Euro PAC is a high performance coagulant solution that can be used for the clarification of both potable water and waste water. In solutions of Euro PAC, aluminum ions have formed into polymers consisting of clusters of ions bridged by oxygen atoms. These polymers only form in solutions of aluminum salts that have been partially neutralized by reaction with a base. As a general rule, the degree of polymerization increases with the extent of neutralization. Euro PAC forms a stable solution in water. As it is highly basic, it is also highly polymerized. On the other hand, alum sulphate solution, which is highly acidic, is not polymerized to any extent. The solution consists of individual hydrated aluminum cations, designated Al3 + (aq).

In water treatment, the purpose of coagulation is to remove suspended matter from water in order to bring about clarification. Coagulation is a chemical and physical process whereby colloidal particles, which normally carry a negative surface charge, collide with positively charged ions formed by the reaction of coagulant chemicals such as Euro PAC with water. The neutralization of the surface charge on the particles results in their cohesion and agglomeration into larger particles, which then settle rapidly. During the process of coagulation, Euro PAC hydrolyses to form a precipitate of aluminum hydroxide, which appears as spongy gelatinous masses that are frequently referred to as “flock”. This flock has a very high surface area that can act to absorb or entrap bacteria, protozoa and other turbidity-causing particles. Since colour-causing humic substances react with most coagulants, removal of natural colour is another desirable outcome of the coagulation process. Emulsion breaking and separation of emulsified oil and grease from wash water are also achievable. Flocculation is a term often used interchangeably with coagulation. Flocculation is the second stage in the overall coagulation process in which “physical processes transform smaller particles into larger aggregates or “flocks”.

Most turbidity once treated by agglomeration can be removed from waters by settlement or entrapment in filtration processes. This may be assisted by treatment with a suitable polyelectrolyte. Basic settlers have the disadvantage of being large and requiring significant retention times. In settlers, sludge is usually removed from the base of the settler while the clarified waters are generally taken as the overflows. Retention times can be reduced by the use of alternative technology, such as in the form of membrane filters or sand filters.