WATER-TREATMENT SYSTEM-DESIGN FOR TURBIDITY REMOVAL .2. OPTIMIZATION

In this second part of the paper, optimization models for design of wa ter treatment plants for turbidity removal are discussed. Application of the models is illustrated with a case study. The results from the c ase study indicate cost differences of about 16-64%, solely due to cha nge in the influent particle size distribution (PSD), with higher cost of treatment for the influents with relatively greater fraction of fi ne particles. The system configuration, level of treatment, and design and operating parameters are found to be different for each influent PSD. Use of other parameters like turbidity units, suspended solids an d volume average diam-ter are unable to explain this variation. The in fluence of PSD on the total cost decreases with inflow. Integration of process optimization in system optimization is justified as the diffe rent design and operating parameters are selected under each level of treatment. The cost of sludge treatment accounts to about 30-50% of th e total plant cost.