Advanced Treatment
Most of the suspended solids as well as biochemical oxygen demand of refinery
wastewater are removed by primary and secondary treatment processes. However, in
most cases, after these treatment processes, the water quality is inadequate to be
reused either in industry or for domestic purposes. Hence, advanced treatment
processes are further incorporated for better separation efficiency of organic matter,
nutrients and harmful chemicals from refinery effluents, with an aim to achieve better
water quality. Advanced treatment may be incorporated into primary, secondary and
tertiary treatment units. Following are some advanced technologies which are used
for wastewater treatment in refineries (International Petroleum Industry Environmental Conservation Association 2010; Central Pollution Control Board, India
2018; Shahryar 2017; Alireza 2014; Mareddy 2017).
A. Activated sludge with powdered activated carbon
B. Sequencing batch reactor
C. Membrane technology
D. Membrane bioreactor
The advanced technology depends on flexibility, operating and maintenance cost,
operability, space availability, etc.
Activated Sludge with Powdered Activated Carbon
The conventional activated sludge process is upgraded by introducing powdered
activated carbon as adsorbent. The powdered activated carbon technology is a
combination of biological oxidation and adsorption. The surface area of adsorption
is increased by using powdered activated carbon, thereby enhancing the removal
efficiency of organic matter. In most cases, the used powdered activated carbon is
recycled with activated sludge, but fresh powdered activated carbon is also required
to maintain the efficiency. This technology is normally applied in situations where
specific standards are required to be met for definite contaminants of refinery
wastewater (International Petroleum Industry Environmental Conservation Association 2010; Shahryar 2017).
Sequencing Batch Reactor
The sequencing semi-batch reactor is a fill-draw biological treatment which consists
of aeration, sedimentation and clarification in a single batch reactor. The aeration and
sedimentation steps are similar between sequencing batch reactor and activated
sludge system. However, these two steps are operated in different chambers in
activated sludge process, whereas in sequencing batch reactor, these two steps are
processed in the same tank consecutively. However, this technology is applied only
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M. Samanta and D. Mitra
Most of the suspended solids as well as biochemical oxygen demand of refinery
wastewater are removed by primary and secondary treatment processes. However, in
most cases, after these treatment processes, the water quality is inadequate to be
reused either in industry or for domestic purposes. Hence, advanced treatment
processes are further incorporated for better separation efficiency of organic matter,
nutrients and harmful chemicals from refinery effluents, with an aim to achieve better
water quality. Advanced treatment may be incorporated into primary, secondary and
tertiary treatment units. Following are some advanced technologies which are used
for wastewater treatment in refineries (International Petroleum Industry Environmental Conservation Association 2010; Central Pollution Control Board, India
2018; Shahryar 2017; Alireza 2014; Mareddy 2017).
A. Activated sludge with powdered activated carbon
B. Sequencing batch reactor
C. Membrane technology
D. Membrane bioreactor
The advanced technology depends on flexibility, operating and maintenance cost,
operability, space availability, etc.
Activated Sludge with Powdered Activated Carbon
The conventional activated sludge process is upgraded by introducing powdered
activated carbon as adsorbent. The powdered activated carbon technology is a
combination of biological oxidation and adsorption. The surface area of adsorption
is increased by using powdered activated carbon, thereby enhancing the removal
efficiency of organic matter. In most cases, the used powdered activated carbon is
recycled with activated sludge, but fresh powdered activated carbon is also required
to maintain the efficiency. This technology is normally applied in situations where
specific standards are required to be met for definite contaminants of refinery
wastewater (International Petroleum Industry Environmental Conservation Association 2010; Shahryar 2017).
Sequencing Batch Reactor
The sequencing semi-batch reactor is a fill-draw biological treatment which consists
of aeration, sedimentation and clarification in a single batch reactor. The aeration and
sedimentation steps are similar between sequencing batch reactor and activated
sludge system. However, these two steps are operated in different chambers in
activated sludge process, whereas in sequencing batch reactor, these two steps are
processed in the same tank consecutively. However, this technology is applied only
262
M. Samanta and D. Mitra