WASTE
MANAGEMENT
James M. Ebeling, Ph.D.
Research Engineer
Aquaculture Systems Technologies, LLC
New Orleans, LA
Solids Management
Solids Capture – Quick Review
• Effluent Treatment for:
–
–
–
–
–
Total Suspended Solids (TSS)
Settleable Solids
Biochemical oxygen demand (BOD5)
Total Phosphorus (TP)
Nitrogen
• Total Ammonia Nitrogen (TAN)
• Nitrate Nitrogen (NO3-N)
– Pathogens
Removed
with
solids
Solids Capture – Quick Review
• Gravity Separation
• Settling Basins
• Quiescent Zones
• Off-line Settling Basins
• Tube/Plate Settlers
• Swirl Separators
• Physical Filtration
• Microscreen Filters (drum, disc, belt)
• Granular Media Filters
Solids Waste Characteristics
Aquacultural
Sludge
Parameter
Domestic Sludge
Range
Mean
Range
Typical
Total Solids (%)
1.4–2.6
1.8
2.0–8.0
5.0
TVS (% of TS)
74.6–86.6
82.2
50–80
65
BOD5 (mg/L)
1,590–3,870
2,760
2,000–30,000
6,000
TAN (mg/L)
6.8–25.6
18.3
100–800
400
pH
6.0–7.2
6.7
5.0–8.0
6.0
Alkalinity
284–415
334
500–1,500
600
Solids Mass Balance
Feed
O2
CO2
Ammonia
BOD, TSS,
N, P
Waste Management Overview
• Treatment processes result in captured solids
that must be managed:
• Storage and Thickening
• Thickening and Stabilization
• Biosolids utilization and disposal
• Stabilization of solids for pathogen destruction
Solids Storage and Thickening
Quiescent Zones
Settling Basins
Solids Storage and Thickening
Earthen Ponds
Solids Storage and Thickening
• Slurrystore Tanks
Engineered Storage Products Company
Solids Thickening and Stabilization
Captured solids require further dewatering:
TSS
Microscreen Filter
Backwash
0.01-0.8%
Quiescent Zone Siphon
3-5%
Quiescent Zone Siphon
3-5%
Solids Thickening
• Solids must be thickened (dewatered) to
reduce disposal costs/management.
– Dewatering reduces sludge volume.
– Sludge volume for 1,000 lb dry weight solids:
– 12,000 gal
– 2,400 gal
– 1,200 gal
– 800 gal
1% TSS
5% TSS
10% TSS
15% TSS
Solids Thickening Methods
• Processes to thicken clarifier/filter backwash
solids:
• offline settling basins (sludge thickening tanks)
• wetlands or sand beds
• coagulation/flocculation
• belt filters
• GeoTextile Bags
Off-line Settling Basins
• Designed for solids collection, thickening
and storage
• Intermittently loaded from
– quiescent zone cleaning
– filter backwashing
– system cleaning
Off-line Settling Basins
Off-line Settling Tanks
at Freshwater Institute
Off-line Settling Basins
Recirculating Aquaculture Systems Short Course
Off-line Settling Basins
LARGE structures with
solids storage capacity
Big Spring FCS (PA)
Off-line Settling Basins Design
Idaho DEQ (1998) design criteria for off-line settling
basins:
•
•
•
•
•
•
overflow rate of 0.0015 ft3/sec flow per ft2 surface area
usually 3.5 ft deep
usually built in pairs
tank MUST capture 85% TSS
TSS effluent CANNOT exceed 100 mg/L in 8 hr composite
settleable solids effluent CANNOT exceed 1.0 ml/L in any
sample
Off-line Settling Basin Solids Removal
• OPTION 1: Decant tank, harvest solids with backhoe or
front end loader
– Let solids dry for several days to 25% to 35% dry weight
• OPTION 2: Sprinkler application to adjacent fields
– 0.2% solids dry weight (after mixing solids)
• OPTION 3: Decant tank, then pump out manure
– 12% avg. solids dry weight
– 20% max. solids dry weight
– pumping method influences % solids removed
Wetlands – Sand Beds
Created Wetlands drying beds:
• combine solids dewatering and disposal
• sand drying bed planted with reeds
• plants facilitate dewatering
• loading
• 30-60 kg dry solids per year per m2 area
