On-site sanitation

In France, non-collective sanitation (ANC) treats the wastewater produced by almost 20% of the population whose homes are not connected to a public collection network. Every year, almost 100,000 ANC systems are installed, half of which involve rehabilitating failing facilities. Several types of system are used: traditional systems (land application and reconstituted filter beds) and, since the entry into force of the "technical specifications" decree of September 2009, "other systems" consisting of compact ANC systems that must be approved in accordance with the requirements of this decree. The majority of approvals are based on the results of CE marking tests carried out on these products in accordance with standard NF EN 12566-3+A2 . These compact systems, now chosen for around 40% of installations, are grouped into three technological families: compact filters, microstations and planted filters. In 2017, the results of a vast campaign to monitor the in situ performance of ANC systems in France highlighted regulatory compliance issues. The best-performing systems were mainly of the biological filter type. There are a number of possible explanations for the problems encountered, but undersizing of several components of failing systems appears to be the most important. What's more, the recent arrival on the French market of increasingly compact ANC systems is not likely to improve the situation. It is against this backdrop that this article presents, for each technology family, the fundamental design criteria, the factors influencing performance and the operation and maintenance requirements to ensure sustainable performance, all in relation to current regulations and the characteristics of the wastewater produced in ANC. Criteria for sustainable infiltration of treated water and factors influencing the carbon footprint of each technology family are also covered.