Pharmaceuticals and personal care products\u2019 (PPCPs) impact on enriched nitrifying cultures

Carla Lopez,Yiu Fai Tsang,Charles W Knapp,Mac-Anthony Nnorom

doi:10.1007/s11356-021-14696-7

Abstract

The impact of pharmaceutical and personal care products (PPCPs) on the performance of biological wastewater treatment plants (WWTPs) has been widely studied using whole-community approaches. These contaminants affect the capacity of microbial communities to transform nutrients; however, most have neither honed their examination on the nitrifying communities directly nor considered the impact on individual populations. In this study, six PPCPs commonly found in WWTPs, including a stimulant (caffeine), an antimicrobial agent (triclosan), an insect repellent ingredient (N,N-diethyl-m-toluamide (DEET)) and antibiotics (ampicillin, colistin and ofloxacin), were selected to assess their short-term toxic effect on enriched nitrifying cultures: Nitrosomonas sp. and Nitrobacter sp. The results showed that triclosan exhibited the greatest inhibition on nitrification with EC50 of 89.1 μg L−1. From the selected antibiotics, colistin significantly affected the overall nitrification with the lowest EC50 of 1 mg L−1, and a more pronounced inhibitory effect on ammonia-oxidizing bacteria (AOB) compared to nitrite-oxidizing bacteria (NOB). The EC50 of ampicillin and ofloxacin was 23.7 and 12.7 mg L−1, respectively. Additionally, experimental data suggested that nitrifying bacteria were insensitive to the presence of caffeine. In the case of DEET, moderate inhibition of nitrification (<40%) was observed at 10 mg L−1. These findings contribute to the understanding of the response of nitrifying communities in presence of PPCPs, which play an essential role in biological nitrification in WWTPs. Knowing specific community responses helps develop mitigation measures to improve system resilience.

Highlights

The widespread presence of pharmaceutical and personal care products (PPCPs) in the environment has drawn the attention of the research community due to the potential adverse effects on ecosystems and human health (Kümmerer 2009; Tran et al 2018)
This study investigated the effect of selected PPCPs, including a stimulant (CF), personal care products (DEET and TCS) and antibiotics (AMP, OFX and CST), on an enriched nitrifying community
Proteobacteria were dominant in all analysed samples, accounting for 63–68% of the total bacterial population; followed by Bacteroidetes, 19 (S1–S2) to 30–32% (S3 and S4); Chlorobi, 10 to 0.4–3% (S3 and S4, respectively); and the remaining bacteria represented

Summary

Introduction

The widespread presence of pharmaceutical and personal care products (PPCPs) in the environment has drawn the attention of the research community due to the potential adverse effects on ecosystems and human health (Kümmerer 2009; Tran et al 2018). TCS concentrations have been reported in different influents of WWTPs worldwide, and the values are as high as 0.47 μg L−1 in China (Zheng et al 2020), 86.1 μg L−1 in the USA (Kumar et al 2010) and 17.6 μg L−1 in South Africa (Lehutso et al 2017). Due to the variable removal efficiencies in WWTPs (Luo et al 2014), TCS and DEET can be found in different environmental matrices, such as treated effluent, surface waters, waste sludge and sediments (Ramaswamy et al 2011; Dai et al 2014; Zhao et al 2010; Dsikowitzky et al 2020)

Methods

Results

Conclusion