Search

The aim of this study was the comparison of two process in pentachlorophenol (PCP: 100 mg L -1 ) removal by combined process bioaugmentation-adsorption and bioaugmentation-phytoremediation in secondary treated wastewater (STWW). The phytoremediation procedure was conducted by using two plants such as Typha angustifolia and Schoenoplectus acutus , and the bioaugmentation procedure was operated by Pseudomonas putida HM 627618 as a plant growth promoting bacteria (PGPR). The adsorption process was performed by palm date activated carbon. The PCP monitoring was assessed by high performance liquid chromatography (HPLC) and the optical density determination at 600 nm (OD 600 ). The performance of the two processes was observed by the determination of total bacteria, chlorophylls and physical and chemical analysis (COD, pH, conductivity, chloride, and organic carbon). The alfalfa seed germination test was conducted to assess the two operational performance procedures. According to the results obtained from the physical and chemical analysis of the treated STWW, there was no significant differences in the pH and in the EC content of the bioaugmentation-phytoremediation treatment, while a significant increase of the EC content was observed in the bioaugmentation-adsorption to 5.08 mS cm -1 . The COD value significantly decreased up to 1320 mg L -1 in bioaugmentation-adsorption treatment (control value 2400 mg L -1 ) and 98 mg L -1 in bioaugmentation-phytoremediation treatment (control value 98 mg L -1 ). Microbial biomass monitoring of P. putida shows significant greater in both processes in the order of 9.18 and 7.01 Log CFU mL -1 for bioaugmentation-adsorption and bioaugmentation-phytoremediation, respectively. The chlorophyll content in Typha angustifolia and Schoenoplectus acutus significantly decreased after 144 h with the exception of the chlorophyll a content of Schoenoplectus acutus in which the content increased up to 3.31 mg mL -1 . Comparing the performance of these two treatments, it was found according to HPLC analysis that the bioaugmentation-adsorption process was more efficient in removing about 97% of PCP after 48 h, against around 90% of PCP after 72 h for the phytoremediation-bioaugmentation. The alfalfa seeds showed a germination rate after the 5th day of incubation of 100% and 95%, respectively for the PCP-non-contaminated and treated STWW, while for wastewater containing PCP the germination was totally inhibited.

Hepatovirus A is known as a waterborne and foodborne virus that can be transmitted from one person to another through contaminated water and raw food. Therefore, it is necessary to survey the circulation of this type of enteric virus in the wastewater to prevent prospective outbreaks. Wastewater samples collected from WWTP El Menzeh I and Charguia I have been the subject for physicochemical, bacteriological (MPN) and virological analyses. Hepatovirus A (HAV) detection was carried out using the standard reverse transcription-polymerase chain reaction (RT-PCR). Hepatovirus A was detected respectively in 62% (63/102) and 66% (92/140) of the collected wastewater samples at El Menzeh I and Charguia I WWTPs. The treated effluent by natural oxidizing lagoon procedure was characterized by a poor physical-chemical and virological qualities but with excellent bacteriological quality. Consequently, this effluent is not suitable to be recycled and reused in agriculture or even dismissed in the environment. The treated sewage by activated sludge and rotating biodisk procedures turned out to be of a very good physical-chemical quality but with a poor bacteriological and virological quality. After tertiary UV-C 254 nm irradiation, the faecal indicator bacteria concentration was mostly reduced and removed. These findings confirmed the need for improvement and upgrade of the treatment processes used in these two studied sewage purification plants and the necessity of implementation and establishment of a proper national virological standard to control the circulation rates of enteric viruses in Tunisian municipal wastewater., (© 2020. Springer-Verlag GmbH Germany, part of Springer Nature.)

