الفهرس 
Introduction
AIM OF THE WORKOnly 14 pages are availabe for public view
 |  | from | 197 |  |  |
| | | from | 197 | | |
Abstract
The bactericidal efficiency of AgNP was evaluated against TBC, TC and FS of water samples collected from surface water, ground water as well as the fish farms water. Silver nanoparticles were synthesized in a typical one-step synthesis protocol through chemical reduction of silver nitrate by soluble starch. Silver nanoparticles were characterized using Transmission Electron Microscopy (size) and Atomic absorption spectrophotometer (concentration), the bactericidal efficiency of AgNP was evaluated by application of it in three concentrations 0.1, 0.05 and 0.01 ppm to each water sample, each concentration allowed to interact with bacterial communities of the water for several contact times, namely 5 min. 15 min., 30 min., 1 h. and 2 hrs, then the bactericidal efficiency of AgNPs was determined by comparing the counting of target organisms before and after treatment for each sample.
The bacteriological quality of water was evaluated using pour plate technique for TBC, Most Probable Number for TC and FS, furthermore some physico-chemical parameters of water such as water temperature, pH, Hardness and organic matter (NOM) were evaluated,
The results obtained in this study revealed that:
I- Effect of silver nanoparticles on bacterial contaminants of water
1- Effect of silver nanoparticles on TBC
The results showed that in the Surface water, the highest bacterial inhibitions were at the highest concentration of AgNP (0.1 ppm) at maximum time used (2 hrs), followed by 0.05 ppm, while the 0.01 ppm showed the lowest bacterial inhibition, where at 0.1 ppm, the mean of total viable bacteria was reduced from 917.65 ±114.80 to 74.76 ±16.66, followed by 0.05 ppm after 2 hrs contact time (81.50 ±15.59 ); 0.1 ppm after 1 h. (105.16 ±16.16) and then 0.05 after 1 h. (147.77 ±20.63) and their inhibition was 91.85 %, 89.14, 88.54 % and 80.30 % respectively. Moreover, in Ground water, the lowest mean of TBC was at 0.1 ppm of AgNP after 2 hrs contact time (40.63 ± 13.72) followed by 0.1 ppm after 1 h. contact time (56.98 ± 13.26); 0.05 ppm after 2 hrs (60.85 ± 17.75) and then 0.1 after 30 min. (106.23 ± 37.64), furthermore the highest concentration (0.1 ppm) exhibited highest antibacterial activity against Total viable bacteria (TVB) and its efficiency reached to 92.33%, 89.25 % after 2 hrs and 1 h. contact times, respectively and these percentage of TBC inhibition was greater than the other 2 concentrations at the same times (85.23 % for 0.05 ppm and 53.17 % for 0.01 ppm at 2 hrs). In Fish farms water the results showed that the lowest mean of TBC was after applications of 0.1 ppm of AgNP after 2 hrs contact time (1519.61 ± 416.57) followed by 0.05 ppm after 2h (2034.21 ± 566.34) and 0.1 ppm after 1 h. contact time (2339.49 ± 706.29). Furthermore, our results showed that the highest concentration produced highest antibacterial activity against TBC and its efficiency reached to 85.33 %, 77.41% and 74.23 % after 2 hrs, 1 h. and 30 min. contact times, respectively and these percentage of TBC inhibition was greater than the other 2 concentrations at the same times (71.93 %, 67.50 % for 0.05 ppm at 2 hrs and 1 h., respectively and 62.19 %, 60.84% for 0.01 ppm at 2 hrs and 1 h., respectively).
Our results showed that the highest concentration of Ag nano particle exhibited highest bactericidal efficiency against TBC, where after 2hours contact time, 0.1, 0.05 and 0.01 mg/L Ag nano particle was sufficient to inhibit (91.85 %, 89.14 % and 74.92 %); (92.33 % , 85.23 % and 53.17 %) and (85.33 %, 71.93 % and 62.19 %) of TBC in surface water, ground water and fish farms water, respectively.
