Unit Operations in Water Treatment (coagulation, sedimentation, flotation and filtration)

IHE Delft drinking water

Target Audience

Professionals dealing with engineering, management and education in the fields of water supply and wastewater and urban infrastructure will benefit greatly from this short course. It is also helpful for post graduate students in environmental engineering. Participants from government organisations (such as local administrations and national agencies), non-governmental organisations and the private sector are encouraged to join. This course is ideal for practicing engineers who are working in the water supply and sewerage systems.


The aim of this short course is to present and exchange state-of-the-art knowledge and experience on the technologies and design practices of conventional water treatment systems.

The course covers the main unit processes of conventional surface water treatment.

The following unit process will be explored in detail through lectures, laboratory sessions and workshops:

– Coagulation: Theory of coagulation and flocculation processes: colloidal stability and mechanisms of destabilization, rapid and slow mixing, coagulation in practice, natural coagulants, coagulation kinetics, effects of coagulation.
– Sedimentation: Hydrodynamic principles of sedimentation and flotation, Stokes law, principles of discrete settling, flocculent settling and hindered settling. Horizontal and vertical continuous flow basins, settling tanks, shape of inlets and outlets. Design of a rectangular horizontal sedimentation tank.
– Dissolved air flotation: Key design parameters, Henry’s law, nucleus theory, Stokes law, rate of rise theory, hydraulic loading rate, solids loading
– Filtration: General introduction to various types of filtration systems, mechanical filtration, slow sand filtration, rapid sand filtration (pilot experiments, removal mechanisms, hydraulics, filter elements, rate control, backwashing, multi-layer filtration, applications, design considerations, filter arrangements, modelling, optimisation). Design aspects of the different filtration types.

Learning Objectives