for Wastewater Treatment Gilles Altner Global Environmental - - PowerPoint PPT Presentation

Ponds for Wastewater Treatment

Gilles Altner

Global Environmental Engineering Ltd

g2e g2e

Rock Filter Membranes Wetland Sand Filter UV Pre Treatment Maturation Pond Anaerobic Pond

The Pond System

Facultative Pond

• 4. Other pond issues.
• 5. When the pond will not do anymore.

(Turning the pond into something else)

• 5. Other pond issues

g2e g2e

(Facultative, aerated, media ponds)

1. Facultative & aerated ponds: How do they work?

Overview

• 2. Pond design aspects & upgrade technologies

(Sludge, inlet, outlet, buffering, hydraulic, aeration, mixing, curtain, media)

Overview

1. Facultative & aerated ponds: How do they work?

• 3. Resource Consents for ponds

(Ponds versus high rate treatment plants)

• 2. Pond design aspects & upgrade technologies.
• 3. Resource Consents for ponds.

g2e g2e

(Facultative, aerated, media ponds)

1. Facultative & aerated ponds: How do they work?

Overview

• ANAEROBIC PONDS
• FACULTATIVE PONDS
• MATURATION PONDS

g2e g2e Waste Stabilization Ponds

1.2 to 5 m

Wind (mixing & aeration) O2 (daylight hours) Sunlight If oxygen is not present in upper layer of pond,

• dorous gases can be

released CO2 + NH3 + H2S + CH4 Organic acids, alcohols O2 Re-aeration H2S + 2O2 H2SO4 H2S CO2 Bottom sludge Wastewater Settleable solids Organic wastes T (temperature) Algae O2 CO2 Bacteria Dead Cells New Cells NH3, PO4

3,

etc NH3, PO4

3,

etc New Cells Dead Cells Aerobic Zone Facultative Zone Anaerobic Zone

The Facultative Pond

Aerobic Zone 0.3 to 0.6m Facultative / Anoxic Zone 0.5 to 0.8m Anaerobic Zone 0.1 to 0.3m Algae O2 CO2 Bacteria Dead Cells New Cells NH3, PO4

3,

etc NH3, PO4

3,

etc New Cells Dead Cells

2 to 5 m deep, HRT 3 to 5 days, partially / completely mixed

• AEROBIC, FLOW THROUGH PONDS

High TSS & BOD loading, no Am-N or TN reduction Temperature dependant, BOD load 100 to 350 kgBOD/m3/day 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

• AEROBIC PONDS WITH SOLIDS RECYCLE

g2e 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 production about 5 to 7 m3/yr/l/sec or about 10mm/yr

g2e 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

Aerated & partially / complete mixed Lagoon Series of low power aerated Lagoons

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 Am-N < 5 mg/l TN < 15 mg/l

g2e g2e Waste Stabilization Ponds

• PONDS with GROWTH MEDIA: Advanced treatment

T

(temperature)

Algae O2 CO2 Bacteria Dead Cells New Cells NH3, PO4

3,

etc NH3, PO4

3,

etc New Cells Dead Cells Aerobic Zone Facultative Zone Anaerobic Zone

1.5 to 3m+ deep, HRT 20 days+, less possible

O2 O2 O2 Biomass

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)

• 4. Other pond issues.
• 5. When the pond will not do anymore.

(Turning the pond into something else)

• 5. Other pond issues

g2e g2e

(Facultative, aerated, media ponds)

1. Facultative & aerated ponds: How do they work?

Overview

• 2. Pond design aspects & upgrade technologies

(Sludge, inlet, outlet, buffering, hydraulic, aeration, mixing, curtain, media)

Overview

1. Facultative & aerated ponds: How do they work?

g2e g2e The Typical New Zealand Pond g2e g2e The Typical New Zealand Pond

Inlet Outlet

POND 1 POND 2 WETLANDS

Aerator Aerator

• Two pond system

100m x 90m x 1.4m 100m x 60m x 1.8m

• Wetlands

150m x 60m plus 110m x 80m

• Odours
• Algae blooms
• Wetland failure
• Discharge out of RC

The Typical New Zealand Pond

Inlet

POND 1

Aerator Aerator

POND 2

Outlet

WETLANDS

g2e g2e The Typical New Zealand Pond

• Sludge Level

Up to 1.3m (90% of water depth)

1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 10 20 30 40 50 60 70 80 90 10 20 30 40

• Wetland clogged

with pond solids and plant overgrowth

WETLANDS

• Poor flow conditions

Inlet Outlet

POND 1 POND 2 WETLANDS

• HRT

Theoretical: 25 days True : 8 days

g2e g2e Simple Pond Improvements

Maintaining & Improving Biological / hydraulic load

Reduce shock loads & hydraulic peaks Costs, community & industry input

Biological / hydraulic load

Reduce shock loads & hydraulic peaks

Desludging

Regain HRT Costs, community & industry input Costs, damage, disposal, verification

Desludging

Regain HRT

Inlet / outlet design

Increase HRT, use flow buffering Costs, damage, disposal, verification Available freeboard, waveband material

Inlet / outlet design

Increase HRT, use flow buffering

Dividing curtains / barriers

Prevent short-circuiting Available freeboard, waveband material Design, quality of materials used

Dividing curtains / barriers

Prevent short-circuiting

Aeration / mixing / DO

Reduce odours and overloading Design, quality of materials used Type, water depth, purpose, power

Aeration / mixing / DO

Reduce odours and overloading Get them right !

