Many reports have documented that the presence of SARS-CoV-2 RNA in the influents of municipal wastewater treatment plants (WWTP) correlates with the actual epidemic situation in a given city. However, few data have been reported thus far on measurements upstream of WWTPs, i.e. throughout the sewer network. In this study, the monitoring of the presence of SARS-CoV-2 RNA in Prague wastewater was carried out at selected locations of the Prague sewer network from August 2020 through May 2021. Various locations such as residential areas of various sizes, hospitals, city center areas, student dormitories, transportation hubs (airport, bus terminal), and commercial areas were monitored together with four of the main Prague sewers. The presence of SARS-CoV-2 RNA was determined by reverse transcription - multiplex quantitative polymerase chain reaction (RT-mqPCR) after the precipitation of nucleic acids with PEG 8,000 and RNA isolation with TRIzol™ Reagent. The number of copies of the gene encoding SARS-CoV-2 nucleocapsid (N1) per liter of wastewater was compared with the number of officially registered COVID-19 cases in Prague. Although the data obtained by sampling wastewater from the major Prague sewers were more consistent than those obtained from the small sewers, the correlation between wastewater-based and clinical-testing data was also good for the residential areas with more than 7,000 registered inhabitants. It was shown that monitoring SARS-CoV-2 RNA in wastewater sampled from small sewers could identify isolated occurrences of COVID-19-positive cases in local neighborhoods. This can be very valuable while tracking COVID-19 hotspots within large cities.

A group of pollutants denoted to as per- and polyfluoroalkyl substances (PFAS) currently comprises more than 4,700 identified substances. Their structure consists of a per- or polyfluorinated hydrocarbon chain forming the hydrophobic part of the molecule and a functional group which in turn forms a hydrophilic part. Depending on the type of functional group, PFAS can be divided into sulfonates, carboxylates, sulfonamides, phosphonates, acrylates, acetates and other minor groups. These substances are nowadays ubiquitous in the environment. In general, they are considered as highly persistent in nature. However, under suitable environmental conditions, some of them may degrade due to the presence of highly polar functional groups. The intermediates or final products of the degradation first step are less or non-polar. These are not readily (bio)degradable and can accumulate in the environment. Current technologies are not able to remove per- and polyfluorinated compounds from drinking water efficiently. It is therefore necessary to develop new technologies or efficient sorption materials that will enable the removal of both per- and polyfluorinated compounds, micropollutants and residual organic substances and thus to eliminate or at least to decrease the risk associated with human exposure to these substances in drinking water.

The study investigates the content of microplastic particles in freshwater and drinking water. Specifically, three water treatment plants (WTPs) supplied by different kinds of water bodies were selected and their raw and treated water was analysed for microplastics (MPs). Microplastics were found in all water samples and their average abundance ranged from 1473 +/- 34 to 3605 +/- 497 particles L-1 in raw water and from 338 +/- 76 to 628 +/- 28 particles L-1 in treated water, depending on the WTP. This study is one of very few that determine microplastics down to the size of 1 mu m, while MPs smaller than 10 mu m were the most plentiful in both raw and treated water samples, accounting for up to 95%. Further, MPs were divided into three categories according to their shape. Fragments clearly prevailed at two of the WTPs and fibres together with fragments predominated at one case. Despite 12 different materials forming the microplastics being identified, the majority of the MPs (>70%) comprised of PET (polyethylene terephthalate), PP (polypropylene) and PE (polyethylene). This study contributes to fill the knowledge gap in the field of emerging microplastic pollution of drinking water and water sources, which is of concern due to the potential exposure of microplastics to humans. (C) 2018 Elsevier B.V. All rights reserved.

