Removing phosphorus from sewage effluent and agricultural runoff using recovered ochre

Widespread closure of deep coal mines in industrialised countries in recent decades has resulted in increased pollution of watercourses by acidic, metal-rich mine drainage following flooding of abandoned mine workings. Schemes for remediation of such polluted mine drainage encourage the precipitation of iron, normally in settlement ponds or constructed wetlands, thereby generating large quantities of ‘ochre’ (i.e., Fe(OH)3 and FeO OH) (see, for instance, Younger et al., 2002). Typically, this ochre is stockpiled pending use or disposal. Although a number of possible end-uses have been considered (e.g. colouring bricks/cement and in synthesising coagulants for drinking water; Tarasova et al., 2002), no single end-use has yet been identified which could consume the projected future production of ochre in the UK and Europe. In this chapter a further possible