Chapter 21 - Emerging micropollutants in municipal wastewater: occurrence and treatment options
Abstract
This chapter will introduce the origin of micropollutants in the water cycle and their impact on the environment and humans. Conventional wastewater treatment plants (WWTPs) can remove these newly emerging contaminants to a limited extent, and this chapter will show the possibilities and limitations of current and future technologies (adsorption by activated carbon, advanced oxidation, and reverse osmosis).
The chapter will present a case study of the broad overview of the research into this topic in Europe, and more specifically in the Netherlands, how the precautionary principle is applied, and how good quality WWTP effluent is obtained. This is very important, especially if the surface water is used as a source of drinking water. Local, social, economic, and environmental parameters determine which technologies are combined. Pilot-scale studies show the possibilities of advanced treatment methods, and how a zero-discharge concept can be realized.
Finally, a small subsection will be dedicated to discussing the polluter pays principle; how a holistic approach to micropollutants throughout the lifecycle is required, not only focusing on end-of-pipe (WWTP) solutions.
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Application of biological early warning systems in wastewater treatment plants: Introducing a promising approach to monitor changing wastewater composition
2023, Journal of Environmental ManagementWastewater treatment plants (WWTPs) are a major source of micropollutants to surface waters. Currently, their chemical or biological monitoring is realized by using grab or composite samples, which provides only snapshots of the current wastewater composition. Especially in WWTPs with industrial input, the wastewater composition can be highly variable and a continuous assessment would be advantageous, but very labor and cost intensive. A promising concept are automated real-time biological early warning systems (BEWS), where living organisms are constantly exposed to the water and an alarm is triggered if the organism's responses exceed a harmful threshold of acute toxicity. Currently, BEWS are established for drinking water and surface water but are seldom applied to monitor wastewater. This study demonstrates that a battery of BEWS using algae (Chlorella vulgaris in the Algae Toximeter, bbe Moldaenke), water flea (Daphnia magna in the DaphTox II, bbe Moldaenke) and gammarids (Gammarus pulex in the Sensaguard, REMONDIS Aqua) can be adapted for wastewater surveillance. For continuous low-maintenance operation, a back-washable membrane filtration system is indispensable for adequate preparation of treated wastewater. Only minor deviations in the reaction of the organisms towards treated and filtered wastewater compared to surface waters were detected. After spiking treated wastewater with two concentrations of the model compounds diuron, chlorpyrifos methyl, and sertraline, the organisms in the different BEWS showed clear responses depending on the respective compound, concentration and mode of action. Immediate effects on photosynthetic activity of algae were detected for diuron exposure, and strong behavioral changes in water flea and gammarids after exposure to chlorpyrifos methyl or sertraline were observed, which triggered automated alarms. Different types of data analysis were applied to extract more information out of the specific behavioral traits, than only provided by the vendors algorithms. To investigate, whether behavioral movement changes can be linked to impact other endpoints, the effects on feeding activity of G. pulex were evaluated and results indicated significant differences between the exposures. Overall, these findings provide an important basis indicating that BEWS have the potential to act as alarm systems for pollution events in the wastewater sector.
A technological approach using a metal-free immobilized photocatalyst for the removal of pharmaceutical substances from urban wastewaters
2023, Chemical Engineering JournalThe presence of micropollutants (MPs) in aquatic compartments poses a great risk to the ecosystems and human health. Advanced oxidation processes (AOPs), such as light-induced systems employing a variety of powder optical semiconductors, have been widely investigated to remove MPs from water and wastewater. In this work, a metal-free photocatalyst (GCN-T) immobilized in the form of a film (GCN-T/PVDF) was activated by visible light (λexc = 417 nm) and successfully tested in both batch and continuous flow mode reactors for the degradation of two pharmaceutical model compounds (metoprolol and venlafaxine) spiked in ultrapure water (UP) and urban wastewater (WW) samples. A total removal of MPs was reached after 3 h reaction using GCN-T/PVDF film in a batch reactor. Under continuous mode operation, a steady state was attained after 2 h, with ca. 64 % removal for both MPs being obtained. The photocatalytic system was also examined using a non-spiked WW sample to study its performance to remove trace concentrations of these and other MPs in this type of complex matrix. MPs, such as bezafibrate, carbamazepine, diclofenac, isoproturon, and tramadol, were detected and efficiently degraded using the GCN-T/PVDF film. Finally, the ecotoxicity of the WW samples was also investigated using the aquatic invertebrate microcrustacean Daphnia magna. The results showed that the toxicity of WW samples decreases with the photocatalytic treatment.