• 7-10 cm sludge at 2% solids every 7-21 days
• series of beds receive sequential batches
• store solids for 10 years
Coagulation/Flocculation
Coagulation
Process of decreasing or neutralizing the electric charge on
suspended particles
Flocculation
Process of bringing together the microfloc particles to form
large agglomerations by the binding action of flocculants
Recirculating Aquaculture Systems Short Course
Suspended Solids Removal
(Alum, Ferric Chloride, AMD)
Alum in wastewater yields the following reaction:
Al2(SO4)314 H2O + 3Ca(HCO3)2  3Ca SO4 + 2Al(OH)3 + 6CO2+ 14H2O
Insoluble aluminum hydroxide is a gelatinous
floc
Ferric Chloride in wastewater yield the following reaction:
2FeCl3 6H2O+ 3Ca(HCO3)2  3CaCl2 +2Fe(OH)3 + 6 CO2 + 12H2O
Insoluble ferric hydroxide is a gelatinous floc
Recirculating Aquaculture Systems Short Course
Phosphorus Removal
(Alum, Ferric Chloride, AMD)
Basic reaction:
Al+3 + HnPO43-n  AlPO4 + nH+
Fe+3 + HnPO43-n  FePO4 + nH+

Simplest form of reaction, bench-scale
test required to establish actual removal
rate
Recirculating Aquaculture Systems Short Course
Coagulation/Flocculation Aids
(Polymers)
• charge
neutralization (low molecular weight polymers)
neutralize negative charge on particle
• bridging
between particles
(high molecular weight
polymers)
long loops and tail connect particles
Recirculating Aquaculture Systems Short Course
Coagulation/Flocculation Aids
(Polymers)
Advantages:
High Molecular Weight Long-chain
Polymers
• lower dosages requirements
• reduced sludge production
• easier storage and mixing
• MW and charge densities optimized “designer” aids
• no pH adjustment required
• polymers bridge many smaller particles
• improved floc resistance to shear forces
Recirculating Aquaculture Systems Short Course
Evaluation: alum/polymers
Total Suspended Solids (mg/L)
Polymer
Optimum
Dosage
Raw
sample
Treated
sample
%
Removal
LT 27
0.8 mg/L
557
7
LT 7995
6 mg/L
859
E 38
3 mg/L
A-120
Reactive Phosphorus (mg/L P)
Raw sample
Treated
sample
%
Removal
99%
10
0.17
98%
10
99%
17
0.26
98%
1566
20
98%
34.8
0.57
98%
0.8 mg/L
654
7
99%
11.4
0.16
98%
CE 834
5 mg/L
719
4
99%
13.7
0.27
98%
CE 1950
5 mg/L
958
10
99%
17.1
0.35
98%
Recirculating Aquaculture Systems Short Course
Synergetic Effect of alum/polymers
Percent Removal
Turbidity (NTU)
Optimal Dosage
polymer
polymer
50 mg/L alum /
polymer
50 mg/L alum /
polymer
Magnafloc LT 7990
No Effect
8
---
95.2%
Magnafloc LT 7991
20 mg/L†
8
86.4%
95.3%
Magnafloc LT 7992
20 mg/L
4
91.6%
95.4%
Magnafloc LT 7995
10 mg/L
6
85.1%
96.3%
Magnafloc LT 20
No Effect
0.8
---
88.1%
Magnafloc LT 22S
1.0 mg/L†
0.3
67.8%
94.8%
Magnafloc LT 26
No Effect
0.8
---
94.4%
Magnafloc E 38
1.0 mg/L
3
45.1%
95.8%
Ciba Specialty Chemicals
Recirculating Aquaculture Systems Short Course
Other WQ Effects of alum/polymers
TAN
NO2-N
NO3-N
TN
CBOD5
COD
(mg/L N)
(mg/L N)
(mg/L N)
(mg/L N)
(mg/L)
(mg/L)
Initial
Sample
0.75
0.430
10.8
34
437.7
719
LT 27
0.32
0.218
3.6
4.8
17.8
36
LT 7995
0.28
0.216
3.7
4.4
8.1
21
E 38
0.24
0.224
3.7
4.7
12.0
27
A-120
0.36
0.222
3.6
4.3
17.7
29
CE 834
0.19
0.191
2.7
3.5
7.7
20
CE 1950
0.24
0.219
3.6
4.5
8.9
21
Recirculating Aquaculture Systems Short Course
Belt Filter
Coagulation/Flocculation Tank
Recirculating Aquaculture Systems Short Course
Belt Filter
Belt Filter
Recirculating Aquaculture Systems Short Course
Belt Filter-Sludge
• Alum
• 13.2% ± 1.1
• Polymer
• 11.6% ± 2.2
• Alum/Polymer
• 12.6% ± 1.4
Recirculating Aquaculture Systems Short Course
What is a Geotube ®?
