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Special Issue "New Advances in Disinfection of Wastewater"

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Water and Wastewater Treatment".

Deadline for manuscript submissions: closed (31 May 2017).

Special Issue Editor

Guest Editor
Dr. Helvi Heinonen-Tanski

Department of Environmental and Biological Sciences, University of Eastern Finland, POB 1627, FI 70211 Kuopio, Finland
Website | E-Mail
Phone: +358405718562
Interests: water hygiene; disinfection of water; wastewater treatment; sanitation; sustainable development; fertilization with human urine and sanitized wastewater sludge

Special Issue Information

Dear Colleagues,

Disinfection of wastewater is often done in order to get irrigation water or to protect receiving surface waters used for fish production, recreational purposes, raw water of drinking water, industrial waters, etc. The needs for disinfection are increasing due to climate change, and its effects on precipitation and evaporation. In addition, the amount of wastewater will be increasing with urbanization and a higher coverage of sanitation. Normal wastewater treatment processes performed in municipal wastewater treatment plants or small-scale treatment units (different small-scale plants, sand filters, wastewater treatment ponds, etc.) do not usually efficiently reduce the number of enteric microorganisms.

In some cases, environmental regulations can control the number of Escherichia coli or other enteric microorganisms in effluent, so that wastewater treatment disinfection must be improved, and disinfection will be necessary (though not always). In these cases, should there be regulations for the numbers of enteric microorganisms in effluents?

There are new disinfection chemicals, which often have better efficiency relative to old ones, but their limitations must be considered. Different technological pre-treatments can be beneficial, as well as different combined treatments. The new disinfection chemicals may change the chemical quality of effluent. Original research articles dealing with these themes are welcome to this Special Issue of Water.

Prof. Dr. Helvi Heinonen-Tanski
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • enteric microorganisms,
  • Escherichia coli,
  • enterobacteria,
  • viruses,
  • BOD,
  • COD,
  • nitrogen,
  • phosphorus,
  • flotation,
  • filters,
  • UV,
  • organic peracids,
  • ozone,
  • bioelectrochemical systems

Published Papers (5 papers)

