7. Conclusion

The flow rates and concentrations of wastewater produced by on-site sewage systems are much more variable than in collective systems. Periods without wastewater input, lasting from a few days to several weeks, are present, requiring systems well adapted to these conditions. A review of the three main technological families and the performance measured under in-situ conditions shows that systems incorporating a biological filter are much better suited to the realities of on-site wastewater treatment. The performance of microstation-type systems is much more variable, due to inadequate sizing or maintenance, resulting in the discharge of sludge into the receiving environment. However, even where a filter medium is present, compact filters must be designed to meet fundamental criteria in terms of sizing (minimum 0.50 m ² /EH), effective distribution...