The applicability of activated carbon for the adsorption of phenylalanine, arginine and aspartic acid from aqueous solution was evaluated in this study. These amino acids are plentiful in low-molecular weight algal organic matter produced by cyanobacteria, which is not satisfactorily removed by chemical coagulation. Because of this they may gravely disturb the water treatment process. Equilibrium adsorption of amino acids was studied on well-characterized activated carbons, Picabiol (PIC) and Filtrasorb (FTL), possessing different chemical and charge properties evaluated by Boehm titration. Adsorption experiments were conducted at various adsorbate initial concentrations, pH values and ionic strengths to elucidate the effect of solution properties on the amino acid removal. Distinct adsorption mechanisms were observed for individual amino acids depending on the pH and the type of carbon applied. Electrostatic interactions between functional groups of the adsorbents and arginine were deemed the predominant adsorption mechanism. The maximum arginine uptake was achieved through electrostatic attraction at pH 9 on PIC, which bears a higher number of acidic functionalities. Hydrogen bonds between protonated functionalities of adsorption participants were suggested as a possible explanation for the observed arginine adsorption on FTL in unfavourable conditions at pH 5 and 7, when electrostatic repulsion prevailed. Phenylalanine adsorption was dominated by hydrophobic interactions under all experimental conditions. Electrostatic interactions then caused the final differences in phenylalanine uptakes at particular pH values. Besides the direct hydrophobic interactions, phenylalanine removal was enhanced by intermolecular hydrophobic interactions leading to the formation of associates consisting of several phenylalanine molecules, which were then adsorbed as a unit. Insignificant adsorption of aspartic acid was observed on both carbons owing to its strong hydrophilicity. Generally, adsorption of amino acids decreased as the ionic strength of the solution increased. The added salt screened attractive electrostatic interactions, altered surface charge of the adsorbents or changed adsorbate solubility. (C) 2016 Elsevier B.V. All rights reserved.

The study investigates the effect of permanganate pre-oxidation on the coagulation of peptides/proteins of Microcystis aeruginosa which comprise a major proportion of the organic matter during cyanobacterial bloom decay. Four different permanganate dosages (0.1, 0.2, 0.4 and 0.6 mg KMnO4 mg(-1) DOC) were applied prior to coagulation by ferric sulphate. Moreover, changes in sample characteristics, such as UV254, DOC content and molecular weight distribution, after pre-oxidation were monitored. The results showed that permanganate pre-oxidation led to a reduction in coagulant dose, increased organic matter removals by coagulation (by 5-12% depending on permanganate dose), microcystin removal (with reductions of 91-96%) and a shift of the optimum pH range from 4.3 to 6 without to 5.5-73 with pre-oxidation. Degradation of organic matter into inorganic carbon and adsorption of organic matter onto hydrous MnO2 are suggested as the main processes responsible for coagulation improvement. Moreover, permanganate prevented the formation of Fe-peptide/protein complexes that inhibit coagulation at pH about 6.2 without pre-oxidation. The study showed that carefully optimized dosing of permanganate improves cyanobacterial peptide/protein removal, with the benefit of microcystin elimination. (C) 2017 Elsevier Ltd. All rights reserved.

The paper deals with the influence of amino acids (AAs) from algal organic matter (AOM) on the water treatment process and with their adsorption onto activated carbon (AC). The structure of the molecule, especially the character of functional groups in the chain, plays the most important role in the adsorption of AOM AAs. In terms of the nature of the solution, adsorption is affected especially by pH and ionic strength (IS). The largest adsorption capacities for a particular AA are achieved under conditions, where the molecules of AAs carry a charge opposite to the AC surface and, therefore, attractive electrostatic forces between the AC and AOM AAs can manifest themselves. Furthermore, the hydrophobic interactions are applied in the adsorption of neutral AAs with hydrophobic chain. Depending on the conditions, an increase of IS can significantly reduce the adsorption efficiency or have no effect.

