Anaerobic treatment of high sulphate containing pharmaceutical wastewater

The effect of different organic loading rate (OLR) to an anaerobic reactor performance and sulphate reduction was investigated. Sulphate concentration in the feed varied from 100 to 3000 mg.L-1 and up to 97% removal efficiency was observed at OLR 0.43 - 1.23 kg COD.m-3.d-1. However, the removal efficiency showed some decline (to 53 – 67% removal) at OLR 1.53 – 3.73 kg COD.m-3.d-1, probably due to high sulphate concentration in the feed during this period. At a reactor OLR of 1.86 kg COD.m-3.d-1 (HRT 4 d), the soluble COD reduction was around 70 - 75%. Nevertheless, when the OLR was increased to 2.48 - 3.73 kg COD.m-3.d-1, the COD removal efficiency decreased to 45%. The microbial aspects of sulphate reducing bacteria (SRB) results indicated that sulfidogenic bacteria, such as Desulfovibrio, had contributed substantially to the treatment process (around 16 – 36% when the reactor was operated at OLR 0.86 – 2.98 kg COD.m-3.d-1)