Source separation for excreta: Bases for professionnal rules

Source separation involves separating the flows usually entering wastewater systems from the household. Like selective sorting for waste, it involves collecting the various wastewater inputs separately, in order to offer simplified treatment (in terms of technique, energy consumption and cost) and recovery routes for the components present in each flow. The main benefits lie in the protection of water resources and the return of nutrients and organic matter to agricultural soil, while limiting health and environmental impacts. This article on the source separation of excreta is more concerned with the return of nutrients and organic matter to agricultural soils than with the protection of water resources, which is already largely covered. As such, the energy recovery associated with human excreta will not be addressed. As for source separation of household wastewater, this will be addressed solely through the prism of an obligation to manage this flow as soon as source separation of excreta has been implemented.

The traditional practice of dry toilets has never completely disappeared. In fact, since the mid-1990s, there has been a resurgence of interest and a diversification of practices. . It's a trend that's gaining momentum both in France and worldwide. Drawing on increasingly widespread event-based practices and deployment on the scale of rural households, a network of French players in the field encouraged the emergence of a regulatory derogation on this subject in 2009.

When it comes to practical implementation, excreta source separation systems need to be designed taking into account all the stages in the material management chain right up to the point where the material is returned to the ground. The layout of all the stages of this process, whether small-scale (individual homes, households), medium-scale (apartment buildings, collective housing) or large-scale (several buildings within one or more towns with a dedicated service), requires compliance with technical specifications to ensure that it functions properly. These prescriptions are set out in various reference documents which, together with the present article, contribute to the production of professional rules.

This article is based on current knowledge of excreta source separation techniques. The aim is to meet the needs of a wide audience of professionals and academics for practical knowledge on the design and operation of such systems. To this end, the article is divided into five parts: the first provides...