor factory waste water, slaughterhouse waste water, farm waste water, coal chemical and food processing plant industrial waste water.
Many customers have been treating sewage on site for many years. They only know that they use water purification agent for sewage treatment, but don't know the specific name. The names such as flocculant, precipitant, degumming agent and coagulant are still in our hearing.
We solemnly tell you that as long as it is the treatment of sewage using only polyaluminum chloride and polyacrylamide.
Commonly known as flocculant, precipitant, degumming agent and coagulant aid, its scientific name is polyaluminum chloride (PAC for short in English), which is a kind of widely used water purification material, in which hydroxide ions blend into sewage, forming a large number of positive charge groups and negative charge groups in water, finally flocculating precipitation, sewage degradation.
1. Principle of PAM flocculant precipitation
The process by which PAM precipitates is a chemical reaction that produces a solution that is insoluble in the reactant.
Literally means to remove sediment by gravity.
Suspension in sewage, so this is a physical, easy to use, good effect, is one of the important sewage treatment.
According to the nature of suspension, concentration and flocculation performance of polyacrylamide, the precipitation can be divided into: natural precipitation, flocculation precipitation, regional precipitation.
The suspended particles in the domain precipitate have a higher concentration (above 5000mg/L), and the sedimentation of particles is affected by other particles around. The relative positions between particles remain unchanged, forming a whole and sinking together, and there is a clear mud-water interface with the clarified water.
Regional precipitation occurred in both secondary sedimentation tank and sludge concentration tank.
Suspended solid concentration in wastewater is not high, and does not have the property of coagulation, in the precipitation, the solid particles do not change shape.
2. Factors affecting PAM dissolution
So what are some of the factors that affect the rate of dissolution of the polyacrylamide.
As a polyacrylamide manufacturer, we found that the product type and the stirring speed of the active ingredients, and the water temperature at the time of dissolution are all related to the product dissolution.
Molecular weight of anionic products related to the speed of its dissolution, can be found that the higher the weight, dissolving speed will be faster, cationic, dissolution rate has something to do with their degree of ion and ionic degree is high, the dissolution rate will be faster, which can be seen from this whether PAM, mainly its effective component content is high, in the use of the use of dissolving speed will be faster.
PAM in dissolved, stirring speed will also affect the rate of dissolution, under normal circumstances, mixing the faster, the product itself will be relatively easy to dissolve, but the pace of mixing is some, once more than this, the impact of PAM is too large, will cause the product molecular chain broken, it will affect the rate of dissolution in use.
In the use of polyacrylamide hydrolysis can be used, this time the product is relatively easy to dissolve, the dissolution time is generally about 60 minutes, non-ionic dissolution time may be longer, about 90 minutes.
Tips: when dissolving, if the water temperature is higher, the dissolving speed is faster.
What are the reasons that affect the decrease of the effect of polyacrylamide flocculant?
Polyacrylamide flocculant needs to be dissolved for use. The viscosity decline and flocculation effect of PAM solution often occur during use, which affect the use effect.
Why does this happen?
1. Storage time the more the PAM solution degrades with storage time, the lower the viscosity will be and the worse the flocculation effect will be.
Generally speaking, anion PAM solution can be stored for seven days and cation PAM solution can be stored for 24 hours.
This is due to the amount of amide group hydrolysis.
It is the influence of cationic group is more obvious, the amide group NH3 formation imide group is caused by the rigidity of the molecular chain.
2. Temperature affects 0.1%PAM solution. When the temperature reaches 80-90℃, the molecular weight of 18 million will degrade to about 5 million within 2-4 hours.
Performance at room temperature of 25℃.
3. Mechanical effects can affect the dissolution speed of PAM dry powder and the stirring speed of PAM, and the molecular chain of anionic polyacrylamide flocculant will be cut. It is recommended to control the online stirring speed of 60 RPM, and do not use the stirring equipment of PAM and high-speed transport equipment.
Light will increase the temperature, dissolve and degrade the anionic polyacrylamide flocculant, and the direct irradiation of ultraviolet light will dissolve and degrade rapidly.
Direct irradiation for 3-5 hours under strong light will reduce the molecular weight of PAM by 30-50%.
5. Influence of impurities to dissolve PAM dry powder, use neutral water with high hardness, or contain impurities, which will affect the viscosity and use effect of PAM.
3. Influencing factors of AM in sewage treatment
Before we sell polyacrylamide, the staff will analyze through the experiment to see whether all kinds of sewage can achieve the expected effect.
Our researchers concluded that polyacrylamide in the treatment of sewage will be affected by some factors, can be roughly divided into the following three: the first is the sewage temperature factor.
