Passive treatment of acid mine drainage at Vryheid Coronation Colliery, South Africa

摘要

A novel passive bio-neutralisation water treatment process has been applied to treat an acidic mine drainage decant emanating from a closed colliery in northern KwaZulu Natal, South Africa. The process has been implemented to treat 200 m~3/day of water and incorporates the following components: a 3.2 km pipeline from the decant point to the water treatment site, a molasses dosing station, a 1,000 m~3 bio-neutralisation reactor, three aeration cascades to oxidise sulphides, passive sulphide gas extraction to a bio-filter to oxidise sulphide gas, three limestone reactors for pH polishing, and an aerobic wetland to remove residual nutrients. The bio-neutralisation technology is a strictly biological process utilising bacterial processes to treat an influent with a pH as low as 2.8 to remove the acidity, iron and aluminium. The plant has already been constructed and commissioning commenced in August 2015.