Analysis of pharmaceuticals, hormones and bacterial communities in a municipal wastewater treatment plant – Comparison of parallel full-scale membrane bioreactor and activated sludge systems

T Leiviskä,S Risteelä

doi:10.1016/j.envpol.2021.118433

T Leiviskä, S Risteelä

Open Access

https://doi.org/10.1016/j.envpol.2021.118433

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Journal: Environmental Pollution	Publication Date: Oct 29, 2021
Citations: 24	License type: cc-by

Affiliation: University of Oulu

Abstract

In this study, the occurrence of pharmaceuticals, hormones and bacterial community structures was studied at a wastewater treatment plant in Finland having two different parallel treatment lines: conventional activated sludge (CAS) treatment with a sedimentation stage, and a membrane bioreactor (MBR). Influent and effluents were sampled seven times over a period of one year. The bacterial communities of the influent samples showed a high degree of similarity, except for the February sample which had substantially lower diversity. There was significant fluctuation in the species richness and diversity of the effluent samples, although both effluents showed a similar trend. A marked decrease in diversity was observed in effluents collected between August and November. The initiation of nitrogen removal as a result of an increase in temperature could explain the changes in microbial community structures. In overall terms, suspended solids, bacteria and total organic matter (COD and BOD) were removed to a greater extent using the MBR, while higher Tot-N, Tot-P and nitrate removal rates were achieved using the CAS treatment. Estrone (E1) concentrations were also consistently at a lower level in the MBR effluents (<0.1–0.68 ng/l) compared to the CAS effluents (1.1–12 ng/l). Due to the high variation in the concentrations of pharmaceuticals, no clear superiority of either process could be demonstrated with certainty. The study highlights the importance of long-term sampling campaigns to detect variations effectively.

Highlights

The release of pharmaceuticals and hormones into water bodies has been a major concern in recent decades
The average total nitrogen (Tot-N) and nitrate concentrations were lower in the conventional activated sludge treatment (CAS) effluent compared to the Membrane bioreactors (MBR) effluent (p-values 0.05)
The MBR process still needs to be optimized for higher nitrogen removal and especially for better denitrification

Summary

Introduction

The release of pharmaceuticals and hormones into water bodies has been a major concern in recent decades. These compounds have adverse effects on aquatic life, for example behavioural alterations and accu mulation in fish (Brodin et al, 2014; Huerta et al, 2018). The main removal mechanism of many pharmaceuticals and hor mones in municipal wastewater treatment plants (WWTP) is biotransformation, while sorption onto sludge is less significant and airstripping and photo-transformation are considered to be insignificant (Gao et al, 2012b; Li et al, 2015; Ottmar et al, 2012; Sipma et al, 2010; Wick et al, 2009; Wijekoon et al, 2013).

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