Innovations in Oxidation Technologies to treat difficult wastewaters Dr Peter Barratt Business Manager Environmental & Clean Technology Air Products (Europe)

Innovations in Oxidation Technologiesto treat difficult wastewaters

Dr Peter BarrattBusiness ManagerEnvironmental & Clean TechnologyAir Products (Europe)

2 TNAV April 2005

Oxidation:The range of technologies

11 22 33 44 55 1010

OrganicOrganic ComponentComponent

Non- or poorly-Non- or poorly-biodegradablebiodegradable

BiodegradableBiodegradable

OzoneOzone&&

BiologicalBiological

ThermalThermalWetWet

OxidationOxidationIncinerationIncineration

Aerobic BiologicalAerobic BiologicalStabilizationStabilization

ororThermal Wet OxidationThermal Wet Oxidation

AerobicAerobicBiologicalBiological

Organics Concentration (%)Organics Concentration (%)Requiring DestructionRequiring Destruction

OzoneOzone

3 TNAV April 2005

High Purity Oxygen in Water for Aerobic Biology… why?Increased Saturation Concentration (Cs)

– Oxygen in Air = 9.1mg/l @ 20oC– Oxygen = 43 mg/l @ 20oC

Rate of Oxygen Mass Transfer– dC/dt = KLa (Cs - C)– Pure oxygen maximises the oxygen

deficit, so oxygen dissolves faster

Process benefits– Microbes enjoy well oxygenated

conditions

4 TNAV April 2005

Treated water

Excess Sludge

ClarifierFeed

Mixed Liquoror“Sludge”

Returned Activated Sludge (RAS)

Settled Sludge

The Activated Sludge ProcessThe Activated Sludge Process

5 TNAV April 2005

Treated water

Excess Sludge

ClarifierFeed

Mixed Liquoror“Sludge”

Returned Activated Sludge (RAS)

Settled Sludge

The Activated Sludge ProcessThe Activated Sludge Process

OXYGEN

OXYGEN

6 TNAV April 2005

Pure Oxygen

Classical Oxygenation bysidestream oxygen injection

Recirculation Pump Activated Sludge Basin

Water Water IntakeIntake

Secondary EjectorSecondary Ejector

Venturi-typedevice

The OXY-DEP® processTypically fromLiquid Oxygen

7 TNAV April 2005

Paper Industry lagoon

8 TNAV April 2005

Technology– Oxygen generator (Vacuum Swing

Absorption) linked to a low energy mixer– Standard sizes:

• 150 lpm (262kg/d)• 500 lpm (875kg/d)• 2800 lpm (5000kg/d)

– Simplicity and cost in line with aeration– Process benefits of oxygen

New developmentOXY-DEP® VSAOn-site generated oxygen

9 TNAV April 2005

OXY-DEP® VSA

OXYGEN GENERATOR

MIXER-OXYGENATOR

10TNAV April 2005

Aerobic Biological Treatment

Aeration• Typically 1 - 2kgCOD/m3/day

– MLSS 1.5 – 5g/l• Up to 0.5kgNH3-N/m3/day

Oxygenation• High Rate Biological Treatment

processes– Typically 2 – 5kgCOD/m3/day

• MLSS 3 – 20g/l– Up to 5kgNH3-N/m3/day

11TNAV April 2005

OXY-DEP® MB Process

Feed

Washtank

EffluentOXY-DEP reactor

Membrane

O2 Inlet

12TNAV April 2005

OXY-DEP® MB benefitsRefractory COD is treatable

High rate system– Above 30kgCOD/m3/day

Low waste sludge production rate– zero in 3 months (rendering)

Provides potentially re-usable water

13TNAV April 2005

Oxygen - common uses in aerobic biological treatment

Increase treatment capacity of an existing aerated plant

Reduce odours, foams and aerosols

Cater for peak organic and ammonia loads as required

Improve sludge quality

Reduce regulatory risk and improve environmental image

14TNAV April 2005

Direct Ambient Oxidation

Oxidation Processes• Rising Main Injection (sewers)

– avoids H2S and corrosion• Sulphide (S-) Oxidation

– e.g. lagoons• Ozone

– Hard COD and colour removal

O2 & O3

15TNAV April 2005

Ozone

Unstable oxidant

Generated on site

Precursor to .OH

Water treatment

In conjunction with biological treatment

16TNAV April 2005

CHEMOX Reactor for O3

GasOutflow

LiquidOutflow

Pump

Gas InflowLiquid Feed

Main Tube

ImpingingZone

Guide Tube

Nozzle

17TNAV April 2005

CHEMOX - landfill leachate

CHEMOX 1.8 O3 :COD ratio*

4 hours HRT

500 mg/l CODin

<150 mg/l CODout

4 kWh/kgO3 Powerdiss

Existing PlantExisting Plant > 2.2> 2.2

10.3 hours10.3 hours

500 mg/l500 mg/l

<150 mg/l<150 mg/l

8 kWh/kgO8 kWh/kgO33

** : ozone applied/COD removed : ozone applied/COD removed

18TNAV April 2005

CHEMOX - landfill leachate

CHEMOX 1.8 O3 :COD ratio*

4 hours HRT

500 mg/l CODin

<150 mg/l CODout

4 kWh/kgO3 Powerdiss

Existing PlantExisting Plant > 2.2> 2.2

10.3 hours10.3 hours

500 mg/l500 mg/l

<150 mg/l<150 mg/l

8 kWh/kgO8 kWh/kgO33

** : ozone applied/COD removed : ozone applied/COD removed

COST ADVANTAGECOST ADVANTAGE

17% lower in capital17% lower in capital

29% lower in operation29% lower in operation

19TNAV April 2005

Other Ozone Applications

Sludge solids oxidation– Activated sludge in-process

Pathogen removal in reused water

Alternative clean oxidant in chemical synthesis

Selective destruction of problem bacteria e.g. bulking

20TNAV April 2005

Oxygen reuse technology after ozone productionNormally, conversion of O2 to O3 is

6% to 12% by weight. Therefore:– Oxygen off-gas use in other

processes– Long Loop Recycle (LLR)– Short Loop Recycle (SLR)

• O2 and O3 separated after the ozoniser, and O2 recycled to produce O3

• 98% conversion of O2

21TNAV April 2005

SLR Benefits - example

Straight Through

Total

OxygenPower

Capital

SLR Total

40% Savings

15% Savings

4 8 12 16Ozone Concentration [wt%]

$0.50

$1.00

$2.00

$2.50

Cost

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