health of living beings both aquatic and non-aquatic. This effluent is generally
discharged to an offsite waste-water treatment plant where the upgradation or
cleaning of wastewater is done by applying modern technology. In wastewater
plant, the wastewater is accumulated in a separate location and subjected to the
different treatment processes. Mainly wastewater is collected in large volumes and
treatment processes are held on either continuous or batch basis (International
Petroleum Industry Environmental Conservation Association 2010; Central Pollution Control Board, India 2018; Patwardhan 2008; Shahryar 2017).
The wastewater treatment processes depend on certain factors such as (Mareddy
2017)
• Quality and quantity of pollutants
• Availability of space of the treatment area
• Degree of automation of the treatment plant
• Capital and operating costs
• Discharge facility without further pollution
• Specification of effluents to be maintained
The wastewater treatment process is mainly subdivided into physical, chemical
and biological processes. The physical process includes sedimentation, screening,
filtration; chemical process includes chlorination, neutralization, bleaching; and
biological means sludge and aerobic-anaerobic treatment (International Petroleum
Industry Environmental Conservation Association 2010; Mareddy 2017).
8.4.1 Physical Treatment Methods
Physical methods are used for improvement and upgradation of wastewater.
Removal of large entrained objects is affected through sedimentation and screening.
At first, wastewater is collected in a tank and allowed to stand for some time where
the suspended solids and large molecules are settled down by centrifugation
followed by separation of the clarified effluents. Lighter materials (paper, wood
particles, plastics, polymeric materials) and oil, grease that float are removed by
screening, trapping and skimming using automated raked bar screens. Sometimes,
agitation is required for floatation of these materials which is done either by applying
air to the bottom of wastewater lagoon or pond to cause the release of harmful gases
such as carbon dioxide, methane, hydrogen sulphide, etc. Another physical step,
filtration, is used for wastewater treatment where both suspended and floatable solids
are filtered through a filtering media, for example, sand (International Petroleum
Industry Environmental Conservation Association 2010; Central Pollution Control
Board, India 2018; Patwardhan 2008; Shahryar 2017).
8 Treatment of Petroleum Hydrocarbon Pollutants in Water
247
discharged to an offsite waste-water treatment plant where the upgradation or
cleaning of wastewater is done by applying modern technology. In wastewater
plant, the wastewater is accumulated in a separate location and subjected to the
different treatment processes. Mainly wastewater is collected in large volumes and
treatment processes are held on either continuous or batch basis (International
Petroleum Industry Environmental Conservation Association 2010; Central Pollution Control Board, India 2018; Patwardhan 2008; Shahryar 2017).
The wastewater treatment processes depend on certain factors such as (Mareddy
2017)
• Quality and quantity of pollutants
• Availability of space of the treatment area
• Degree of automation of the treatment plant
• Capital and operating costs
• Discharge facility without further pollution
• Specification of effluents to be maintained
The wastewater treatment process is mainly subdivided into physical, chemical
and biological processes. The physical process includes sedimentation, screening,
filtration; chemical process includes chlorination, neutralization, bleaching; and
biological means sludge and aerobic-anaerobic treatment (International Petroleum
Industry Environmental Conservation Association 2010; Mareddy 2017).
8.4.1 Physical Treatment Methods
Physical methods are used for improvement and upgradation of wastewater.
Removal of large entrained objects is affected through sedimentation and screening.
At first, wastewater is collected in a tank and allowed to stand for some time where
the suspended solids and large molecules are settled down by centrifugation
followed by separation of the clarified effluents. Lighter materials (paper, wood
particles, plastics, polymeric materials) and oil, grease that float are removed by
screening, trapping and skimming using automated raked bar screens. Sometimes,
agitation is required for floatation of these materials which is done either by applying
air to the bottom of wastewater lagoon or pond to cause the release of harmful gases
such as carbon dioxide, methane, hydrogen sulphide, etc. Another physical step,
filtration, is used for wastewater treatment where both suspended and floatable solids
are filtered through a filtering media, for example, sand (International Petroleum
Industry Environmental Conservation Association 2010; Central Pollution Control
Board, India 2018; Patwardhan 2008; Shahryar 2017).
8 Treatment of Petroleum Hydrocarbon Pollutants in Water
247