How to decrease the carbon footprint of wastewater treatment? David J. I. Gustavsson (VA SYD) and Susanne Tumlin (Gryaab) IWA Conference: European Utility Management May 14-16, 2014, Oslo IPCC (2013) Swedish consumption Emissions in other countries Emissions in Sweden -1 CO2e (million tonnes year ) 200 180 160 11% increase of CO2e emissions 140 120 100 80 60 40 20 0 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Swedish EPA (2013) What is a carbon footprint? A ‘carbon footprint’ measures the total greenhouse gas (GHG) emissions caused directly and indirectly by a person, organisation, event or product. It has units of tonnes (or kg) of carbon dioxide equvivalents (CO2e). System boundary System boundary System boundary System boundary Excel tool developed http://www.svensktvatten.se/FoU/SVU/Rapporter/Avlopp-Miljo/ Today A Swede WWTP 12 t CO2e 50 kg CO2e Car 2030 Meat Housing Flights Consumption A Swede WWTP 1 t CO2e 50 kg CO2e Fract 20 0 Results -20 -40 120 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 7-108 kg CO2e P.E.-1 year-1 9 10 11 12 13 14 15 16 9 10 11 12 13 14 15 16 Carbon footprint -1 -1 (kg CO2e P.E. year ) 100 80 60 40 20 0 WWTP Gustavsson & Tumlin (2013) How to decrease the carbon footprint of wastewater treatment? David J. I. Gustavsson (VA SYD) and Susanne Tumlin (Gryaab) IWA Conference: European Utility Management May 14-16, 2014, Oslo Most important contributions to the carbon footprint (+/-) Direct emissions of nitrous oxide (N2O) and methane (CH4) from WWTP Biogas usage Biosolids handling Energy usage Plant nutrients Heat pump Fossil based C source The COD in the wastewater is 100% biogenic (IPCC, 2006) Nitrification-denitrification – the main source of N2O How to detect N2O? Mønster et al. (2014) Anammox is not producing N2O Closed CH4 handling system important Mønster et al. (2014) Increase biogas production Kanders et al. (2013) Increase biogas production Fe3+ COD Nitrogen WWF HLAS Fe2+ PS ST HLAS MeOH MBBR PAC DAF NTF Fe2+ PS ST HLAS GT BGT PE SBR AD PE CF MBBR NaOH Sjölunda WWTP, Malmö Biogas usage CH4 Energy self-sufficiency is preferred Aeration is very energy demanding Minimise hydrolysis COD Maximise adsorption Aeration control Nitrite shunt Maximise assimilation NH4+ Anammox External energy Generate your own renewable energy: solar, wind and water power, or at least buy renewable energy Heat pumps on WWTP effluent COP > 4.0 External carbon source Methanol Available and”cheap” But mostly produced from natural gas Alternatives Renewable carbon source Sludge hydrolysis Denitrifying PAOs Nitritation-anammox Nitritation-anammox (deammonification) Theoretical savings -57% oxygen -86% organic carbon Competition NOB HB HNO2 Intermittent aeration NO2- COD NH4+ O2 T NH3 Continouos inoculum HCO3SRT AOB Biofilm Anammox Manammox pilot at Sjölunda WWTP Nutrient recovery – the future = source separation Introduction of urine separation in Malmö, Sweden – a concept of nutrient recovery and cadmium wash-out Gustavsson & la Cour Jansen (2014) Nutrient recovery – the future = source separation 40% less GWP impact from source-separating systems than from conventional wastewater treatment Spångberg et al. (2014) Inside or outside the fence? Communication to the citizens Communicate the real problems – hot water and meat consumption! Inside or outside the fence? Hot water consumption Primary energy usage in the society W/person Western countries >5000 Traffic >1000 Food (Western countries) ~115 Wastewater treatment 3-15 Goal 2000 Wastewater BOD 23 (1.6% of goal) Nitrogen 6 (0.3% of goal) Phosphorus 0.8 (0.04% of goal) Heat 110 (5.5% of goal) Hofman et al. (2011), Maurer et al. (2006), Rittmann (2013), Svardal & Kroiss (2011) Inside or outside the fence? Meat consumption Tumlin & Mattsson (2013) Inside or outside the fence? Nitrogen load/person is increasing 20 18 16 -1 g N person d -1 14 12 10 8 6 4 2 0 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 Tumlin & Mattsson (2013) How to decrease the carbon footprint of wastewater treatment? • Try to estimate your direct N2O and CH4 emissions, and try to prevent these emissions • Buy or produce your own renewable energy • Increase biogas production, and use it in a smart way • Avoid fossil carbon source • Implement the anammox process • Go for source-separating systems Conclusions Do you take the train to Lisbon? Thank you for your attention! David J. I. Gustavsson [email protected] @DrKolfot #IWAEUC2014 waterenergyclimate.blogspot.se Susanne Tumlin [email protected] How does wastewater contribute? The COD in the wastewater is 100% biogenic (IPCC, 2006) Recovery of energy Chemical energy - ~ 14 MJ/kg COD Thermal energy – 4.2 MJ/(m3*degree C) Potential energy – 9.8 kJ/(m3*m) Kinetic energy – 0.18 kJ/m3 (0.6 m/s) Nutrient recovery Water reuse Cellulose reuse