**2.4 Sulphate and arsenate concentration**

Sulphate concentration is the most consistent feature of AMD as its origin comes from sulphate oxidation. Various studies show that the effectiveness of sulphide oxidation depends on sulphate concentration and flow of effluent from the zone of

**Figure 3.** *Various factors for the formation of AMD.*

oxidation and any subsequent dilution. Arsenate does not form in such a higher concentration as that of sulphate but this metal has a different area of concern due to its toxic nature [7].