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Research

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Open AccessFeature PaperArticle
Photodynamic Action against Wastewater Microorganisms and Chemical Pollutants: An Effective Approach with Low Environmental Impact
Water 2017, 9(9), 630; https://doi.org/10.3390/w9090630
Received: 21 June 2017 / Revised: 12 August 2017 / Accepted: 12 August 2017 / Published: 23 August 2017
Cited by 7 | PDF Full-text (3245 KB) | HTML Full-text | XML Full-text
Abstract
Wastewater (WW) from urban and industrial activities is often contaminated with microorganisms and chemical pollutants. To reduce the concentration of microorganisms in WW to levels comparable to those found in natural waters, the sewage effluent is usually subjected to disinfection with chlorine, ozone, [...] Read more.
Wastewater (WW) from urban and industrial activities is often contaminated with microorganisms and chemical pollutants. To reduce the concentration of microorganisms in WW to levels comparable to those found in natural waters, the sewage effluent is usually subjected to disinfection with chlorine, ozone, or ultraviolet light, which may lead to the formation of toxic products and contribute to the selection of resistant genes. Moreover, the changing patterns of infectious diseases and the emerging of multidrug resistant microbial strains entail the development of new technologies for WW decontamination. Microbial photodynamic inactivation (PDI) with photosensitizers, oxygen, and visible light has demonstrated to be effective in the inactivation of microorganisms via photogeneration of reactive oxygen species able to induce microbial damage at the external structures level. The promising results of PDI suggest that this principle can be applied to WW treatment to inactivate microorganisms but also to photodegrade chemical pollutants. The aim of this study was to assess the applicability of PDI for the microbial and chemical decontamination of secondarily treated WW. To evaluate the efficiency of bacterial inactivation in WW, experiments were done in both phosphate buffer saline (PBS) and filtered WW with the bioluminescent Escherichia coli, using small and large volumes of WW. The potential of PDI to inactivate the native bacteria (E. coli and Enterococcus) present in WW was tested and assays without the adding of bacteria to the WW were performed. It was also tested if the same PDI protocol was able to induce phototransformation of phenol. The cationic porphyrin 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin tetra-iodide (Tetra-Py+-Me) was shown to be effective against both bacterial groups representing both Gram-negative and Gram-positive bacteria used as microbiological parameters to instigate water quality and even showing the power to photooxidate organic compounds. As the photosensitizer when immobilized on solid matrixes can be easily removed, recovered, and reused, an effective, less-expensive, easy-applicable, and environmentally friendly technology can be applied to treat WW, inactivating microorganisms and degrading chemical contaminants at the same time. Full article
(This article belongs to the Special Issue New Advances in Disinfection of Wastewater)
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Open AccessArticle
Ecological and Public Health Implications of the Discharge of Multidrug-Resistant Bacteria and Physicochemical Contaminants from Treated Wastewater Effluents in the Eastern Cape, South Africa
Water 2017, 9(8), 562; https://doi.org/10.3390/w9080562
Received: 23 March 2017 / Revised: 22 July 2017 / Accepted: 23 July 2017 / Published: 1 August 2017
Cited by 1 | PDF Full-text (1693 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
This study assessed the prevalence of fecal indicator bacteria (FIB) and Vibrio species, as well as the physicochemical qualities of the discharged effluents of two wastewater treatment facilities, in the Eastern Cape, South Africa over a one-year sampling period using standard methods. Bacteriological [...] Read more.
This study assessed the prevalence of fecal indicator bacteria (FIB) and Vibrio species, as well as the physicochemical qualities of the discharged effluents of two wastewater treatment facilities, in the Eastern Cape, South Africa over a one-year sampling period using standard methods. Bacteriological assessment revealed presumptive E. coli counts ranging from 3 to 1.2 × 105 CFU/100 mL, while counts of Vibrio spp. ranged from 11 to 1.4 × 104 CFU/100 mL. Molecular identification of the isolates by polymerase chain reactions (PCR) yielded positive reaction rates of 76.2% (381/500) and 69.8% (279/400) for E. coli and Vibrio species, respectively. The antibiotic susceptibility profiles of 205 randomly selected PCR-confirmed Vibrio isolates against 18 antibiotics revealed resistance frequencies ranging from 0.5% (imipenem) to 96.1% (penicillin G), based on recommended breakpoint concentrations. About 81% (166/205) of the Vibrio isolates exhibited multidrug resistance (resistance to three or more classes of antibiotics), while nine different antibiotic resistance genes were detected by PCR. The physicochemical qualities of the effluents also ranged as follows: pH (6.5–7.6), temperature (12–27 °C), turbidity (1.5–65.7 mg/L), total dissolved solids (95–171 mg/L), dissolved oxygen (2.1–9.8), electrical conductivity (134–267 µS/cm), free chlorine (0.08–0.72 mg/L), biochemical oxygen demand (0.12–9.81 mg/L), nitrate (1.04–21.5 mg/L), nitrite (0.11–0.76 mg/L), phosphate (1.03–18.3 mg/L) and chemical oxygen demand (27–680 mg/L). The discharged effluents fell short of the regulatory guidelines for some of the parameters assessed. We conclude that the discharged effluents are potential sources of environmental pollution and can contribute to drug resistant bacteria load in the receiving watershed, with the associated ecological and human health risks. Full article
(This article belongs to the Special Issue New Advances in Disinfection of Wastewater)
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Open AccessArticle
Inactivation Effect of Antibiotic-Resistant Gene Using Chlorine Disinfection
Water 2017, 9(7), 547; https://doi.org/10.3390/w9070547
Received: 19 June 2017 / Revised: 14 July 2017 / Accepted: 17 July 2017 / Published: 21 July 2017
Cited by 5 | PDF Full-text (525 KB) | HTML Full-text | XML Full-text
Abstract
The aim of this study was to elucidate the inactivation effects on the antibiotic-resistance gene (vanA) of vancomycin-resistant enterococci (VRE) using chlorination, a disinfection method widely used in various water treatment facilities. Suspensions of VRE were prepared by adding VRE to [...] Read more.
The aim of this study was to elucidate the inactivation effects on the antibiotic-resistance gene (vanA) of vancomycin-resistant enterococci (VRE) using chlorination, a disinfection method widely used in various water treatment facilities. Suspensions of VRE were prepared by adding VRE to phosphate-buffered saline, or the sterilized secondary effluent of a wastewater treatment plant. The inactivation experiments were carried out at several chlorine concentrations and stirring time. Enterococci concentration and presence of vanA were determined. The enterococci concentration decreased as chlorine concentrations and stirring times increased, with more than 7.0 log reduction occurring under the following conditions: 40 min stirring at 0.5 mg Cl2/L, 20 min stirring at 1.0 mg Cl2/L, and 3 min stirring at 3.0 mg Cl2/L. In the inactivation experiment using VRE suspended in secondary effluent, the culturable enterococci required much higher chlorine concentration and longer treatment time for complete disinfection than the cases of suspension of VRE. However, vanA was detected in all chlorinated suspensions of VRE, even in samples where no enterococcal colonies were present on the medium agar plate. The chlorine disinfection was not able to destroy antibiotic-resistance genes, though it can inactivate and decrease bacterial counts of antibiotic-resistant bacteria (ARB). Therefore, it was suggested that remaining ARB and/or antibiotic-resistance gene in inactivated bacterial cells after chlorine disinfection tank could be discharged into water environments. Full article
(This article belongs to the Special Issue New Advances in Disinfection of Wastewater)
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Open AccessArticle
Peracetic Acid (PAA) Disinfection: Inactivation of Microbial Indicators and Pathogenic Bacteria in a Municipal Wastewater Plant
Water 2017, 9(6), 427; https://doi.org/10.3390/w9060427
Received: 4 May 2017 / Revised: 7 June 2017 / Accepted: 8 June 2017 / Published: 13 June 2017
Cited by 2 | PDF Full-text (546 KB) | HTML Full-text | XML Full-text
Abstract
Several studies have noted that treated and untreated wastewaters are primary contributors of a variety of pathogenic microorganisms to the aquatic ecosystem. Conventional wastewater treatment may not be sufficient to achieve microbiologically safe effluent to be discharged into natural waters or reused, thus [...] Read more.
Several studies have noted that treated and untreated wastewaters are primary contributors of a variety of pathogenic microorganisms to the aquatic ecosystem. Conventional wastewater treatment may not be sufficient to achieve microbiologically safe effluent to be discharged into natural waters or reused, thus requiring wastewater effluents to be disinfected. In recent years, peracetic acid (PAA) has been adopted as a disinfectant for wastewater effluents. The aim of this study was to evaluate the disinfection efficiency of PAA at low doses (range 0.99–2.10 mg/L) against microbial indicators and pathogenic bacteria in a municipal wastewater plant. Samples of untreated sewage and effluents before and after PAA treatment were collected seasonally for 1 year and were analysed for pathogenic Campylobacter, Salmonella spp., E. coli O157:H7 and E. coli virulence genes using molecular methods; moreover, the detection of specific microbial indicators (E. coli, faecal coliforms, enterococci, C. perfringens) and Salmonella spp. were carried out using culturing methods. Salmonella spp. DNA was found in all untreated sewage and effluent before PAA treatment, whereas it was recovered in 50% of the samples collected after PAA treatment. Although E. coli O157:H7 was never identified, the occurrence of Shiga-like toxin I amplicons was identified in 75% of the untreated sewage samples, in 50% of the effluents assayed before PAA treatment, and in 25% of the effluents assayed after PAA treatment, whereas the stx2 gene was never found. Campylobacter coli was only detected in one effluent sample before PAA treatment. In the effluents after PAA treatment, a lower load of indicator bacteria was observed compared to the effluents before treatment. The results of this study highlight that the use of low doses of PAA seems to lead to an improvement of the microbiological quality of the effluent, although it is not sufficient to guarantee its suitability for irrigation. These results underscore the need for additional studies to further assess the efficiency of PAA disinfection in municipal wastewater plants. Full article
(This article belongs to the Special Issue New Advances in Disinfection of Wastewater)
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Review

