1.2 Historical Findings
3
sludge process by adding the media into its existing basin in Broomfield wastewater
treatment plant for improving the biological nutrient removal process [4].
After the IFAS process, the LINPOR process was developed as a modified activated sludge system, where highly porous suspended plastic foams cubes were used
as a movable media in the aeration tank. The LINPOR process produced a treated
effluent quality far better than the conventional ASP process [5, 6].
The suspended carrier biofilm process (Kaldenes moving bed biofilm reactor)
was applied in the existing treatment facilities [7–10, where high-density polyethylene dispersed biofilm media was used as biofilm attachment surface. This process
resulted in efficient carbon removal and improved nitrification and denitrification in
the system. For a process design of the hybrid bioreactor, a user-friendly mathematical modeling is required for finding out the relevant outputs. The first mathematical
model of the hybrid bioreactor was developed by Lee [11]. Thereafter, one computer
program was developed for hybrid bioreactor for removing soluble COD and nutrients [12]. Plastic nets as an attached surface were inserted into the aeration tank
and the mathematical model of the reactor was accordingly developed [13, 14]. One
mathematical model was developed for a steady-state biofilm activated sludge reactor
to calculate the substrate flux in the biofilm under substrate limiting condition [15].
Effort has also been made to develop a simplified mathematical model for designing
the steady state biofilm activated sludge reactor under limiting substrate condition
[15]. Earlier one activated sludge model (ASM2d) was developed for biological phosphorus removal with simultaneous nitrification–denitrification in the activated sludge
process [16]. The said model was further extended to a steady-state IFAS model by
Boltz et al. [17] using the input taken from biofilm modeling techniques [18]. Eventually, a simplified mathematical model was proposed to provide an accurate tool
for describing the steady-state suspended-growth biofilm system in the treatment of
municipal wastewater [19].
The present model developed by the author is not only found very simple, fast and
accurate method in determining the output parameter, but also it can calculate the
effective biofilm thickness unlike other solution models. Actually, it is the effective
biofilm thickness which contains the biomass actively metabolizing the substrate
beyond which the substrate flux ceases to get utilized further. Moreover, from the
effective biofilm thickness it can be ascertained whether the biofilm is a shallow or
deep biofilm. Apart from that, the solution model employed the kinetics of suspendedand attached-growth biomass in integrated manner considering their simultaneous
growth. Unlike other existing models, average substrate flux (Javg) is considered in
the present mathematical model, considering a variation in substrate flux from biofilm
layer to layer on account of substrate gradient. The results of performance study on
the laboratory-scale hybrid bioreactor also established the accuracy of the present
solution model. Such experimental validation can be carried out with different types
of wastewater of varying strength for examining its versatility. All these may lead to
exploring a generalized mechanism for process design of a hybrid bioreactor.
In case of municipal wastewater like low strength wastewater, suspended biomass
is subjected to washout if there is no recirculation of biomass. Thus, the addition of
3
sludge process by adding the media into its existing basin in Broomfield wastewater
treatment plant for improving the biological nutrient removal process [4].
After the IFAS process, the LINPOR process was developed as a modified activated sludge system, where highly porous suspended plastic foams cubes were used
as a movable media in the aeration tank. The LINPOR process produced a treated
effluent quality far better than the conventional ASP process [5, 6].
The suspended carrier biofilm process (Kaldenes moving bed biofilm reactor)
was applied in the existing treatment facilities [7–10, where high-density polyethylene dispersed biofilm media was used as biofilm attachment surface. This process
resulted in efficient carbon removal and improved nitrification and denitrification in
the system. For a process design of the hybrid bioreactor, a user-friendly mathematical modeling is required for finding out the relevant outputs. The first mathematical
model of the hybrid bioreactor was developed by Lee [11]. Thereafter, one computer
program was developed for hybrid bioreactor for removing soluble COD and nutrients [12]. Plastic nets as an attached surface were inserted into the aeration tank
and the mathematical model of the reactor was accordingly developed [13, 14]. One
mathematical model was developed for a steady-state biofilm activated sludge reactor
to calculate the substrate flux in the biofilm under substrate limiting condition [15].
Effort has also been made to develop a simplified mathematical model for designing
the steady state biofilm activated sludge reactor under limiting substrate condition
[15]. Earlier one activated sludge model (ASM2d) was developed for biological phosphorus removal with simultaneous nitrification–denitrification in the activated sludge
process [16]. The said model was further extended to a steady-state IFAS model by
Boltz et al. [17] using the input taken from biofilm modeling techniques [18]. Eventually, a simplified mathematical model was proposed to provide an accurate tool
for describing the steady-state suspended-growth biofilm system in the treatment of
municipal wastewater [19].
The present model developed by the author is not only found very simple, fast and
accurate method in determining the output parameter, but also it can calculate the
effective biofilm thickness unlike other solution models. Actually, it is the effective
biofilm thickness which contains the biomass actively metabolizing the substrate
beyond which the substrate flux ceases to get utilized further. Moreover, from the
effective biofilm thickness it can be ascertained whether the biofilm is a shallow or
deep biofilm. Apart from that, the solution model employed the kinetics of suspendedand attached-growth biomass in integrated manner considering their simultaneous
growth. Unlike other existing models, average substrate flux (Javg) is considered in
the present mathematical model, considering a variation in substrate flux from biofilm
layer to layer on account of substrate gradient. The results of performance study on
the laboratory-scale hybrid bioreactor also established the accuracy of the present
solution model. Such experimental validation can be carried out with different types
of wastewater of varying strength for examining its versatility. All these may lead to
exploring a generalized mechanism for process design of a hybrid bioreactor.
In case of municipal wastewater like low strength wastewater, suspended biomass
is subjected to washout if there is no recirculation of biomass. Thus, the addition of