What Chemicals Are Commonly Used In Sewage Treatment Plants?

When Considering Your Wastewater Treatment Process, Start By Determining What You Need To Remove From The Water In Order To Meet Discharge Requirements. With Proper Chemical Treatment, You Can Remove Ions And Smaller Dissolved Solids From Water, As Well As Suspended Solids. Chemicals Used In Sewage Treatment Plants Mainly Include: Flocculant, Ph Regulator, Coagulant.

Flocculant
Flocculants Are Used In a Wide Range Of Industries And Applications To Help Remove Suspended Solids From Wastewater By Concentrating Pollutants Into Sheets Or “Flocs” That Float On The Surface Or Settle On The Bottom. They Can Also Be Used To Soften Lime, Concentrate Sludge And Dehydrate Solids. Natural Or Mineral Flocculants Include Active Silica And Polysaccharides, While Synthetic Flocculants Are Commonly Polyacrylamide.
Depending On The Charge And Chemical Composition Of The Wastewater, Flocculants May Be Used Alone Or In Combination With Coagulants. Flocculants Differ From Coagulants In That They Are Usually Polymers, Whereas Coagulants Are Usually Salts. Their Molecular Size (Weight) And Charge Density (The Percentage Of Molecules With Anionic Or Cationic Charges) Can Vary To “Balance” The Charge Of The Particles In The Water And Cause Them To Cluster Together And Dehydrate. In General, Anionic Flocculants Are Used To Trap Mineral Particles, While Cationic Flocculants Are Used To Trap Organic Particles.

PH Regulator
To remove metals and other dissolved contaminants from wastewater, a pH regulator can be used. By raising the pH of the water, and thus increasing the number of negative hydroxide ions, this will cause positively charged metal ions to bond with these negatively charged hydroxide ions. This results in the filtering out of dense and insoluble metal particles.

Coagulant
For Any Wastewater Treatment Process That Treats Suspended Solids, Coagulants Can Consolidate Suspended Contaminants For Easy Removal. Chemical Coagulants Used For The Pretreatment Of Industrial Wastewater Are Divided Into One Of Two Categories: Organic And Inorganic.
Inorganic Coagulants Are Cost-Effective And Can Be Used For a Wider Range Of Applications. They Are Particularly Effective Against Raw Water Of Any Low Turbidity, And This Application Is Not Suitable For Organic Coagulants. When Added To Water, Inorganic Coagulants From Aluminum Or Iron Precipitate, Absorbing Impurities In The Water And Purifying It. This Is Known As The “Sweep-And-Flocculate” Mechanism. While Effective, The Process Increases The Total Amount Of Sludge That Needs To Be Removed From The Water. Common Inorganic Coagulants Include Aluminum Sulfate, Aluminum Chloride, And Ferric Sulfate.
Organic Coagulants Have The Advantages Of Low Dosage, Little Sludge Production And No Effect On The Ph Of The Treated Water. Examples Of Common Organic Coagulants Include Polyamines And Polydimethyl Diallyl Ammonium Chloride, As Well As Melamine, Formaldehyde And Tannins.