Optimal design parameters for hydraulic vertical flocculation in the package surface water treatment plant

Abstract

After 2003, hundreds projects were completed to provide drinking water to rural areas in most governorates in Iraq. These projects consist of the package water treatment plant, which treats surface water from the Tigris and Euphrates rivers. All the package water treatment plant contains a mechanical flocculators, which suffers from continuous faults and needs periodic maintenance and needs electric energy to operate, which leads to an increase in the cost of water production and lack of quality of water produced. In this project, the possibility of changing the type of flocculators from mechanic to hydraulic was tested for a 100 m3·h–1 package water treatment plant in the Al-Eskan water treatment project in the south of Diwaniyah city in Iraq. There are many challenges facing the design involving findings ways to improve the effi ciency of the flocculation system. Computational Fluid Dynamics (CFD) package, ANSYS Fluent 16.1 software have been used to simulate turbulent fluid flow in hydraulic flocculators for Al-Eskan package water treatmen plants (EPWTP). The flocculator simulations in ANSYS Fluent are used to obtain turbulent kinetic energy dissipation rate to determine the distance between baffles, the quantity of baffles, velocity gradient, residence time, and flocculation performance. The results obtained from ANSYS Fluent simulation are used in designing a hydraulic flocculator, so our finding can be utilized to validate the hydraulic flocculator model. The results confi rmed that the method used to design certain parameters of the tank are fairly accurate. Overall the design of the flocculation tank produced reasonable results which match expected results of hydraulic fl occulation tanks found in literature. The results of the report suggest that a height to baffl e spacing ratio of 22.5 creates intersecting energy dissipation regions that produce the greatest formation of fl ocs per reactor volume.