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Biological sludge is waste generated in wastewater treatment plants, as a consequence of the sedimentation of suspended material and by the growth of biomass in the biological treatment. This sludge represents a generation that for some countries, reaches figures of 1,400 t / day in Canada, 2,000 t / day in the United States of North America, 1,753 t / day in Mexico, 1,232 t / day in Brazil, among others, with growth 60% expected by 2050. Historically, this type of solids has been disposed of in sanitary landfills, contributing to the environmental, social and economic impacts related to waste management; However, in recent decades and globally, the application of anaerobic digestion has been proposed as an alternative for the treatment of solids, given its easy operation, economic value and the possibility of obtaining by-products such as biogas and compost. In Latin American countries this situation is not particularly different, where some researches have focused their efforts on studying the different variables that are related to anaerobic digestion. In this bibliographic review article, 56 research works related to anaerobic co-digestion processes, pretreatment, mathematical models, microorganisms, operating parameters and economic evaluation were analyzed; where, although there is an important advance in relation to the subject, greater efforts are required to allow the understanding and adjustment of the different parameters, especially in pilot and real scales, enabling their implementation in waste management. [ABSTRACT FROM AUTHOR]