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MIXING. Mixing dalam operasi TL. Equalisasi Netralisasi Koagulasi flokulasi Aerasi Disinfeksi. Alat dalam operasi mixing. Mekanikal (Rotating impeller propeler, turbin, paddle) Pneumatik (Air agitator, mixing jet/pump) Baffle basin. Tipe Impeller. Propeller. Turbine.
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Mixing dalam operasi TL • Equalisasi • Netralisasi • Koagulasi flokulasi • Aerasi • Disinfeksi
Alat dalam operasi mixing • Mekanikal (Rotating impellerpropeler, turbin, paddle) • Pneumatik (Air agitator, mixing jet/pump) • Baffle basin
Tipe Impeller • Propeller
oblique paddle agitator Straight padle agitator
Paraboladisc turbin Arc disc turbin
Agitator spread around Helical ribbon impelller
Posisi mixer • Top entering mixer • Bottom enter • Side enter
Vortex • The motion of the fluid swirling rapidly around a center is called a vortex. • The speed and rate of rotation of the fluid are greatest at the center, and decrease progressively with distance from the center. • The fluid pressure in a vortex is lowest in the center (where the speed is greatest) and rises progressively with distance from the center. • Vorteks menghalangi operasi mixing dengan cara mengurangi kecepatan impeller relatif terhadap cairan
Vortex dapat dikurangi dengan baffling yang tepat (1/10 – 1/12 dari diameter tangki)
Contoh operasi mixing • Koagulasi flokulasi • Rapid mixing koagulasi • Slow mixing flokulasi
G value (velocity gradient) • The degree of mixing is based on the power imparted to the water • GT (rapid mixing) (Slow mixing) Sumber: Reynolds, 1982
Praktek/demo jar test • Rapid mixing 100 rpm selama 60 det • Slow mixing 60 rpm selama 5 min 40 rpm selama 10 min • Latihan: hitung G value