CHEMICALS USED IN WATER & WASTEWATER TREATMENT
A. COAGULANTS
Used for turbidity, color, and suspended solids removal
- Aluminium Sulphate (Alum)
- Ferric Chloride
- Ferric Sulphate
- Ferrous Sulphate
- Polyaluminium Chloride (PAC – liquid & powder)
- Polyferric Sulphate (PFS)
- Polyaluminium Ferric Chloride (PAFC)
- Aluminium Chlorohydrate (ACH)
B. FLOCCULANTS
Used to agglomerate fine particles after coagulation
Organic Flocculants
- Anionic Polyacrylamide (APAM)
- Cationic Polyacrylamide (CPAM)
- Non-ionic Polyacrylamide (NPAM)
Natural Flocculants
- Starch-based polymers
- Chitosan
- Guar gum
C. pH ADJUSTMENT & NEUTRALIZATION CHEMICALS
Acids
- Hydrochloric Acid (HCl)
- Sulphuric Acid (H₂SO₄)
- Nitric Acid (HNO₃)
- Acetic Acid
- Carbon Dioxide (CO₂)
Alkalis
- Caustic Soda (NaOH – lye & flakes)
- Soda Ash (Na₂CO₃)
- Lime (Quick Lime – CaO)
- Hydrated Lime (Ca(OH)₂)
- Magnesium Hydroxide
D. DISINFECTION CHEMICALS
Used to kill bacteria, viruses & pathogens
- Chlorine Gas
- Sodium Hypochlorite
- Calcium Hypochlorite
- Chlorine Dioxide
- Ozone
- Hydrogen Peroxide
- Peracetic Acid
- Bromine compounds (limited use)
E. OXIDIZING AGENTS
Used for iron, manganese, sulfide, COD reduction
- Potassium Permanganate (KMnO₄)
- Hydrogen Peroxide
- Ozone
- Sodium Hypochlorite
- Chlorine Dioxide
- Sodium Persulfate
F. ADSORBENTS & MEDIA CHEMICALS
- Activated Carbon (Powdered – PAC)
- Activated Carbon (Granular – GAC)
- Activated Alumina
- Ion Exchange Resins (Cation / Anion / Mixed Bed)
- Iron-based adsorption media
- Manganese dioxide media
- Zeolite media
G. SCALE INHIBITORS & ANTISCALANTS
Used mainly in RO, NF, DTRO systems
- Phosphonate-based antiscalants
- Polycarboxylate-based antiscalants
- Sulfonate-based antiscalants
- Threshold inhibitors
- Silica control antiscalants
H. CORROSION INHIBITORS
- Sodium Hexametaphosphate (SHMP)
- Orthophosphates
- Polyphosphates
- Zinc Phosphate
- Sodium Silicate
- Filming amines
I. BIOCIDES (NON-OXIDIZING)
Used in RO, cooling towers, reuse plants
- Isothiazolin
- Glutaraldehyde
- DBNPA
- Quaternary Ammonium Compounds (QAC)
- Bronopol
- THPS
J. NUTRIENTS (FOR BIOLOGICAL TREATMENT)
- Urea
- Ammonium Sulphate
- Diammonium Phosphate (DAP)
- Mono Ammonium Phosphate (MAP)
- Phosphoric Acid
K. DEFOAMERS / ANTIFOAMS
- Silicone-based antifoams
- Non-silicone antifoams
- Oil-based defoamers
- Alcohol-based defoamers
L. SLUDGE CONDITIONING CHEMICALS
- Cationic Polymer
- Lime
- Ferric Chloride
- Alum
- Polymer coagulants
M. HEAVY METAL REMOVAL CHEMICALS
- Sodium Sulphide
- Sodium Hydrosulphide
- Dithiocarbamates
- Chelating agents
- Ferric salts
- Lime
N. ODOR CONTROL CHEMICALS
- Sodium Nitrate
- Hydrogen Peroxide
- Ferric Chloride
- Activated Carbon
- Bio-enzymes
- Masking agents
O. MEMBRANE CLEANING CHEMICALS (CIP)
Alkaline Cleaners
- Sodium Hydroxide
- Sodium Tripolyphosphate
- Surfactant blends
Acid Cleaners
- Citric Acid
- Hydrochloric Acid
- Sulphamic Acid
- Phosphoric Acid
Specialty Cleaners
- EDTA
- Enzymatic cleaners
- Biocide cleaners
P. SPECIALTY & ADVANCED TREATMENT CHEMICALS
- Fenton’s Reagent (H₂O₂ + Fe²⁺)
- Advanced Oxidation Chemicals (AOP)
- Carbon sources (Methanol, Acetate)
- Enzymes for COD/BOD reduction
- Decolorizing agents
Q. ZLD & HIGH-TDS SYSTEM CHEMICALS
- Antiscalants for DTRO
- Foam control chemicals
- Evaporator cleaning chemicals
- Crystallizer conditioning agents
- Salt separation aids
✅ QUICK INDUSTRY CLASSIFICATION
| Application | Main Chemicals |
| Drinking Water | Alum, PAC, Chlorine |
| STP | Nutrients, Polymers, Disinfectants |
| ETP | Coagulants, pH chemicals |
| RO / UF | Antiscalant, Biocide |
| Sludge | Cationic polymer |
| ZLD | Antiscalant, CIP chemicals |
PRACTICAL INSIGHT
- 80% plants use only 10–12 core chemicals
- Correct chemical selection = lower OPEX
- Overdosing is the #1 reason for plant failure
- Chemical compatibility is critical for membranes