APPLICATION OF CFD AND DYNAMIC PROCESS SIMULATION FOR RETROFITTING OF A 800,000 PE TRICKLING FILTER WWTP
Tomasz Janus 1*, 4 , David Burt 2, Anna Taylor 3 and Vincent Glancy 1
1ARUP, UK
2MMI, UK
3Yorkshire Water, UK
4Water Software Systems, De Montfort Univ, UK *formerly of Arup
(free)
Esholt is Yorkshire Water’s second largest wastewater treatment plant (WwTP), serving the
city of Bradford and parts of Leeds. Currently the secondary treatment process at Esholt
comprises of mineral media trickling filters designed to nitrify to 5 mgN/L on a 95%-ile basis.
Effluent from the trickling filters is clarified in humus tanks (HT) and then flows to sand filters
for tertiary treatment. As a result of the new Freshwater Fish Directive, coming into force in
April 2010, the plant is to be retrofitted to an activated sludge plant (ASP) which will be
required to meet a tighter effluent Ammonia consent of 3 mgN/L. Nitrogen and Phosphorous
removal will not be required by 2010 but the plant needs to be designed to allow for easy
upgrading to Biological Nutrient Removal (BNR) in the next Asset Management Programme
(AMP5). The retrofit design assumed a reuse of the existing humus tanks as final settlement
tanks (FSTs) for the ASP. Assessment of the performance of humus tanks for activated
sludge was demonstrated using CFD. Design of the bioreactor was optimised by using a
calibrated Activated Sludge Model (ASM). The combination of CFD and dynamic process
modelling provided substantial financial savings for the project and it also identified the
process risks arising from the specific character of the influent and the catchment.
KEY WORDS
Activated Sludge, ASM, ANSYS CFX, CFD, Design, GPS-X, Retrofit, Simulation, Wastewater