Enteric viruses, generally found in sewage, are recognized as the main cause of waterborne and foodborne public health outbreaks. Among leading enteric viruses, the Rotavirus A (RVA) detection in wastewater appeared to be a novel approach to monitor the emergence of these viruses in some countries where the viral gastroenteritis surveillance is almost absent such as in Tunisia. The RVA detection and quantification in an industrial sewage purification plant of Charguia I (Tunis, Tunisia) were achieved to evaluate the performance of activated sludge procedures coupled to a macrofiltration monolamp ultraviolet irradiation type C (UV-C 254 ) disinfection reactor. This UV-C 254 system was preceded by a fiberglass cartridge filter system with an average porosity of 45 μm to clarify the water and thus increase its UV transmittance. A total of 140 composite sewage samples was collected from this line of treatment and analyzed for RVA detection. The detection and the viral load quantification of RVA were performed using real-time reverse transcription polymerase chain reaction (RT-PCR). The virological results showed in general that RVA were detected at high frequency of 98% (137/140). In fact, the RVA detection rates at the exit of the two studied wastewater treatment were about 100% at the exit of the activated sludge procedure. It means that all wastewater sampled at this last step of treatment was positive for RVA detection. On the other hand, 92.5% of the wastewater samples taken at the exit of the monolamp UV-C 254 reactor were positive for the RVA. However, the RVA quantification results expressed as viral load showed a significant reduction in the means of RVA viral loads at the exit of the biological activated sludge procedure and the tertiary UV-C 254 treatment, showing in general an improved treated wastewater virological quality. Therefore, the RVA load removal rates recorded at the two successive stages of treatment, the activated sludge and the UV-C 254 treatment, were around 85% and 73%, respectively, as compared to the one with 100% registered for the raw wastewater. In addition, good physical-chemical and bacteriological qualities of the treated sewage were found at the exit of the two considered wastewater treatment procedures. The present investigation represents the first Tunisian environmental report showing the good effectiveness and performance of the biological and the tertiary treatments for RVA removal. Therefore, an improved and an optimized tertiary disinfection treatment was needed since it could be a good means for getting better viral water quality and for minimizing the transmission and dissemination of human infectious viral diseases.

The efficiency of rotating biodisks and natural oxidizing lagoon procedures is investigated at a Tunisian semi-industrial pilot plant, El Menzeh I, where the wastewater is mainly provided by three different neighbouring hospital clinics. Throughout 2011, 102 wastewater samples were collected from the two mentioned wastewater treatment procedures. Results showed that the Sapovirus (SaV) frequency was approximately 29.4% using the real-time reverse transcription polymerase chain reaction (RT-PCR) technique, and about 16.6% using the conventional RT-PCR. Also, the SaV genogroups and genotypes were identified and genotyping revealed that all of the four Tunisian SaV strains obtained belonged to the two genogroups GIV.1 and GGI.3. In addition, two new genotypes, D and C, were detected. A moderate decrease in the SaV frequencies was observed at the exit of the two treatment processes and the SaV removal rate was around 90% in the natural oxidizing lagoons and 94% in the rotating biodisks procedure showing the temperate sensitivity of these viruses to the implemented biological wastewater. Therefore, an urgent disinfection process should be implemented downstream of the two biological treatment procedures for safe release of treated effluent in the different natural environments. Abbreviations: NoV: Noroviruses; SaV: Sapoviruses; EC: Electrical Conductivity; COD: Chemical Oxygen Demand; BOD5: Biological Oxygen Demand; SS: Suspended Solids; NH4-N: Ammonium Nitrogen; P-PO4: Ortho-Phosphate; AlCl3: aluminum chloride.

