Abstract — This paper discusses the validation of the use of sludge generated at UASB wastewater treatment plants and an input for the recovery of agricultural soils based on compositing. In the first place, it presents the legal framework that currently governs the management and use of biosolids. IN the second place, it describes the sludge generation process in a UASB WWTP and the output conditions of the sludge generated thereby. Another section explains the standardized compositing process for organic waste; and finally, it discusses the laboratory and legal tests necessary to ensure the safety of the sludge and its use in agricultural processes.