Dechlorination — Process Challenge

Dechlorination (Residual Chlorine Removal)

Plants must neutralize residual free and combined chlorine before NPDES discharge or before it reaches chlorine-sensitive RO/nanofiltration membranes. Buyers dose sulfite-family reductants in bulk through metering systems, making sodium metabisulfite a large recurring commodity buy
Updated Jun 2026
Solution Approach

RawSource supplies the base chemicals that go into these programs. We can help with product selection, grade matching, and sourcing from multiple origins for supply security.

Typical Treatment Workflow
1
Water & System Assessment
Characterize the water and the system — hardness, alkalinity, pH, TDS/conductivity, microbial load, and the metallurgy and temperatures of the equipment being protected.
2
Program & Chemistry Selection
Match coagulants, flocculants, scale and corrosion inhibitors, biocides, or pH adjusters to the water profile and discharge limits, factoring compatibility with any existing program.
3
Jar Testing & Dosing
Confirm coagulant and flocculant dose and feed point by jar test, set inhibitor and biocide treat rates, and size packaging (drums, totes, bulk) to consumption.
4
Monitoring & Control
Track residuals, turbidity, ORP, corrosion coupons, and effluent compliance, adjusting chemistry and dose as feedwater and load change.
Recommended Chemistries (6)
Sodium Bisulfite
CAS 7631-90-5
Specialty Additives
Liquid sulfite scavenger
3260 (SODIUM BISULFITE) · Class
In catalog. Bisulfite reduces free chlorine/hypochlorite to chloride and is oxidized to sulfate, removing chlorine residual in seconds
Melting Point: Decomposes   Boiling Point: Decomposes   Density: 1.48 at 20 °C
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Potassium Metabisulfite (Technical/Food Grade)
CAS 16731-55-8
Specialty Additives
Preservation
1759 (POTASSIUM METABISULFITE) · Class
In catalog. Dissolves to release bisulfite, the active reductant for chlorine removal; dry form is convenient for makedown
Melting Point: Decomposes at approximately 150 °C   Density: 2.3 g/cu cm   Solubility: Freely soluble in water; insoluble in alcohol
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Sodium thiosulfate
CAS 7772-98-7
Acids & Salts
Preservation
In catalog. Mild reductant that quenches chlorine and chloramine, favored where over-reduction of dissolved oxygen must be avoided
Melting Point: 48.5 °C   Density: 1.667   Solubility: PRACTICALLY INSOL IN ALCOHOL
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Ammonium Bisulfite, 60%
CAS 10192-30-0
Acids & Salts
Ammonium-based scavenger
2693 (AMMONIUM BISULFITE, SOLID) · Class
In catalog. Liquid bisulfite source for high-volume dechlorination and oxygen-scavenging dosing skids
Melting Point: -10 °C   Boiling Point: Sublimates at 150 °C   Density: 2.03 at 20 °C 1.40 (72% aqueous solution)
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Sodium metabisulfite
CAS 7681-57-4
Specialty Additives
Preservation
1759 (SODIUM METABISULFITE) · Class
Sourced on demand. The most-searched dechlorination active; in water it forms bisulfite that reduces chlorine to chloride
Melting Point: > 150 °C (Decomposes)   Boiling Point: Decomposes   Density: 1.4
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Ascorbic Acid (Vitamin C), Food Grade
CAS 50-81-7
Acids & Salts
Preservation
Sourcing option. Reductant used where sulfite residual or pH depression must be avoided, e.g. sensitive receiving-water dechlorination
Melting Point: 190–192 °C (decomposes)   Density: 1.65   Solubility: ≥ 100 mg/mL at 23 °C
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