Objectives: This study aimed to isolate and characterise extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) isolates from animals and wastewater in Tunisia., Methods: ESBL-E from wastewater (n=123 samples), faeces of healthy animals (poultry, sheep, goats and calves) (n=140) and raw milk from healthy cows (n=42) and goats (n=20) were investigated. Antimicrobial susceptibility was determined according to CLSI recommendations. The bla TEM , bla SHV , bla CTX-M and bla OXA-48 genes were analysed by PCR and sequencing. Phylogenetic groups were determined by PCR for Escherichia coli isolates. The clonality of E. coli and Klebsiella pneumoniae isolates was determined by XbaI-PFGE and MLST., Results: A total of 81 E. coli, 20 K. pneumoniae, 4 Enterobacter cloacae, 1 Citrobacter freundii and 1 Citrobacter braakii were isolated. The bla CTX-M-1 and bla CTX-M-15 genes were predominant in E. coli and K. pneumoniae isolates. E. cloacae and C. braakii isolates harboured the bla SHV-12 gene. The C. freundii isolated from wastewater carried bla CTX-M-15 , bla TEM-1 and bla OXA-204 . E. coli isolates belonged to phylogroups A (37), B1 (25), B2 (7) and D (12). Seventy-eight E. coli isolates were typeable by PFGE and were classified into 34 pulsotypes. The K. pneumoniae isolates belonged to 11 pulsotypes. The E. coli isolates belonged to sequence types ST131, ST224, ST162, ST845, ST5204, ST69, ST141 and ST10. The K. pneumoniae isolates belonged to ST405, ST147, ST564, ST307, ST152, ST45, ST661 and ST1564., Conclusion: This is the first report of O25b-B2 3 -CTX-M-27-ST131 E. coli isolates and of C. freundii carrying bla CTX-M-15 , bla TEM-1 and bla OXA-204 in Tunisia., (Copyright © 2019 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.)

Hospital wastewater (HWW) represents a major source of the diffusion of many antibiotics and some toxic pathogenic microorganisms in the aquatic environment. Sanitation services play a critical role in controlling transmission of numerous waterborne pathogens, especially enteric human adenoviruses (HAdVs) that can cause acute gastroenteritis. This study intended to evaluate the human adenoviruses (HAdVs) detection rates, to determine the genotype of these viruses and to assess the efficiency of HAdVs removal in hospital pilot wastewater treatment plant (PWWTP) in Tunis City, Tunisia. Therefore, hospital wastewater samples (n = 102) were collected during the study year from the two biological wastewater treatment techniques: natural oxidizing ponds and the rotating biological disks or biodisks. Nested polymerase chain reaction (Nested PCR) was used to evaluate the HAdVs detection rates. The genotype of HAdVs positive samples was achieved by the sequencing of the PCR products. HAdVs were detected in 64% (65/102) of positive wastewater samples. A substantial increase in the frequencies of HAdVs was observed at the exit of the two wastewater treatment techniques studied. The typing of HAdVs species F showed the occurrence of only HAdVs type 41. This data acquired for the first time in Tunisia showed high persistence and survival of HAdVs in the two biological wastewater treatment techniques experienced, and mainly highlighted the poor virological quality of the treated wastewater intended for recycling, agriculture reuse, and discharges into the natural receiving environments. Consequently, tertiary wastewater treatment appeared necessary in this case to decrease the load of enteric viruses flowing in the water environment.

