Selection of Flocculation Type Unit in the Design of Sumamusi Water Treatment Plant (WTP) Bekasi City

Abstract

One common process that comes with an important part in water treatment is
flocculation. Flocculation is preceded by coagulation and followed by sedimentation or
filtration. Flocculation aims to agitate destabilized colloidal particles and produce large and
rapid-settling flocs by means of slow-gentle mixing. In water treatment plants, flocculation
units are often classified into mechanical flocculators and hydraulic flocculators. The proper
selection of flocculation unit plays an important role to the overall treatment process. In the
design of Sumamusi Water Treatment Plant (WTP) in Bekasi City, horizontal shaft paddles or
vertical baffled channel (hexagonal cyclone flow) system was to be selected. This study aims
to select the most suitable flocculation unit in based on economic and technical benefits.
Selection of the flocculation type unit was evaluated through annual cost of investment,
operating and maintenance costs estimation by preliminary design and technical benefits
given by each type. Estimated annual cost for paddle and vertical baffled flocculation was
found IDR 782.682.552 and IDR 732.895.993 respectively, hence vertical baffled flocculation
is more economical by about 6.8%. Paddle flocculation proven less economical but offers
more flexibility in operation regarding raw water quality fluctuations and not being
susceptible to flowrate changes. Additional technical advantage given by paddle flocculation
is the capability of operating at higher discharge and the possibility for future plant
expansion at minimal cost. Paddle flocculation was selected for use in Sumamusi WTP