scholarly journals Low-nutrient R2A medium in monitoring microbiological quality of drinking water

2010 ◽  
Vol 16 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Slavica Ciric ◽  
Olga Petrovic ◽  
Dragan Milenkovic

The possibility of using low-nutrient R2A medium for determining the total count of aerobic mesophilic bacteria was investigated. Sampling of water from particular points of water treatment and distribution at Krusevac drinking water treatment plant was conducted. The samples were inoculated simultaneously on Plate Count Agar (PCA) and R2A media, and incubated at 37 ?C and at room temperature. The bacterial count was determined after 48, 72, 120 and 168 h. The statistical analysis of the results showed significantly higher bacterial count on R2A medium compared to PCA. Moreover, a significantly higher bacterial count developed at room temperature compared to the temperature of 37?C. R2A medium recorded 3.6% of unsafe samples in the distribution system after the 7-day incubation at room temperature. On the basis of the obtained results, an optimum method for determining the total count of aerobic mesophilic bacteria for all investigated waters has been defined. The process of incubation is predictable and it can be described by a mathematical model in the form of a polynomial of the second or the third power.

2020 ◽  
Vol 20 (8) ◽  
pp. 3301-3317
Author(s):  
Rafael Paulino ◽  
Pierre Bérubé

Abstract Artificial neural networks (ANNs) are increasingly being used in water treatment applications because of their ability to model complex systems. The present study proposed a framework to develop and validate ANNs for drinking water treatment and distribution system water quality applications. The framework was used to develop ANNs to identify the optimal ozone dose required for effective UV disinfection and to meet regulatory requirements for disinfection by-products (DBPs) in the distribution system. Treatment at a full-scale treatment plant was successfully modelled, with treated water UV transmittance as the output variable. ANNs could be used to identify operating setpoints that minimize operating costs for effective disinfection during drinking water treatment. However, because of the limited data available to train and validate the distribution system ANNs (i.e. n = 48; 15 years of quarterly measurements), these could not be used to reliably identify operating setpoints that also ensure compliance with DBP regulations.


1986 ◽  
Vol 32 (3) ◽  
pp. 226-230 ◽  
Author(s):  
G. A. Burlingame ◽  
I. H. Suffet ◽  
W. O. Pipes

Granular activated carbon (GAC) beds may be used for removal of dissolved organic matter during the treatment of drinking water. However, they might also change the microbiological quality of the water entering the distribution system either by changing the predominant bacteria or the bacterial density of the treated water. A 3-year pilot plant study of water treatment using GAC beds was conducted at the Baxter Water Treatment Plant in Philadelphia. During the study, bacteria were isolated from the raw water and from the effluents of the GAC treatment units. At the end of the study, bacteria were also isolated from the GAC units and from sand beds operated in parallel with the GAC units. Bacterial genera in the GAC effluents and in the GAC units themselves were similar to those found in the raw water and in the sand beds. Prechlorination and (or) preozonation of the water before GAC treatment had no noticeable effect on the bacterial genera found as compared with GAC unit having no predisinfection. The bacterial genera found in this study were similar to those found in seven other studies of GAC water treatment that used a variety of treatment schemes and a variety of heterotrophic plate count techniques to evaluate bacterial populations. From these several studies it appears that GAC treatment does not change the nature of the bacterial populations associated with drinking water.


2016 ◽  
Vol 16 (4) ◽  
pp. 922-930 ◽  
Author(s):  
L. Richard ◽  
E. Mayr ◽  
M. Zunabovic ◽  
R. Allabashi ◽  
R. Perfler

The implementation and evaluation of biological nitrification as a possible treatment option for the small-scale drinking water supply of a rural Upper Austrian community was investigated. The drinking water supply of this community (average system input volume: 20 m3/d) is based on the use of deep anaerobic groundwater with a high ammonium content of geogenic origin (up to 5 mg/l) which must be treated to prevent the formation of nitrites in the drinking water supply system. This paper describes the implementation and operation of biological nitrification despite several constraints including space availability, location and financial and manpower resources. A pilot drinking water treatment plant, including biological nitrification implemented in sand filters, was designed and constructed for a maximum treatment capacity of 1.2 m3/h. Online monitoring of selected physicochemical parameters has provided continuous treatment performance data. Treatment performance of the plant was evaluated under standard operation as well as in the case of selected malfunction events.


2017 ◽  
Vol 29 (12) ◽  
pp. 2665-2670
Author(s):  
Soleha Mohamat Yusuff ◽  
K.K. Ong ◽  
W.M.Z. Wan Yunus ◽  
A. Fitrianto ◽  
M. Ahmad ◽  
...  

Author(s):  
Ivone Vaz-Moreira ◽  
Vânia Figueira ◽  
Ana R. Lopes ◽  
Alexandre Lobo-da-Cunha ◽  
Cathrin Spröer ◽  
...  

A Gram-positive, aerobic, non-motile, endospore-forming rod, designated DS22T, was isolated from a drinking-water treatment plant. Cells were catalase- and oxidase-positive. Growth occurred at 15–37 °C, at pH 7–10 and with <8 % (w/v) NaCl (optimum growth: 30 °C, pH 7–8 and 1–3 % NaCl). The major respiratory quinone was menaquinone 7, the G+C content of the genomic DNA was 36.5 mol% and the cell wall contained meso-diaminopimelic acid. On the basis of 16S rRNA gene sequence analysis, strain DS22T was a member of the genus Bacillus. Its closest phylogenetic neighbours were Bacillus horneckiae NRRL B-59162T (98.5 % 16S rRNA gene sequence similarity), Bacillus oceanisediminis H2T (97.9 %), Bacillus infantis SMC 4352-1T (97.4 %), Bacillus firmus IAM 12464T (96.8 %) and Bacillus muralis LMG 20238T (96.8 %). DNA–DNA hybridization, and biochemical and physiological characterization allowed the differentiation of strain DS22T from its closest phylogenetic neighbours. The data supports the proposal of a novel species, Bacillus purgationiresistans sp. nov.; the type strain is DS22T ( = DSM 23494T = NRRL B-59432T = LMG 25783T).


2010 ◽  
Vol 10 (2) ◽  
pp. 121-127 ◽  
Author(s):  
Kim van Schagen ◽  
Luuk Rietveld ◽  
Alex Veersma ◽  
Robert Babuška

The performance of a drinking-water treatment plant is determined by the control of the plant. To design the appropriate control system, a control-design methodology of five design steps is proposed, which takes the treatment process characteristics into account. For each design step, the necessary actions are defined. Using the methodology for the pellet-softening treatment step, a new control scheme for the pellet-softening treatment step has been designed and implemented in the full-scale plant. The implementation resulted in a chemical usage reduction of 15% and reduction in the maintenance effort for this treatment step. Corrective actions of operators are no longer necessary.


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