| Summary: | The main objective of this research was to evaluate the effectiveness of pH as a
real-time control parameter in swine wastewater treatment. This real-time control process
was implemented into a Two Stage Sequencing Batch Reactor (TSSBRs) system. The
first SBR is known as the Anoxic/Oxic (A/O) reactor. The real time process was applied
here as most of the reactions occurred in this reactor. The second reactor is known as the
anoxic reactor and was mainly designed for nitrate removal. The reproducibility of the pH
patterns was tested under three different organic loadings. The treatment efficiencies for
C, N, and P were examined to determine the capability of this newly developed process.
The pH pattern was also compared to the more established ORP pattern for the purpose
of cross-referencing. The differences between an attached growth system using Ringlace
as a medium and a suspended growth system, both using the same real-time control
strategy, were also examined in this research.
It was determined from the results of this study that pH can be a valuable
parameter in a real-time control process. The pH patterns were consistent and uniform,
despite the fluctuations in wastewater concentrations. The pH pattern clearly
demonstrated its ability to monitor all the respiratory states. Several well defined control
points on the pH curve such as the nitrate apex during the anoxic phase, and the Nitrogen
Break Point (NBP) and Residual Carbon Manipulation Point (RCMP) during the aerobic
phase were identified. The clarity of each feature makes real-time control using pH
possible. It should be noted that the time allotted for the anoxic phase was four hours, while the aerobic phase was adjusted by the real time control process with the control
point set in between the NBP and RCMP.
The success of this real-time control process was marked by the flexible HRT
provided for the system. It was found in this research that the application of the real-time
process either ensured a complete removal of carbon and ammonia, or reduced the overall
cycle time (maximized energy savings). A constant effluent quality was also produced for
each run.
It was demonstrated in this study that the treatment efficiency for nitrate and
phosphorus can be greatly affected by the carbon content in the wastewater. It was found
that the optimal treatment efficiency for each nutrient (C, N, and P) was achieved during
the high organic loading run. The high nutrient loading rate ensured rapid denitrification
and phosphorus release during the anoxic phase, while creating a favourable environment
for carbon oxidation, nitrification, and phosphorus uptake during the aerobic stage. It
was also found that the anoxic reactor was not needed under conditions of high organic
loadings. A high carbon content in the influent created simultaneous
nitrification/denitrification in the aerobic phase. This reduced the nitrate loading into the
anoxic reactor.
From the results of this research, it was found that pH pattern correlated well with
the ORP curve. Each distinct feature identified on the pH curve coincided with the ORP
pattern. The ORP pattern was affected more by the aeration rate than pH. Nonetheless, it
can be concluded that both pH and ORP can be used as a real-time control parameter.
The results obtained from this research suggested that the only difference between
the attached growth and suspended growth systems was the hydraulic retention time. The higher biomass retained in the attached growth system enabled the bacteria to complete
the necessary reactions in a shorter period of time. The effluent quality produced from
both systems were virtually the same for each run. === Applied Science, Faculty of === Chemical and Biological Engineering, Department of === Graduate
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