Ponds for Wastewater Treatment
Ponds
for Wastewater Treatment
Gilles Altner Global Environmental Engineering Ltd
The Pond System
Pre Treatment
Anaerobic Pond
Facultative Pond
Maturation Pond
Rock Filter
Sand Filter
Wetland
Membranes
UV
g2e
Overview 1. Facultative & aerated ponds: How do they work? (Facultative, aerated, media ponds)
2. design aspects aspects & & upgrade upgrade technologies technologies. 2. Pond Pond design (Sludge, inlet, outlet, buffering, hydraulic, aeration, mixing, curtain, media)
3. Consents for for ponds. ponds 3. Resource Resource Consents (Ponds versus high rate treatment plants)
4. Other pond issues.
5. the pond will not do anymore. 5. When Other pond issues (Turning the pond into something else)
g2e
Overview 1. Facultative & aerated ponds: How do they work? (Facultative, aerated, media ponds)
g2e
Waste Stabilization Ponds The Facultative Pond Sunlight Wind (mixing & aeration) O2 (daylight hours)
O2 Re-aeration
Settleable solids Bottom sludge Organic wastes
CO2
1.2 to 5 m
Algae
New Cells
Wastewater
If oxygen is not present in upper layer of pond, odorous gases can be released H2S
NH3, PO43, etc O2
NH3, PO43, etc
Dead Cells
T (temperature)
CO2 H2S + 2O2
Bacteria
H2SO4
New Cells • ANAEROBIC PONDS Dead Cells
• FACULTATIVE PONDS CO + NH + H S + CH
Organic acids, alcohols
2
3
2
• MATURATION PONDS
4
Aerobic Aerobic Zone Zone 0.3 to 0.6m Facultative / Anoxic Facultative Zone 0.5 to 0.8m Anaerobic Anaerobic Zone Zone 0.1 to 0.3m
g2e
Waste Stabilization Ponds • FACULTATIVE PONDS: For domestic and mixed loading Depth 1.5 to 2m, HRT 20 to 60 days, in NZ up to 90 days Up to 80% BOD, in theory up to 80% Am-N reduction (T !!) In theory up to 90% TN reduction, not in New Zeand At temperatures 20 to 25 dgrC, BOD load 100 - 400 kgBOD/ha/day
• Sludge AEROBIC, FLOW about THROUGH PONDS 3/yr/l/sec or about 10mm/yr production 5 to 7 m 2 to 5 m deep, HRT 3 to 5 days, partially / completely mixed
High TSS & BOD loading, no Am-N or TN reduction Temperature dependant, BOD load 100 to 350 kgBOD/m3/day
• AEROBIC PONDS WITH SOLIDS RECYCLE Depth 1 to 1.5m, HRT 5 to 10 days Some BOD, some Am-N reduction, some TN reduction, but mainly TSS (algae) reduction and disinfection
g2e
Waste Stabilization Ponds • AERATED PONDS, with or without solids return Generally 3m+ deep, HRT 1 to 3 d, 1d, 1d, 1d to limit algae growth MLSS of about 400 mg/l, no algae, TN reduction only if recycle Power for aeration and mixing 6W/m3 first, 1 to 1.5 W/m3 others Sludge production +/- 40m3/yr/l/sec (= 6 to 7 times normal pond)
Treatment BOD < 20 mg/l TSS < 30 mg/l
Aerated & partially / complete mixed Lagoon
Series of low power aerated Lagoons
Am-N < 5 mg/l TN < 15 mg/l
g2e
Waste Stabilization Ponds • PONDS with GROWTH MEDIA: Advanced treatment 1.5 to 3m+ deep, HRT 20 days+, less possible MLSS low, but high TSS (biomass growth), aeration required
BOD5< 15mg/l, Am-N< 1 mg/l, TN< 10 mg/l Sludge production 5 to 7 m3/yr/l/sec (10mm/year) Algae
New Cells
NH3, PO43, etc O2
NH3, PO43, etc
Dead Cells
CO2
Biomass
Aerobic Zone
T (temperature)
Bacteria New Cells Dead Cells
O2
O2
O2
Facultative Zone Anaerobic Zone
g2e
Overview 1. Facultative & aerated ponds: How do they work? (Facultative, aerated, media ponds)
2. Pond design aspects & upgrade technologies (Sludge, inlet, outlet, buffering, hydraulic, aeration, mixing, curtain, media)
