Use of Ochre from an Abandoned Metal Mine in the South East of Ireland for Phosphorus Sequestration from Dairy Dirty Water

Ochre found at coal mine drainage sites in the United Kingdom shows a high phosphorus (P) retention capacity with little mobilization of metals. This indicates that ochre has the potential to adsorb P from agricultural wastewaters for possible use as a fertilizer. Little research has focused on the ability of metal mine ochre to sequester P in an environmentally sustainable way. Untreated acid mine drainage from an abandoned copper-sulfur mine in the Avoca-Avonmore catchment in the south east of Ireland results in extensive low-value ochre deposition. In this study, P-amended water (50 mL) was mixed with this ochre (2.5 g) in batch experiments, and a maximum P adsorption capacity, calculated from the Langmuir equation, of between 16 and 21 g P kg(-1) was calculated. However, mobilization of heavy metals from Avoca ochre in distilled, surface, and dirty water batch experiments was observed. This mobilization may inhibit ochre's use in P removal from wastewaters.