The goal of Water2REturn (an Innovation Action that is co-funded by the European Commission under its Horizon 2020 programme) is to provide, in compliance with the Circular Economy Package, an innovative, sustainable, and convenient solution to process slaughterhouse wastewater and turn it into value-added products. The project was launched in July 2017 and the consortium met on July 10th – 11th, 2018 in Seville, Spain to evaluate the outcomes from the first year before building starts at the pilot plant in the autumn.
At this stage, most of the design work has been done for each line (water line, sludge line and algae line) of the demonstrator. The water line includes the biological treatment through the sequencing batch reactor (SBR) and the module for the recovery of nitrates, from which a nitrates concentrate will be obtained. This concentrate forms the base for producing the biofertiliser. The water line is one of the most important parts of the Water2REturn system as it is the part that treats the wastewater and starts the whole process.
Work is now focused on provisioning issues, prior to the installation of the equipment at Matadero del Sur, theWater2REturn’s demonstration site.
The sludge line takes the sludge from the water line and puts it through a fermentation process to get a solid fraction that is mainly composed of organic matter and bacteria. A biostimulant product will be produced from this. The liquid fraction is highly-methanisable and it will be the source of energy to make the Water2REturn system self-sufficient in terms of energy use. This will be possible because of an Anaerobic Sequential Batch Reactor (ASBR) which will be used to produce biogas from the liquid fraction.
In this context, many different sludge pre-treatments, including the addition of different co-adjuvants, have been tested during the past year to find the best conditions to get the maximum possible efficiency out of the fermentation process. Different tests were also carried out to find the best conditions to obtain the maximum efficiency. It was concluded that the highest biogas production rates are reached for Hydraulic Retention Times (HRT) between 5 and 4 days, producing 0.75 m3 biogas/m3 of substrate per day.
The last part of the system is the algae line which captures the CO2 that is released by the energetic valorisation unit (ASBR) to produce algal biomass; the basis to produce a second biostimulant. During the past year, different pre-treatments for algae from biogas digestate treatment ponds have been tested for their biostimulative and fertilising effects on crop growth. For further testing and algal production, several variations of algal ponds have been installed in the Algal Park: a purpose-built facility in the University of Ljubljana, Slovenia. These designs will be used to optimise the algal unit in Matadero del Sur.
As well as the technological work, the consortium is also involved in stakeholder engagement and communication and dissemination activities which are important for understanding the specific market needs and how Water2REturn addresses them.
Five different stakeholder groups (slaughtering industry, wastewater treatment industry, fertiliser industry, consumers & NGOs, and farmers) have been identified and the consortium aims to gather their technical inputs, as well as their main needs and concerns, and to communicate with them as potential future end-users of the Water2REturn system. In order to achieve this, tailored questionnaires were distributed with the aim of identifying the stakeholders’ influence, their interest in cooperating with the project, the challenges they face, and the opportunities for them.
Stakeholders have been updated about ongoing and future project activities, such as specific workshops to deeply analyse the technical aspects of the project. Thanks to these initiatives, stakeholders will be able to understand the environmental and economic benefits of the Water2REturn project.