pnd –a novel wastewater treatment process designed around biology dr. ralf cord ruwisch
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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)