Sewer Mining as A Basis for Technological, Business and Governance Solutions for Water in the Circular Economy: The NextGen Athens Demo

Abstract

The Athens Water in the Circular Economy demo case examines all three of the following as associated with Circular Economy (CE) in wastewater streams: water, energy and materials. The application area is the Athens Urban Tree Nursery, which is located in the center of Athens, in order to address real world problems in water-scarce cities. The Athens demo application includes sewer mining, a technology first pioneered in Australia related to mobile wastewater treatment units in containers that are able to treat and provide reused water at the point of demand in dense urban environments. The installed pilot unit consists of a membrane bioreactor unit (MBR) and a UV disinfection unit. The sewer mining is achieved with a prefabricated pumping statiοn that will be demonstrated in the main sewer network for feeding the sewer mining unit with wastewater. The unit will produce fresh water that will be used for irrigation needs, and also during the winter for aquifer discharge. The Athens Tree nursery also has significant amounts of pruning materials that, until now, have remained untapped resources. The excess sludge produced from the unit along with the green and wood waste will go through a rapid composting process in order to produce fertilizer. The first stage will be a pre-treatment unit that includes the shredding, homogenizing and sorting of the pruning materials. The second stage is rapid composting that will last approximately 2 weeks. The last stage is the compost that will be used again on-site as a fertilizer full of nutrients as part of a renewable energy solution for the area to support more complete autonomy.