If the sewage temperature is low, the hydrolysis reaction, the polyacrylamide is not fully dissolved, the effect of this product is not good.
Similarly, if the water temperature is too high, it will adversely affect polyacrylamide.
The second factor: wastewater PH and other factors.
If the sewage is treated effectively in the case of strong acid or alkali, we first apply the water quality of the sewage before using, if found in the case of strong acid or alkali, we use the regulator of sewage neutral or polyacrylamide use.
Third factor: the use of polyacrylamide in the presence of some impurities can promote coagulation.
For example, inorganic metal salts other than sulfur and phosphorus compounds can compress the diffusion layer thickness of colloidal particles and promote colloidal polymerization.
The higher the concentration, the stronger the promoting ability, and can enlarge the solidification area.
And some materials will help solidify.
4. The choice of PAM in sewage treatment
Polyacrylamide selection is mainly depending on the type of charge sewage water quality with different to decide, based on the characteristics of water quality to select the cationic polyacrylamide, anionic polyacrylamide and nonionic polyacrylamide, etc., the process is usually from test in the laboratory to manufacturers try, eventually determine product selection, specific analysis.
In water treatment engineering and online services, the company has complete testing, construction, installation, commissioning and other technical services.
Company through the core technical team tailor integrated water treatment solutions for customers, and by using the core technology and independent skilled workers, through independent procurement of raw materials, independent production and manufacturing, and provide corresponding engineering construction, installation, debugging, and technical services, such as industry down large industrial projects to provide water treatment products and services.
Mesh number of polyacrylamide: mesh number refers to the particle size or thickness of the material, mesh number is the number of squares per unit area.
The general definition refers to the number of mesh holes in the area of 1 inch *1 inch, that is, the number of mesh screen.
If 600 mesh is 600 square mesh per square inch, the mesh number of polyacrylamide 20 mesh ~80 mesh, that is, 0.85mm~0.2mm, this is the number of granular polyacrylamide mesh.
Flocculant has this effect, but according to the nature of water quality in the industry to choose the anionic or cationic type to achieve good use effect.
What role does polyacrylamide play in oil fields and drilling?
Organic flocculant mainly means the polyacrylamide, product effect is good, the use of small, price is some more expensive inorganic flocculant, but the cost is very cost-effective, both in the sewage treatment and sludge dewatering, recommend choosing inorganic flocculant and organic flocculant combined use, this effect is better, use a lower cost.
Therefore, polyaluminium chloride is a flocculating agent, polyacrylamide flocculant, different areas have different name, and in some areas will say polyaluminium chloride coagulant, polyacrylamide is coagulant aid, both help setting and coagulation, name in there is a setting, that is the role of the two products are flocculation, therefore, you don't need to care about the different name, let's choose products mainly to see the effect.
The content of 30 polyaluminum chloride is more special, this polyaluminum chloride heavy metal is very low, control under five parts per thousand, environmental protection, suitable for tap water treatment.
This several polyaluminium chloride has a good solubility in water, dissolve into the water immediately, in dissolved, hydroxyl ions released a lot of positive charge the negatively charged ions in the water, the adsorption form flocculation body quickly and precipitation, high active, fast and reach the purpose of decomposition, sewage treatment, the high turbidity water purification effect is obvious, it can adapt to all of the sewage.
To understand the role of polyacrylamide you must know its properties, including flocculation, thickening, adhesion and drag reduction.
Because of its characteristics, it is widely used in water treatment industry, oil field drilling industry, glue mortar thickening industry, dispersant, adhesive industry and can be used as shale gas fracturing resistance reducing agent.
What role does polyacrylamide play in water treatment?
According to its flocculation, adsorption, bridging, surface adsorption and precipitation net capture mechanism can be suspended in sewage flocculation into large particles.
5. Considerations for PAM in use
When dissolving polyaluminum chloride, it is important to note that the dissolved water must be clean tap water, adding medicament to the dissolved water, constantly stirring, so that PAC can be evenly dissolved in the water, so that the use effect will be better.
Also has is the attention in the operation, completes the guard measure!
Dissolve PAC, can be used, after the agent, such as sedimentation tank alum less, more turbid, add too little;
If see sedimentation tank alum large and upside down, then add excessive dosage, should be appropriate.
The degradation effect of polyacrylamide flocculant under bad conditions is generally referred to as the decrease of molecular weight, solution viscosity, poor flocculation performance or even failure.
There are many factors for the degradation of flocculants, so high molecular weight PAM is rather delicate.
Moreover, the higher the molecular weight of PAM, the more susceptible it is to these changes and the more sensitive it is to the relevant factors.