الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Water quality and safety is an important aspect of public health. Water is the basic requirement of almost all living organisms, it should be fully treated before being supplied to consumers through the distribution system. Water related diseases caused by insufficient safe water supplies coupled with poor sanitation and hygiene can be contaminated with different types of pathogens. But as a matter of fact, it is not possible to test all kind of pathogens in water samples; scientist choose to monitor water quality by measuring biological and microbiological parameters. Microbiological parameters are indicator bacteria such as coliforms, and E.coli. Biological indicators of water quality include algae specially Cyanobacteria.
Household water filters serve to render water cleaner, it has many types and it can be a combination of 2 or more type of filters, and can act in three different ways. A water filter can be a physical barrier to debris and other undesirable water components, a chemical processes upon the water so that minerals and other compounds are precipitated out and easily removed, and a biological barrier as it remove bacteria, algae, etc.
This cross sectional study was carried out during a 5-months period. It was carried out on a total of 340 drinking water samples; 170 were collected from municipal drinking water (58 samples from tap water, and 112 samples from roof tanks), and the other 170 samples were collected from filter devices (68 samples from 3 stages (ACF) water filter, and 102 samples from 7 stages (RO) water filter). These samples were collected randomly from houses of 4 different districts in Alexandria city, Egypt.
The present study aimed to assess the effect of 2 types of household water filters (3 and 7 stages water filters) on biological and microbiological quality of drinking water, and to compare the results with national and international standards for drinking water. All municipal and filtered samples were tested according to the Standard Methods for the Examination of Water and Wastewater by enumeration of THPC and detection of TC, E.coli, and FS. In addition all water samples were examined for the biological parameters (total algal count and Cyanobacteria).
Summary, Conclusion & Recommendations
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Results of this study showed a significant difference between tap water samples and roof tank water samples regarding the THPC and TC (p=0.02, p= 0.03 respectively), while there was no significant difference between them regarding the biological parameters.
Filter 3 and 7 stages showed no significant difference between them regarding the bacteriological and biological parameters, but there was a significant difference between municipal drinking water samples (tap water-roof tanks) and with both 3 and 7 stages filters samples concerning the THPC, and total algal count (p=0.00). Also significant difference was detected between municipal drinking samples (tap water-roof tanks) and 7 stages filter concerning TC (p= 0.00). E.coli was detected in 8 (5%) municipal drinking water samples, while it was detected in 1 (1.5%) samples of 3 stages filter and 1 (≈1%) in 7 stages filter samples. FS was not detected in all municipal and filtered drinking water samples.
According to the Egyptian drinking water quality standards it was revealed that the highest percentage of the unacceptable water samples as it contained each of THPC >50 CFU/ml, TC and E.coli; was from roof tank (35%), followed by tap water samples (32%), then (10%) of 3 stages water filter and (4%) from 7 stages water filter. According to the EPA and WHO the highest percentage of the unacceptable water samples that detected TC and E.coli was from roof tank (15%), followed by tap water (7%), (6%) from 3 stages filter, and (4%) from 7 stages filter.
According to the Egyptian drinking water quality standards the highest percentage of unacceptable tap water sample was from Western district (100%), followed by El-Montazah Awal (35%) then Eastern district (25%). While the highest percentage of unacceptable roof tank water samples were from Western district (100%), followed by Eastern district (40%), then (32%) from El-Montazah Awal district and (24%) from Central district. On the other hand the highest unacceptable percentage from 7 stages filter was from El-Montazah Awal district (8%), followed by Central district (6%), then Eastern district (2%) and (0%) from Western district. While the highest unacceptable percentage from 3 stages filter was from Western (25%), followed by Central district (11%), then El-Montazah Awal district (10%) and (8%) from Eastern district.
The frequency of isolation of the indicator organism (TC and E.coli) was higher in water samples from 3 stages (42%, and 14% respectively) and 7 stages water filters (11% and 5% respectively) when filter was installed >18 months while there was no indicator organism (TC and E.coli) in water samples from 7 stages filter and E.coli from 3 stages water filter when filter was installed 0->6 months. TC and E.coli were detected in 3 stages (22%, and 4% respectively) and 7 stages (9% and 3% respectively) water filters when there was no proper maintenance according to manufacturer’s instructions.
Four types of algae were detected in municipal and filtered water samples (Green-algae, Cyanobacteria (blue-green algae), and Diatoms). Green algae different genera (Coelastrum, Phytoconis, and Scenedesmus) were detected in 64% and 60% from samples respectively, followed by Cyanobacteria different genera (Anacystis, Gomphospheria, Oscillatroia, and Anabaena) were detected in 17% and 14% respectively, while Diatoms 2 genera (Asteronilla, and Cyclotella) were detected in 8% and 7% respectively from tap water and roof tank samples.
Those figures were much reduced after filtration with 3 and 7 stages water filters where 2 genera of Green algae (Coelastrum and Phytoconis) were detected in 14% and 7 % respectively, 2 genera of Cyanobacteria (Anacystis and Anabaena) were detected in 3% and 0.98% respectively, and one Diatoms genera (Asteronilla) were detected in 1.4% only in 3 stages filter samples.
The use of 7 stages filter was associated with high percentage reduction in THPC, TC, Cyanobacteria and total algal count (63%, 89%, -97%, and -99% respectively) compared to 3 stages filter (60%, 80%, -93%, and -95% respectively) with no significant difference.