Modeling of class I settling tanks

Sedimentation is one of the earliest and most important unit operations in water and wastewater treatment. Conventional approaches for studying sedime ntation of Class I settling tanks did not present enough information on sus pended particle size distribution in the effluent. This information is very important for further treatment units such as filtration. In this research , a relatively simple and practical mathematical model is introduced to stu dy sedimentation of non-uniform particle size in Class I settling tanks. Th e model is capable of providing such information as removal efficiency, siz e distributions in sludge and in effluent suspension, and thickness of bott om sludge. If desired removal efficiency is provided, the length of the tan k can also be determined. Through numerical experiments, a sensitivity anal ysis was performed to examine the effects of tank dimensions, overflow rate , and detention time on the removal efficiency. Comparison with other model s and a set of experimental data indicates a goad agreement.