Emerging pollutants

Organic micropollutants are compounds which are normally detected at concentrations up to microgram per liter in the aquatic environment and they are considered to be potential threats to the ecosystem. Some of them have been studied in detail since 1980s and are already included in existing national or international legislative documents, while others are characterized as emerging contaminants (ECs) and no regulations currently require their environmental monitoring. During the last decade, several studies have been focused on the investigation of possible sources of emerging contaminants’ distribution into the environment. According to the literature, sewage treatment plants are considered as major point sources of these compounds into the environment, as they receive domestic and industrial wastewater, as well as urban and -in some cases- agricultural runoff (Ratola et al., 2012; Luo et al., 2014; Arvaniti and Stasinakis, 2015). On the other side, the contribution of landfills, via the produced leachates, in transferring emerging pollutants to the environment, is not well reported so far (Oturan et al., 2015). Besides European policy for recycling and waste-to-energy, landfilling still remains one of the alternative options for municipal solid waste management in EU-28, where 58 × 106 tonnes of municipal solid waste were disposed to landfills in 2017 (Eurostat, 2018).

In recent years, the technical-scientific community has been paying increasing attention to the presence of emerging contaminants that are intercepted in surface water and wastewater since these compounds could have harmful effects on human health and on environment too.
Conventional wastewater treatment installations represent a source of pollution from emerging contaminants because they are not designed to remove these compounds from the wastewater in their treatment cycle.
Several studies have shown the possibility of removing successfully these compounds from wastewater through the use of membrane bioreactors (MBR) combined with electrochemical processes, using conventional membranes.
The present study first examined the possibility of combining electrochemical processes with MBR (eMBR), through the use of self-forming dynamic membranes (SFDM) for the removal of emerging contaminants from municipal wastewater.
Thanks to this extremely innovative hybrid system, it has been possible to reduce the problems linked to the use of traditional membranes, in particular the high costs both of initial investment and of cleaning following fouling.

Monitoring activities over several decades have revealed the ubiquitous presence of organic contaminants in environmental compartments. Asopos river basin, located in Sterea Ellada, has been the focus of many environmental studies over the last decades, mainly due to its geomorphology and the extensive industrial activities that take place in this territory. The detection of high Cr(VI) concentrations, causing potential carcinogenic effects, have attracted the attention of media and raised the consciousness of the citizens. Although there are many studies in recent literature focusing on the occurrence of heavy metals in Asopos river basin, there is a lack of information concerning the presence of emerging contaminants. The aim of this study is the determination of thousands of emerging contaminants in the environmental samples (river water and sediments) form Asopos river basin, following wide-scope target screening methodologies. Solid-Phase Extraction (SPE) by mixed-mode sorbent was used during the sample preparation of river water samples to ensure the extraction of various classes of compounds with a wide range of physicochemical properties. The extracts were analyzed by complimentary chromatographic techniques, including Reversed Phase (RP) and Hydrophilic Interaction Liquid Chromatography (HILIC) coupled to Quadrupole-Time-of-Flight Mass Spectrometry (QToF-MS).

Polychlorinated biphenyls (PCBs) are substances of wide distribution, high toxicity, persistence, and ability to long-distance migration. They are characterized by unique properties: temperature stability; high boiling point; non-combustibility; resistance to chemical and physical influences; high dielectric constants.
The presence and concentration of dioxin-like and non- dioxin-like PCBs in old and new landfills of Dilijan district (Republic of Armenia) were investigated. Municipal waste dumps of Dilijan are active sources of PCBs accumulation and spread. In soil samples from both the old and new landfills excess concentrations of PCBs were found in 100% of cases compared to normative level, and the summary concentrations of the latter multiply exceeded the normative level.
PCBs-related environmental pollution is of great concern because the emergence and spread of PCBs in nature is not always subject to control and regulation, as the sources of PCBs formation are diverse.

