ผลของการปั่นกวนต่อประสิทธิภาพการกำจัดความขุ่นของกระบวนการสร้างเพลเล็ตแบบไหลขึ้นขนาดต้นแบบ / สุขุม ดีประหลาด = Effect of agitation on turbidity removal efficiency of a prototype upflow pelletization process
In this study, a prototype upflow pelletization process was tested with a 40-150 NTU Chao Phraya river using a 1.5 m diameter and 3.0 m height pelletizer with the upflow rate of 8.5 m/hr continousty for 72 hours for each run. Alum and nonionic polymer (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 varing 0.8 and 1.0 mg Al/l of alum, 0.3, 0.4 and 0.5 mg/l of nonionic polymer, and 2, 3, 4 and 5 rpm of paddle speed (G = 13.0, 23.9, 36.8 and 51.4 s-1). And the second studied the effect of recirculation rate by varing 0, 0.1 and 0.2 of recirculation ratio (Q/QR), alum dose of 1.0 mg Al/l, nonionic polymer dose of 0.4 mg/l and 3 rpm of paddle speed. The solid mass was developed in the reactor by a special start-up process in only the first run. Each run was tested continuously with no special start-up. This study was concluded as follows: 1. This process could develope a 30% (w/w) partial pellet and needed a special start-up. 2. The high water quality (less than 5 NTU) was obtained from the treatment using the above process. To treat 60 NTU raw water, 0.8 mg Al/l alum and 0.3-0.4 mg/l nonionic polymer or 1.0 mg Al/l alum and 0.3-0.5 mg/l nonionic polymer were used. And 0.8 mg Al/l alum and 0.3-0.5 mg/l nonionic polymer or 1.0 mg Al/l alum and 0.4-0.5 mg/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 effected on the increasing of turbidity removal efficiency, solid mass and pellet mass. In addition the diameter, settling velocity and density of pellet were raised. 4. The appropriate paddle speed in this experiment was 3-4 rpm (G = 23.9-36.8 s-1 or Gt = 12,906-19,872). 5. The increasing recirculation ratio rate (Q/QR) in the range of 0-0.2 effected on the reducing of turbidity removal efficiency, solid mass and pellet mass. Furthermore diameter, settling velocity and dessity of pellet were also increased because the high turbulant of recirculation pump broke down floc and pellet which increased loading to the process.