| dc.description | Activated Sludge Model N°3 (ASM3) was chosen as a basis to model an activated sludge
system treating effluents from a mechanical pulp and paper mil!. The wastewater
treatment plant (WWTP) selected, located in Port Albemi, consists of a pH adjuster,
primary clarifier (not modeled), five complete mixed bioreactors in series, and a
secondary clarifier. The plant treats an average of 74,000 rn3d4 , with the foliowing
average influent characteristics (primary effluent): COD of 594 g m 3 , BOD of 250 g rn 3,
TSS of 27 g m 3 , pH of 7.2, and temperature of 32°C.
A simplified version of the ASM3 model (excluding nitrification and anoxic conditions)
was successfiully calibrated for this p!ant. A single set of parameters, with minor
variations, was able to fit a variety of batch test respirographs, and performed relatively
well when a full-scale simulation was performed using the calibrated parameters values
over a time period of nine days.
Three measurement campaigns were undertaken in order to calibrate the model properly.
The rnost sensitive parameters (Y sTo, YFI, bH, ksTo, PH, KSTO, and kH), as well as the
wastewater influent COD fractions (S1, S5, X1, and Xs), were evaluated using three
cornplementary tools: batch respirometric tests, analytical measurements, and mass
balance equations.
Even though the authors of ASM3 advises not to apply that model for industrial
wastewaters and outside the temperature range of 8 - 23°C, the model was found suitable
for modelling the COD removal in a WWTP treating pulp and paper effluents at
temperatures around 32°C. The importance of this finding is that the application of
widely used modeis, developed originally for municipal wastewater, in pu!p and paper
applications would sirnp!ify considerably the task of rnodelling and designing WWTP for
this industry. Sorne assumptions of the model, however, proved not to be app!icable and
sorne adjustment would be necessary in building a dynamic model for the treatment of
these effluents.
The least sensitive parameters were not calibrated, so they were either assurned from the
literature (fs1, fx, Kx, and Ks) or assumed to be equal to other estimated parameters (bsTo
afld °T,bsto, assumed to be equal to bH and 0T,bH respectively).
Sensitivity and structural identifiability analysis were also performed of the ASM3
simplified model. Only the calibration of the heterotrophic growth rate (!IH) presented
sorne identifiability problerns, which were solved by estimating an auxiliary parameter
(tOBS),
A few novel calibration procedures were developed for estimating sorne of the
parameters (bH, OT,bH), which could be used for any type of effluents. In addition,
different methods were used for the estimation of many of the model parameters and
wastewater fractions, and sorne recommendations were done in order to select the best
method for estimating different model cornponents. | |
