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