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Open AccessReview
Chemical and Microbiological Quality of Effluents from Different On-Site Wastewater Treatment Systems across Finland and Sweden
Water 2017, 9(1), 47; https://doi.org/10.3390/w9010047
Received: 24 November 2016 / Revised: 19 December 2016 / Accepted: 7 January 2017 / Published: 13 January 2017
Cited by 2 | PDF Full-text (466 KB) | HTML Full-text | XML Full-text
Abstract
Domestic wastewaters, which cannot be disposed through sewage networks, must be treated with different on-site treatment systems; these are usually commercial, small-scale treatment plants or built sand filters. These systems are usually maintained by the house’s inhabitants. This study was achieved by analysing [...] Read more.
Domestic wastewaters, which cannot be disposed through sewage networks, must be treated with different on-site treatment systems; these are usually commercial, small-scale treatment plants or built sand filters. These systems are usually maintained by the house’s inhabitants. This study was achieved by analysing the chemical and microbiological data of 717 effluents collected in Finland and Sweden. There were inadequate reductions in 31% of phosphorus effluents, 22% of nitrogen effluents and 5% of biological oxygen demand compounds. The addition of a coagulant capable of precipitating phosphorus improved the performance of sand filters and biorotors. There are no legally binding limitations on the number of enteric microorganisms that can be present in an effluent, but the number of Escherichia coli and enterococci exceeded more than 100 colony forming units per 100 mL in 59% and 53% effluents studied, with the highest numbers for these indicators being more than 100,000 cfu per 100 mL. The number of E. coli and enterococci were lower when the concentration of phosphorus in effluent was less than 1 mg/L. The treatment efficiency varied extensively, even between similar plant models, possibly due to either irregular use, or after long pauses, when they were not being used. In addition, it is possible that the end users are not capable of properly maintaining these wastewater treatment plants. Full article
(This article belongs to the Special Issue New Advances in Disinfection of Wastewater)
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