Application of anaerobic biotechnology for pharmaceutical wastewater treatment

Abstract

The wastewater generated from pharmaceutical industry generally contain high organic load and the treatment is primarily carried out using two major types of biological methods; aerobic and anaerobic. However, due to high strength, it is infeasible to treat some pharmaceutical wastewater using aerobic biological processes. As an alternative, an anaerobic process is preferred to remove high strength organic matter. Anaerobic wastewater treatment is considered as the most cost effective solution for organically polluted industrial waste streams. In particular the development of high rate systems, in which hydraulic retention times (HRT) are uncoupled from solids retention times (SRT), has led to a worldwide acceptance of anaerobic wastewater treatment. In this paper, literature on anaerobic digestion, anaerobic reactor technology and existing anaerobic treatment of pharmaceutical wastewater are presented. In addition, fate of pharmaceuticals in the environment was also discussed in brief. A case study of a laboratory investigation into the treatment of pharmaceutical wastewater containing the antibiotic Tylosin in an anaerobic reactor was also given. Specifically, it was determined whether the anaerobic reactor could be used as a pre-treatment system at an existing pharmaceutical production plant. The performance of the reactor treating real pharmaceutical wastewater at various organic loading rate (OLR) was investigated and showed efficient substrate removal at low OLRs (0.43 – 1.86 kg COD.m-3 .d-1 ) by promoting efficient chemical oxygen demand (COD) reduction (70 – 75%). Under these conditions, an average of 95% Tylosin reduction was achieved in the UASR. However, increasing the OLRs to 3.73 kg COD.m-3 .d-1 by reducing the hydraulic retention time (HRT) (4 – 2 d) reduced the COD removal efficiency (45%). Changes in the organic loading affected the treatment performance of the anaerobic reactor, and at high OLRs, it was not able to withstand the short HRT, probably due to the complexity of pharmaceutical wastewater.