The
general goal of passive acid mine drainage (AMD) treatment is to reduce levels
of acidity and metals to acceptable levels. Most treatment systems use either an
oxidising or a reducing strategy. In oxidising systems, alkalinity is added
along with dissolved oxygen; in reducing systems, dissolved oxygen is removed
(if present) and then alkalinity is added. It is recommended that small-scale
field trials be conducted as part of the methodology of selecting the best
remediation strategy at AMD sites. Following successful field trials at the
Sullivan Mine AMD, the Pike River Coal Company (PRCC) has shown foresight by
using the same system to treat AMD generated as a result of taking a bulk sample
of coal at the Pike River coal field. The
system reduced acidity
by 100 per cent, iron by 99 per cent, aluminium by 96 per cent, nickel by 95 per
cent, manganese by 51 per cent and zinc by 99 per cent. The success of this
field trial suggests that a system using a reducing strategy may be appropriate
for the Pike River Adit AMD site.