Wastewater treatment plant upgrade induces the receiving river retaining bioavailable nitrogen sources

doi:10.1016/j.envpol.2020.114478

Environmental Pollution

Volume 263, Part A, August 2020, 114478

https://doi.org/10.1016/j.envpol.2020.114478 Get rights and content

Highlights

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WWTP upgrade significantly decreased organic nitrogen in the receiving river.
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Composition and interaction of N-metabolizing bacteria were accordingly altered.
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Nitrifying bacteria decreased but denitrifying and DNRA bacteria increased.
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The receiving river was inclined to retain N sources after WWTP upgrade.

Abstract

Currently, wastewater treatment plant (WWTP) upgrades have been implemented in various countries to improve the water quality of the receiving ecosystems and protect aquatic species from potential deleterious effects. The impact of WWTP upgrades on biological communities and functions in receiving waters is a fundamental issue that remains largely unaddressed, especially for microbial communities. Here, we selected two wastewater-dominant rivers in Beijing (China) as study sites, i.e., one river receiving water from an upgraded WWTP to explore the impacts of upgrade on aquatic ecosystems and another river receiving water from a previously upgraded WWTP as a reference. After a five-year investigation, we found that WWTP upgrade significantly decreased total organic nitrogen (N) in the receiving river. As a biological response, N-metabolism-related bacterioplankton are accordingly altered in composition and tend to intensively interact according to the network analysis. Metagenomic analysis based on the N-cycling genes and metagenomic-assembled genomes revealed that WWTP upgrade decreased the abundance of nitrifying bacteria but increased that of denitrifying and dissimilatory nitrate reduction to ammonium (DNRA) bacteria in the receiving river, according to their marker gene abundances. After calculation of the ratios between DNRA and denitrifying bacteria and quantification of genes/bacteria related to ammonium cycling, we deduced the changes in N-metabolism-related bacteria are likely an attempt to provide enough bioavailable N for plankton growth as conservation of ammonium was enhanced in receiving river after WWTP upgrade.

Graphical abstract

Introduction

Wastewater treatment plants (WWTPs) discharge water containing nutrients and micropollutants, which can lead to aquatic eutrophication and ecosystem dysfunction in receiving streams, rivers, and lakes (Gucker et al., 2006; Wakelin et al., 2008; Stamm et al., 2016). To improve the water quality of receiving ecosystems and protect aquatic species from potential deleterious effects, conventional WWTPs based on activated sludge treatment need be upgraded using additional oxidation, sorption, and filtration technologies (Volker et al., 2019). At present, some countries have begun to upgrade their WWTPs; for instance, Switzerland is implementing additional ozonation followed by activated carbon treatment in approximately 100 WWTPs to reduce micropollutant discharge in receiving waters (Eggen et al., 2014); China has applied various upgraded treatment technologies (e.g., ozonation, adsorption, and membrane filtration) in Beijing WWTPs for gray water recycling and to reduce nutrient discharge into the ambient environment (Wang et al., 2015; Wang et al., 2018).

WWTP upgrades may change the biological community structure and function in receiving aquatic ecosystems. As such, questions regarding how community structure and function are altered and how quickly additional treatments result in improved in ecosystem health need to be addressed. Previous studies have demonstrated that additional ozonation treatment can increase the relative abundance of vulnerable macroinvertebrates (Ashauer, 2016), and additional powdered activated carbon adsorption treatment can lead to improvements in fish health (Wilhelm et al., 2017) in receiving water bodies. However, the changes in microbial communities in aquatic ecosystems following WWTP upgrades remain largely unexplored.

Microbial species each have specific function in ecosystems, e.g., nutrient cycling. Microbes interact with the environment and respond to anthropogenic activities (Montuelle et al., 1996; Hamilton et al., 2011; Liao et al., 2018). Previous studies have demonstrated that sewage discharge enhances the capability of microbial communities residing in the receiving river/stream to transform water nutrients/micropollutants, as functional genes associated with degradation or transformation of these compounds are generally overrepresented (Li et al., 2016; Su et al., 2018; Guo et al., 2019). Therefore, we may use variations in microbial gene abundance as an indicator of the effect of WWTP upgrades on aquatic ecosystem function.

Here, we conducted a long-term investigation on bacterioplankton in a wastewater-dominant river during a WWTP upgrade. We also examined another river receiving wastewater from a previously upgraded WWTP as a reference to clarify potential microbial responses to WWTP upgrade. We aim to explain how WWTP upgrade affects the ecological function in the receiving aquatic ecosystem through decreasing pollutant discharge.

