Rationale

Considering the strong EU commitment towards full implementation of a European circular economy, it is necessary to extend and to improve available options for resource recovery from the organic fraction of waste of urban origin, especially towards higher value products than energy and compost. Within the urban environment, significant amounts of organic residues originate from the separate collection of urban solid waste (OFMSW) and the sludge from urban wastewater treatment plants (WWS). Although OFMSW and WWS originate from the same urban area and contain similar amount of organic carbon and of similar nature, usually these two streams are handled separately. This historical separation of treatment options creates an interesting opportunity to identify processes and strategies that allow for the effective conversion of organic carbon contained in urban wastes into useful bio-based products, while also reducing the global impacts on water and climate caused by their treatment and disposal. The integrated treatment of civil wastewater along with organic solid wastes (mostly of municipal origin, while not excluding residues from food-processing industry of comparable composition) in a novel “bio-waste biorefinery” is a key option to practically implement a synergic treatment of all relevant bio-waste streams of urban origin. Indeed, this integrated and flexible “bio-waste biorefinery approach” can present several advantages, in both environmental and economic terms, especially because it allows to achieve the critical operating capacity of the bio-waste biorefinery even in small “waste basins”. In order to define appropriate strategies, it is thus necessary to take into account that driving forces and constraints highly depend on the territorial conditions. In other words, it is necessary to create autonomous clusters where the recovery strategies are affordable and recovery cycles can be closed within the cluster itself, e.g. without the need to transport either bio-waste or the resulting bio-based products for long distances.