Objectives: Oxazolidinone resistance is a serious limitation in the treatment of MDR Enterococcus infections. Plasmid-mediated oxazolidinone resistance has been strongly linked to animals where the use of phenicols might co-select resistance to both antibiotic families. Our goal was to assess the diversity of genes conferring phenicol/oxazolidinone resistance among diverse enterococci and to characterize the optrA genetic environment., Methods: Chloramphenicol-resistant isolates (>16 mg/L, n = 245) from different sources (hospitals/healthy humans/wastewaters/animals) in Portugal, Angola and Tunisia (1996-2016) were selected. Phenicol (eight cat variants, fexA, fexB) or phenicol + oxazolidinone [cfr, cfr(B), optrA] resistance genes were searched for by PCR. Susceptibility (disc diffusion/microdilution), filter mating, stability of antibiotic resistance (500 bacterial generations), plasmid typing (S1-PFGE/hybridization), MLST and WGS (Illumina-HiSeq) were performed for optrA-positive isolates., Results: Resistance to phenicols (n = 181, 74%) and phenicols + oxazolidinones (n = 2, 1%) was associated with the presence of cat(A-8) (40%, predominant in hospitals and swine), cat(A-7) (29%, predominant in poultry and healthy humans), cat(A-9) (2%), fexB (2%) and fexA + optrA (1%). fexA and optrA genes were co-located in a transferable plasmid (pAF379, 72 918 bp) of two ST86 MDR Tunisian Enterococcus faecalis (wastewaters) carrying several putative virulence genes. MICs of chloramphenicol, linezolid and tedizolid were stably maintained at 64, 4 and 1 mg/L, respectively. The chimeric pAF379 comprised relics of genetic elements from different Gram-positive bacteria and origins (human/porcine)., Conclusions: To the best of our knowledge, we report the first detection of optrA in an African country (Tunisia) within a transferable mosaic plasmid of different origins. Its identification in isolates from environmental sources is worrisome and alerts for the need of a concerted global surveillance on the occurrence and spread of optrA., (© The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The objective was to characterize Staphylococcus aureus isolated from two wastewater treatment plants (WWTPs) located in Tunis City (Tunisia), during the period 2014-2015. Genetic lineages, antibiotic resistance mechanisms and virulence factors were determined for the recovered isolates. S. aureus isolates were recovered from 12 of the 62 wastewater samples tested (19.35%), and one isolate/sample was characterized, all of them being methicillin-susceptible (MSSA). Six spa types (t587, t674, t224, t127, t701 and t1534) were found among the 12 isolates, and the spa-t587, associated with the new sequence type ST3245, was the most predominant one (7 isolates). The remaining isolates were assigned to five clonal complexes (CC5, CC97, CC1, CC6 and CC522) according to the sequence-type determined and/or the spa-type detected. S. aureus isolates were ascribed to agrI (n = 3), agrII (n = 7) and agrIII (n = 1); however, one isolate was non-typeable. S. aureus showed resistance to (number of isolates): penicillin (12), erythromycin (7), tetracycline (one) and clindamycin (one). Among the virulence factors investigated, only one isolate harboured the tst gene, encoding the TSST-1 (toxic shock syndrome toxin 1). Despite the low number of studied isolates, the present study reports the occurrence of both human- and animal-associated S. aureus clonal complexes in WWTPs in Tunisia.

Enteric viruses are released in important quantities into the environment where they can persist for a very long time. At very low doses, they can cause human gastroenteritis, and are responsible for a substantial number of waterborne diseases. The aims of this study were multiple: firstly, to study the circulation of Aichi viruses (AiV) in wastewater sampled at the scale of a pilot wastewater treatment plant; secondly, to evaluate the performance of two wastewater treatment procedures, as natural oxidizing lagoons and rotating Biodisks, concerning the AiV removal; and finally, to determine the different type of AiV genotype found during this study. Hence, the pilot wastewater treatment plant is principally irrigated by the wastewater of three neighbouring clinics. Wastewater samples were collected during 2011 from the two lines of biological treatment procedures. AiV detection in wastewater were achieved using the Reverse Transcription Polymerase Chain Reaction (RT-PCR) technique, and the identification of AiV genotype was realized by the direct sequencing of PCR products. The result revealed that AiV strains were identified in 50% (n = 51) of the wastewater samples. A significant increase of the AiV detection frequency was registered from upstream to downstream of the five ponds constituting the natural oxidizing lagoon process, and at the exit of the rotating Biodisks procedure. All detected AiV strains showed the highest nucleotide sequence identity to genotype B that has been recently observed in patients in Asia. This finding represented the first Tunisian survey that revealed and mentioned the first detection of AiV genotype B in sewage and by the same argued for a noticeable resistance or survival of this type of virus in the two lines of treatment considered., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Biological treatment systems use the natural processes of ubiquitous organisms to remove pollutants and improve the water quality before discharge to the environment. In this paper, the nitrification/denitrification reactor allowed a reduction in organic load, but offered a weak efficiency in nitrate reduction. However, the additions of the activated sludge in the reactor improve this efficiency. A decrease of [Formula: see text] values from 13.3 to 8 mg/l was noted. Nevertheless, sludge inoculation led to a net increase of the number of pathogenic bacteria. For this reason, a UV-C pilot reactor was installed at the exit of the biological nitrification-denitrification device. Thus, a fluence of 50 mJ.cm -2 was sufficient to achieve values of 20 MPN/100 ml for fecal coliform and 6 MPN/100 ml for fecal streptococci, conforms to Tunisian Standards of Rejection. On the other hand, the DGGE approach has allowed a direct assessment of the bacterial community changes upon the treated wastewater.

