AWWA QTC98308

This paper demonstrates that pH and temperature are the critical variables with regard to soluble aluminum control in finished water. It also examines the use of alum alone, alum in combination with sulfuric acid, acidified alum products, polyaluminum chloride (PAC1), and PAC1 in combination with CO2 for pH control. The pilot plant used in this study had two identical process trains constructed of organically inert materials (stainless steel, glass, or fluorocarbons). Each side of the pilot plant shared identical physical characteristics which allowed for direct comparison between the two sides of the plant with a common raw water quality. Unit pilot plant processes used in this study included: a storage tank from which raw water was split into two streams; rapid mixers for coagulant and coagulant aid addition; and, parallel flocculation, sedimentation and settled water storage tanks.