In recent years intensively investigated remediation technologies based on in situ chemical oxidation focus on utilizing oxidation characteristics of sodium peroxodisulfate (PDS). Applicable use of this oxidizing agent, which comparing to the other routinely applied practices based on use of on hydrogen peroxide, has higher stability in bedrock and less non-target reactions, presents a possible solution for problematic distribution of active agent in low permeable contaminated matrix. By effective activation of persulfate (thermal effect, base activation, activation by heavy metals or ultimately, by direct electric current) free radicals are generated. These particles have higher oxidizing-reductive potential than persulfate ions, which might increase the effectiveness of remediation. In this paper level of the persulfate activation by direct electric current was evaluated. Evaluation was done according to results of kinetic tests of trichloroethylene (TCE) degradation. Analysis of TCE was done by GC-ECD method. Determination of persulfate concentration was done by iodometric titration. Additionally, values of pH, oxidation-reduction potential and temperature were measured. Measured first-order kinetic rates for TCE destruction have higher values in runs, where electric current was applied comparing to runs without application of electric current. Identically, rate of persulfate destruction increased as well. Results have proven positive effect on persulfate activation, which opens a possibility of applying this method in practice. System has been continuously tested in terms of possible by-products and influence of naturally occurring compounds.

This paper looks at chemistry of individual oxyhalogens such as chlorite, chlorate, perchlorate and bromates, their origin in drinking water and health effects which restrict their concentrations. It is concluded that with understanding of mechanisms of formation of individual oxyhalogens and undertaking practical steps during water treatment and disinfection processes their concentration can, in the majority of cases, be controlled within the drinking water guideline limits.

This study focuses on the effects of molecular interactions between two natural organic matter (NOM) fractions, peptides/proteins derived from cyanobacterium Microcystis aeruginosa (MA proteins) and peat humic substances (HS), on their removal by coagulation. Coagulation behaviour was studied by the jar tests with MA protein/HS mixtures and with single compounds (MA proteins or HS). Aluminium sulphate was used as a coagulant. Besides MA proteins, bovine serum albumin (BSA) was used as a model protein. For the MA protein/HS mixture, the removal rates were higher (80% versus 65%) and the dose of coagulant substantially lower (2.8 versus 5.5 mg L-1 Al) than for coagulation of single HS, indicating the positive effect of protein-HS interactions on the coagulation process. The optimum coagulation pH was 5.2-6.7 for MA proteins and 5.5-6 for HS by alum. The optimum pH for the removal of MA protein/HS mixture ranged between pH 5.5-6.2, where the charge neutralization of negatively charged acidic functional groups of organic molecules by positively charged coagulant hydroxopolymers lead to coagulation. MA proteins interacted with HS, probably through hydrophobic, dipole dipole and electrostatic interactions, even in the absence the coagulant. These interactions are likely to occur within a wide pH range, but they result in coagulation only at low pH values (pH < 4). At this pH, the negative charge of both MA proteins and HS was suppressed due to the protonation of acidic functional groups and thus the molecules could approach and combine forming aggregates. Virtually the same trends were observed in the experiments with HS and BSA, indicating that BSA is a suitable model for MA proteins under experimental conditions used in this study. The study showed that increases in organic content in source water due to the release of algae products may not necessarily entail deterioration of the coagulation process and a rise in coagulant demand. (C) 2015 Elsevier Ltd. All rights reserved.

Extensive traditional use of medical plants leads to research dealing with chemical composition of essential oils. The aim of this work was evaluation of quality of the essential oil and extending of the knowledge about chemical composition of essential oil from ribwort (Plantago lanceolata L.) and proportional representation of compounds. Extractions of essential oils from samples of ribwort were performed by hydrodistillation. GC-MS and GC-FID techniques were used for investigation of the qualitative and semi-quantitative content of aromatic compounds in the essential oils, respectively. Major aroma constituents of ribwort leaves were groups of fatty acids 28.0-52.1 % (the most abundant palmitic acid 15.3-32.0 %), oxidated monoterpenes 4.3-13.2 % (linalool 2.7-3.5 %), aldehydes and ketones 6.9-10.0 % (pentyl vinyl ketone 2.0-3.4 %) and alcohols 3.8-9.2 % (1-octen-3-ol 2.4-8.2 %). In relative high amount were identified apocarotenoids (1.5-2.3 %) which are important constituents because of their intense fragrant. The importance is in potential manufacture control of feedstocks before producing of food supplements.

