Scenarios for innovative management of urban wastewaters based on source separation – DESIGN

This project combines different works carried out in parallel:
(1) Sanitation simulator: Development of a software tool for the environmental and economic assessment of the collection, treatment and valorization sectors of the flows produced within a specific urban structure (different urban configurations are taken into account) .
(2) Technologies developed: Urine separation toilets and a pilot for recovering nutrients N and P. For the latter, a pilot treating 2.4 m3.d-1 of urine combines the recovery of phosphorus by precipitation in the form of struvite and ammonia by a promising new technique: transmembrane chemosorption (TMCS). Free ammonia gas (NH3) passes through a hydrophobic membrane from the liquid flow to an acidic solution, producing ammonium sulfate which is an agricultural fertilizer.
(3) Appropriation by the actors: a socio-technical study of the scenarios with professional actors and users was carried out showing how they appropriate the benefits but also the constraints of the decentralized sanitation and recovery sectors. This study materialized on concrete cases such as in Bordeaux during the experiment of La Fumainerie, the first initiative of
separate collection network for excreta in urban areas, as also in Grenoble and other sites. The database generated can help the players in the sector for the implementation of source separation and recovery systems.
(4) Urban integration: the scenario simulation tool is applied to concrete neighborhoods. These simulations provide precise knowledge on the relationships between urban typologies and the choice of sectors integrating various constraints. This work will help orient the first demonstrators and bring out the first references for the most promising scenarios.

1) Functional simulation software tool for decision support on sanitation policies to be implemented in a city. This tool made it possible to carry out a multi-criteria comparative study on typical sectors. It was adapted to model real study cases from GIS (Geographic Information System) data. It is now used for other projects in which it is a central part (Sudoe ecoval project ...)
2) technological component: A database on technologies, scenarios and experience feedback (http://design.cnrs.fr/contexte/); An experimental evaluation of the ammonia separation process at laboratory and pilot scale for demonstration on site; A urine-separating toilet pilot called WCesar developed and a first live-site demonstration took place at the Garorock festival (June 27-30, 2019). 3) Sociotechnical component: Survey to measure the perception by users (600 including 150 surveyed) of «WCesar« toilets at the Garorock festival; An educational video for the general public concerning the separation at source of urine and its use as fertilizer has been produced; case studies: Grenoble surveys (participatory housing, dry toilets with in situ treatment); La Fumainerie Bordeaux, collection of faeces for local treatment; Parisian territory several cases, sensitive area (in the commune of Saint Denis is that going to happen); Saclay trays, Saint Vincent de Paul (urine collection).
4) Application component: Around ten responses to Calls for Expressions of Interest on opportunities for implementing source separation on a pilot site and for the transition from prototype to small series.

the project was based on two main axes: 1) technological development and 2) socio-technical assessment. These two axes were carried out in parallel to end up lifting the brakes for the application of separation at the source of domestic effluents. The sanitation sector scenario simulation tool providing comparisons of environmental impacts and overall costs is operational and is now used for other projects. The separating toilets are working and a production of the prototype is being discussed with SMEs. The separation of nitrogen by chemosorption allows substantial recovery of nitrogen with reasonable energy consumption. Source separation significantly increases nutrient recovery rates in the form of fertilizers, from 6% to a minimum of 48% for nitrogen and from 13% to 58% for phosphorus. Concrete projects are multiplying and the actors of the Design projects wish are for some stakeholders.

The various communications that were made on the urine separation toilet test in Garorock: www.eau-adour-garonne.fr/fr/toute-l-actualite/annee-2018-1/er-semestre -2018 / la-separation-a-la-source-garorock.html; Seminar «The separation of urban effluents: the sanitation of the future? »Https://solagro.org/separation-des-effluents-a-la-source-un-colloque-stimulant-40-actu-105; Articles were produced explaining the technologies developed or the results of simulations of source separation scenarios. For example: communication to Water, Megacities and global change 7-11 December 2020, Unseco or article DOI: 10.1016 / j.jclepro.2021.126868; A workshop on «source separation and the making of the city«.

The source separated management of urban effluents (brown waters, grey water, urine) could lead to a sustainable transformation of the current sanitation methods and constitutes a major innovation in the field of wastewater management in the environment.

The DESIGN project aims to develop and evaluate innovative scenarios for source separation and wastewater recovery. The challenge of the project is to evaluate the real benefits and constraints of these alternative approaches by integrating different criteria: (1) in the environmental field, firstly, by assessing the reduction in pressures on sanitation systems and receiving bodies due to a reduction in pollutant fluxes and their temporal variations; By assessing the reduction of greenhouse gas emissions and energy consumption; By identifying and quantifying recyclable materials and their local recovery (nitrogen, phosphorus, organic matter, treated water); (2) from a technological and economic point of view: by developing key technologies for new pipelines, ie vacuum separation toilets that do not currently exist, new ammonia nitrogen recovery technology to produce fertilizer; (3) from a sociological point of view, by measuring the appropriateness of these new systems for managing human waste and decentralized systems by urban communities, users and professionals; (4) and finally, on the urban plan, by evaluating the adequacy of the separation scenarios at source to the different urban typologies.

The project involves two research laboratories, two research departments specializing in the environment, and two companies developing innovative equipment. This project combines (1) the development of a methodology and an environmental and economic assessment tool, (2) the pilot study and demonstration at the pre-industrial scale of promising innovative technologies, (3) the sociological study of the scenarios with the professional actors and the users, and finally, (4) the urban feasibility study, based on real cases on a large French city. By projecting these scenarios on real cases, this project will guide the first demonstrators and bring out the first references for the most promising scenarios.