A Gritty Face-Off: Mechanical Vortex Versus Stacked Tray ... · A Gritty Face-Off: Mechanical...
Transcript of A Gritty Face-Off: Mechanical Vortex Versus Stacked Tray ... · A Gritty Face-Off: Mechanical...
A Gritty Face-Off:A Gritty Face Off:Mechanical Vortex Versus Stacked
Tray Grit RemovalTray Grit RemovalJeff Sober
May 27, 2011
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Today, we will discuss:
1 North Texas Municipal Water District’s 1. North Texas Municipal Water District s Panther Creek Regional WWTF
2. Why we decided to put two technologies y e dec ded to put t o tec o og esside-by-side
3. How we did it for as cheap as possiblep p4. The grit testing methods used5. The results!5. The results!
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Forced vortex basins have a low capital costcapital cost
95%65%
100 200 300 400Micron Size
• Low headloss
Micron Size
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The Headcell in theory provides higher efficiency grit removalhigher efficiency grit removal
95%
100 200 300 400Micron Si e
• Large surface area in a small
Micron Size
• Large surface area in a small footprint
• Short settling distanceN i t i b i• No moving parts in-basin
• Same level of O&M effort
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How can we provide this at the lowest possible cost? Don’t design Headcell for peak flow Don t design Headcell for peak flow Provide system in existing footprint Optimize flow between systems Optimize flow between systems
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To compare the units, we utilized two testing protocols
l1. Total grit accumulation testing performed by performed by NTMWD
2. Third Party vertical flow profile testingp g
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There was a significant difference in the total pounds
2,000
1,600
1,800
1,000
1,200
1,400
un
ds
Week 2Vortex Week 4
Vortex
600
800
,000
Po
u
Week 1Headcell Week 3
200
400
Week 3Headcell
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We also measured TS and VS
7,000Total Pounds Removed
5 000
6,000 Total Solids Removed
Grit Removed (Inorganics)
4,000
5,000
Per
Week
2,000
3,000
s R
em
oved
P
1,000Po
un
ds
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Week 1 (Headcell) Week 2 (Vortex) Week 3 (Headcell) Week 4 (Vortex)
Results were not as expected250
y
200
ed
Per
Day
150
ds
Rem
ove
Grit Removed (Inorganics)
100
ag
e P
ou
nd
50
Avera
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Headcell Average Vortex Average
The results show that the grit basin was working as designed6,000
88% Removal
5,000
6,000
97% Removal
Removal
3,000
4,000
unds
2,000
Tota
l Pou
0
1,000
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Headcell Influent
Headcell Effluent
Vortex Influent
Vortex Effluent
The system was adjusted
1 Blow down sequence frequency increased1. Blow down sequence frequency increased2. Wash water rates increased
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Another week of testing had improved results
2,000
1,600
1,800
1,200
1,400
s
Week 2Vortex
Week 4Vortex
800
1,000
Po
un
d
Week 1
SeparateTest
Headcell
400
600Headcell
Week 3Headcell
Headcell
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0
200
Another week of testing had improved results
1,200
1,000 Pounds Removed
Solids Removed
800
emoved
Solids Removed
Grit Removed (Inorganics)
400
600
Poun
ds Re
200
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0
Headcell Average Vortex Average Headcell Test 2 Average
Let this be a lesson, your eyes can fool you!
Don’t assume a system is optimized, even if it is proprietary black box information
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it is proprietary black box information
In summary, the new grit system does remove less organicsg
80%
Vortex Average Headcell Average
74%
80%
45%
30%
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Percent Solids Percent Inorganics