1. Protecting Our Waterways Removal of Nutrients from Wastewater
David Rei Miller
Masters Student
Sumit Banker
PG Diploma Student
Dr Steven Pratt
Lead Author
Dr Andy Shilton
CETE Director

2. Nutrient Removal Research
Domestic Centralised
PNCC, RDC
Industrial
Forest Research
Nutrient pollution is seen as the challenge of the next decade.
Domestic Other
Gould Systems,
Steelserv
Industrial
Fonterra

3. Presentation Outline 1 Problem Nutrient Pollution
2 Solutions Nitrogen Removal
Biological Filter
Phosphorus Removal Active Rock Filter
First… PROBLEM of Nutrient Pollution. Then… SOLUTIONS for N and P removal. My Masters project is on N removal.

4. Nutrient Pollution Groundwater Blue Baby Syndrome NO3-
carcinogen production NO3-
Surface Waters
toxic to fish NH3
algal blooms N and P
eutrophication N and P
Methemoglobinemia
similar to “Blue Baby”
Many of you will have seen evidence of nutrient pollution in the news. NP = Nitrogen and Phosphorus.

5. Eutrophication Nutrient enrichment Algal growth Decay of algae
Oxygen consumption
Oberlin, OH (before)
Oberlin, OH (after)

6. Eutrophication in Hawkes Bay region
HB pic is eutrophication from agricultural runoff (not OWTS).
Eutrophication in Hawkes Bay region

7. Sustainability Protecting Our Waterways drinking, recreation resource
cultural values
kaitiakitanga, legal obligations
Sustainable Technology
low energy, cost, maintenance
low environmental impact
Effective wastewater treatment is needed to protect our waterways. Essential part of sustainable society. RMA reflects importance.

8. Nitrogen Domestic Wastewater urea, proteins, amino acids
80 mg-N/L total (from onsite)
Discharge Limits
10 mg-N/L NO2-/NO USEPA
30 mg-N/L total (from onsite) Hawkes Bay
For OWTS resource consent in Hawkes Bay. Pressure to remove N in OWTS before disposal to land due to variability of soils, etc.

9. Nitrogen Removal Foam Media Biofilter biological (microorganisms)
onsite wastewater treatment
target 10 mg-N/L effluent
Key Results to Date
30 mg-N/L effluent typical
nitrification, denitrification confirmed
nitrification identified as limiting
likely limited by lack of oxygen
Research project to improve current Gould system. Removal varies between sites. Effluent concs are TN.

10. Septic Tank + Biofilter
Flotation & Settling
Nitrification & Denitrification
Influent Wastewater
Treated Effluent
Hydrolysis and ammonification in septic tank.
Org-N  NH3-
NH3-  NO3-  N2

11. Nitrogen Removal in Biofilter
Aerobic NH3  NO3-
Anoxic NO3-  N2
Cutaway of one foam block showing anoxic zone
Good air flow properties; superior to sand filters. NH3/NH4+ to NO2/NO3- to N2. Define aerobic and anoxic.
Foam media for biomass growth

12. Nitrogen Removal Sustainability Potential no forced aeration
no addition of carbon
inert end product
But…
foam life, regeneration uncertain
electricity required (pumps, controls)
Overall N management includes reduction, planting (Gunn 04). FIRST get it out of the river, then look at power, etc. Further research.

13. Phosphorus Domestic Wastewater detergents, various foods
5-20 mg-P/L as DRP
Discharge Limits
1 mg-P/L as TP (to bay) Brisbane
1 mg-P/L as DRP (to stream) Waipukurau
not set for onsite
Discovery of P (1669)
Amateur alchemist Brand discovered P in 1669 by heating urine in the absence of air.

14. Phosphorus Removal Active Rock Filter physical + other mechanisms
small community treatment
can add to existing pond (or onsite)
Key Results to Date
limestone 64% P removal
steel slag 72% P removal
Retrofit to pond or wetland systems (Ashhurst 2000 ppl). * explain results set-up: two media for active rock filters have been tested (shown in literature to be promising). Both show significant P removal can be achieved….

15. Active rock filter bed, Waiuku
Phosphorus Removal
Place after pond/lagoon (after solids have been removed).
Active rock filter bed, Waiuku

16. Phosphorus Removal P Possible mechanisms: ion exchange adsorption
Treated Effluent P
74% P Removal
Possible mechanisms:
ion exchange
adsorption
precipitation
Now let’s look at what’s happening in there! Different media support various mechanisms (paper).
Influent Wastewater

17. Phosphorus Removal Sustainability Potential no energy input required
low cost
simple and “low tech” like ponds
But…
design life, loadings need research
regeneration, extraction of P needs research
No problems with heavy metal leaching have been reported in literature. Alternative is to use chemical dosing or EBPR.

18. Summary Nutrient removal is essential for
sustainability of water resources.
N Removal can be achieved onsite
by foam media biofilter.
Low cost P Removal possible with
an active rock filter.
CETE will research oxygen limitation in N removal, also P Removal studies with Dr Ibrahim Elmetri, formerly of UQ, 2 yrs PostDoc.

19. Acknowledgments Warrick Gould Gould GT Systems Technology NZ
Palmerston North City Council
Steelserv
Rock Filter Researchers
Thanks to PNCC for access to pond effluent for rock filter study; other rock filter researchers included Lynaire, Sumit, Babar, Rachel.