Freshwater Ecosystems Profit from Activated Carbon-Based Wastewater
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Triebskorn et al. Environ Sci Eur (2019) 31:85 https://doi.org/10.1186/s12302-019-0267-0 RESEARCH Open Access Freshwater ecosystems proft from activated carbon-based wastewater treatment across various levels of biological organisation in a short timeframe Rita Triebskorn1,4* , Ludek Blaha5, Claudia Gallert6, Sabrina Giebner7,8, Harald Hetzenauer9, Heinz‑R. Köhler1, Bertram Kuch10, Frauke Lüddeke9, Jörg Oehlmann7, Katharina Peschke1, Frank Sacher11, Marco Scheurer11, Simon Schwarz1,2, Paul Thellmann1,3, Karl Wurm12 and Sabrina Wilhelm1 Abstract Background: Wastewater treatment plants are known as major sources for the release of micropollutants and bacteria into surface waters. To reduce this contaminant and microbial input, new technologies for efuent treatment have become available. The present paper reports the chemical, microbiological, biochemical, and biological efects of upgrading a wastewater treatment plant (WWTP) with a powdered activated carbon stage in the catchment area of the Schussen River, the largest German tributary of Lake Constance. Data were obtained prior to and after the upgrade between 2011 and 2017. Results: After the upgrading, the release of antibiotic resistant and non‑resistant bacteria, micropollutants, and their efect potentials was signifcantly lower in the efuent. In addition, in the Schussen River downstream of the wastewa‑ ter treatment plant, reduced concentrations of micropollutants were accompanied by both a signifcantly improved health of fsh and invertebrates, along with a better condition of the macrozoobenthic community. Conclusions: The present study clearly provides evidence for the causality between a WWTP upgrade by powdered activated carbon and ecosystem improvement and demonstrates the promptness of positive ecological changes in response to such action. The outcome of this study urgently advocates an investment in further wastewater treat‑ ment as a basis for decreasing the release of micropollutants and both resistant and non‑resistant bacteria into receiv‑ ing water bodies and, as a consequence, to sustainably protect river ecosystem health and drinking water resources for mankind in the future. Keywords: Wastewater treatment plant upgrade, Micropollutants, Bacteria, Fish and invertebrate health Background particular public concern when drinking water resources Te increasing presence of micropollutants and could not be used at all or only to a limited extent, such microbes, including resistant bacterial strains, in the as after contamination with Legionella sp. [8], or when water cycle, has increasingly been in the focus of scien- bathing bans had to be issued after levels of faecal indica- tifc, political, and public interest during the last years tor bacteria were exceeded [9]. Recently, worldwide fnd- [1–7]. Microbial contamination of water became a ings of antimicrobial resistance in sewage plant efuents, surface waters, and sediments, against both commonly used antibiotics and last-line antibiotics such as colistin, *Correspondence: rita.triebskorn@uni‑tuebingen.de have caused great concern [7, 10]. Chemical contamina- 1 Animal Physiological Ecology, University of Tübingen, Tübingen, Germany tion of water attracted the attention of the public follow- Full list of author information is available at the end of the article ing reports on trace substance residues in drinking water © The Author(s) 2019. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creat iveco mmons .org/licen ses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Triebskorn et al. Environ Sci Eur (2019) 31:85 Page 2 of 16 resources [11–14] and spectacular efects in aquatic unknown) transformation products of chemicals and organisms, such as sex or behavioural changes in fsh mixture efects is also taken into account. induced by xenohormones or neuroactive substances Being important sites of micropollutant and microbe [15, 16]. In this context, active ingredients of pesticides removal from raw wastewater but also point sources and pharmaceuticals, but also compounds in products for the release of chemicals and microbes into surface of everyday life (e.g. cosmetics, phytosanitary products, waters, improving the efciency of wastewater treat- cleansing agents, artifcial sweeteners, cofee, etc.), have ment plants (WWTP) by additional cleaning steps has become a matter of concern. become a research area of priority and also a matter of At present, there are numerous challenges for main- discussion among political groups during the last dec- taining good water quality: ade. Many research projects worldwide