What are common coagulants?
Coagulation and flocculation have been used to clarify water since ancient times - the Egyptians used almonds to clarify river water in 2000 B.C. The Romans began using alum as a coagulant around 77 AD.
Today, coagulation and flocculation are still integral components of treatment processes, such as reducing water turbidity. Wastewater treatment operations also require coagulation, such as chemical phosphorus removal and reduction of suspended solids.
Organic coagulants versus inorganic coagulants.
Chemical coagulants used in wastewater treatment are divided into two main categories: organic and inorganic.
Organic coagulants are generally used for solid-liquid separation and sludge generation. Organic agents are based on the following chemical compositions.
Polyamines and poly polyamines - the most widely used organic coagulants, which are cationic in nature and function only in charge neutralization. Cationic coagulants neutralize the load of colloids and form sponge-like substances called microflocs.
The main advantage of organic coagulants is that they are used in small quantities, have less sludge and do not affect pH.
Inorganic coagulants save cost and are suitable for all kinds of water and wastewater. Inorganic coagulants are particularly effective for raw water with low turbidity, which can be treated in cases where organic coagulants cannot.
Inorganic coagulants added to water will form aluminum or iron precipitates. These precipitates absorb the impurities in the water and purify it. This process is known as the "scavenging-coagulation" mechanism. However, one of the disadvantages of metal hydroxide precipitates is that the total amount of sludge that must be treated and removed increases.
Examples of inorganic coagulants are as follows.
Aluminum sulfate (alum) - one of the most commonly used water treatment chemicals in the world. Alum is manufactured in liquid form and crystalline alum is dehydrated.
Aluminum Chloride - The next best choice to alum because it is more expensive, dangerous, and corrosive.
Polyaluminium Chloride (PAC) and Aluminium Chloride Hydrate (ACH)
Ferric sulfate and ferrous sulfate Ferric sulfate is commonly used, but ferrous sulfate is usually used for applications requiring reducing agents or excessively soluble iron ions. Iron coagulants work similarly to aluminum coagulants, but costs may vary depending on local supply sources.
Ferric chloride-the least expensive inorganic coagulant-is made from the waste from steelmaking operations. However, it is by far the most corrosive and hazardous inorganic coagulant, and use is limited to facilities with safe treatment capabilities.
A mixture of organic and inorganic coagulants
Polyamine-This blend brings the advantages of both organic and inorganic coagulants.
vcycle offers a range of coagulants and coagulants. If you need more information or advice, please contact us.
What are the applications of coagulants?
Flocculation and coagulation treatment agents are used in wastewater wastewater treatment technologies for solids removal, clear water, lime softening, sludge thickening and solids dewatering.
Coagulation treatment neutralizes the load on the particles and destroys the stabilizing force that keeps the colloids separated. Water treatment coagulants consist of positively charged molecules that are added to water and mixed to complete that charge neutralization. Inorganic, organic or a combination of both types of coagulants are generally used to treat water and remove suspended solids.
When inorganic coagulants are added to water containing colloidal suspensions, the cationic metal ions in the coagulant and the negatively charged double electric layer in the colloid. The same condition occurs with organic coagulants, but the positive charge is most often the molecularly attached amine group (NH4+). chemTreat has NSF certified and GRAS approved coagulation products. examples of ChemTreat coagulation products include aluminum salts, iron salts and polyelectrolytes.
How do flocculation chemicals work?
Flocculants hold unstable particles together, causing them to aggregate and come out of solution. chemTreat flocculants include low, medium and high molecular weight polymers.
Learn how ChemTreat's water treatment flocculants and flocculants achieve optimal water output.
For some water sources, organic coagulants are more suitable for solid-liquid separation. Organic coagulants are generally used when sludge generation needs to be reduced. In addition, a mixture of organic and inorganic chemicals is often more effective than using organic or inorganic chemicals alone. The right mix can often combine the advantages of using the clear-coagulation mechanism of inorganic coagulants with the sludge generation reducing properties of organic coagulants.ChemTreat's formulations are based on the following chemistries.
Polyamines and PolyDADMAC
These are the most widely used organic coagulation chemicals. Because only charge neutralization is available, there is no advantage to the scavenging-coagulation mechanism. Polyamines are generally effective in treating raw water with high turbidity (about >20 NTU). Polyamines are also effective in treating a wide range of wastewaters. PolyDADMACs are a special type of polyamines that meet this requirement.
Melamine formaldehyde and tannin resins.
These all-inorganic polymers act similarly to inorganic coagulant products, not only coagulating colloidal materials in water, but also providing their own precipitating agglomerates. This cotton-like precipitate tends to adsorb organic materials such as oil and grease. Such precipitates are typically dewatered at low moisture concentrations, making this coagulant option particularly suitable for operation of units that produce hazardous sludge, such as DGF and IGF units in oil refineries. The cost of using this self-settling chemistry is typically much higher than inorganic coagulant chemistry, but is economical when sludge removal and treatment costs are taken into account.
Inorganic coagulants are cost-effective and suitable for a wide range of water and wastewater. Inorganic coagulant treatment is particularly effective for raw water with low turbidity (total suspended solids concentration), and if organic coagulants cannot be treated, such water can often be treated.
Inorganic coagulant agents are added to water and react with alkalinity and hydration to form a metal (aluminum or iron) hydroxide precipitate, which acts as a sweeping mechanism. This mechanism can be compared to snow falling on dirty air. When snow falls, it adsorbs particle-like substances in the air and precipitates them together, purifying the air. In water treatment, metal hydroxide sweep-floc acts on water as snowfall does on air. Many difficult to treat colloidal suspensions can be effectively treated with inorganic coagulants.
Metal hydroxide precipitates sweep-floc have advantages in water purification, but these precipitates must be treated and the total amount of sludge removed increases. These precipitates also reduce the overall density and dewaterability of the sludge compared to the precipitates produced by using organic coagulants. In influent and raw water applications, the sludge is generally not hazardous and the penalty for generating more sludge with high water content is minimal. For wastewater applications containing hazardous sludge, the economic loss may be greater.
The health effects and corrosive properties of alum are similar to those of dilute sulfuric acid and are slightly hazardous. It is produced in liquid form and crystallized form is dewatered from the liquid. Alum is one of the most commonly used water treatment chemicals in the world.
Generally, aluminum chloride has similar effects to alum, but is usually more expensive, dangerous and corrosive. Therefore, it is usually a second choice to alum.ChemTreat offers aluminum chloride as a liquid.
ChemTreat has a wide variety of polyaluminum chloride (PACl) and aluminum chloride hydrate (ACH) combinations to meet your water's basic requirements.
Ferric sulfate and ferrous sulfate.
Iron coagulants work similarly to aluminum coagulants, but costs may vary depending on local supply sources. Ferric sulfate is more commonly used, but ferric sulfate is typically used in applications requiring reducing agents or excessively soluble iron ions.
Ferric chloride is usually the cheapest inorganic coagulant. This is because it is a waste product of steelmaking operations (spent pickling solution). However, it is by far the most corrosive and dangerous inorganic coagulant, and use is limited to facilities capable of safely handling it.
Vcycletech is a famous China Coagulants and Flocculants manufacturers and suppliers, making high-quality products for our customers. Our high quality and economical Coagulants and Flocculants produced by our factory have got most of the certification. Please contact our company for more information.