In this study, a prototype upflow pelletization process was tested with a40-150 NTU Chao Phraya river using a 1.5 m diameter and 3.0 m height pelletizer withthe upflow rate of 8.5 m/hr continousty for 72 hours for each run. Alum and nonionicpolymer (MW. 12 million) were used as a coagulant and a coagulant aid, respectively.This study was divided into 2 cases, first studied the effect of agitation by varing0.8 and 1.0 mg Al/l of alum, 0.3, 0.4 and 0.5 mg/l of nonionic polymer, and 2, 3, 4and 5 rpm of paddle speed (G = 13.0, 23.9, 36.8 and 51.4 s('-1) ). And the secondstudied the effect of recirculation rate by varing 0, 0.1 and 0.2 of recirculationratio (Q/Q(,R)), alum dose of 1.0 mg Al/l, nonionic polymer dose of 0.4 mg/l and 3rpm of paddle speed. The solid mass was developed in the reactor by a specialstart-up process in only the first run. Each run was tested continuously with nospecial start-up. This study was concluded as follows: 1. This process could develope a 30 % (w/w) partial pellet and needed a specialstart-up. 2. The high water quality (less than 5 NTU) was obtained from the treatmentusing the above process. To treat 60 NTU raw water, 0.8 mg Al/l alum and 0.3-0.4 mg/lnonionic polymer or 1.0 mg Al/l alum and 0.3-0.5 mg/l nonionic polymer were used And0.8 mg Al/l alum and 0.3-0.5 mg/l nonionic polymer or 1.0 mg Al/l alum and 0.4-0.5mg/l nonionic polymer were used for 100 NTU raw water turbidity. 3. The increasing nonionic polymer dose in the range of 0.3-0.5 mg/l effectedon the increasing of turbidity removal efficiency, solid mass and pellet mass. Inaddition the diameter, settling velocity and density of pellet were raised. 4. The appropriate paddle speed in this experiment was 3 - 4 rpm (G = 23.9-36.8s('-1) Of' Gt = 12,906 19,872). 5. The increasing recirculation ratio rate (Q/Q(,R)) in the range of 0-0.2effected on the reducing of turbidity removal efficiency, solid mass and pellet mass.Furthermore diameter, settling velocity and density of pellet were also increasedbecause the high turbulant of recirculation pump broke down floc and pellet whichincreased loading to the process.