Title page for ETD etd-05232003-204831

Type of Document Master's Thesis
Author Dauphinais, Jennifer L.
Author's Email Address jdauphin@vt.edu
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
  • respiration
  • cyanide
  • pH
  • toxicity
  • Activated sludge
Date of Defense 2003-04-23
Availability restricted
Upset 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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[VT] 01Thesis.PDF 761.79 Kb 00:03:31 00:01:48 00:01:35 00:00:47 00:00:04
[VT] 02AppendixA.PDF 72.23 Kb 00:00:20 00:00:10 00:00:09 00:00:04 < 00:00:01
[VT] 03AppendixB.PDF 49.63 Kb 00:00:13 00:00:07 00:00:06 00:00:03 < 00:00:01
[VT] 04AppendixC.PDF 95.97 Kb 00:00:26 00:00:13 00:00:11 00:00:05 < 00:00:01
[VT] 05AppendixD.PDF 109.59 Kb 00:00:30 00:00:15 00:00:13 00:00:06 < 00:00:01
[VT] 06AppendixE.PDF 40.49 Kb 00:00:11 00:00:05 00:00:05 00:00:02 < 00:00:01
[VT] 07AppendixF.PDF 28.91 Kb 00:00:08 00:00:04 00:00:03 00:00:01 < 00:00:01
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