PND –A Novel WasteWater Treatment Process Designed Around Biology Dr. Ralf Cord Ruwisch.

PND –A Novel WasteWater Treatment Process Designed Around Biology

Dr. Ralf Cord Ruwisch

PND - Wastewater Treatment Technology Adopted from Nature

Dr. Ralf Cord Ruwisch

Background of Invention:

•15 Years of R&D on Advanced Wastewater Treatment

•4 PhD candidates (now working as engineers/scientists)

•Numerous publications

•Most promising outcome (PND) now a patent application in international phase

•Inventor team: Dr. Ralf Cord-Ruwisch, Dr. Leonie Hughes

•IP holder: Murdoch University

Objective of Waste Water Treatment

Avoid:

1. Outbreaks of disease

2. Pollution by solids (Prim.

Treatment)

3. Pollution by soluble organics (Sec.

Treatment)

4. Pollution by nutrients, e.g. N (Tert.

Treatment)

The last two steps are biological and essential to minimise pollution and enable water reclamation

Pollution by Nitrogen

N-pollution leads to algal blooms

Key pollutants are:•Ammonia•Nitrate

Pollution by NitrogenAlgal blooms can be spectacular

Pollution by NitrogenAlso at “normal levels around cities” N

pollution can turn toxic

Pollution by NitrogenEvan at “low levels” N pollution can kill

reefs and other ecosysmtems

Pollution by NitrogenLegislation asks for lowest N-levels with

best proven technology

N-Removal inWastewater Treatment

In Wastewater Nitrogen is present as ammonia.

Extremely high numbers of biodegrading bacteria are needed to remove it.

Arial view of Biological Wastewater Treatment in Perth“Challenge to keep up with expanding population”

Why is N removal difficult ?

N removal requires 2 processes:

Aerobic: Ammonia + O2 nitrate (nitrification)

Anoxic: Nitrate + Organics N2 (denitrification)

Traditional plants can’t make both processes work

Residual N pollution in urban areas

Reason: Traditional Design based on maximum O2

supply

Problem of Traditional Approach

O2

CO2

Organics

Nitrate

• Organics are converted to CO2.

• Nitrogen is merely converted into another form.

• Additional nitrate removal is needed.

AerobicAmmonia

Problem of Traditional Approach

O2

CO2

Organics

Nitrate

Nitrate con only be removed by anoxic denitrification.However…

N2

Aerobic AnoxicAmmonia

Problem of Traditional Approach

O2

CO2

Organics

Nitrate

To carry out Nitrate removal, organics are needed !

N2

Aerobic AnoxicAmmonia

Problem of Traditional Approach

O2

CO2

Organics

Nitrate

The organics needed for pollutant release as N2 have been destroyed in the aerobic step.

N2

Aerobic AnoxicAmmonia

Problem of Traditional Approach

O2

CO2

Organics

Nitrate

Current practice is to take a portion of the untreated organics from raw wastewater. Problem: Ammonia addition.

N2

Aerobic AnoxicAmmonia

Problem of Traditional Approach

O2

CO2

Organics

Nitrate

Various add-on technologies have been developed:• Multiple aerobic/anoxic steps• Sophisticated O2 control (SND)

N2

Aerobic AnoxicAmmonia

Problem of Traditional Approach

O2

CO2

Organics

Nitrate

Problems of existing plants:Expensive, Incomplete N removal, High maintenance,

N2

Aerobic AnoxicAmmonia

Learning from Biology (Nature)

O2

CO2

Organics

Nitrate

What happens in nature when highly polluted waste comes in contact with bio-degrading bacteria ?

N2

Aerobic AnoxicAmmonia

A

C

Continued over-supply with organics

trains wastewater bacteria to store lipids (fat)

PHB

Learning from Biology (Nature)

Organics

Ammonia

In nature: •No energy for excessive O2 supply. •Organics removal by anoxic storage as lipid

AnoxicAmmonia

Lipid

Learning from Biology (Nature)

Organics

Ammonia

Subsequent O2 supply can initiate Nitrification

Anoxic AerobicAmmonia

Lipid

Nitrate

O2

Learning from Biology (Nature)

Organics

Ammonia

Needed: •Organics for Nitrate removal.•Oxidation of Lipids (either needs O2 or Nitrate).

Anoxic AerobicAmmonia

Lipid

Nitrate

O2

Learning from Biology (Nature)

Ammonia

By recycling Nitrate containing water back:•N removal is completed•Nitrification and Denitrification operate in parallel…

Anoxic AerobicLipid

O2

N2 Nitrate

Learning from Biology (Nature)

AmmoniaAnoxic AerobicLipid

O2

N2 Nitrate

… resulting in unrestricted N removal.

Parallel Nitrification and Denitrification (PND)

Trad. Design:Heavy handed O2 supply +Fixing up the consequences.

PND:Building around the biology

AnoxicAerobic

Lipid

O2

N2 Nitrate

Ammonia

Performance of PND

Compared to state of art SBR technology: PND removed N more completely, faster, with less O2

(direct competition between PhD students: “Beaten hands-down without even trying”)

AnoxicAerobic

Lipid

O2

N2 Nitrate

Ammonia

0 100 Time (min) 400

3

2

1

0

SBR

PND

N (mM)

Performance of PND

Theory (modelling) supports results:Nitrifying bacteria percentage:

>80% in PND < 10% in SBRHence 8 times faster rates expected

AnoxicAerobic

Lipid

O2

N2 Nitrate

Ammonia

0 100 Time (min) 400

3

2

1

0

SBR

PND

N (mM)

Performance of PND

Key disadvantage of PND:Separation of biomass from liquid required repeatedly:

PND: (3-5) Trad. Systems (2)However, other advantages to users:

AnoxicAerobic

Lipid

O2

N2 Nitrate

Ammonia

0 100 Time (min) 400

3

2

1

0

SBR

PND

N (mM)

Advantages for Users of the Technology

• Can meet lowest demands (>98%) for N removalBarrier Reef Water Re-use

• Less (about 20%) aeration energy

• Smaller footprint (upgrading)

• Less process control !

• No risk of the greenhouse gas N2O emission

• Enables P removal (insufficient time to explain)

Implementation Options

• New plants (however industry is very

conservative)

• Retrofitting existing plants

• Step by Step implementation (pizza)

• Set to become The New Standard ?

Arial view of Biological Wastewater Treatment in Perth“Challenge to keep up with expanding population”

Development Stage

We are Here!

Pilot or Demonstration Site required +$$$’s

Licensee required

Engineering & market input required

We are looking for…

•A potential demonstration site•Engineering and Market expertise

•A potential licensee

Please Contact

Samantha Dymond Email: [email protected] Phone: 08.9360.7481

Ralf Cord-RuwischEmail: [email protected]

Spare

Nitrif.De-nitrif.

SND

React

ion

Rate

Precise O2 control needed

Skilled operators Not always reliable Slowing down incr. footprint Wasteful: COD and O2 Emerging evidence of N2O emission

Current State of the Art: Simultaneous Nitrification and Denitrification

Dissolved O2 (mg/L)