Pairing a coagulant with a polyelectrolyte
Alum, PAC or ferric chloride: how each behaves, and which Sunfloc charge usually completes the job.
Alum
Economical and long proven, but happiest in a narrow pH window of roughly 6.5 to 7.5, and slower in cold water. It produces more sludge than PAC for the same load.
PAC
Pre-hydrolysed, so it usually needs a lower dose than alum. It works across a wider pH range, roughly 5 to 9, and makes less sludge.
Ferric chloride
A strong coagulant for heavy, coloured or phosphate-bearing effluent. It is corrosive and produces iron-bearing sludge.
Which polymer follows
After any of these metal-salt coagulants, an anionic grade is the usual partner: Anionic HQ or Anionic MQ. The coagulant has already neutralised the particles; the anionic chains bridge them.
A polymer as coagulant
On organic streams, a liquid cationic polymer such as SunMac SC04 can take the coagulant's role, often with less sludge. Confirm in a jar test.
Related
Polyelectrolyte dosing guide
Starting doses, solution strength and how to work out kilograms per day.
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