have addressed this topic, such as the Swiss project “Strategy Micropoll” (a) Te global abundance of antibiotic resistant bacte- [20], or the EU projects “SWITCH” [21] and “Pills” [22]. ria is increasing dramatically [10]. In addition, the German Federal Ministry of Education (b) Over 140 million organic and inorganic chemi- and Research (BMBF) launched a funding programme cals are registered worldwide (cas.org) and, among called RiSKWa (Risk management of new pollutants and those, 30,000 to 70,000 are in daily use in industri- pathogens in the water cycle) in 2012, which allowed alised countries [17]. It is unknown how many of 12 research consortia to investigate the efciency of them reach the water cycle. advanced wastewater and storm water treatment for the (c) Te mixture of micropollutants is highly complex reduction in micropollutants and bacteria release into and contains mother compounds in the pg-µg/L the water cycle. Te core messages of all 12 projects are range, plus transformation products of often described and summarised by Track [23]. unknown quality and quantity. Te risk posed by One of these projects (named SchussenAktivplus) such chemical mixtures for aquatic wildlife is far did not only focus on the efciency of advanced sew- from being understood and most probably underes- age and rainwater treatment technologies regarding the timated due to monitoring practices regarding only removal of micropollutants and bacteria from efuents, a small portion of selected or priority substances. but also investigated the consequences of an additional (d) Te demographic change in developed countries powdered activated carbon-based treatment step for the will lead to a further increase in product and drug receiving water body. Te efects of the WWTP upgrade consumption, which will also result in increased were comprehensively monitored, with a special focus emissions of substances via the wastewater path. on chemical and microbiological parameters, as well as (e) Climate change will increase the frequency and on ecosystem health. Te present paper is a compila- length of low-water periods, with rising chemical tion of the results that were gathered by 11 (out of 22) and bacterial concentrations in pure surface waters. project partners by analysing samples collected between However, a higher frequency of severe rainfall 2011 and 2017 in the catchment area of the Schussen events is also predicted with future climate change, River, the largest German tributary of Lake Constance. resulting in an increased volume of raw wastewater Te structure and concept of the project have been pub- released into surface water bodies via storm water lished by Triebskorn et al. [24], and the fnal report [25] overfow basins. (in German) is available at https ://publi katio nen.uni- tuebi ngen.de/xmlui /handl e/10900 /74316 . Terefore, a sustainable and preventive management of water resources, integrating actions applied after the Methods entry of pollutants and pathogens into the watercourse Upgraded wastewater treatment plant (“end of pipe” approaches), but also those at the source With about 170,000 population equivalents, the WWTP (i.e. at the level of producers and consumers of the Langwiese, Association for Sewage Treatment (AZV) chemicals), is urgently required, and in accordance with Mariatal, Germany, represents a large WWTP in a the Water Safety Plans of the World Health Organi- densely populated catchment of an industrialised coun- zation [18] and the requirements and goals of the EU try. Te WWTP was equipped with an activated carbon Water Framework Directive as described by Brack et al. stage in autumn 2013 and, ever since, 100% of the sew- [19]. Such preventative measures are of heightened age has been treated with powdered activated carbon, importance when considering the uncertainties associ- added after biological treatment and before entering a ated with the fate of resistant bacteria in the environ- connected sand flter. During this study, the dosage was ment and the possible risk posed by micropollutants to 10 mg ± 5 mg powdered activated carbon per litre of aquatic wildlife, especially when the formation of (often wastewater. Te dosage was adjusted according to the Triebskorn et al. Environ Sci Eur (2019) 31:85 Page 3 of 16 need of an 80% reduction in micropollutants. Te loca- predominantly via mixed channel systems. Te wastewa- tion of the WWTP Langwiese in the catchment area of ter in the Schussen catchment is treated by 20 municipal the Schussen River is displayed in Fig. 1. sewage treatment plants. Tese include, in addition to the upgraded WWTP Langwiese with 170,000 popula- Investigated rivers and catchments tion equivalents (size class 5), fve