This work describes AMD techniques of neutralization, with lime, flocculation of the precipitates and comparative flocs/liquid separation by flotation with microbubbles or by lamellar settling (LS). The AMD treated water was characterized by its quality for recycling in terms of inorganic or organic elements, suspended or dissolved solids, among others. Two types of flocs were formed, "aerated" or not, in a special flocculation reactor, patented by this research group (RGF (R)). Aerated flocs formed (within seconds) entered into contact with microbubbles under high shearing and raised-up at rates>120 mh(-1) allowing a rapid solid-liquid separation by flotation (HR-high rate), at about 13-15 m(3)m(-2)h(-1) loading capacity. Conversely, the non-aerated flocs settled at about 5-6 m h(-1) in a lamella settler. Both AMD treatment techniques showed similar efficiencies (removal of ions>90%) but the separation by lamella settling presented advantages, namely less reagents (no flotation collector required). lower power requirements and easier to operate. The operating costs (approximate values) of the AMD treatment by LS at pH 9 reaches about 0.3 US$ m(-3) against 0.6 US$ m(-3) for the HR-flotation process. Results found were proved to be similar to those found in recent ADM treatment installations in South Brazil. The quality of the treated water is fairly good, nearly free of heavy metals ion, low BOD (biological oxygen demand) and TOC (total organic content), low solids content and may be readily reused for irrigation, industrial processes and as wash water (among others, streets, vehicles, dust control). However. there is a need to extend the use of this treated water resource, but this, at least in Brazil, has not been legislated properly. It is concluded that this research will contribute in the discussion of this old and complex problem in acid mining effluents worldwide. (C) 2009 Elsevier B.V. All rights reserved.