Treatment of Metformin-Containing Wastewater by a Hybrid Vertical Anaerobic Biofilm-Reactor (HyVAB).

Janka Janka,Carvajal Carvajal,Dinamarca Dinamarca,Bakke Bakke,Wang Wang

doi:10.3390/ijerph16214125

Abstract

Several series of batch and continuous experiments were performed to investigate the removal of metformin and other contaminants from two wastewaters: wastewater I (WWI) containing 4 mg/L metformin and wastewater II (WWII) containing 110 g/L butanol. Biomethane potential (BMP) tests on WWII showed 77% of total chemical oxygen demand (tCOD = 110 g/L) degradability, and no apparent inhibition effects were observed. BMP tests on WWI showed an apparent inhibitory effect reflected in lower biogas production with increasing metformin concentration in the wastewater. Continuous flow hybrid vertical anaerobic biofilm (HyVAB®) experiments were consistent with the batch test findings. It was necessary to co-digest WWI (metformin) with WWII (easily degradable organics) to achieve complete metformin removal. After a period of adaptation, WWI and WWII co-digestion achieved up to 98% tCOD removal and 100% metformin removal. Most of the contaminants were removed in the anaerobic section of the HyVAB®, which implies that higher chemical oxygen demand (COD) loads than tested here are possible, given some optimization. The pilot reactor was able to manage organic loads of 11 g COD/d and above 10 mg/L metformin with a removal of 98% and 100% for tCOD and metformin, respectively.

Highlights

The rapid development of large-scale pharmaceutical manufacturing has contributed to increased concentrations of contaminants present in wastewater and surface waters [1,2]
The methane potential test showed that biogas production rate and accumulation decreased with increased metformin concentration as shown in Figure 2A,B, respectively
Maximum production rates decreased by factors of 5, 19, and 56 when the concentration of metformin increased to 1.0, 2.1, and 4.2 mg/L, respectively (Figure 2A)

Summary

Introduction

The rapid development of large-scale pharmaceutical manufacturing has contributed to increased concentrations of contaminants present in wastewater and surface waters [1,2]. Pharmaceutical wastewaters are produced during the drug manufacturing processes (i.e., fermentation, extraction, chemical synthesis, formulation, packaging and washing of solid cake and equipment) [3,4]. Several studies have shown that pharmaceutical drugs (and their derived metabolites) are found in effluents of wastewater treatment plants (WWTPs) and their removal is very inefficient [1,6]. Wastewater originating during the manufacturing of antidiabetic drugs is an important environmental challenge due to the high production volume [7,8]. Several research papers have reported the occurrence, degradability, and environmental impact of antidiabetic drugs in wastewater [9,10,11,12], and substantial efforts to achieve environmental improvements in line with regulations and legislation have been implemented [13]

Methods

Results

Conclusion