Assessment of photoreactivation following ultraviolet light disinfection

1996 ◽  
Vol 33 (10-11) ◽  
pp. 261-269 ◽  
Author(s):  
Koji Kashimada ◽  
Naoyuki Kamiko ◽  
Kazuo Yamamoto ◽  
Shinichiro Ohgaki

Photoreactivation of microorganisms following UV disinfection is one of the research topics of interest in assessing the performance of UV disinfection, because there is little consensus on how the visible light intensity relates to the photoreactivation rate and the maximum survival in wastewater treatment processes. Apparent photoreactivation by a fluorescent lamp was observed in case of indicator bacteria (heterotrophic bacteria, coliform bacteria, fecal coliforms) in raw sewage, but not E. coli B and E. coli K12 A/λ(F+). Inactivation of fecal coliform was observed simultaneously during photoreactivation process by sunlight. Dose rate at 360 nm wave length as visible light intensity showed that it was a useful indicator for assessing the photoreactivation rate and the maximum survival when photoreactivation took place by both fluorescent lamp and sunlight. The model for photoreactivation was developed. The photoreactivation rate increased with increasing visible light intensity at 360 nm. However, the maximum survival value may not be affected by visible light intensity.

2007 ◽  
Vol 73 (12) ◽  
pp. 3771-3778 ◽  
Author(s):  
Winfried B. Ksoll ◽  
Satoshi Ishii ◽  
Michael J. Sadowsky ◽  
Randall E. Hicks

ABSTRACT Epilithic periphyton communities were sampled at three sites on the Minnesota shoreline of Lake Superior from June 2004 to August 2005 to determine if fecal coliforms and Escherichia coli were present throughout the ice-free season. Fecal coliform densities increased up to 4 orders of magnitude in early summer, reached peaks of up to 1.4 � 105 CFU cm−2 by late July, and decreased during autumn. Horizontal, fluorophore-enhanced repetitive-PCR DNA fingerprint analyses indicated that the source for 2% to 44% of the E. coli bacteria isolated from these periphyton communities could be identified when compared with a library of E. coli fingerprints from animal hosts and sewage. Waterfowl were the major source (68 to 99%) of periphyton E. coli strains that could be identified. Several periphyton E. coli isolates were genotypically identical (≥92% similarity), repeatedly isolated over time, and unidentified when compared to the source library, suggesting that these strains were naturalized members of periphyton communities. If the unidentified E. coli strains from periphyton were added to the known source library, then 57% to 81% of E. coli strains from overlying waters could be identified, with waterfowl (15 to 67%), periphyton (6 to 28%), and sewage effluent (8 to 28%) being the major potential sources. Inoculated E. coli rapidly colonized natural periphyton in laboratory microcosms and persisted for several weeks, and some cells were released to the overlying water. Our results indicate that E. coli from periphyton released into waterways confounds the use of this bacterium as a reliable indicator of recent fecal pollution.


1997 ◽  
Vol 43 (6) ◽  
pp. 583-588 ◽  
Author(s):  
J. J. Shirey ◽  
G. K. Bissonnette

The effect of decreased oxygen concentration during incubation of M-Endo medium on detection of coliforms from rural groundwater supplies was examined. Incubation oxygen concentrations of 0 (anaerobic GasPak), 4, 8, and 21% (atmospheric) were examined. Our findings point to several advantages of using anaerobic incubation for the isolation of coliforms: (i) higher verification rates with concomitant decreases in occurrence of false-positive coliforms; (ii) overall reduction in growth of nonsheen colonies; and (iii) reduction in colony size for nonsheen organisms, thereby minimizing crowding effects and facilitating enumeration of coliform colonies. However, these advantages were not sufficient to permit increased recovery of total coliforms as compared with standard aerobic incubation. In addition, the increased frequency of detecting false-negative coliforms during anaerobic incubation is a disadvantage to this method. While detection of total coliforms was reduced under conditions of anaerobiosis, the detection of fecal coliforms and (or) E. coli was not impeded.Key words: coliforms, anaerobiosis, groundwater, sheen formation.


1993 ◽  
Vol 39 (10) ◽  
pp. 973-977 ◽  
Author(s):  
Allen N. Hagler ◽  
Carlos A. Rosa ◽  
Paula B. Morais ◽  
Leda C. Mendonça-Hagler ◽  
Georgia M. O. Franco ◽  
...  

Yeasts and coliform bacteria were isolated from water that accumulated in the central cups and adjacent leaf axilae of two bromeliads, Neoregelia cruenta of a coastal sand dune and Quesnelia quesneliana of a mangrove ecosystem near the city of Rio de Janeiro, Brazil. The mean total coliform counts were above 10 000 per 100 mL for waters of both plants, but the mean fecal coliform counts were only 74 per 100 mL for Q. quesneliana and mostly undetected in water from N. cruenta. Of 90 fecal coliform isolates, 51 were typical of Escherichia coli in colony morphology and indol, methyl red, Volges–Proskauer, and citrate (IMViC) tests. Seven representatives of the typical E. coli cultures were identified as this species, but the identifications of nine other coliform bacteria were mostly dubious. The yeast community of N. cruenta was typical of plant surfaces with basidiomycetous yeasts anamorphs, and the black yeast Aureobasidium pullulans was prevalent. Quesnelia quesneliana had a substantial proportion of ascomycetous yeasts and their anamorphs, including a probable new biotype of Saccharomyces unisporus. Our results suggested that the microbial communities in bromeliad waters are typically autochtonous and not contaminants.Key words: yeasts, fecal coliforms, bromeliad waters, mangrove, Restinga.


