The Rhizopur® process ten years on: a green solution for sewage treatment in small communities

Ten years ago the Rhizopur® process was conceived in order to treat sewage from small towns. Since 1999 when the first Rhizopur® plant was commissioned, the number of facilities has been growing steadily and today there are more than fifty Rhizopur® facilities in France. This process combines three existing technologies, i.e. biofilm, infiltration/percolation and mineralisation in constructed wetlands, to conduct both wastewater and sludge treatment in a very cost-effective fashion. A trickling filter or a rotating biological contactor is combined with constructed wetlands to produce a high quality effluent, i.e. BOD₅<20 mg/l, COD<100 mg/l and TSS<30 mg/l, and to achieve high removal efficiencies, i.e. BOD₅ removal >90%, COD removal >80% and TSS removal >90%. Nitrification can also be achieved by increasing the size of the trickling filter. Part of the success of this process has been its modularity and compactness that have resulted in its easiness for extension, as well as its capacity to blend with the environment. The characteristics of this process make of it an appropriate solution for sewage treatment in the developing countries. The objective of this work is to give an overview of the performance and features of this process according to the operational experience gained during the last 10 years.