The bacterial community structure and diversity were assessed at the scale of rotating biodisk procedure (RB) in a semi-industrial pilot plant. As well, the Salmonella community was particularly monitored, and the effects of ultraviolet (UV-C 254 ) on the bacterial community were studied. The identification of dominant bacteria revealed the presence of beneficial and useful species that could play an important role in the process of wastewater purification. Several species as Enterobacter agglomerans, Cronobacter sakazakii, and Pantoea agglomerans known for their bioremediation activities were revealed in the majority of biofilm samples. Common detection of Salmonella community provides evidence that the RB system did not seriously affect Salmonella. Furthermore, the investigation on the (UV)-C 254 inactivation of the whole bacterial community, in secondary treated wastewater, showed variable UV resistance results. No Salmonella detection was registered at a dose of around 1440 mW s cm -2 since a total disappearance of Salmonella was recorded.

Several wastewater stabilization ponds (WSP) in Tunisia suffer periodically from the 'red-water' phenomenon due to blooming of purple sulfur bacteria, indicating that sulfur cycle is one of the main element cycles in these ponds. In this study, we investigated the microbial diversity of the El Menzeh WSP and focused in particular on the different functional groups of sulfur bacteria. For this purpose, we used denaturing gradient gel electrophoresis of PCR-amplified fragments of the 16S rRNA gene and of different functional genes involved in microbial sulfur metabolism (dsrB, aprA, and pufM). Analyses of the 16S rRNA revealed a relatively high microbial diversity where Proteobacteria, Chlorobi, Bacteroidetes, and Cyanobacteria constitute the major bacterial groups. The dsrB and aprA gene analysis revealed the presence of deltaproteobacterial sulfate-reducing bacteria (i.e., Desulfobacter and Desulfobulbus), while the analysis of 16S rRNA, aprA, and pufM genes assigned the sulfur-oxidizing bacteria community to the photosynthetic representatives belonging to the Chlorobi (green sulfur bacteria) and the Proteobacteria (purple sulfur and non sulfur bacteria) phyla. These results point on the diversity of the metabolic processes within this wastewater plant and/or the availability of sulfate and diverse electron donors.

In this study, the detection rates of four enteric viruses, Human Astrovirus (HAstVs), Aichivirus (AiVs), Human Adenovirus (HAdVs), and Sapovirus (SaVs) are carried out to assess the virological quality of the treated wastewater. A total of 140 samples was collected from wastewater treatment plant WWTP of Tunis-City. Real-time RT-PCR and conventional RT-PCR results showed high frequencies of detection of the four enteric viruses investigated at the entry and exit of the biological activated sludge procedure and a significant reduction in viral titers after tertiary treatment with UV-C254 irradiation. These results revealed the ineffectiveness of the biological activated sludge treatment in removing viruses and the poor quality of the treated wastewater intended for recycling, agricultural reuse, and safe discharge into the natural environment. The UV-C254 irradiation, selected while considering the non-release of known disinfection by-products because of eventual reactions with the large organic and mineral load commonly present in the wastewater. [ABSTRACT FROM AUTHOR]

