From Wastewater Treatment to Total Resource Recovery – Changes are Happening in Auckland, NZ

Wastewater is becoming one of the world's greatest sustainable resources (WERF et.al. 2011). According to a 2011 Water Environment Research Foundation Study, the energy contained in wastewater and biosolids exceed the energy required for its treatment by 10 fold. If the renewable energy contained in wastewater is captured cost effectively, wastewater utilities have the potential to become energy neutral or near neutral. The Wastewater nexus provides four potential renewable, revenue streams – water-energy-biosolids-biogases.Many utilities are looking at or are starting to realise wastewater nexus revenue generation potentials (WERF 2011, Forbes et.al. 2011, and Witherspoon et.al. 2011). However, wastewater treatment plants are an on-going expense for municipalities to operate. The challenge is in the efficient harnessing of wastewater renewable potential under the backdrop of ever tightening environmental regulations, technology limitations, and increasing demand requirements, all within limited municipal funds. Watercare has taken this challenge head on at Auckland's Rosedale Wastewater Treatment Facility (WWTP) by delivering more for the same funding. Watercare is responsible for water services to the 1.5 million people in Auckland, New Zealand.Working with CH2M Hill and U.S. Water Environment Research Foundation (WERF et.al. 2011) tools, Watercare is transforming its Rosedale WWTP from a net fund consumer to a net revenue generator. Watercare is using an innovative, staged, “total” Resource Recovery (2R) Master Plan approach. The 2R Master Plan is focused on generating revenue, marketable products, electricity, and/ or thermal energy from the wastewater nexus. The Rosedale plant is being upgraded over a staged period that matches population growth and allowable capital spend from a net energy importer to a net energy exporter. Moreover, it is being transformed to a net revenue generator through resource recovery technologies, all within the previously established “regulation and growth” 20-year investment plan. The 2R Master Plan consists of 9 tasks to be implemented and tied into one strategy with technology gateways, economic touch points, and end use product line development strategy.This paper presents the first stage evaluation under the 2R Master Plan. This stage is focused on “true cost” and technology considerations along with key economic parameters when selecting a biogas energy recovery option. Lessons learnt from Rosedale WWTP will be provided that allows clear decision making on biogas recovery options and at what cost impact and/or benefit each option provides the utility.