Protecting Our Waterways Removal of Nutrients from Wastewater

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

Nutrient Removal Research Domestic Centralised PNCC, RDC Industrial Forest Research Domestic Other Gould Systems, Steelserv Industrial Fonterra

Presentation Outline 1 Problem Nutrient Pollution 2 Solutions Nitrogen Removal Biological Filter Phosphorus RemovalActive Rock Filter

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”

Eutrophication • 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-USEPA • 30 mg-N/L total (from onsite) 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 Nitrification & Denitrification Flotation & Settling Influent Wastewater Treated Effluent Org-N  NH3- NH3-  NO3-  N2

Cutaway of one foam block showing anoxic zone Nitrogen Removal in Biofilter Aerobic NH3 NO3- Anoxic NO3-  N2 Foam media for biomass growth

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) Brisbane • 1 mg-P/L as DRP(to stream) Waipukurau • not set for onsite Discovery of P (1669)

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 • adsorption • precipitation Influent Wastewater

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 • Warrick Gould • Gould GT Systems • Technology NZ • Palmerston North City Council • Steelserv • Rock Filter Researchers

Protecting Our Waterways Removal of Nutrients from Wastewater