Abstract: Provided is a process for the treatment of aqueous effluents containing organic and inorganic matter and having a solids content of at most 12% by weight to provide a purified liquid phase and a solid organic fertilizer or organic soil improver. The process includes subjecting the effluent to one or more primary liquid/solid separation steps to obtain a liquid medium containing no more than 3% by weight of dry matter and having a turbidity of at most 300 NTU and a collection of concentrates containing in total 15% by weight dry matter. The liquid medium is subjected to ultra filtration or micro filtration to obtain an ultra filtrate or a micro filtrate containing at most 1% by weight dry matter and having a turbidity of at most 100 NTU. The ultra filtrate or micro filtrate is subjected to a reverse osmosis operation to obtain a concentrate and a permeate. The permeate constitutes a purified aqueous phase.