Basic improvements

g2e g2e Simple Pond Improvements

g2e g2e Advanced Pond Improvements

What has to be achieved? Dividing ponds

Improve treatment efficiency What type of pond? HRT

Dividing ponds

Improve treatment efficiency

Heighten the embankment

Increase HRT, prepare for the future What type of pond? HRT What for? Costs

Heighten the embankment

Increase HRT, prepare for the future

Rockfilter (aer/non-aer)

Improve TSS, BOD5, Am-N and TN What for? Costs Costs, design, references !!

Rockfilter (aer/non-aer)

Improve TSS, BOD5, Am-N and TN

Growth media

Increase BOD5, Am-N, TN treatment Costs, design, references !! Costs, aeration required, HRT

Growth media

Increase BOD5, Am-N, TN treatment

Floating wetlands

Improve TSS, BOD5 (TN, TP), ((Am-N)) Costs, aeration required, HRT Site data, site specific, costs, quality

Floating wetlands

Improve TSS, BOD5 (TN, TP), ((Am-N))

g2e 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 promotes bacterial biofilms & acts as hydraulic barrier for BOD5 and TSS removal Upper UltraWeave layer promotes growth of sessile algae and higher

• rganisms for uptake of

DRP and ammonia

g2e g2e Growth Media Installed

Biomass Support Media Aerobic Zone

Air flow

Air release at >200 mbar dP

g2e g2e Typical results at start-up

g2e g2e Floating Wetlands

Floating wetlands shortly after installation Floating wetlands January 2012 Know what you need – avoid ’’ one system fits all ’’

g2e g2e Example 1: Ponds not achieving RC

Inlet Outlet

POND 1 POND 2 WETLANDS

• Domestic & Industriel

Flow: 680  960 m3/d Peak: 1,600 m3/d BOD5 175 kg/d TKN 43 kg/d

• Treatment Required

TSS/BOD5 < 20 mg/l TKN < 6 mg/l Am-N < 3 mg/l TP < 3 mg/l

g2e g2e Example 1: Ponds not achieving RC > Insufficient HRT

POND 1 POND 2

2.3m 1.4m 2.6m 1.6m

g2e g2e Example 1: Pond not achieving RC

• 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 > Improve treatment

• 4. Other pond issues.
• 5. When the pond will not do anymore.

(Turning the pond into something else)

• 5. Other pond issues

g2e g2e

(Facultative, aerated, media ponds)

1. Facultative & aerated ponds: How do they work?

Overview

• 2. Pond design aspects & upgrade technologies

(Sludge, inlet, outlet, buffering, hydraulic, aeration, mixing, curtain, media)

Overview

1. Facultative & aerated ponds: How do they work?

• 3. Resource Consents for ponds

(Ponds versus high rate treatment plants)

• 2. Pond design aspects & upgrade technologies.

(Rockfilter aer./non-aer.)

Target TN and TP reduction

Floating wetlands

Increase treatment capacity

Install Ultrasound

Target TSS & organics discharge

(Rockfilter aer./non-aer.)

Target TN and TP reduction

Install trickling filter

Reduce TSS & organics loading

Install Ultrasound

Target TSS & organics discharge

Install interm. sandfilter

Reduce BOD5, TSS, TN, TP

Install trickling filter

Reduce TSS & organics loading

g2e g2e Resource Consents for Ponds

Ponds Versus High Rate Treatment Plants HRT

Pond: 20 – 80 days, HRTP: hours  Increase sampling frequency

HRT

Pond: 20 – 80 days, HRTP: hours

Discharge Quality

Pond: day/night, season, HRTP: stable  Increase sampling frequency  Time / season related requirements

Discharge Quality

Pond: day/night, season, HRTP: stable

Discharge Flows

Pond: precipitation, HRTP: no influence  Time / season related requirements  Weather / stream level dependent

Discharge Flows

Pond: precipitation, HRTP: no influence

Treatment Capacity

Pond: Incrementally upgradable HRTP: Built for T0 + 20 yrs  Weather / stream level dependent  Staged upgrade consents

Treatment Capacity

Pond: Incrementally upgradable HRTP: Built for T0 + 20 yrs  Staged upgrade consents Review overseas experience

Disposal to land

Conditions should be pond specific

Resource Consents

Review overseas experience

Disposal to land

g2e g2e Pond System Upgrades It is possible !

Questions ?