WHAT ARE COAGULANTS?
A quick look in a dictionary reveals that a coagulant is “an agent that induces curdling or congealing”. In a water treatment sense, what we talking about is a chemical that will remove colour and turbidity present in a raw water in the form of flocs. Coagulants are may be classified as being inorganic or organic. Inorganic coagulants include those commonly used chemicals that rely on aluminium or iron. Organic coagulants include the so-called polyDADMAC (polydiallyldimethyl ammonium chloride) range of cationic polymers. These are special and expensive chemicals that are sometimes used in direct filtration plants when the low doses required make their use appropriate. However, they can sometimes be used in combination with inorganic types, often with spectacular results. More on that later! Here are a few Rules to remember when looking at coagulants.
