demand, oil, and suspended solids removal efficiencies of 84.5%, 94%, and 83.4%,
respectively. Santo et al. (2013) used activated sludge biological treatment technique
to treat the petroleum refinery wastewater with the total carbon, chemical oxygen
demand, and suspended solids removals of 85–87%, 94–95%, and 98–99%, respectively. The pseudo first-order reaction kinetic model was used to portray the rate of
oil degradation with the rate constant (k) values of 0.055 and 0.059 L/mg VSS day
for the treatment with and without the sludge recovering, respectively.
11.3 Membrane Filtration
Recently, membrane filtration technology has received tremendous attention for
effective oily wastewater separation. The high emulsion separation efficiency, no
phase change operation involving minimum use of chemicals, as well as the easy and
low-cost operation have made this technology particularly attractive (Arnot et al.
2000; Dickhout et al. 2017). Generally, the membrane technology used for the oily
wastewater treatment is driven by pressure. In the conventional membrane separation process, the oil-contaminated feed solution is pushed towards the membrane by
pressure. The membrane pore size will act as a selective barrier which allows the
smaller particles and solution to pass through, while the larger-sized oil particles will
be blocked and retained at the feed compartment. In general, microfiltration, ultrafiltration, nanofiltration, and reverse osmosis are the major types of membrane
technologies for oily wastewater treatment.
11.3.1 Microfiltration
Microfiltration is a separation process which involves the sieving effects by a series
of well-defined membrane pore size. Typically, the microfiltration membranes have
the pore size of 0.1–10 μm. The microfiltration membranes are commonly fabricated
from a wide range of polymers, such as cellulose nitrate, polyamide, polyacrylonitrile, polyvinyl alcohol, polyamide, and polysulfone. It should be noted that the
membranes should have great tolerance towards chemicals and temperatures. Hence,
the development of ceramic microfiltration membranes from alumina, kaolin, zeolite, and fly ash has also been vibrantly growing in recent years.
Microfiltration process is generally used to separate insoluble suspended particles, yeast cell, broth, bacteria, and colloids from aqueous streams. Since the
microfiltration membranes exhibit large pore size, the solution is usually transported
through the membrane pores via convection. The rate of the passage of the solution
through the pores is directly proportional to the pressure difference across the
membrane, assuming the membrane pores are in the cylindrical dimension. In
other words, the microfiltration process is driven by the pressure gradient across
the membrane pores, which can be in the range of 50–200 kPa (Winston and Sirkar
11 Oily Wastewater Treatment
365
respectively. Santo et al. (2013) used activated sludge biological treatment technique
to treat the petroleum refinery wastewater with the total carbon, chemical oxygen
demand, and suspended solids removals of 85–87%, 94–95%, and 98–99%, respectively. The pseudo first-order reaction kinetic model was used to portray the rate of
oil degradation with the rate constant (k) values of 0.055 and 0.059 L/mg VSS day
for the treatment with and without the sludge recovering, respectively.
11.3 Membrane Filtration
Recently, membrane filtration technology has received tremendous attention for
effective oily wastewater separation. The high emulsion separation efficiency, no
phase change operation involving minimum use of chemicals, as well as the easy and
low-cost operation have made this technology particularly attractive (Arnot et al.
2000; Dickhout et al. 2017). Generally, the membrane technology used for the oily
wastewater treatment is driven by pressure. In the conventional membrane separation process, the oil-contaminated feed solution is pushed towards the membrane by
pressure. The membrane pore size will act as a selective barrier which allows the
smaller particles and solution to pass through, while the larger-sized oil particles will
be blocked and retained at the feed compartment. In general, microfiltration, ultrafiltration, nanofiltration, and reverse osmosis are the major types of membrane
technologies for oily wastewater treatment.
11.3.1 Microfiltration
Microfiltration is a separation process which involves the sieving effects by a series
of well-defined membrane pore size. Typically, the microfiltration membranes have
the pore size of 0.1–10 μm. The microfiltration membranes are commonly fabricated
from a wide range of polymers, such as cellulose nitrate, polyamide, polyacrylonitrile, polyvinyl alcohol, polyamide, and polysulfone. It should be noted that the
membranes should have great tolerance towards chemicals and temperatures. Hence,
the development of ceramic microfiltration membranes from alumina, kaolin, zeolite, and fly ash has also been vibrantly growing in recent years.
Microfiltration process is generally used to separate insoluble suspended particles, yeast cell, broth, bacteria, and colloids from aqueous streams. Since the
microfiltration membranes exhibit large pore size, the solution is usually transported
through the membrane pores via convection. The rate of the passage of the solution
through the pores is directly proportional to the pressure difference across the
membrane, assuming the membrane pores are in the cylindrical dimension. In
other words, the microfiltration process is driven by the pressure gradient across
the membrane pores, which can be in the range of 50–200 kPa (Winston and Sirkar
11 Oily Wastewater Treatment
365