107
5.2.1.1 Aeration
Aeration is a process that brings water and air by introducing small bubbles of air or
thin sheets of water to the air or exposing drops of water in air. Aeration is done to
remove dissolved gases (such as carbon dioxide, ammonia, chlorine, hydrogen sulphide, methane and volatile organic chemicals) and oxidizes dissolved metals like
iron and manganese.
5.2.1.2 Sedimentation
Sedimentation is the process of settling suspended solids in the water. It is used for
when surface water bodies are chosen as the drinking water sources.
5.2.1.3 Flocculation
Some of the light and minute suspended solids will not settle easily due to buoyancy, electrical charges possessed by particles and turbulence. Hence, sedimentation is augmented with another process called flocculation wherein light-weight
suspended solids are clumped together to form flock using flocculating agents. The
coagulants include sodium aluminate, aluminium chloride, aluminium sulphate,
ferric sulphate, ferrous sulphate, ferric chloride sulphate, ferric chloride, magnesium carbonate, hydrated lime, pre-polymerized inorganic coagulants, prehydrolysed inorganic coagulants and polymers.
5.2.1.4 Filtration
Filtration in the context of water treatment is a process to separate particles larger
than the pore size of the filtering media. The process is augmented by electrostatic
forces and adhesion that help the filter to remove particles bigger than pore size.
Filters are made up of normally sand, gravel and anthracite. But filtration by members is favoured where space is constrained.
Filtration is used for physical removal of suspended solids through a membrane.
An ultrafiltration filter has a pore size of about 0.01 micron. A microfiltration filter
has a pore size of about 0.1 micron. Nanofiltration membranes have pore sizes
between 1 and 10 nanometres.
The term reverse osmosis in Table 5.1 is discussed in Chapter 1 of Volume 1 and
process is explained in Sect. 5.2.1.8.
5.2 Engineering Control
5.2.1.1 Aeration
Aeration is a process that brings water and air by introducing small bubbles of air or
thin sheets of water to the air or exposing drops of water in air. Aeration is done to
remove dissolved gases (such as carbon dioxide, ammonia, chlorine, hydrogen sulphide, methane and volatile organic chemicals) and oxidizes dissolved metals like
iron and manganese.
5.2.1.2 Sedimentation
Sedimentation is the process of settling suspended solids in the water. It is used for
when surface water bodies are chosen as the drinking water sources.
5.2.1.3 Flocculation
Some of the light and minute suspended solids will not settle easily due to buoyancy, electrical charges possessed by particles and turbulence. Hence, sedimentation is augmented with another process called flocculation wherein light-weight
suspended solids are clumped together to form flock using flocculating agents. The
coagulants include sodium aluminate, aluminium chloride, aluminium sulphate,
ferric sulphate, ferrous sulphate, ferric chloride sulphate, ferric chloride, magnesium carbonate, hydrated lime, pre-polymerized inorganic coagulants, prehydrolysed inorganic coagulants and polymers.
5.2.1.4 Filtration
Filtration in the context of water treatment is a process to separate particles larger
than the pore size of the filtering media. The process is augmented by electrostatic
forces and adhesion that help the filter to remove particles bigger than pore size.
Filters are made up of normally sand, gravel and anthracite. But filtration by members is favoured where space is constrained.
Filtration is used for physical removal of suspended solids through a membrane.
An ultrafiltration filter has a pore size of about 0.01 micron. A microfiltration filter
has a pore size of about 0.1 micron. Nanofiltration membranes have pore sizes
between 1 and 10 nanometres.
The term reverse osmosis in Table 5.1 is discussed in Chapter 1 of Volume 1 and
process is explained in Sect. 5.2.1.8.
5.2 Engineering Control