2- Effect of Ag nano particle Total Coliform (TC)
The results showed that in surface water samples, the lowest mean of TC was at 0.1 ppm of AgNP after 2 hrs contact time (0.63 ± 0.36) followed by 0.05 ppm after 2 hrs contact time (4.88± 3.86); 0.1 ppm after 1 h. (9.52 ± 4.93) and then at 0.05 ppm after 1 h. (13.25 ± 6.43), moreover when the time was increased to 2hours, 0.1, 0.05 and 0.01 mg/L Ag nano particle was sufficient to inhibit 99.88 %, 98.86 % and 93.78% of bacterial growth, respectively. Moreover, in Ground water samples, the results showed that the lowest mean of TCC was at 0.1 ppm of AgNP after 2 hrs and 1 h. contact times (2.47 ± 0.92 and 13.79 ± 6.43, respectively). Moreover, the inhibition efficiency of the highest concentration (0.1 ppm) reached to 95.54 % and 99.20 % after 1 h. and 2 hrs contact times, respectively and that percentage inhibition was greater than the other 2 concentrations at the same times (84.04 %% for 0.05 ppm and 64.82 %% for 0.01 ppm at 2 hrs). In fish farms water samples, the results showed that the lowest mean of TCC was at 0.1 ppm of AgNP after 2 hrs contact time (144.21 ± 99.94). Moreover, the highest concentration caused the highest antibacterial activity its efficiency reached to 92.48 % and their percentage of TC inhibition was higher than the other 2 concentrations at the same times (58.34 %for 0.05 ppm and 31.01 %for 0.01 ppm at 2 hrs).
3- Effect of silver nanoparticles on Faecal streptococcus (FS)
The results showed that in surface water samples, the lowest mean of FS was at 0.1 ppm (16.79 ± 10.43), 0.05 ppm (17.13 ± 10.41) and 0.01 ppm (17.13 ± 9.92) after 2 hrs contact time. Furthermore, the highest concentration (0.1 ppm) resulted in 91.68 % and 86.14% inhibition of FS after 2hs and 1 h. respectively, in addition to 84.25% and 84.44 % inhibition of FS at 0.05ppm, while 0.01 ppm caused 82.02% and 77.21% inhibition after 2hs and 1 h., respectively. Moreover, in ground water samples, our obtained results revealed that the lowest mean of FS was 0.1 ppm of AgNP after 2 hrs contact time (0.5 ± 0.28) followed by 0.05 ppm after 2hr contact time (1.33 ± 0.36). Moreover, the results revealed that the highest concentration (0.1 ppm) resulted in the highest antibacterial activity against FS and its efficiency reached to 98.02 % followed by 0.05 ppm, which resulted in 91.62 % inhibition of FS after 2 hrs. While in fish farm water samples, the results illustrated that the lowest mean of FS was the mean of 0.1 ppm of AgNP after 2 hrs contact time (155.50 ± 60.86) followed by 0.1 ppm after 1 h. contact time (212.46 ± 97.46). Moreover, the highest concentration (0.1 ppm) produced highest antibacterial activity against FS and its efficiency reached to 90.48 % followed by 0.05 ppm, which resulted in 87.82 % inhibition of FS after 2 hrs, furthermore the percentage of FS inhibition at 0.1 ppm was higher than the other 2 concentrations at the same times (87.82 % for 0.05 ppm and 31.41 % for 0.01 ppm at 2 hrs), the mean value of 0.1 ppm at 1 h. (87.00%) nearly equal in their inhibition to 0.05 at 2 hrs (87.82%), while the inhibition of 0.1 at 5 min.. (58.56%) was higher than 0.01 at 2 hrs (31.41) contact time.
II- Physico-chemical quality of water
The results of physico-chemical parameters of water showed that, the mean values of water temperatures and pH were (15.08, 25.73 and 23.72) and (8.49, 7.75 and 7.92) for fish farms water, surface water and ground water, respectively, moreover the mean values of water hardness and COD were (295.41, 124.63 and 218.48) and (330.81, 24.81 and 17.95) for the same water sources, respectively.
The results revealed that there were significant positive correlations between water pH, hardness, COD and TBC, TC, FS count this means that when water pH, hardness, COD increased there were increases in the bacterial count (decreased AgNP efficiency), while there were significant negative correlations between water temperature and TBC, TC, FS, this means that when the water temperature increased there was decrease in the bacterial count (increased AgNP efficiency) and vice versa.