ROSSO (2013) Aeration Research - for pdf

49 Pages·2014·53.85 MB·English

URBAN
WATER
RESEARCH
CENTER
OXYGEN TRANSFER IN ACTIVATED
SLUDGE PROCESSES:!
BUBBLES, MIXERS et al.!
Diego Rosso
University of California, Irvine
SUMMARY
I.  EFFECTS OF WASTEWATER CONTAMINANTS ON
OXYGEN TRANSFER
II.  AERATION SYSTEMS
III.  MEASUREMENT OF OXYGEN TRANSFER IN CLEAN
WATER
IV.  MEASUREMENT OF OXYGEN TRANSFER IN WASTEWATER
V.  ENERGY CONSIDERATIONS
VI.  SITE-SPECIFIC DESIGN CONSIDERATIONS
VII.  CONCLUSIONS
I. EFFECTS OF WASTEWATER
CONTAMINANTS ON OXYGEN
TRANSFER
Terminology
OTE: Oxygen Transfer Efficiency (%)
OTR: Oxygen Transfer Rate (kg /h)
O2
SOTE: Standardized OTE in clean water (%)
αSOTE: Standardized OTE in process water (%)
α  = αSOTE/SOTE (water quality estimate)
DWP = Dynamic wet pressure (diff. headloss, Pa)
WHAT ARE THESE CONTAMINANTS?
CONTAINS:
15-25% anionic
surfactants
0-15% non-ionic
surfactants
0-15% soap
0-15% cationic
surfactants
fillers to 100%
SURFACTANT STRUCTURE
Amphiphilic structure  Interfacial accumulation
(Fujimoto, 1985)
Hydrophobic Polar
tail head
SURFACTANT INTERFACIAL ACCUMULATION
LOW INTERFACIAL VELOCITY =
HIGH SURFACTANT ACCUMULATION =
LOW ALPHA (BUT HIGH SOTE)
LIQUID GAS
STAGNANT TURBUL.
LIQUID GAS
HIGH INTERFACIAL VELOCITY =
LOW SURFACTANT ACCUMULATION =
STAGNANT TURBUL.
HIGH ALPHA (BUT LOW SOTE)
Alpha and SOTE
a
h
p
a l
FINE-BUBBLES COARSE-BUBBLES
BUBBLE SIZE