Transcript Sustainable Technology for Nutrient Removal from Wastewater

Protecting Our Waterways
Removal of Nutrients from Wastewater
David Rei Miller
Dr Steven Pratt
Masters Student
Lead Author
Sumit Banker
Dr Andy Shilton
PG Diploma Student
CETE Director
Nutrient Removal Research
Domestic
Centralised
Industrial
PNCC, RDC
Forest Research
Domestic
Other
Industrial
Gould Systems,
Steelserv
Fonterra
Presentation Outline
1
Problem
Nutrient Pollution
2
Solutions
Nitrogen Removal
Biological Filter
Phosphorus Removal
Active Rock Filter
Nutrient Pollution
Groundwater
• Blue Baby Syndrome
• carcinogen production
NO3NO3Methemoglobinemia
Surface Waters
• toxic to fish
• algal blooms
• eutrophication
similar to “Blue Baby”
NH3
N and P
N and P
Eutrophication
1.
2.
3.
4.
Nutrient enrichment
Algal growth
Decay of algae
Oxygen consumption
Oberlin, OH (before)
Oberlin, OH (after)
Eutrophication
Eutrophication in Hawkes Bay region
Sustainability
Protecting Our Waterways
• drinking, recreation resource
• cultural values
• kaitiakitanga, legal obligations
Sustainable Technology
• low energy, cost, maintenance
• low environmental impact
Nitrogen
Domestic Wastewater
• urea, proteins, amino acids
• 80 mg-N/L total (from onsite)
Discharge Limits
• 10 mg-N/L NO2-/NO3• 30 mg-N/L total (from onsite)
USEPA
Hawkes Bay
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
Septic Tank + Biofilter
Flotation
& Settling
Influent
Wastewater
Nitrification &
Denitrification
Treated
Effluent
Org-N  NH3-
NH3-  NO3-  N2
Nitrogen Removal in Biofilter
Aerobic
NH3  NO3-
Foam media for biomass growth
Anoxic
NO3-  N2
Cutaway of one foam block
showing anoxic zone
Nitrogen Removal
Sustainability Potential
• no forced aeration
• no addition of carbon
• inert end product
But…
• foam life, regeneration uncertain
• electricity required (pumps, controls)
Phosphorus
Domestic Wastewater
• detergents, various foods
• 5-20 mg-P/L as DRP
Discharge Limits
• 1 mg-P/L as TP (to bay)
• 1 mg-P/L as DRP (to stream)
• not set for onsite
Discovery of P (1669)
Brisbane
Waipukurau
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
Phosphorus Removal
Active rock filter bed, Waiuku
Phosphorus Removal
Treated
Effluent
P
74% P
Removal
Possible mechanisms:
• ion exchange
Influent
Wastewater
• adsorption
• precipitation
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
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.
Acknowledgments
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Warrick Gould
Gould GT Systems
Technology NZ
Palmerston North City Council
Steelserv
Rock Filter Researchers