Algal-Sludge Granules as a Novel
Technique for Wastewater
Treatment
Ahmed S. Abouhend1,2
1
Civil & Env. Eng. Dep., Umass Amherst, USA
2 Marine Pollution Lab., NIOF, Egypt
The Northeast Residuals And Biosolids Symposium,
Oct. 19, 2015
Civil & Environmental Engineering
Background
!  Conventional Wastewater Treatment Process
Cost (Energy):
https://www.britannica.com/technology/wastewater-treatment/images-videos
Civil & Environmental Engineering
"  3-4 % of US Electricity
2
Secondary Treatment
!  Activated Sludge System
Cost (Energy):
"  25-60% of costs
http://www.ewisa.co.za/misc/wastewater/defaultas1.htm
https://www.lakelandgov.net/water/education/plant-tours/water-reclamation-plant/tour-stop-no-5
Civil & Environmental Engineering
3
Wastewater as a Significant Energy Source
"  Chemical energy in wastewater
!  Based on COD; 1 m3 = 6-8 MJ
"  Energy used for treatment
!  1 m3 = 0.6 kW h = 2.16 MJ
Wastewater holds about 2-5 times the
energy used to treat it.
!  The Question: How to Recover This Energy?
Civil & Environmental Engineering
4
Alternative Technologies
!  Algal-based Wastewater Treatment Technologies
"  Most wastewater
treatment lagoons in the
U.S. do not harvest algae
biomass.
http://algaebiogas.eu/algal_bacterial_wwt
Civil & Environmental Engineering
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The Novel Technology: Algae-Sludge Granules
Algae
Bacteria
Civil & Environmental Engineering
6
How the opportunity was identified?
Granules
Seed Granule 10 mm
Wastewater
Treated
Seed Granules
water
Biomass
Reactor Granules
Settling
Civil & Environmental Engineering
Granules 2-4 mm
7
Application: Sequenced Batch Reactors
#  2 SBRs (1.5 L each) by 4- 6 hrs cycles/day. R1
#  The WW is the primary effluent of AWWTP.
#  150 days of operation.
#  2 Light sequences were studied;
R1: 3.5 hr l- 2.5 h d
R2: 2.5 hr d- 3.5 h l
R2
# HRT:
1 day
0.75
46
1
17
47
0.5
8
64 72
0.75 day
79
150
Days of Operation
Civil & Environmental Engineering
8
Potential Impact of Treatment Process
Influent WW
Cycling and Mixing
Civil & Environmental Engineering
After 15 min Settling
9
Effluent Quality
!  COD Removal
Conentration (mg/L)
250
TCOD
200
150
Inf
100
R1
R2
50
0
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
Days of Operation
Civil & Environmental Engineering
10
Effluent Quality
!  Total Nitrogen (TN)
TN
Conentration (mg/L)
50
40
Inf
30
R1
20
R2
10
0
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
Days of Operation
Civil & Environmental Engineering
11
Effluent Quality
!  Ammonia (NH3)
50
NH3
45
Conentration (mg/L)
40
35
Io
30
G1
25
G2
20
15
10
5
0
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
Days of Operation
Civil & Environmental Engineering
12
Effluent Quality
!  Phosphate (PO4)
10
Conentration (mg/L)
PO4
8
C5H7O2NP0.1
Io
6
G1
G2
4
2
0
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
Days of Operation
Civil & Environmental Engineering
13
Self Aeration : Natural Oxygenation
O2 Production Rate
14
O2 Production
DO (mg/l)
12
Specific Oxygen
Production Rate:
10
y = 0.2011x + 1.7461
R² = 0.96267
8
6
8.0 (mg/gVSS)/hr
4
2
0
0
10
20
30
40
Time (Min)
Civil & Environmental Engineering
50
60
14
Biomass Separation and Energy Production
!  Algal-sludge granules settled with an average
settling velocity of Biofeed
12 m/h.Stock
Energy Generation
0 min
1/2 min
1 min
Fermentation
5 min
15 min
Anaerobic Digestion
Transesterification
<< 99% Biomass Separation Efficiency
Civil & Environmental Engineering
15
The Yield (Biomass-Energy Conversion)
!  The biomass yields were up to 400% higher than
typical activated sludge:
1 g COD Consumed
1.41 g COD (Biomass)
Algal Granules
Civil & Environmental Engineering
0.34 g COD (Biomass)
Activated Sludge
16
Conclusion
Algae-Sludge Granules Technology
!  Demonstrated wastewater treatment without external
aeration.
!  Allows for recovery of energy laden in WW in the form
of harvestable biomass and leads to substantial cost
reduction in WW treatment.
!  Achieves environmental benefits reducing the green
house gases emitted into the atmosphere
!  The successful application could provide an alternative
to the activated sludge process.
Civil & Environmental Engineering
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Current and Future Research
!  Operating a pilot ASG unit at AWWTP:
* Now; 30 L reactor as SBR
* Our goal: 1000-2000 L System
!  Investigation on several others
$  Pathogens
$  Heavy metals
!  Anaerobic digestion of ASG biogranules.
Civil & Environmental Engineering
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Acknowledgement
#  Park Lab Group
#  NIOF, Egypt
$  Chul Park, Ph.D.
$  Khalid El-Moselhy, Ph.D.
$  Jeongmi Seo
$  Christopher Watt
$  Adam McNair
Funding
Civil & Environmental Engineering
19
Civil & Environmental Engineering
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