Experimentation of passive treatment, for example: direct osmosis and Raps units
for acid mining waters. Direct osmosis is an emerging technique under development
and is based on the use of a semi-permeable membrane fitted between the aliment and
a strong synthetic saline water (draw solution, DS). A spontaneous flow is established
(i.e. without the application of any hydraulic pressure, at atmospheric pressure)
of fresh water from the aliment (which is concentrated) to the DS (which is diluted).
Once fresh water is recovered, DS restored to initial concentration levels can be
recycled for reuse in the process. RAPS units: passive treatment process of acid mining
water. Currently laboratory and pilot scale experimentation is under way of main treatment
units, including a drainer-reducer, RAPS, which consists of a series of organic compost
and calcium beds, along with an oxidation-sedimentation unit.