NUI Galway – UL Alliance First Annual ENGINEERING AND - ARAN ...

DEVELOPMENT AND CALIBRATION OF A NEW MODEL FOR DESIGNING AND OPTIMISING THE PUMPED
FLOW BIOFILM REACTOR (PFBR) WASTEWATER TREATMENT TECHNOLOGY
Noelle Jones, Dr. Eoghan Clifford, Edmond O’Reilly
jonesnoelle@gmail.com
Abstract
A Civil Engineering research team from NUI Galway
developed and patented a novel wastewater treatment
technology known as the pumped flow biofilm reactor –
(PFBR). It is proposed to model the PFBR using the
modeling package GPS-X as part of this project.
Wastewater Treatment Plant modelling is a useful tool
for performing plant capacity assessments and
improving plant operations; therefore, saving energy
and chemical costs. Once implemented and calibrated,
a model offers many advantages such as:
• Determining Maximum Flow Conditions
• Evaluating Chemical Usage Changes
• Preparing for Upcoming Regulations
• Energy Saving Evaluations
• Pre-Treatment Considerations
• Identify Plant Bottlenecks
• Predicting Weather Events
• Equipment Evaluations
Devisscher et al., (2006) noted that mathematical
modelling can optimise plant efficiencies resulting in
cost savings of; (i) aeration energy in the range from 10
to 20% and (ii) chemical dosing up to 30%. The PFBR
technology is currently undergoing commercial
evaluation; thus a predictive model capable of
simulating performance for both municipal and
industrial strength wastewaters will add further value to
the commercial offering.
1. Introduction
The PFBR is a two-reactor-tank technology that has
been extensively tested at laboratory-scale and fieldscale
for populations ranging from 15 – 400 population
equivalents (PE). It is proposed to model the pumped
flow biofilm reactor using the modelling package GPS-
X. GPS-X is a modular, multi-purpose computer
programme for the modelling and simulation of
municipal and industrial wastewater treatment plants.
GPS-X can be used whether designing a new facility or
simulating an existing plant. GPS-X can help
significantly improve the design and operating
efficiency of wastewater treatment plants (WWTP).
2. Operation of the PFBR
In a typical cycle of the PFBR hydraulic pumps are
used to circulate wastewater from one reactor tank to
another. These biofilm systems comprise no moving
parts or compressors, other than hydraulic pumps or air
pumps and motorised valves. Aeration is achieved by
alternately exposing the biofilm (attached to plastic
media) in each of the two reactor tanks to atmospheric
air, thereby eliminating the need for forced aeration.
Anoxic/anaerobic conditions can be achieved by
keeping the biofilm media immersed in the wastewater.
By operating the system in a sequencing batch reactor
(SBR) mode to EU and UK design loadings, the
following can be achieved: 5-day biochemical oxygen
demand (BOD5), chemical oxygen demand (COD) and
suspended solids (SS) removal; nitrification; and
150
denitrification – biological phosphorus removal has
been achieved at laboratory-scale and will be trialled at
field-scale. The PFBR system is operated as a
sequencing batch reactor and, as such, requires primary
settlement and a balance storage volume up-stream of
the reactor tanks.
3. Modelling of PFBR
A model is a representation of a real system. The
biggest challenge of model developers is to utilise
model concepts and equations to represent the WWTP
process dynamics. Due to the novel nature of the
technology, it may be necessary to develop specific
code and implement it in GPS-X to describe the aeration
and hydraulic characteristics of the PFBR. The project
methodology will be as follows:
1. Collation of all experimental data relating to both
technologies including aeration studies, biofilm
measurement data and phase studies.
2. Completion of small aeration trials in the laboratory
PFBR reactors to improve understanding of the
aeration dynamics.
3. Development of a model that is both physically
representative and allows treatment cycle regimes
to be described (including pump run times,
quiescent times, anoxic, aerobic and anaerobic
phases etc).
4. Initial model runs.
5. Sensitivity analysis and parameter estimation.
6. Model calibration and further sensitivity analysis.
7. Final optimisation of the predictive models.
4. Application of PFBR
There are numerous decentralised wastewater
treatment plants in Ireland with a population between 15
and 2000. These plants may often not have permanent
plant operators. The PFBR is particularly suited to such
sites as it can be remotely controlled and operated. The
development of a model for this technology will
enhance the design and operational efficiencies that can
be achieved.
5. Summary
In summary, the proposed development of the new
GPS-X model for the PFBR will enhance the
understanding of this technology and lead to better
designed and more cost-effective wastewater treatment
systems.
6. References
[1] O’Reilly, E., Rodgers, M. and Zhan, X.-M. (2008).
Pumped flow biofilm reactors (PFBR) for treating municipal
wastewater. Water Science & Technology 57(12): 1857–1865
[2] Rodgers, M., Zhan, X.-M., and O’Reilly, E. (2006).
Small-scale domestic wastewater treatment using an
alternating pumped sequencing batch biofilm reactor system -
Bioprocess Biosystems Engineering. 28: 323–330
[3] Devisscher M., (2006) - Estimating costs and benefits of
advanced control for wastewater treatment plants – the
MAgIC methodology. Water Science and Technology, 52(45).