4. Other pond issues.
5. the pond will not do anymore. 5. When Other pond issues (Turning the pond into something else)
g2e
The Typical New Zealand Pond
0 0
Sludge Level Two pond system Up to 1.3m 100m x 90m x 1.4m (90% waterx depth) 100m of x 60m 1.8m
WETLANDS 10
10
20
20
30
30
50
50
60
60
70
70
POND 1
80
80 90
10
10
POND 1
0
0
Inlet
20
20
150m x 60msolids plus with pond 110m x 80m and plant overgrowth
40
40
Wetlands Wetland clogged
Aerator
30
30
40
50 60 70
90
POND 2
80
Odours Poor flow conditions Algae blooms
40
Aerator
Wetland failure HRT Discharge out of RC Theoretical: 25 days True : 8 days
g2e
Outlet
Simple Pond Improvements Maintaining & Improving Biological / hydraulic load
Reduce shock loads & hydraulic peaks Costs, community & industry input
Desludging
Regain HRT Costs, damage, disposal, verification
Inlet / outlet design
Increase HRT, use flow buffering Available freeboard, waveband material
Dividing curtains / barriers
Prevent short-circuiting Design, quality of materials used
Aeration / mixing / DO
Reduce odours and overloading
Basic improvements
Type, Get them water right depth, ! purpose, power
g2e
Simple Pond Improvements
g2e
Advanced Pond Improvements What has to be achieved? Dividing ponds
Improve treatment efficiency What type of pond? HRT
Heighten the embankment
Increase HRT, prepare for the future What for? Costs
Rockfilter (aer/non-aer)
Improve TSS, BOD5, Am-N and TN Costs, design, references !!
Growth media
Increase BOD5, Am-N, TN treatment Costs, aeration required, HRT
Floating wetlands
Improve TSS, BOD5 (TN, TP), ((Am-N)) Site data, site specific, costs, quality
g2e
Growth Media Carbon black sleeve with floatation tube. Mats are connected to stainless steel wires attached on each side of the treatment pond
Lower UltraWeave layer Upper UltraWeave layer promotes growth of promotes bacterial sessile algae and higher biofilms & acts as hydraulic barrier for organisms for uptake of DRP and ammonia BOD5 and TSS removal
g2e
Growth Media Installed
Aerobic Zone
Air release at >200 mbar dP Biomass Support Media
Air flow
g2e
Typical results at start-up
g2e
Floating Wetlands
Floating wetlands 2012 fits all ’’ Floating wetlands installation Know what you need –shortly avoidJanuary ’’after one system
g2e
Example 1: Ponds not achieving RC
Domestic & Industriel Flow: 680 960 m3/d Peak: 1,600 m3/d BOD5 175 kg/d TKN 43 kg/d
WETLANDS
POND 1
Inlet
Treatment Required TSS/BOD5 < 20 mg/l TKN < 6 mg/l Am-N < 3 mg/l TP < 3 mg/l
POND 2
g2e
Outlet
Example 1: Ponds not achieving RC > Insufficient HRT
2.6m
2.3m 1.4m
1.6m
POND 1
POND 2
g2e
Example 1: Pond not achieving RC > Improve treatment
Improve flow at inlet, transfer & outlet WETLANDS
Automatic screening & flow metering
Aeration
& mixing in inlet area
Biological growth media & aeration
Alkalinity dosing & Fe dosing for TP reduction
g2e
Overview 1. Facultative & aerated ponds: How do they work? (Facultative, aerated, media ponds)
2. design aspects aspects & & upgrade upgrade technologies technologies. 2. Pond Pond design (Sludge, inlet, outlet, buffering, hydraulic, aeration, mixing, curtain, media)
3. Resource Consents for ponds (Ponds versus high rate treatment plants)
4. Other pond issues.
5. the pond will not do anymore. 5. When Other pond issues (Turning the pond into something else)
g2e
Resource Consents for Ponds Ponds Versus High Rate Treatment Plants HRT
Pond: 20 – 80 days, HRTP: hours Increase sampling frequency
Discharge Quality
Pond: day/night, season, HRTP: stable Time / season related requirements
Discharge Flows
Pond: precipitation, HRTP: no influence
Floating wetlands
Increase treatment Weather / streamcapacity level dependent
(Rockfilter Capacity aer./non-aer.) Treatment
Target Incrementally TN and TP reduction Pond: upgradable HRTP: Built for T0 + 20 yrs Target TSS & organics discharge Staged upgrade consents Reduce TSS & organics loading Review overseas experience Reduce BOD TN, TP specific 5, TSS,be Conditions should pond
Install Ultrasound Install trickling filter Disposal to land Install interm. sandfilter Resource Consents
g2e
Pond System Upgrades It is possible !