The objective was to characterize Staphylococcus aureus isolated from two wastewater treatment plants (WWTPs) located in Tunis City (Tunisia), during the period 2014-2015. Genetic lineages, antibiotic resistance mechanisms and virulence factors were determined for the recovered isolates. S. aureus isolates were recovered from 12 of the 62 wastewater samples tested (19.35%), and one isolate/sample was characterized, all of them being methicillin-susceptible (MSSA). Six spa types (t587, t674, t224, t127, t701 and t1534) were found among the 12 isolates, and the spa-t587, associated with the new sequence type ST3245, was the most predominant one (7 isolates). The remaining isolates were assigned to five clonal complexes (CC5, CC97, CC1, CC6 and CC522) according to the sequence-type determined and/or the spa-type detected. S. aureus isolates were ascribed to agrI (n = 3), agrII (n = 7) and agrIII (n = 1); however, one isolate was non-typeable. S. aureus showed resistance to (number of isolates): penicillin (12), erythromycin (7), tetracycline (one) and clindamycin (one). Among the virulence factors investigated, only one isolate harboured the tst gene, encoding the TSST-1 (toxic shock syndrome toxin 1). Despite the low number of studied isolates, the present study reports the occurrence of both human- and animal-associated S. aureus clonal complexes in WWTPs in Tunisia. [ABSTRACT FROM AUTHOR]

The main objectives of this work are: firstly, the study of the circulation of Rotavirus A (RVA) in wastewater sampled from a semi-industrial wastewater pilot plant. The plant is situated in a residential area of Tunis and irrigated by three different neighboring hospitals; and secondly, the evaluation of the functioning of two wastewater biological treatment procedures (natural lagoons and biodisks) in a semi-industrial pilot plant for RVA removal using molecular characterization and quantification technology. A total of 102 wastewater samples were collected from two biological treatment processes in a semi-industrial pilot plant that receives effluents of the sewage system of Tunis City (Tunisia). RVA was detected and quantified in 51 wastewater samples (50%) from the pilot plant. The mean values of viral content (genome copies/μL) obtained in the effluent of the two treatments procedures showed a significant decrease in the prevalence and viral content of RVA observed from upstream to downstream of the studied procedure: natural lagoons and at the exit of the biodisks line. The main G-type was G8 (35.5%), followed by G9 (16%), G1 (13%), G10 (10%), G3 (13%) and three mixed combined genotypes: G3/G9 (3%), G8/G10 (3%), G9/G8 (6.5%) were identified. The data obtained in this study represent the first documentation in Tunisia dealing with the effectiveness of wastewater biological treatment for the removal of RVA through two biological treatment procedures in a semi-industrial pilot plant located in the area of Tunis (Tunisia). [ABSTRACT FROM AUTHOR]

The large discharges of wastewater in different natural receiving environments, particularly the marine environment, have massively contributed to pollution. This study examined the physicochemical and microbiological quality of wastewater discharged along the Mediterranean Sea. This investigation is one of the few works carried out by scientists along with the Mediterranean countries. Wastewater sampling was carried out in Egypt, Morocco, Algeria, Tunisia, and Italy. Analyses confirmed that the quality of treated wastewater was always better than the ones registered as raw wastewater. In addition, the quality of the treated wastewater and seawater appeared to be adequate and satisfied the standard and recommended limits in vigor in all these Mediterranean countries. These results showed that the wastewater treatment process used in Italy allowed a higher reduction in most tested parameters (COD: 80.44%, BOD5: 58.9%, OM: 70.74%, TOC: 78.4%). The bacteriological quality of these waters and their diversification was assessed by the denaturing gradient gel electrophoresis (DGGE) technique. Firmicutes, Gamma-Proteobacteria, and Beta-Proteobacteria in 42% of the DGGE DNA bands, and predominately some lineages affiliated to cultivable and non-cultivable clones of Bacteroides (58%), were found. The examination of antibiotic susceptibility at the level of 18 strains isolated from various arbitrary water samples showed that most of these isolates exhibited resistance to at least one antibiotic family, and 11 isolates exhibited 100% resistance against aztreonam. This result confirms the large antibiotic-resistance spreading and circulation registered these last decades in the natural environment, conditioned by the extensive and non-controlled use of antibiotics for human therapy and animal feeding. [ABSTRACT FROM AUTHOR]

