Discussion
403
failure. Nitrification is a problem for this culture particularly in the covered tank type processes where
C0 2 recirculation leads to lower pH. Safety can be a problem if hydrocarbons such as gasoline are
spilled and contact high oxygen levels. Maintenance problems are not really known and it will require
high levels of mechanical competence to operate and maintain 0 2 plants. The city of Los Angeles is
designing a 40 mgd activated sludge facility. It thoroughly considered pure oxygen and found no
monetary advantage over conventional design. In view of the points listed above a conventional design
was chosen.
M. Klegerman, USA
What are the settling characteristics of the mixed liquor from oxygen reactors in final clarifiers
particularly with respect to required overflow rates? Based on at least one pilot plant which we
operated utilizing Unox system we found such overflow rates to be about 550 gals/sq.ft./day. Need
final settling tanks in pure oxygen plants be larger than air plants? What is the shallowest or deepest
aeration tank that can be used with pure oxygen?
M. Spiegel, USA
What proportion of the generated oxygen is required for mixing to maintain suspension of solids?
What is the resultant D.O. level in the mixed liquor? If in the range of 8 - 9 mgl 0 2 , what is the benefit
of such a range?
R.M. Stein, USA
Could the author supply data in support of his statement that pure oxygen induces a higher
reaction rate of aerobic digestion? How does the digestion affect dewaterability?
PWMARY CLARIFIER
OVERFLOW
FLOWSHEET V
<9>
£
LT^
o,·
REORCULATION
(R)
OXYCENATION
UNIT
i
11
UMMM
^U
EFFLUENT
SLUDGE
BLANKET
PRIMARY CLAR. OVERFLOW
FLOWSHEET "Β*
«0
WASTE ACTIVATED
SLUDGE
Fig. 1 Schematic Flow Diagram for Bioprecipitation Process Using Pure Oxygen (after Budd and
Lambeth)
403
failure. Nitrification is a problem for this culture particularly in the covered tank type processes where
C0 2 recirculation leads to lower pH. Safety can be a problem if hydrocarbons such as gasoline are
spilled and contact high oxygen levels. Maintenance problems are not really known and it will require
high levels of mechanical competence to operate and maintain 0 2 plants. The city of Los Angeles is
designing a 40 mgd activated sludge facility. It thoroughly considered pure oxygen and found no
monetary advantage over conventional design. In view of the points listed above a conventional design
was chosen.
M. Klegerman, USA
What are the settling characteristics of the mixed liquor from oxygen reactors in final clarifiers
particularly with respect to required overflow rates? Based on at least one pilot plant which we
operated utilizing Unox system we found such overflow rates to be about 550 gals/sq.ft./day. Need
final settling tanks in pure oxygen plants be larger than air plants? What is the shallowest or deepest
aeration tank that can be used with pure oxygen?
M. Spiegel, USA
What proportion of the generated oxygen is required for mixing to maintain suspension of solids?
What is the resultant D.O. level in the mixed liquor? If in the range of 8 - 9 mgl 0 2 , what is the benefit
of such a range?
R.M. Stein, USA
Could the author supply data in support of his statement that pure oxygen induces a higher
reaction rate of aerobic digestion? How does the digestion affect dewaterability?
PWMARY CLARIFIER
OVERFLOW
FLOWSHEET V
<9>
£
LT^
o,·
REORCULATION
(R)
OXYCENATION
UNIT
i
11
UMMM
^U
EFFLUENT
SLUDGE
BLANKET
PRIMARY CLAR. OVERFLOW
FLOWSHEET "Β*
«0
WASTE ACTIVATED
SLUDGE
Fig. 1 Schematic Flow Diagram for Bioprecipitation Process Using Pure Oxygen (after Budd and
Lambeth)