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Mobile Treatment Unit for septage emptying and safe disposal in Dindigul, India
Aaron Forbis-Stokes1,2
Arumugam Kalimuthu3, L. Peter3, Marc Deshusses1
1Duke University, Dept. of Civil & Environmental Engineering, Durham, NC, USA2Triangle Environmental, Durham, NC, USA
3WASH Institute, Kodaikanal, India
Background
2
Urban septage treatment solutions are needed at
decentralized level
38% of urban households in India62% of households in cities <1 million
Background
3
Treat and discharge septage onsite.Save time, fuel, and money.
Mobile Treatment Unit – Technology overview
4
MTU uses off-the-shelf separation technologies to produce a clean
effluent quickly and cost-effectively
Septic Tank
Centrifuge
Holding Tank(58 µm mesh)
Dual-Media(Pebbles & Sand)
GAC(#4x8 mesh)
MF (x2)(10 & 5 µm)
UF(0.02 µm)
Discharge
Solids collection(Compost/Disposal
Partial UF return
Methods
• Phase I – 1 unit• No backwash
• Operational: Pressure, flow & power every 15 minutes
• Treatment: First pass & final pass sample each location
• Phase II – 4 units (3 new)• Reverse flow backwash every 30
minutes
• Operational: Pressure, flow & power every 15 minutes
• Treatment: Final pass septage & UF effluent
5
Target flow: 3,000 L/hrPressures: membrane life and fouling
Effluent quality: Meet Indian discharge standards
Operational performance – Phase I
0
200
400
600
800
1.000
1.200
1.400
1.600
1.800
2.000
0 20 40 60 80 100 120 140 160
Flo
w r
ate
(L/h
)
Time (h)
6
Initial flow-rates decreased and did not fully recover.
0 20.000 40.000 60.000 80.000 100.000
0,00
0,50
1,00
1,50
2,00
2,50
3,00
0,00
0,50
1,00
1,50
2,00
2,50
3,00
0 20 40 60 80 100 120 140 160
Volume treated (L)TM
P (
bar
)
Time (h)
MF UF
Operational performance – Phase I
7
Rapid increase of Transmembrane Pressure for MF
Treatment performance – Phase I
8
Total Coliform (CFU / 100 mL)
10
100
1,000
10,000
100,000
1,000,000
Effluent meets Indian discharge limits
1
COD (mg / L)
Phase I Conclusions
9
Phase I Challenge Phase II Improvement
Maintain high target flow rates Routine backwashing during run
Rapid MF fouling Increase MF surface area
Occasional high solids tanks Additional low-cost pre-screening
Standard India CPCB WASHi Effluent
pH 6.5-9.0 7.7 ✔
COD (mg/L) [old, not in new] 100 66 ✔
BOD (mg/L) 30 24 ✔
TSS (mg/L) 100 103 ✘
Total Coliform (CFU/100 mL) 1,000 83 ✔
0
500
1.000
1.500
2.000
2.500
3.000
3.500
4.000
4.500
0 5 10 15 20 25
Flo
w r
ate
(L/h
)Time (h)
0
500
1.000
1.500
2.000
2.5003.000
3.500
4.000
4.500
0 10 20 30 40
Flo
w r
ate
(L/h
)
Time (h)
0
500
1.000
1.500
2.000
2.500
3.000
3.500
4.000
4.500
0 5 10 15 20 25 30 35
Flo
w r
ate
(L/h
)
Time (h)
0
500
1.000
1.500
2.000
2.500
3.000
3.500
4.000
4.500
0 50 100 150
Flo
w r
ate
(L/h
)
Time (h)
Operational performance – Phase II
10
MTU-1
MTU-3MTU-4
MTU-2Flow rates maintained,
TMP decreased
Treatment performance – Phase II
11
Expenses
$9.317
$3.617
$132
$2.620
$0
$5.000
$10.000
$15.000
$20.000
$25.000
$30.000
$35.000
Traditional septic MTU
CapEx
Hardware
Monitoring
Filtration
Vehicle
12
$0
$2
$4
$6
$8
$10
$12
$14
$16
$18
MTU
OpEx($ / 3,000 L Septic tank)
Cleaning
Power
Diesel
Filtration
Vehicle
$46 typical fee for 3,000 L septic tank
Case Study: MTU in Kerala
13
• 4 MTUs sent to Kerala in response to severe flooding, August 2018
• First 9 days:• 330,000 L septage treated• 34,965 beneficiaries
• Aug. 25th – Dec. 14th 2018: • 156 septic tanks emptied• 918,222 L treated• ~200,000 beneficiaries• Effluent samples met all discharge
standards
Next steps
Patent:Filed and awaiting finalization
Commercialization In discussion with partners
Interested customers: relief agencies, small-scale entrepreneurs
Automation:Improve operation efficiency, decrease operator requirements
14
Thank you!
15
Arumugam Kalimuthu Marc Deshusses Aaron Forbis-Stokes
[email protected] [email protected] [email protected]
Program Director Professor Sanitation Technology Consultant
WASH Institute Duke University Triangle Environmental
www.washinstitute.org www.sanitation.pratt.duke.edu www.triangle-environmental.com
Additional slides
16
0 20.000 40.000 60.000
0,00
0,50
1,00
1,50
2,00
2,50
3,00
3,50
0 5 10 15 20
Volume treated (L)
TMP
(b
ar)
Time (h)
MF UF
0 10.000 20.000 30.000
0,00
0,50
1,00
1,50
2,00
2,50
3,00
3,50
0 10 20 30
Volume treated (L)
TMP
(b
ar)
Time (h)
MF UF
Operational performance – Phase II
17
MTU-2 MTU-4
MF no longer foulingLow TMP,
likely undersized pump