How to Choose the Right Coagulant for Your Water Treatment Plant

Raw water turbidity, colour, alkalinity and pH determine which coagulant performs best — high-colour water often needs PAC or ferric chloride over alum.

Target contaminants (TSS, COD, phosphorus, heavy metals) dictate coagulant type; ferric salts excel at phosphorus and arsenic removal.

Sludge volume and dewaterability affect operating cost — PAC typically produces less sludge than alum at equivalent removal efficiency.

Process constraints (pH adjustment capability, dosing equipment, storage space) influence choice between liquid and powder coagulants.

Alum (ferric/non-ferric): lowest cost, well-understood, but narrow pH window and higher sludge volume.

PAC: broader pH range, lower dose, less sludge — preferred for modern ETP and municipal plants.

Ferric chloride: excellent for phosphorus, colour and heavy metals; corrosive — requires FRP or HDPE dosing systems.

Ferrous sulphate: economical for chromium reduction and some heavy metal precipitation applications.

Conduct bench-scale jar tests with 3–5 coagulant options at varying doses before full-scale changeover.

Evaluate floc size, settling velocity, supernatant clarity and sludge volume at each dose point.

Request coagulant samples from shortlisted suppliers and compare COA parameters (Al2O3, basicity, iron content).

Select a coagulant supplier offering technical support, bulk delivery, consistent quality and competitive pricing for long-term contracts.

Drashti Chemicals stocks related industrial chemicals from Vadsar with batch COA, MSDS and GST invoicing (24AGLPC6288M1ZX). We are a supplier/stockist — share grade and quantity for a documented bulk quote. No public list prices.