• Geotubes are
constructed of Mirafi®
high strength woven
geotextile
• Geotube ® containers are
custom fabricated with
seaming techniques that
resist pressures during
pumping operations.
• High flow rate allows
liquid to dewater, while
containing solids.
Recirculating Aquaculture Systems Short Course
Benefits of Geotube® Technology
•
•
•
•
•
•
•
•
Effective high volume containment.
Efficient dewatering & volume
reduction.
Cost effective.
No special equipment required.
Custom site specific fabrication.
Lower equipment cost.
Low maintenance.
Low labor cost.
Recirculating Aquaculture Systems Short Course
Containment
Containment
Dewatering
Disposal
Recirculating Aquaculture Systems Short Course
Applications for Aquaculture
Freshwater Applications
• Winter Storage of Biosolids
• Composting
Marine Applications Tested by Miratech
• Marine benthic waste
• Marine fresh cage waste
• Hatchery recirculation and pass through waste
• Processing plant blood water
• Biofouling waste from cleaning shellfish cages
• Biofouling toxic waste (copper) from salmon net
cleaning
Recirculating Aquaculture Systems Short Course
Research – Large Geobags
• Each of the three bags were operated at a mean hydraulic
loading rate of 58.7 Liters/day/m2 geotextile material.
• Solids pumped to the bags for 0.5 minutes each hour (24/7).
Recirculating Aquaculture Systems Short Course
Results of Study
Bag Influent
Bag Effluent
% Removal
1875 ± 811
98 ± 25
93.0 ± 3
Total Phosphorus (mg/l)
40.6 ± 16
12.7 ± 4.1
65 ± 12
Dissolved Reactive P
(mg/l)
Total Nitrogen (mg/l)
1.1 ± 0.7
10.8 ± 3.2
63.8 ± 25
37.9 ± 12
-1145 ±
574
32 ± 24
TAN (mg/l)
1.7 ± 0.6
28.1 ± 9.9
-1587 ±
490
cBOD5 (mg/l)
517 ± 241
309 ± 80
47 ± 15
TSS (mg/l)
36 Samples over 3 months
Recirculating Aquaculture Systems Short Course
Biosolids Utilization/Disposal
• Composting
• Land Application
– Slurry (<1% solids)
– Thickened Sludge (>5% solids)
• Contract hauling
Composting
Composting Bin
Composting Bin
Cantrell Creek Trout Farm (NC)
Land Application
• Liquid/Slurry Application
– Solids are easily transferred and distributed when they are >1%
solids
– Designed as a Slow Rate Land Treatment (crop irrigation)
• Thickened Sludge Application
– Designed as a soil amendment or fertilizer (as part of a crop
nutrient management plan)
– Applied from tanker trucks: surface spreading, incorporation,
direct injection
Land Application
When the solids content is less
than 1%, solids and slurries are
easily pumped and distributed
Contract Hauling
Questions?