Tim Muster - Ammonia Stripping for N Recovery

CSIRO MATERIALS SCIENCE AND ENGINEERING

Ammonia stripping for N recovery

Tim Muster | Group Leader: Functional Interfaces & Coatings

1st May 2012

Nitrogen

[CO2] = 387Boundary = 350

Ammonia Stripping for N Recovery

J. Foley, Scientific American, April 2010, pp 38 -44

N = 133 Mt/yrBoundary = 39

P = 10 Mt/yrBoundary = 12

Extinction rate > 100 species/MyrBoundary = 10

IS AMMONIA in wastewater a WASTE or RESOURCE?

Global ammonia production ~177m tonnes (2008)

Energy intensive to make; 40 GJ/tonne or 10.2 MWh/t

Nitrogen is initially present as NH3 in wastewater (urea + protein breakdown)

At ~40-45 mg/l, accounts for >55% of total N of treatment plant influent

Builds up to high concentration during anaerobic digestion

Nitrogen & Ammonia Summary

Builds up to high concentration during anaerobic digestion

Limits methane production

Encourages struvite precipitation

Special properties

Ammonia is highly water soluble

Present as ammonium ion below pH 9 (pKa = 9.5).

Ammonia Stripping for N Recovery

Biological

- Nitrification/denitrification

- Many variations: SBR, Bardenpho, Anammox etc.

Physico-chemical

- Ion exchange

Methods for N Removal

Generally cost effectiveCan be energy-intensive due to aeration/mixing/carbon additionsProduction of N2O (strong GHG)

- Ion exchange

- Breakpoint chlorination

- Stripping

- Electrodialysis

- Reverse Osmosis

- Precipitation

Ammonia Stripping for N Recovery

Table: Comparison of removal costs for ammonia-N

Process Cost $/kg N removed or captured Captured ammonia

Nitrification/Denitrification 1.8* No

CASTion ammonia recovery 6.7* Yes

Air stripping 2.4* Yes

Clinoptilolite (adsorption/exchange) 2.8* Yes

Commercial return for ammonia 0.4

Data: *Phillips et al. (2011)

Ammonia Stripping Many ConfigurationsEncouraged by:

Increase air : water contact

Increased Temperature

High pHW

a

t

e

r

i

n

Ammonia Stripping for N Recovery

Aerated Column

Packed Column

Spray(or vacuum) Lagoon

A

i

r

i

n

Air flow over lagoon

Reduction of ammonia to nitrogen gas:

- Can be achieved by chemical addition or electrochemical oxidation

Chloride oxidation

Ammonia Stripping for N Recovery

During electrochemical oxidation of chloride, chloride ion is replenished.

Precipitation with Phosphorus as Struvite

Many processes: Phostrip, Prisa, DHV Crystalactor, Ostara, Prophos,

Multiform Harvest, Recyphos, Phosiedi, Berlin, Airprex,

Fixphos

Wastewater Primary Treatment

SludgeReturn30 ppm P1000 ppm NH

Ammonia Stripping for N Recovery

P / (N)Fertilizer

Mg2+, Ca2+caustic delivery,

or addition of adsorbent

Fermentation

Sludge

Anaerobic Digestion

CentrifugeCentrate600 ppm P1200 ppm NH3

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1000 ppm NH3

Nitrogen is still in excessadditional technology required to meet N requirements

Overall: Capture the value of Water + C + N + P

Likely return value: Water > Carbon > Phosphorus > Nitrogen

Likely cost of removal: Carbon > Nitrogen > Phosphorus

What to do with nitrogen:

Approach

What to do with nitrogen:

-reduce cost of removing nitrogen (with capture of ammonia if possible)

-WWTP influent starts off as ammonia

aim to develop method for physical separation of NH3 into both vapour and solid phase

- Developing a combined process:

Ammonia Stripping for N Recovery

Stripping Breakpoint chlorination Precipitation

Wastewater treatment will continue to transform into Energy and Resource Recovery Centres

Need to develop concentration and separation processes

There is an opportunity to combine several physico-chemical methods to improve ammonia-N removal and recovery

Summary

There is an opportunity to combine several physico-chemical methods to improve ammonia-N removal and recovery WATCH THIS SPACE

Question: what are the industry priorities for these processes?

Now: Sanitation > Water > N > Heavy Metals > C > P?

The future: Sanitation > Water > C > P > Heavy Metals > N?

Ammonia Stripping for N Recovery

Thank youThank youTim MusterGroup Leader: Functional Interfaces & Coatings

t +61 3 9545 7964e [email protected] www.csiro.au/

CSIRO MATERIALS SCIENCE AND ENGINEERING