Type of Document Master's Thesis Author Dauphinais, Jennifer L. Author's Email Address email@example.com URN etd-05232003-204831 Title Evaluating the Source-Effect relationship of Industrial Toxins In wastewater Treatment Degree Master of Science Department Environmental Engineering Advisory Committee
Advisor Name Title Love, Nancy G. Committee Chair Little, John C. Committee Member Novak, John T. Committee Member Keywords
- Activated sludge
Date of Defense 2003-04-23 Availability restricted AbstractUpset events due to the inflow of toxic chemicals are a critical issue for wastewater
treatment facilities. Understanding the source-effect relationship of toxic chemicals can
facilitate the prevention or improved reaction to upset events. Part one of this study was
conducted to investigate the source of upset events at a regional industrial wastewater
treatment plant (WWTP). Part two of this study determined the process performance
effects of two chemical shocks, cyanide (zinc-cyanide complex) and pH, on nitrifying
and non-nitrifying activated sludge.
A modified respirometric assay protocol was developed to allow the industrial WWTP to
screen industrial wastewaters for inhibitory properties. All five industrial wastewaters
tested revealed inhibitory properties. Large day-to-day variations were found, illustrating
the need for a large database of results for comparison over time. Additionally, a small
volume contributor, that was thought by the utility to be an unlikely source of problems,
contributed significantly to the wastewater oxygen demand and demonstrated inhibitory
properties. The modified respirometric procedure enabled the WWTP to identify possible
industrial sources that could cause an upset event.
Lab-scale sequencing-batch reactors were used to determine the effects of cyanide and
pH shock on activated sludge. Three reactors were shocked with increasing weak-acid
complexed zinc cyanide or pHs of 5, 9, and 11. The resulting effects were compared to an
un-shocked control reactor. It was found that respiration and nitrification were affected
by the zinc cyanide complex, while COD removal, effluent TSS and dewaterability were
not. Recovery was seen in less than 2 X solids residence time (SRT) for the nitrifying
biomass and within 3 X SRT for the non-nitrifying biomass. The results of the pH
experiment showed that the pH 11 shock affected the settleability, nitrification, COD
removal, and effluent TSS levels of the reactors, while pH 5 and pH 9 shocks had no
effect. Recovery was seen within 3 X SRT for both the nitrifying and non-nitrifying
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