Pulles, W, Lodewijks, HM, Toerien, A, Muhlbauer, R, van Niekerk, JA & Richardt, A 2016, 'Passive treatment of acid mine drainage at Vryheid Coronation Colliery, South Africa', in AB Fourie & M Tibbett (eds), Mine Closure 2016: Proceedings of the 11th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 425-438, https://doi.org/10.36487/ACG_rep/1608_31_Pulles (https://papers.acg.uwa.edu.au/p/1608_31_Pulles/) Abstract: 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 m³/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 m³ 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. Keywords: passive treatment, acid mine drainage, coal mining