1997 ◽  
Vol 60 (11) ◽  
pp. 1302-1305 ◽  
Author(s):  
TODD M. SILK ◽  
ELLIOT T. RYSER ◽  
CATHERINE W. DONNELLY

The main objective of this research was to determine the easiest and most reliable media for enumerating coliform bacteria and Escherichia coli levels in apple cider. During the autumn of 1994 a total of 59 apple cider samples were collected directly from 12 cider producers and were assessed for bacterial levels and pH. Plate count agar was used to determine heterotrophic bacteria levels. Coliform levels were determined using three different media: violet red bile agar (VRBA), Petrifilm High Sensitivity Coliform Count Plates (PHSCCP), and Trypticase soy agar with a VRBA overlay (TSA/VRBA) for attempted recovery of coliforms injured by the low pH of the apple cider. Eosin methylene blue agar (EMBA) and Petrifilm E. coli Count Plates were used to screen cider samples for E. coli. Apple cider had an average pH of 3.34 ± 0.08. Heterotrophic bacterial levels ranged from 2.30 to 7.11 log CFU/ml. All cider samples contained coliform bacteria with levels varying greatly; on the different media, we found the following: on VRBA, <1.00 to 4.37 log CFU/ml; on TSA/VRBA, 1.20 to 4.40 log CFU/ml; and on PHSCCP, < 1.00 to 4.56 log CFU/ml. Coliform levels were most easily determined in apple cider by using PHSCCP. However TSA/VRBA proved to be more reliable; coliform detection was significantly (P < 0.05) increased. EMBA was ineffective for screening apple cider for E. coli, with the low pH of the cider producing many false-positive results. E. coli was only recovered by using Petrifilm E. coli Count Plates with one of the 59 samples positive for E. coli (non-O157:H7) at a level of 10 CFU/ml.


2000 ◽  
Vol 42 (10-11) ◽  
pp. 165-170 ◽  
Author(s):  
K. L. Nelson

A reveiw of recent experiments on the particle-association of fecal coliforms in wastewater effluents and the effect that this has on UV disinfection is presented. The most significant finding is that a direct linear correlation was observed between the total number of particles with associated coliform bacteria and the residual coliform bacteria concentration after UV disinfection. In contrast to the other treatment systems, effluents from an aerated and a facultative pond system had very low numbers of particles with associated coliforms. Therefore, despite high suspended solids concentrations, the pond effluents were easily disinfected with UV because the majority of the coliforms were not associated with particles. More research is needed, in particular, on the effect of UV irradiation on algal solids and the implications for the discharge or reuse of pond effluents. The main factors affecting the costs of UV compared to chlorine disinfection are also discussed.


2020 ◽  
Vol 20 (6) ◽  
pp. 2216-2225
Author(s):  
Xiu-Feng Yin ◽  
Na Shi ◽  
Ting Meng ◽  
Ying-Xue Sun

Abstract This study investigated the simulated solar light disinfection of Escherichia coli CGMCC 1.1595, a multidrug-resistant (MDR) strain resistant to tetracycline and ampicillin. With the increase of light intensity, the maximum inactivation efficiency reached 0.74 log in 60 min following visible light irradiation with an intensity of 115.8 mW/cm2 and following UVA–visible light irradiation, using a 98% UVA-ray contribution at 6.5 mW/cm2 and 95% contribution at 20.0 mW/cm2, the inactivation efficiency was up to 6.09 log. The inactivated MDR E. coli did not regrow after light irradiation or in the dark after 24 or 48 h after visible light disinfection, demonstrating that visible light disinfection can prevent MDR E. coli self-repair. The MDR E. coli plasmid electrophoresis band gradually went dark with increase of the light irradiation time and could be completely eliminated by high UVA light intensity treatment, however, simulated sunlight irradiation had minimal influence on both tetracycline and ampicillin resistance of the MDR E. coli strain.