New sustainable technologies are needed to tackle pharmaceuticals contamination in different environmental compartments. Bioremediation technology, using native microorganisms with capacity for partial or complete elimination of contaminants, can be considered. This work investigated the capability of different bacterial strains to biodegrade paroxetine and bezafibrate, either as a bacterial consortium or as a single strain. These strains were isolated from bacterial cultures previously enriched under static conditions with paroxetine or bezafibrate, using as inoculum an estuarine sediment. All strains were identified through 16S rRNA gene sequencing. Degradation potential was accessed by analyzing pharmaceutical compounds in the culture medium and fluoride ion release (only for paroxetine). The genus Pseudomonas, widely reported in biodegradation studies, was predominant among the isolated bacterial strains. Most bacterial strains showed potential to degrade paroxetine (55%-100%) as a single strain in co-metabolism with sodium acetate. Furthermore, bacterial consortia also presented high removal efficiencies (>85%) for paroxetine throughout 4 weeks. For bezafibrate, tests showed a high potential of the bacterial consortia to degrade this compound (>90%).

A novel laboratory-scale continuous flow wastewater treatment system, consisting of an anaerobic moving bed biofilm reactor (AnMBBR) and an aerobic MBBR, was used for investigating the removal of hydroxybenzothiazole (OH-BTH) and selected benzotriazoles from municipal wastewater. The system was operated under three different Experimental Phases where different organic loadings were applied: 0.82 kg COD m-3 d-1 (Phase A), 0.2 kg COD m-3 d-1 (Phase B) and 2.1 kg COD m-3 d-1 (Phase C). The system achieved sufficient COD removal, nitrification and biogas production. All target micropollutants were partially removed during the experiments. Total removal efficiencies ranged from 32% for 5-methyl-1H-benzotriazole (5TTR) to 97% for OH-BTH. The contribution of the strictly anaerobic bioreactor was important for 5TTR, 5-chlorobenzotriazole (CBTR) and xylytriazole (XTR), while the use of aerobic bioreactors resulted to important increase of target compounds removal and it was exclusively responsible for the removal of OH-BTH and benzotriazole (BTR).

This work identified transformation products (TPs) from 16 antibiotics, 1 anti-parasitic, 1 analgesic and 1 hormone, present in spiked real piggery wastewater (PWW) before and after two different treatments in two open photobioreactors operated continuously with a consortium of microalgae-bacteria and purple photosynthetic bacteria. For this purpose, suspect and non-target strategies based on liquid chromatography quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS) were used. The application of quantitative structure-retention relationship (QSRR) prediction models, in addition to a comprehensive evaluation of the obtained MS/MS spectra, provided valuable information to support the identifications. The confirmation of the TPs was carried out with the corresponding reference standards, when these were commercially available. Alternatively, probable structures of the TPs based on diagnostic evidence were proposed. To the best of our knowledge, some of the identified TPs have never been reported before. A transformation pathway for their biotransformation has been proposed. The presence of the identified TPs was assessed in real PWW samples through retrospective analysis. Ultimately, the potential ecotoxicological risk posed by these nineteen veterinary drugs and their TPs was evaluated by means of risk quotients.

Per- and polyfluoroalkyl substances (PFAS) are considered emerging contaminants and have been increased their attention due to their distribution in water body. These compounds are acid and characterized by a thermal stability to make them resistant to degradation processes. Activities such as tannery, paper and cardboard production, waterproof cloths, produce wastewater rich in PFAS and heavy metals. The adsorption process is one of the technologies used for the treatment of wastewater and food residues are getting increased attention as bio-adsorbent because they can be found easily as wastes or by-products and at almost no cost. In this work the removal of PFAS was performed by using food waste such as Yerba Mate (YM) as bio-adsorbent. To achieve the mineralization of Heptadecafluorooctanesulfonic acid adopted as model compounds TiO2 photocatalysis tests were performed. The concentration of pollutants was determined by HPLC, UV-VIS and TOC analysis. SEM-EDS, XRD, FT-IR and BET were done to achieve a characterization of the adsorbent material.

Various toxic contaminants when are present in the environment pose a threat to the inhabitants of natural ecosystems owing to their non-biodegradable nature that increases their high toxicity towards non-target organisms. The large mass of solid wastes that are generated from waste rubber tires unquestionably consists a serious threat of environmental pollution around the world. Consequently, scientific interest has focused on several recycling strategies and practices converting them into more valuable products such as adsorbents widely utilized for the removal of several different inorganic and organic compounds from environmental samples. Hence, the main objective of the present study is to review all the data in the available published bibliography concerning the recent research and future trends on using granulated adsorbent materials and activated carbons obtained and prepared from waste tires and afterwards applied for the removal of persistent and residual quantities of pollutants.