through the biofilms. During this process, oxygen may be supplied downwards or
upwards which might eventually diffuse through the water to reach the biofilms. The
next generation of suspended solids available in trickle-bed biofilm bioreactor
necessitates a liquid–solid separation through a clarifier. It has been observed that
the presence of biofilms in dome reactor may not have enough feed in some areas
and may led to decrease in productivity.
Moreover, it has been observed that the fluidized-bed reactor works based on the
coating of beads inside a column with biofilms in which polluted water is pumped
upwards and allows the biofilm beads to be suspended during the ecorestoration of
polluted water (Shieh and Keenan 1986). This constitutes the major difference
between these types of bioreactor and fixed-bed reactor where the media is not
suspended. The solids are suspended by flow of gas or liquid at some certain
velocity. The application of fluidization allows biofilms to develop on a very big
surface area to generate a larger biomass. Oxygen is normally supplied through the
application of oxygenator or through the bottom of the reactor. The fluidized-bed
reactor is applied for the treatment of streams polluted with inorganic and organic
compounds (Shieh and Keenan 1986; Denac and Dunn 1988; Kumar and Saravanan
2009; Costley and Wallis 2001).
Also, it has been observed that rotating biological contactors or modified types of
rotating biological contactors are normally applied for the bioremediation of heavily
polluted environment majorly wastewater treatment by decreasing biochemical
oxygen demand or chemical oxygen demand as well as their high application during
the process of denitrification and nitrification (Costley and Wallis 2001; Eker and
Kargi 2008, 2010). Rotating biological contactors applied a thin biofilm produced
from aerobic microorganisms grown on a bio-discs or rotating cylinder. This work is
based on the principle of lowering the disc into the partially submerged effluents and
gradually rotating the disc so that the biofilm microorganisms are slowly exposed to
effluents and air present, and this allows the biofilm on the disc to enhance the rate of
biodegradation of the pollutants. They are also utilized for the bioremediation of
PAH, heavy metals, volatile organic compounds and degradation of dyes (Eker and
Kargi 2008, 2010; Abraham et al. 2003; Jeswani and Mukherji 2012).
Membrane biofilm reactor generate oxygen or pressurized air through the gas
permeable membranes to the joined biofilms developed on the membrane exterior.
This type of bubble-free, enormous movement of oxygen disallows the stripping of
volatile organic compounds, greenhouse gasses and foaming when an adjuvant such
as surfactant is applied. This is normally utilized for the remediation of high oxygen
demanding wastewater. The membrane normally serves as a support for the development of biofilms. It has been observed that hydrogen-based membrane biofilm
reactor works basically based on the delivery of hydrogen to the biofilm entailing
autotrophic bacteria which possess that capability to oxidize hydrogen and utilize
electron donor to numerous pollutants such as nitrate and chlorate (Sarayu and
Sandhya 2012; Rittmann 2006; Nerenberg and Rittmann 2004). Some other type
of reactor includes methane-fed membrane biofilm reactor which is normally utilized
for the removal of pesticides and nitrates from polluted water (Modin et al. 2008).
Also, it could be utilized for the biodegradation of polychlorinated hydrocarbons
9 Utilization of Microbial Biofilm for the Biotransformation and Bioremediation. . .
239
upwards which might eventually diffuse through the water to reach the biofilms. The
next generation of suspended solids available in trickle-bed biofilm bioreactor
necessitates a liquid–solid separation through a clarifier. It has been observed that
the presence of biofilms in dome reactor may not have enough feed in some areas
and may led to decrease in productivity.
Moreover, it has been observed that the fluidized-bed reactor works based on the
coating of beads inside a column with biofilms in which polluted water is pumped
upwards and allows the biofilm beads to be suspended during the ecorestoration of
polluted water (Shieh and Keenan 1986). This constitutes the major difference
between these types of bioreactor and fixed-bed reactor where the media is not
suspended. The solids are suspended by flow of gas or liquid at some certain
velocity. The application of fluidization allows biofilms to develop on a very big
surface area to generate a larger biomass. Oxygen is normally supplied through the
application of oxygenator or through the bottom of the reactor. The fluidized-bed
reactor is applied for the treatment of streams polluted with inorganic and organic
compounds (Shieh and Keenan 1986; Denac and Dunn 1988; Kumar and Saravanan
2009; Costley and Wallis 2001).
Also, it has been observed that rotating biological contactors or modified types of
rotating biological contactors are normally applied for the bioremediation of heavily
polluted environment majorly wastewater treatment by decreasing biochemical
oxygen demand or chemical oxygen demand as well as their high application during
the process of denitrification and nitrification (Costley and Wallis 2001; Eker and
Kargi 2008, 2010). Rotating biological contactors applied a thin biofilm produced
from aerobic microorganisms grown on a bio-discs or rotating cylinder. This work is
based on the principle of lowering the disc into the partially submerged effluents and
gradually rotating the disc so that the biofilm microorganisms are slowly exposed to
effluents and air present, and this allows the biofilm on the disc to enhance the rate of
biodegradation of the pollutants. They are also utilized for the bioremediation of
PAH, heavy metals, volatile organic compounds and degradation of dyes (Eker and
Kargi 2008, 2010; Abraham et al. 2003; Jeswani and Mukherji 2012).
Membrane biofilm reactor generate oxygen or pressurized air through the gas
permeable membranes to the joined biofilms developed on the membrane exterior.
This type of bubble-free, enormous movement of oxygen disallows the stripping of
volatile organic compounds, greenhouse gasses and foaming when an adjuvant such
as surfactant is applied. This is normally utilized for the remediation of high oxygen
demanding wastewater. The membrane normally serves as a support for the development of biofilms. It has been observed that hydrogen-based membrane biofilm
reactor works basically based on the delivery of hydrogen to the biofilm entailing
autotrophic bacteria which possess that capability to oxidize hydrogen and utilize
electron donor to numerous pollutants such as nitrate and chlorate (Sarayu and
Sandhya 2012; Rittmann 2006; Nerenberg and Rittmann 2004). Some other type
of reactor includes methane-fed membrane biofilm reactor which is normally utilized
for the removal of pesticides and nitrates from polluted water (Modin et al. 2008).
Also, it could be utilized for the biodegradation of polychlorinated hydrocarbons
9 Utilization of Microbial Biofilm for the Biotransformation and Bioremediation. . .
239