الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
This study is performed in order to establish whether Peracetic acid (PAA) could possibly be used in drinking water disinfection, identify the advantages and disadvantages of PAA as a primary disinfectant and its effect on drinking water properties, product by-products and cost compared to chlorine as a primary disinfectant.
The applied PAA doses (Dose1, Dose2 and Dose 3) was applied with the same dose as optimum chlorine dose as well as with doses below and above optimum dose over the different months to identify the optimum dose of PAA in consideration to all physical, chemical and microbiological analyses and the removal efficiencies were calculated as well as the by-products resulting from used chlorine in raw water and its economic cost.
Results of the present study can be summarized as the following achievements:
A. There was no temperature and EC limits in the Egyptian Code (Law), but results showed almost the same ranges before and after treatment.
B. For the pH levels, both raw and treated drinking water with different doses of PAA showed levels within the permissible range and were compatible with regulation along the study period.
C. The highest R% of the TBC (99.7 %) was recorded by Dose 2 reaching residual density of 4 CFU/ml that is much lower than its MPL (50.0 CFU/ml) .
D. The highest R% of the TC (> 99.7 %) was recorded by Dose 1,2 and 3 reaching residual density < 18 MPN/ 100 ml.
E. The highest R% of the TAC (98.9%) was recorded by Dose2 reaching residual density of 35 U/ml that is slightly higher than its MPL (0.0 U/ml) .
F. The highest R% of the NH3 (89.6%) was recorded by Dose 3 reaching residual concentration of 0.25 mg/l that is much lower than its MPL (0.5 mg/l) and much higher than the R% of NH3 (75%) obtained by traditional Prechlorination, reaching residual concentration (0.6 mg/l) that is higher than MPL.
G. The highest R% of the COD (75.0%) was recorded by Dose 2 reaching residual concentration of 15 mg/l , which has no limits in the Egyptian Code (Law),.
H. The highest residual concentration of the THMs (50 µg/l) was recorded by Dose 1 that is much lower than its MPL (100 µg/l) while residual concentration (112 µg/l) obtained by traditional treatment, which higher than the MPL.
I. The highest residual concentration of the DCA (37 µg/l) was recorded by Dose 1 that is much lower than its MPL (50 µg/l) while residual concentration (48 µg/l) obtained by traditional treatment, but still lower than the MPL.
J. The highest residual concentration of the TCA (46 µg/l) was recorded by Dose 1 that is much lower than its MPL (50 µg/l) while residual concentration (46 µg/l) obtained by traditional treatment, but still lower than the MPL.
In conclusion, The PAA treatment could bring the NH3, COD, TBC and TC to levels lower than their MPLs according to the Egyptian Code for drinking water. Moreover, pH, temperature and EC in the prechlorinated and PAA water are within the permissible limits. Concerning total algal count that was slightly higher than its MPL could be over-come, by increasing contact time with the PAA.
5.2. Conclusion
This study is performed in order to establish whether Peracetic acid (PAA) could possibly be used in drinking water disinfection, identify the advantages and disadvantages of PAA as a primary disinfectant and its effect on drinking water properties, product by-products and cost compared to chlorine as a primary disinfectant.
Generally the sudy concluded that:
1. Using the proposed PAA as predisinfectant is remarkably efficient since it minimizes the health risks posed by chlorine disinfection by- products (DBP’s), and in general minimizing costs of the entire production process.
2. PAA treatment showed many advantages in the removal of the included contaminants (NH3,COD, TBC and TC), compared to the traditional treatment.
3. The unique properties of PAA as antimicrobial agent has confirmed its superiority for disinfection of raw drinking water and purification of all the tested parameters in a very short time.
4. Moreover, pH, temperature and EC in the prechlorinated and PAA treatment are not affected by the proposed treatment system and still within the permissible limits.
5. THMs, DCA and TCA in treated water were lower than MPL,compared to the traditional treatment .
6. Total algal count (TAC) that was slightly higher than its MPL can be solved, by increasing contact time with the PAA.
7. The future for PAA in drinking water purification looks very promising by its own, not only for removal of microorganisms but may be for other contaminants as well.
5.3 Recommendations
The achieved results recommend the following points:
1. The PAA has attracted growing attention as an alternative oxidant and disinfectant
2. PAA can replace chlorine in the disinfection process , in case of lack of chlorine.
3. PAA can add with chlorine as predisinfectant to minimize adding of alum., to minimize disinfectant byproducts to protect the public health.
4. Further studies
Study the effect of mixing between Cl2 &PAA with different dose as a predisinfectant.