One of the obstacles to resource recovery from wastewater is the “end of the pipe” problem: today, all waste material gets mixed – to be flushed away with clean water, normally to a treatment plant sited “not in my backyard” – far away from any user of the reuse water, energy or fertilizer. An alternative approach to keep the resources closer to the user is the decentralized treatment, and separation of sources – trying to recover energy in a concentrated stream, and reuse the less contaminated grey water.
This concept of local source separation and reuse was demonstrated in an office building in Vigo (Fig. 1), as part of the EU H2020 project www.run4life-project.eu , and in a few other locations in Ghent/Belgium and Helsingborg/Sweden in new harbour developments with hundreds of apartments, where energy is reused and fertilizer recovered in nearby factories.
A continuation of this concept is now implemented in www.rewaise.eu in a major car factory in Vigo, a large user of water and energy. By putting a compact reactor on the sewer within the factory premises, the wastewater can be converted to biomethane and reuse water to be recycled into the production. The technology demonstrated is the MEMB-RANER (Membrane Reactor for Anaerobic Nutrient and Energy Recovery), which allows to convert organic matter directly to biomethane, without wasting electricity on aeration.
Similar to aerobic Membrane Bioreactors (MBR), this process uses microfiltration submerged in the treatment tanks to concentrate the biomass, and to reach a disinfected effluent free of solids, but rich in nutrients for irrigation (Fig. 2). As a compact, enclosed structure, it can be easily placed on a skid in the cellar of a building or in a container on a parking lot, for instance to convert local sewage into irrigation water for a golf course or for industrial uses as washing or cooling water. Memb-Raner was demonstrated in the project www.life-memory.eu for several years on industrial scale, and is now installed in handful of plants for a variety of effluents.
In the car factory in Vigo, a prototype housed in a container is being installed in a parking lot close to the main sewer. The installation is designed for a flow 10 m3/h, which will allow to establish exact material balances on the energy recovery and water reuse potential. As aqualia is the operator of the water system in Vigo, it can then offer a more sustainable service to one of its main customers, in partnership with the owner of the site, Zona Franca de Vigo (ZFV).