Abstract: This study investigated four methods for the recovery of enteroviruses from sterilized raw wastewater, activated sludge, thickened sludge and treated wastewater, inoculated with Echovirus 11, Gregory prototype. The adsorption–elution method recommended by the US Environmental Protection Agency (EPA) was better for Echovirus 11 recovery than a sonication method, a modified EPA method and a membrane adsorption elution method since it resulted in the highest detection levels by cell culture and RT-PCR (Friedman’s test, p <0.00041 and p =0.041, respectively). [Copyright &y& Elsevier]

The radiation field for an annular-type photo-catalytic reactor, used for wastewater disinfection by UV radiation, has been modelled. The spatial domain was described in terms of two cylindrical coordinates and the field of direction with two angular variables. The UV radiation entering through the inner reactor wall was obtained from the extended source with volumetric emission (a UV lamp). The system parameters for the radiative-transfer equation were taken from experimental measurements. Resorting to computational experiments, the effects produced by different concentrations of radiation absorbing particles (bacteria) were investigated. We have succeeded in determining the incident radiation profiles and local volumetric rate of energy absorption profiles, both as a function of the spatial position inside the reactor. The experimental values were compared with the theoretical predictions, good agreement was obtained. The errors were never higher than 10%. [Copyright &y& Elsevier]

Abstract: Salmonella serovars are increasing in importance as significant pathogens of both human and animals. Although water and wastewater are treated to eliminate pathogenic microorganisms, they still play an important role in the transmission of Salmonella spp. In this study, bacteriophages infecting Salmonella spp. were isolated from wastewater and evaluated; for their potential to lyse environmental Salmonella strains in vitro at different MOIs and temperatures; and to control the wastewater bacterial community. Three distinct phages designated sww65, sww275, and sww297; as defined by plaque morphology, electron microscopy and host range; were obtained from wastewater. Challenge tests were performed at 37, and 30°C with the infection of the Salmonella cultures with individual phage, a mixture of two phages, and cocktail of three phages at MOIs of 100, 102, and 104 PFU/CFU. At 30, and 37°C, a cocktail of three phages reduced all of the Salmonella cultures tested. These results required a high multiplicity of infection. However, when infected with only one phage or a mixture of two phages at MOIs of 100 or 10 2 PFU/CFU, an emergence of bacterial resistance was observed. The dynamic monitoring of wastewater enterobacterial community was conducted using Enterobacterial Repetitive Intergenic Consensus-PCR (ERIC-PCR). The number of bands decreased gradually with the use of individual phage or phage cocktails. Moreover, the dynamic monitoring of Salmonella community during wastewater treatment was performed using PCR detection of virulence gene invA. The results correlated with the ERIC-PCR fingerprints, and suggested that Salmonella community was affected by the phage treatment. Indeed, in wastewater, bacteriophages are reducing Salmonella and other members of the Enterobacteriaceae. These results indicated that dynamic changes are closely related with the process of treatment. The introduction of wide host range bacteriophages in wastewater can have a potential impact on the dynamics of the microbial communities, manifested by the reduction or the elimination of microbial species. [Copyright &y& Elsevier]

Abstract: For small settlements sanitation, constructed wetland systems offer a suitable social economic alternative to the classic wastewater treatment plants. In order to study the treatment mechanisms occurring in the soil–plant system, we set up a small-scale pilot wastewater treatment plant composed by a settler/digester followed by two trains combining two different types of subsurface flow constructed wetlands called ‘hybrid systems’. The first train represents a combination of a vertical flow reed (Phragmites australis) bed followed by a horizontal bed, planted with Typha, whereas in the second one, the combination is reversed. The hybrid systems are fed intermittently with a hydraulic load of 0.2 m per day given in two sequences of one hour separated by a six-hour rest period. We followed the quality of the effluent at the outlet of the beds. The two hybrid systems present satisfactory performances: yields higher than 90% in organic matter removal are registered. For the first system we could obtain a substantial nitrification but uncompleted denitrification whereas for the second system we observed that the total nitrogen (NTK) reduction was achieved by denitrification and nitrification remains almost complete. The pathogenic bacteria abatement is satisfactory for the two systems but more remarkable for the second (2 u log). [Copyright &y& Elsevier]