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

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

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.

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.

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

Eutrophication in Hawkes Bay region HB pic is eutrophication from agricultural runoff (not OWTS). 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 Effective wastewater treatment is needed to protect our waterways. Essential part of sustainable society. RMA reflects importance.

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 For OWTS resource consent in Hawkes Bay. Pressure to remove N in OWTS before disposal to land due to variability of soils, etc.

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.

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

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

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.

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.

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….

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

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

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.

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.

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.