I. LEHACI, V. MUNTEAN, A. SABIE, M. BUDECAN - MICROBIOLOGICAL AND PHYSICO-CHEMICAL ANALYSES ON THE WATER FROM THE TREATMENT PLANT BISTRIŢA

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  Studii şi cercetri, Biology 1 6 , Bistriţa, p. 35-43 35 MICROBIOLOGICAL AND PHYSICO-CHEMICAL ANALYSES ON THE WATER FROM THE TREATMENT PLANT BI STRIŢA   I. LEHACI * , V. MUNTEAN, Alexandrina SABIE, Mariana BUDECAN Abstract: The study was carried out seasonally, at the water treatment plant Bistriţa. Three bacteriological groups were studied: total coliform bacteria, faecal coliforms and faecal enterococci. The following physico-chemical parameters of water were also analysed: pH, conductivity, organic matter and dissolved O 2 . The presence of the total coliforms was noticed at every sampling site, each season, as well as the presence of the faecal coliforms. The number of faecal coliforms was lower, generally by an order of magnitude as compared to the total coliforms. The faecal enterococci were not been present in all the analysed samples. The number of coliforms and the organic matter content significantly decrease at the emergence as compared to the entrance in the treatment plant, indicating a good efficiency of the water treatment plant.  Key words: total coliforms, faecal coliforms, enterococci, water. Introduction The microbiological pollution of water is a real problem when it affects rivers used as sources of drinking water for large populations. Many studies aim at identification in natural waters of so called indicator organisms , in order to avoid contamination of people with pathogenic microorganisms. According to Bitton (2005), the main criteria for an ideal indicator organism would be the following: - it should be a member of the intestinal micro biota of warm-blooded animals; - it should be present when pathogens are present, and absent in uncontaminated samples; - it should be present in greater numbers than the pathogen; - it should be at least equally resistant as the pathogen to environmental factors and to disinfection in water and wastewater treatment plants; - it should not multiply in the environment; - it should be detectable by means of easy, rapid, and inexpensive methods; *   MA student, Ecology, Faculty of Biology and Geology, Babeş -Bolyai University, Cluj-Napoca, Romania Babeş -Bolyai University, Faculty of Biology and Geology, Department of Experimental Biology, Cluj-Napoca, Romania. AQUABIS Co., The Water Treatment Plant, Bistriţa, Bistriţa -  Nsud County, Romania   Corresponding author: Vasile Muntean, Babeş -Bolyai University, Faculty of Biology and Geology, Department of Experimental Biology, 1 Koglniceanu Str., 400084, Cluj -Napoca, Romania,E-mail: vamutiro@yahoo.co.uk   36  I . LEHACI, V. MUNTEAN, Alexandrina SABIE, Mariana BUDECAN - the indicator organism should be non pathogenic. The group of coliform bacteria fulfils these criteria and was adopted as an indicator of faecal contamination of drinking water as early as the beginning of last century. In water treatment plants, total coliforms are one of the best indicators of treatment efficiency of the plant. The  total coliforms  belong to the family Enterobacteriaceae, order Enterobacteriales, class Gammaproteobacteria, phylum BXII  –   Proteobacteria (Garrity, 2005). The total coliforms include the aerobic and facultative anaerobic, non-spore-forming, Gram-negative, rod-shaped bacteria that ferment lactose with gas production within 48 hours at 35°C. The group includes four bacterial genera:  Escherichia, Klebsiella, Enterobacter   and Citrobacter  . Faecal coliforms  are thermo tolerant bacteria that include all coliforms that can ferment lactose at 44.5°C. The presence of faecal coliforms indicates the presence of faecal material from warm-blooded animals. Faecal coliforms display a survival pattern similar to that of bacterial pathogens, but they are not reliable with regard to contamination of aquatic environments with viruses and protozoans. Faecal enterococci  are members of the  Enterococcus  and Streptococcus  genera, living in the intestinal tract of man and other animals. They also fulfill the requirements of Bitton for being a good indicator microorganism. Noble et al . (2003a) compare the bacterial indicators (total coliforms, faecal and enterococci) of water quality for ocean water used in leisure activities. Same year, Noble et al . (2003b) make another comparison of measurement methods for bacterial indicators of water quality in oceanic water from seashore zone. Many studies were also carried out in our country, pursuing the same task: Millea et al. , 1993; Papp and Fodorpataki, 2002 ; Ştef et al. , 2005; Muntean et al. , 2008, 2010; Szöke-  Nagy şi Muntean, 2011. The present study aimed to detect the presence of microorganisms used as faecal pollution indicators in the water from the treatment plant in Bistriţa . We also aimed to appreciate the level of some physico-chemical parameters (organic matter, O 2 , pH and conductivity) at the same treatment plant. Materials and Methods The microbiological analyses were carried out seasonally, five consecutively days, as follows: July 2009, October 2009, January 2010 and April 2010. The three sampling sites were appointed as follows: P1  –   entrance in the treatment plant, P2  –   clarifying tank, P3  –   filters. The number of coliform bacteria was determined the according to the STAS 3001-91 , using the McCrady matrix (Cuşa, 1966).  