iv. These processes can upgrade the plant by reducing the solids loading on the existingsedimentation tank.b. Disadvantagesi. Because of the complexity of the process and issues related to understanding the biofilmarea and activity, the processes designs are empirical and based on prior pilot-plant or limitedfull-scale results.ii. When upgrading existing treatment plants that operate without primary settling and rather largescreen sizes, the carrier material should be chosen appropriately to prevent clogging.iii. In the aeration tank of these processes, the concentration of dissolved oxygen (D O) has tobe relatively high because the D O concentration is the limiting factor in the biofilm processes.A high driving force in terms of D O concentration across the biofilm is therefore required.5.18.13.5 Typical Design Parametersa. Linpor® processTypical design parameters of the Linpor process are shown below:i. MLSS suspended: 3,800 (mg/L)ii. MLSS fixed: 15,000 (mg/L)iii. MLSS total: 5,800 (mg/L)iv. Carrier volume: 22 (%)v. F/M: 0.12 (1/d)(Gilligan and Morper, 1999)b. Pegasus®/Bio-cube processTypical design parameters of the Pegasus process are shown below:i. HRT (Anoxic tank + Oxic tank): 6-8 (hours)ii. Carrier volume: 10-20 (%)iii. Circulation ratio of nitrified liquor to influent flow: 1.5-3.0 (-)iv. Final sedimentation tank hydraulic application rate: about 1.0 (m/hr)(Hitachi Plant Technologies, Ltd.)c. Kaldnes® processTypical design parameters of the Kaldnes process are shown below:i. Anoxic detention time: 1.0-1.2 (hours)ii. Aerobic detention time: 3.5-4.5 (hours)iii. Biofilm area: 200-250 (m2/m3)iv. BOD loading: 1.0-1.4 (kg/ m3/d)v. Final sedimentation tank hydraulic application rate: 0.5-0.8 (m/hr)(Metcalf & Eddy, 2003)