Section snippets

Water sampling and physicochemical analyses in receiving rivers of two WWTPs

Two wastewater-dominant rivers (>80% wastewater in composition), i.e., the Tonghui River and Qing River, which receive wastewater from the Gaobeidian WWTP (116.5 °E, 40.0 °N) and Qinghe WWTP (116.4 °E, 40.0 °N) in Beijing, respectively, were selected as study sites. The Gaobeidian and Qinghe WWTPs were upgraded in April 2017 and December 2013, respectively, by the addition of ozonation plus membrane processes. The characteristics of the two WWTPs and receiving rivers are described in

WWTP upgrade significantly decreased dissolved organic N in the receiving river

Based on the water quality indices, the concentrations of NO₂^–-N, NH₄⁺-N, total phosphorus (TP), and dissolved organic carbon (DOC) in the Tonghui River did not vary significantly after the Gaobeidian WWTP upgrade; however, NO₃^–-N showed a small decrease (Fig. S1), and total nitrogen (TN) showed a marked decline (Fig. 2, left). This finding is in accordance with public monitoring data showing changes in effluent TN after a WWTP upgrade (from 20 to 30 mg L⁻¹ before to 10 mg L⁻¹ after the

Discussion

Due to the differential effluent water qualities in WWTPs using common biological treatments, the upgrade technologies adopted by the WWTP management are also correspondingly different. Ozonation is widely adopted among current upgrades of wastewater and drinking water treatment plants, and this technique can efficiently remove micropollutants (Gunten, 2018; Iakovides et al., 2019). Beijing WWTPs have largely adopted ultrafiltration membranes plus ozonation technology, but the motivation has

Conclusions

We performed a long-term water quality and microbial investigation in two wastewater-dominant rivers (one used as a reference) to observe the impacts of WWTP upgrade on the microbial community composition and function in the receiving river. Our study showed that WWTP upgrade decreased the concentration of TN (mainly reflected in TON) in the receiving river. As a result, it significantly changed the composition of microbes involved in N cycling and increased the interaction between

CRediT authorship contribution statement

Qiaojuan Wang: Investigation, Data curation, Methodology, Writing - original draft. Jinsong Liang: Software, Methodology, Writing - review & editing, Validation. Chen Zhao: Investigation. Yaohui Bai: Conceptualization, Investigation, Supervision, Writing - review & editing, Validation. Ruiping Liu: Conceptualization. Huijuan Liu: Conceptualization. Jiuhui Qu: Conceptualization.

Declaration of interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work was supported by the National Natural Science Foundation of China (Funding No. 51578537, 51820105011, and 51778603) and Chinese Academy of Sciences (QYZDY-SSW-DQC004). The authors thank the Beijing Genomics Institute Central China for providing high-throughput sequencing services.

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^☆: This paper has been recommended for acceptance by Charles Wong.

¹: These authors contributed equally to this work.

View full text

Wastewater treatment plant upgrade induces the receiving river retaining bioavailable nitrogen sources☆

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Water sampling and physicochemical analyses in receiving rivers of two WWTPs

WWTP upgrade significantly decreased dissolved organic N in the receiving river

Discussion

Conclusions

CRediT authorship contribution statement

Declaration of interests

Acknowledgments

Water Res.

Soil Biol. Biochem.

China. Sci. Total Environ.

Water Res.

Water Res.

Chemosphere

Water Res.

Sci. Total Environ.

Appl. Soil Ecol.

Environ. Int.

Water Res.

Water Res.

Water Res.

Adv. Ecol. Res.

Mar. Pollut. Bull.

J. Clean. Prod.

J. Environ. Sci.-China

Aquat. Toxicol.

Post-ozonation in a municipal wastewater treatment plant improves water quality in the receiving stream

Environ. Sci. Eur.

Reproducible, interactive, scalable and extensible microbiome data science using QIIME 2

Nat. Biotechnol.

DON as a source of bioavailable nitrogen for phytoplankton

Biogeosciences

Denaturing gradient gel electrophoretic analysis of ammonia-oxidizing bacterial community structure in the lower Seine River: impact of Paris wastewater effluents

Appl. Environ. Microbiol.

The family Nitrospiraceae

VEGAN, a package of R functions for community ecology

J. Veg. Sci.

Reducing the discharge of micropollutants in the aquatic environment: the benefits of upgrading wastewater treatment plants

Environ. Sci. Technol.