Questions ? g2e
for Wastewater Treatment
Gilles Altner Global Environmental Engineering Ltd
The Pond System
Pre Treatment
Anaerobic Pond
Facultative Pond
Maturation Pond
Rock Filter
Sand Filter
Wetland
Membranes
UV
g2e
Overview 1. Facultative & aerated ponds: How do they work? (Facultative, aerated, media ponds)
2. design aspects aspects & & upgrade upgrade technologies technologies. 2. Pond Pond design (Sludge, inlet, outlet, buffering, hydraulic, aeration, mixing, curtain, media)
3. Consents for for ponds. ponds 3. Resource Resource Consents (Ponds versus high rate treatment plants)
4. Other pond issues.
5. the pond will not do anymore. 5. When Other pond issues (Turning the pond into something else)
g2e
Overview 1. Facultative & aerated ponds: How do they work? (Facultative, aerated, media ponds)
g2e
Waste Stabilization Ponds The Facultative Pond Sunlight Wind (mixing & aeration) O2 (daylight hours)
O2 Re-aeration
Settleable solids Bottom sludge Organic wastes
CO2
1.2 to 5 m
Algae
New Cells
Wastewater
If oxygen is not present in upper layer of pond, odorous gases can be released H2S
NH3, PO43, etc O2
NH3, PO43, etc
Dead Cells
T (temperature)
CO2 H2S + 2O2
Bacteria
H2SO4
New Cells • ANAEROBIC PONDS Dead Cells
• FACULTATIVE PONDS CO + NH + H S + CH
Organic acids, alcohols
2
3
2
• MATURATION PONDS
4
Aerobic Aerobic Zone Zone 0.3 to 0.6m Facultative / Anoxic Facultative Zone 0.5 to 0.8m Anaerobic Anaerobic Zone Zone 0.1 to 0.3m
g2e
Waste Stabilization Ponds • FACULTATIVE PONDS: For domestic and mixed loading Depth 1.5 to 2m, HRT 20 to 60 days, in NZ up to 90 days Up to 80% BOD, in theory up to 80% Am-N reduction (T !!) In theory up to 90% TN reduction, not in New Zeand At temperatures 20 to 25 dgrC, BOD load 100 - 400 kgBOD/ha/day
• Sludge AEROBIC, FLOW about THROUGH PONDS 3/yr/l/sec or about 10mm/yr production 5 to 7 m 2 to 5 m deep, HRT 3 to 5 days, partially / completely mixed
High TSS & BOD loading, no Am-N or TN reduction Temperature dependant, BOD load 100 to 350 kgBOD/m3/day
• AEROBIC PONDS WITH SOLIDS RECYCLE Depth 1 to 1.5m, HRT 5 to 10 days Some BOD, some Am-N reduction, some TN reduction, but mainly TSS (algae) reduction and disinfection
g2e
Waste Stabilization Ponds • AERATED PONDS, with or without solids return Generally 3m+ deep, HRT 1 to 3 d, 1d, 1d, 1d to limit algae growth MLSS of about 400 mg/l, no algae, TN reduction only if recycle Power for aeration and mixing 6W/m3 first, 1 to 1.5 W/m3 others Sludge production +/- 40m3/yr/l/sec (= 6 to 7 times normal pond)
Treatment BOD < 20 mg/l TSS < 30 mg/l
Aerated & partially / complete mixed Lagoon
Series of low power aerated Lagoons
Am-N < 5 mg/l TN < 15 mg/l
g2e
Waste Stabilization Ponds • PONDS with GROWTH MEDIA: Advanced treatment 1.5 to 3m+ deep, HRT 20 days+, less possible MLSS low, but high TSS (biomass growth), aeration required
BOD5< 15mg/l, Am-N< 1 mg/l, TN< 10 mg/l Sludge production 5 to 7 m3/yr/l/sec (10mm/year) Algae
New Cells
NH3, PO43, etc O2
NH3, PO43, etc
Dead Cells
CO2
Biomass
Aerobic Zone
T (temperature)
Bacteria New Cells Dead Cells
O2
O2
O2
Facultative Zone Anaerobic Zone
g2e
Overview 1. Facultative & aerated ponds: How do they work? (Facultative, aerated, media ponds)
2. Pond design aspects & upgrade technologies (Sludge, inlet, outlet, buffering, hydraulic, aeration, mixing, curtain, media)