We also measured the following physico-chemical parameters: pH, conductivity, organic matter and concentration of dissolved O 2 . The measurements were carried out on the same days as the microbiological ones, but only at the P1 and the P3 sampling sites.     Microbiological and physico-chemical analyses   on the water from the treatment plant Bistriţa   37 Results and Discussions Figs. 1-3 present the seasonal variation of the number of total coliforms, faecal coliforms and faecal enterococci in the three sampling sites. As one can see, the total coliforms were present at every sampling site, each season. The faecal coliforms missed once (second day, in winter), and the faecal enterococci missed 8 times from a total of 20 samples analysed. Fig. 1.  The number of total coliforms (logarithmic expression). Fig. 2.  The number of faecal coliforms (logarithmic expression). 110100100010000100000 Day and sampling site    G  e  r  m  s   /   1   0   0  m   l Summer Autumn Winter SpringEntrance Clarifying tank Filters 110100100010000100000 Day and sampling site    G  e  r  m  s   /   1   0   0  m   l Summer Autumn Winter SpringEntrance Clarifying tank  Filters  38  I . LEHACI, V. MUNTEAN, Alexandrina SABIE, Mariana BUDECAN Fig. 3.  The number of faecal enterococci (logarithmic expression). The total coliforms were always present in the highest number, ant the faecal enterococci in the lowest one. The highest numbers of germs were registered always at the entrance (P1) sampling site, as follows: total coliforms (53000 germs/100 ml water), in summer, the fifth day; faecal coliforms (35000 germs/100 ml) in autumn, the second and the fourth day; faecal enterococci (130 germs/100 ml) in autumn, the second day. The decrease of number of all the germs in order entrance (P1) > clarifying tank (P2) > filters (P3) is also obvious. This is the most important observation and its s ignificance is that the water treatment plant in Bistriţa has a good efficiency in reducing the number of the faecal contaminants. Based on the mean values, calculated from the 5 monthly analyses carried out each season, one can observe the seasonal evolution of the three bacterial groups analysed (Fig. 4). Autumn seems to be the season with the highest charge of water in coliforms. As one can expect, the lowest number of germs is registered in winter, with one exception: at filters, the faecal enterococci register the lowest mean values in summer, and the highest one in winter. Results of the physico-chemical parameters are presented in Figs. 5-8. It is obvious the difference between the entrance and the emergence of the treatment plant, as regard the organic matter content and the pH. The content of the organic matter in water decreases in the treatment plant 2.1 (summer, first day)  –   6.5 times (autumn, fifth day). This is also a parameter which sustain the good efficiency of the treatment plant. The pH values also decrease, remaining slight alkaline: the highest value of the pH at entrance  –   8.3 (summer, fourth day) and the lowest value of the pH at 1101001000 Day and sampling site    G  e  r  m  s   /   1   0   0  m   l Summer Autumn Winter SpringEntrance Clarifying tank Filters     Microbiological and physico-chemical analyses   on the water from the treatment plant Bistriţa   39 emergence  –   7.1 (winter, second day). The content of organic matter in water is higher in summer and in autumn. Higher values of pH were also noticed in autumn. Fig. 4. The Seasonal evolution of the number of coliforms (mean values; logarithmic expression). The oxygen content of water does not change significantly during the passage of the treatment plant: sometimes slightly increases and other times slightly decreases. The conductivity slightly increases in all the cases: the highest value at emergence  –    299 μS/cm (spring, second day) and the lowest one at entrance –   156 μS/cm (summer, fifth day). No signif  icant seasonal variation is noticed as regard the pH and the conductivity. Fig. 5.  The organic content of water. 110100100010000100000      J    u     l    y     O    c     t    o     b    e    r     J    a    n    u    a    r    y     A    p    r     i     l     J    u     l    y     O    c     t    o     b    e    r     J    a    n    u    a    r    y     A    p    r     i     l     J    u     l    y     O    c     t    o     b    e    r     J    a    n    u    a    r    y     A    p    r     i     l Month and sampling site    G  e  r  m  s   /   1   0   0  m   l Toatal coliforms Faecal coliforms Faecal enterococciEntrance Clarifying tank  Filters 024681012    O  r  g  a  n   i  c  m  a   t   t  e  r   (  m  g   /   l I II III IV V I II III IV V I II III IV V I II III IV VEntrance Emergence July October January April
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