Keywords: aluminium species, charge neutralisation, coagulation, PACl, polyaluminium chloride, precipitation, water treatment, hydroxide precipitates, wastewater treatment, kaolin suspensions, zeta potential, turbidity removal, floc growth
Coagulation behaviour of polyaluminium chloride with different aluminium speciation
The coagulation behaviour of polyaluminium chloride (PACl) with different contents of aluminium species (Al
27Al NMR spectroscopy) was investigated by using the conventional jar test together with studying the rate of floc size development, the zeta potential of particles and turbidity removal efficiency. Results show that Al
13has higher charge neutralisation ability, while Al
uspecies contribute to the formation of hydroxide precipitates which have a rather open structure for capturing particles. The charge neutralisation plays a less important role in coagulation after the coagulant dosage reaching a certain value, while precipitate formation improves coagulation significantly.