4. Other pond issues.
5. the pond will not do anymore. 5. When Other pond issues (Turning the pond into something else)
g2e
The Typical New Zealand Pond
0 0
Sludge Level Two pond system Up to 1.3m 100m x 90m x 1.4m (90% waterx depth) 100m of x 60m 1.8m
WETLANDS 10
10
20
20
30
30
50
50
60
60
70
70
POND 1
80
80 90
10
10
POND 1
0
0
Inlet
20
20
150m x 60msolids plus with pond 110m x 80m and plant overgrowth
40
40
Wetlands Wetland clogged
Aerator
30
30
40
50 60 70
90
POND 2
80
Odours Poor flow conditions Algae blooms
40
Aerator
Wetland failure HRT Discharge out of RC Theoretical: 25 days True : 8 days
g2e
Outlet
Simple Pond Improvements Maintaining & Improving Biological / hydraulic load
Reduce shock loads & hydraulic peaks Costs, community & industry input
Desludging
Regain HRT Costs, damage, disposal, verification
Inlet / outlet design
Increase HRT, use flow buffering Available freeboard, waveband material
Dividing curtains / barriers
Prevent short-circuiting Design, quality of materials used
Aeration / mixing / DO
Reduce odours and overloading
Basic improvements
Type, Get them water right depth, ! purpose, power
g2e
Simple Pond Improvements
g2e
Advanced Pond Improvements What has to be achieved? Dividing ponds
Improve treatment efficiency What type of pond? HRT
Heighten the embankment
Increase HRT, prepare for the future What for? Costs
Rockfilter (aer/non-aer)
Improve TSS, BOD5, Am-N and TN Costs, design, references !!
Growth media
Increase BOD5, Am-N, TN treatment Costs, aeration required, HRT
Floating wetlands
Improve TSS, BOD5 (TN, TP), ((Am-N)) Site data, site specific, costs, quality
g2e
Growth Media Carbon black sleeve with floatation tube. Mats are connected to stainless steel wires attached on each side of the treatment pond
Lower UltraWeave layer Upper UltraWeave layer promotes growth of promotes bacterial sessile algae and higher biofilms & acts as hydraulic barrier for organisms for uptake of DRP and ammonia BOD5 and TSS removal
g2e
Growth Media Installed
Aerobic Zone
Air release at >200 mbar dP Biomass Support Media
Air flow
g2e
Typical results at start-up
g2e
Floating Wetlands
Floating wetlands 2012 fits all ’’ Floating wetlands installation Know what you need –shortly avoidJanuary ’’after one system
g2e
Example 1: Ponds not achieving RC
Domestic & Industriel Flow: 680 960 m3/d Peak: 1,600 m3/d BOD5 175 kg/d TKN 43 kg/d
WETLANDS
POND 1
Inlet
Treatment Required TSS/BOD5 < 20 mg/l TKN < 6 mg/l Am-N < 3 mg/l TP < 3 mg/l
POND 2
g2e
Outlet
Example 1: Ponds not achieving RC > Insufficient HRT
2.6m
2.3m 1.4m
1.6m
POND 1
POND 2
g2e
Example 1: Pond not achieving RC > Improve treatment
Improve flow at inlet, transfer & outlet WETLANDS
Automatic screening & flow metering
Aeration
& mixing in inlet area
Biological growth media & aeration
Alkalinity dosing & Fe dosing for TP reduction
g2e
Overview 1. Facultative & aerated ponds: How do they work? (Facultative, aerated, media ponds)
2. design aspects aspects & & upgrade upgrade technologies technologies. 2. Pond Pond design (Sludge, inlet, outlet, buffering, hydraulic, aeration, mixing, curtain, media)
3. Resource Consents for ponds (Ponds versus high rate treatment plants)
4. Other pond issues.
5. the pond will not do anymore. 5. When Other pond issues (Turning the pond into something else)
g2e
Resource Consents for Ponds Ponds Versus High Rate Treatment Plants HRT
Pond: 20 – 80 days, HRTP: hours Increase sampling frequency
Discharge Quality
Pond: day/night, season, HRTP: stable Time / season related requirements
Discharge Flows
Pond: precipitation, HRTP: no influence
Floating wetlands
Increase treatment Weather / streamcapacity level dependent
(Rockfilter Capacity aer./non-aer.) Treatment
Target Incrementally TN and TP reduction Pond: upgradable HRTP: Built for T0 + 20 yrs Target TSS & organics discharge Staged upgrade consents Reduce TSS & organics loading Review overseas experience Reduce BOD TN, TP specific 5, TSS,be Conditions should pond
Install Ultrasound Install trickling filter Disposal to land Install interm. sandfilter Resource Consents
g2e
Pond System Upgrades It is possible !
Questions ? g2e