2005 ◽  
Vol 68 (12) ◽  
pp. 2527-2532 ◽  
Author(s):  
BRETT KOONSE ◽  
WILLIAM BURKHARDT ◽  
STUART CHIRTEL ◽  
GEORGE P. HOSKIN

In this study, we examined the prevalence of Salmonella and coliform bacteria on shrimp aquaculture farms to develop guidelines or preventative measures for reducing Salmonella and fecal contamination on products harvested from these farms. The U.S. Food and Drug Administration, in conjunction with foreign government regulatory agencies, the aquaculture industry, and academia affiliates, analyzed 1,234 samples from 103 shrimp aquaculture farms representing six countries between July 2001 and June 2003 for fecal coliforms, Escherichia coli, and Salmonella. A significant relationship was found (P = 0.0342) between the log number of fecal bacteria and the probability that any given sample would contain Salmonella. The likelihood of any given sample containing Salmonella was increased by 1.2 times with each 10-fold increase in either fecal coliform or E. coli concentration. The statistical relationship between Salmonella concentration and that of both fecal coliforms and E. coli was highest in grow-out pond water (P = 0.0042 for fecal coliforms and P = 0.0021 for E. coli). The likelihood of finding Salmonella in grow-out pond water increased 2.7 times with each log unit increase in fecal coliform concentration and 3.0 times with each log unit increase in E. coli concentration. Salmonella is not part of the natural flora of the shrimp culture environment nor is it inherently present in shrimp grow-out ponds. The occurrence of Salmonella bacteria in shrimp from aquaculture operations is related to the concentration of fecal bacteria in the source and grow-out pond water.


2020 ◽  
Vol 71 (4) ◽  
pp. 313-316
Author(s):  
Alina Roxana Banciu ◽  
Lucian Ionescu ◽  
Daniela Liliana Ionica ◽  
Monica Alexandra Vaideanu ◽  
Simona Mariana Calinescu ◽  
...  

Wastewater treatment plants are major interface between rural and urban activities and the natural environment with problems relating to the survival and transmission of the fecal bacteria into streams and rivers. The main goal of this paper was to showed the impact of WWTPs on fecal populations bacteria and their dissemination into the aquatic ecosystems. The sampling campaigns were conducted in 2019 where the hospital and WWTPs wastewater from three cities from the south-eastern part of Romania and the surface water of their emissaries were trimestral collected. The quantitative and qualitative analysis of total and fecal coliforms indicated the efficiency of wastewater treatment processes but at the same time, the contribution of contamination with hospital effluents has been demonstrated. Also, the microbiological results showed the selectivity of the destruction of fecal coliform bacteria between wastewater and surface water.


2013 ◽  
Vol 5 (1) ◽  
Author(s):  
Lies Indah Sutiknowati

The objective of this research was to evaluate waters quality in Pari island waters for aquaculture purpose based on bacteriological information conducted in Mei and September 2011. Microbiological parameters analyzed were total density of bacteria for coliforms, E.coli, pathogenic, heterotrophic, halotoleran, phosphate-nitrate-ammonia breaker, and total cells. Method to analyze coliform bacteria was filtration, identification of pathogenic bacteria using biochemical test, density analises for heterotrophic bacteria, analises for phosphate-nitrate-ammonia breaker bacteria using pour plate, and total cell using Acridine Orange Epifluorescence Microscopy. Results showed that the abundance of total coliform cell was about 1000-7000 colony forming unit (cfu)/100 ml. The abundance of heterotrophic, halotolerant, phosphate-nitrate-ammonia bacteria in seawater was (3.6-4.3)x105 cfu/ml, (1.1-1.3)x105 cfu/ml, (0.5-3.44)x103cfu/ml; and (3.6-6.7)x105 cfu/ml, (1.6-2.7)x105 cfu/ml, (0.6-5.22)x103 cfu/ml in sediment, respectively. The total cell of bacteria was (0.05-2.1)x107cells/ml. The dog-conch (Strombus turturella) and blood-clamps (Anadara granosa) can survive in Pari Island and there was a significant increase in sea grass litter with growth average of 0.67 mm/day and 0.90 mm/day. During snails and clamps growth, there were found several genus of pathogenic bacteria such as Salmonella, Vibrio, Aeromonas, Pseudomonas, Citrobacter, Proteus, Shigella, Hafnia, and Yersinia. The results showed that Pari island waters was suitable for developing shellfish aquaculture dog conch and blood clamps. Keywords: bacteria, parameter, shellfish, aquaculture.


2019 ◽  
Vol 14 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Banin Maghfirotin Marta ◽  
Utami Tyas ◽  
Cahyanto Muhammad Nur ◽  
Widada Jaka ◽  
Rahayu Endang Sutriswati

Consumption of probiotics is known to influence the gut microbiota. The aim of this study was to assess the effect of probiotic powder containing Lactobacillus plantarum Dad-13 on bacterial composition in the gut by examining fecal samples of school-age children in Yogyakarta, Indonesia. This is a randomized, double-blind, placebo-controlled study. A total of 40 healthy subjects were recruited for this study and were divided into two groups: placebo group and probiotic group. The placebo group consumed skim milk and the probiotic group consumed probiotic powder containing L. plantarum Dad-13 (2 × 109 CFU/g) for 65 days. The results showed that placebo intake had no significant effect on gut microbiota; however, probiotic caused a significant increase in L. plantarum and Lactobacillus population, while decreasing the population of E. coli and non-E. coli coliform bacteria by 55% and 75%, respectively and Bifidobacteria count did not change significantly. The study concluded that consumption of probiotic powder L. plantarum Dad-13 could increase propionic acid thereby decreasing the gut pH which has an effect on the microbial population.


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