materials, inorganic solids, excessive oils and greases. These wastes are generated
during drilling as well as refining of crude (Environmental Protection Agency,
Washington 2003; Shahryar 2017). Following devices are used in preliminary
treatment -.
Screener
It removes plugging or clogging materials like polymeric materials, large suspended
solids, grit which may damage the pipelines, pump, etc. Examples are rack, bar
or fine.
Comminuting Device
This device is used to cut or reduce the size of larger materials into smaller ones in
order to protect the equipment, lines and channels from clogging or plugging.
Examples are grinder, cutters and shredders.
Grit Chamber
This long channel type chamber is used to remove suspended particles, grit to protect
subsequent equipment like sedimentation tanks, sludge digesters, pumps from tear,
wear, corrosion as well as deposition in pipelines and channels. In these chambers,
the flow rate of wastewater is sufficiently reduced so as to allow deposition of the
heavy solids.
Pre-aeration Tank
Pre-aeration is a part of wastewater treatment where external air is injected to the
tank at the rate of 0.028–0.11 m
3 /min for about 20–30 min to achieve the following:
(a) To reduce biochemical oxygen demand and chemical oxygen demand of
wastewater
(b) To flocculate lighter floating solids into heavier ones to facilitate settling
(c) To separate oil and grease from wastewater and transfer them to the surface
(d) To maintain aerobic conditions in the septic wastewater
Pre-chlorination
Pre-chlorination may be sometimes used in pre-treatment of industrial wastewater to
control odour, prevent wastewater decomposition and accelerate sedimentation.
8 Treatment of Petroleum Hydrocarbon Pollutants in Water
251
during drilling as well as refining of crude (Environmental Protection Agency,
Washington 2003; Shahryar 2017). Following devices are used in preliminary
treatment -.
Screener
It removes plugging or clogging materials like polymeric materials, large suspended
solids, grit which may damage the pipelines, pump, etc. Examples are rack, bar
or fine.
Comminuting Device
This device is used to cut or reduce the size of larger materials into smaller ones in
order to protect the equipment, lines and channels from clogging or plugging.
Examples are grinder, cutters and shredders.
Grit Chamber
This long channel type chamber is used to remove suspended particles, grit to protect
subsequent equipment like sedimentation tanks, sludge digesters, pumps from tear,
wear, corrosion as well as deposition in pipelines and channels. In these chambers,
the flow rate of wastewater is sufficiently reduced so as to allow deposition of the
heavy solids.
Pre-aeration Tank
Pre-aeration is a part of wastewater treatment where external air is injected to the
tank at the rate of 0.028–0.11 m
3 /min for about 20–30 min to achieve the following:
(a) To reduce biochemical oxygen demand and chemical oxygen demand of
wastewater
(b) To flocculate lighter floating solids into heavier ones to facilitate settling
(c) To separate oil and grease from wastewater and transfer them to the surface
(d) To maintain aerobic conditions in the septic wastewater
Pre-chlorination
Pre-chlorination may be sometimes used in pre-treatment of industrial wastewater to
control odour, prevent wastewater decomposition and accelerate sedimentation.
8 Treatment of Petroleum Hydrocarbon Pollutants in Water
251