The paper deals with adsorption of AOM peptides during water treatment. The adsorption is affected by many circumstances. However, the principal factors are size distribution of the adsorbent pores, pH value of the solution and its ionic strength. For the adsorption of peptides having molecular weight lower than 4 kDa, the most important role play mesopores (d > 2 nm) and micropores (d = 0.8-2 nm). Charge characteristics of AOM functional groups and surface activated carbon functional groups are determined by pH value of the solution. These charge relationships affect prevailing mechanisms of interactions between peptides and the activated carbon surface. The biggest adsorption capacities are reached at weakly acidic region of pH due to an effect of attractive electrostatic forces between the activated carbon surface and AOM peptides. The next factor influencing the AOM adsorption is ionic strength of the solution. Its increasing value can have a positive effect on the adsorption efficiency, but the adsorbent character and pH value of the water to be treated, should be taken into account.

Supercritical water (SCW) is defined as water at parameters above its critical point (374 degrees C, 22.1 MPa). Typical application parameters of this medium are 600 degrees C and 25 MPa. Due to a rapid change in physical and chemical properties while crossing the critical point, SCW is a very interesting medium for innovations in many industrial fields such as fuel production, power engineering, chemical production and waste elimination. High corrosive effects of this medium is currently a big barrier to its wider usage.

The effects of tungsten material used as a high-voltage needle electrode on the production of hydrogen peroxide and the degradation of dimethylsulfoxide (DMSO) caused by a pulsed corona discharge in water were investigated. A reactor of needle-plate electrode geometry was used. The erosion of the tungsten electrodes by the discharge was evaluated. The yields of H2O2 production and the decomposition of DMSO by the discharge, which were obtained using the tungsten electrodes, were compared with those determined for titanium electrodes. The electrode erosion increased significantly with an increase in the solution conductivity. A large fraction (50-70%) of the eroded tungsten electrode material was released into the solution in dissolved form as tungstate WO42- ions. A correlation between the amount of eroded tungsten material released into the solution and the chemical effects induced by the discharge was determined. Lower yields of H2O2 and a higher degradation of DMSO by the discharge were obtained using the tungsten electrodes than were determined using titanium electrodes. Tungstate ions were shown to play a dominant role in the decomposition of H2O2, which was produced by the discharge using a tungsten electrode. The higher degradation of DMSO that was determined for tungsten was attributed to the tungstate-catalyzed oxidation of DMSO by H2O2, in addition to the oxidation of DMSO by OH radicals. Such a mechanism was supported by the detection of degradation by-products of DMSO (methanesulfonate, sulfate and dimethyl sulfone). The catalytic role of tungstate ions in the plasmachemical activity of the discharge generated using a tungsten electrode was also demonstrated on a pH-dependent decomposition of H2O2 and DMSO.

Humic matter is the prevailing constituent of natural organics in many surface water resources Humic matter is a class of complex polyclic high-molecular-weight compounds with molecular weights ranging from ten thousands to hundred thousands Humic matter often varies in different types of surface water and for that reason different treatment technologies are used The most common method is chemical water treatment based on coagulation/floculation of humic substances Besides, chemical processes and other methods can be used for removal of humic matter in water treatment, such as sorption, ion exchange, membrane filtration, oxidation and biological methods

Inactivation of bacteria Escherichia coli and Enterococcus faecalis by the pulsed corona discharge in liquid phase has been investigated. The reactor with point to plate geometry of electrodes was used for generation of the discharge in liquid phase. The effects of the solution conductivity and the pulse repetition frequency on the bacterial inactivation have been determined. Better efficiency of inactivation was observed for both types of bacteria with the increasing solution conductivity and the pulse repetition frequency since E. faecalis was more sensitive to these changes then E. coli. The role of UV radiation emitted by the electrical discharge in the overall bacterial efficiency was evaluated in dependence on the solution conductivity using UV light transparent spectrometric cell. It was determined that UV radiation contributes about 40% to the overall inactivation of bacteria by the discharge.