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Egypt suffers from water scarcity. In water treatment plants using sand filters, a significant amount of treated water is consumed, estimated at 10%–15% of the filtered water during backwashing. The objective of this study is to determine the most effective way to reduce the amount of treated water used for backwashing. The methodology of this study was to evaluate the effects of air and water rates, treated water turbidity of 1.6 NTU or slightly higher synthetic turbidity of 4.0 NTU, and media type with single or dual media on reducing treated water consumption during rapid sand filter backwashing procedures. The experimental set up was a bench-scale filter operated at a filtration rate of 189 m3/m2/day. Backwashing with the right water and air rates reduce water usage by 18%, enhanced process performance, and reduced the ripening period. Backwashing using synthetic turbid water recovered 100% of the treated water and improved the ripening duration without affecting backwashing efficiency. This study concluded that backwashing the dual media filter with silica sand and activated carbon achieved the highest treated backwash water consumption by approximately 60%. While anthracite coal was utilized as a dual-media filter, the least reduction in treated water consumption was discovered. [ABSTRACT FROM AUTHOR]

Background: The Nile River included diverse phytoplankton compositions belonging to five main phytoplankton categories. Algae have been classified and identified through comparative morphology. Results: The Pyrrophyta, Charophyta, Cyanophyta, Chlorophyta, and Bacillariophyta were presented through the full period of investigation with 1, 3, 14, 23, and 28 species, respectively. Therefore, it may be important to note that diatoms were recorded as an abundant group in all investigated samples. The numbers of diatoms ranged between 1.45 × 106 and 1.18 × 107 Organism/l, this was followed by green algae that ranged from 7.0 × 105 to 1.22 × 106 Organism/l. While the lowest count of blue-green algae was ranged between 1.6 × 105 and 7.03 × 105 Organism/l. The treatment of Nile water using two chemical coagulants "aluminum sulfate (Al2(SO4)3⋅16H2O) and aluminum oxide (Al2O3)" removed algae by about 85% and 90%, respectively. As for, the Cyanophyceae species, they were removed completely in treated water using the sedimentation, filtration, and chlorination process. The sedimentation basins removed from 20 to 100% of the total algal count while the rapid sand filters removed from 65 to 100% of the total algal count during the water treatment that depends on the species of algae. Conclusions: This study concluded that the removal of algae from the Nile water may be more or less easy depending on the nature of the prevailing algal group. Water treatment plants must modify alum and chlorine doses in their water treatment processes according to the count and species of the algal groups, to provide an aesthetically acceptable and biologically safe water supply. [ABSTRACT FROM AUTHOR]

This work aims to study the technical problems of algal blooms that hinder the purification process of surface water used for drinking purposes and not its harmful effect on human health and the surrounding environment. It is also related to the demonstration of the improved coagulation process as an efficient technique in the algal removal from surface water by its application in jar tests. The study was carried out in the water purification plant in Nazlet Abdellah near the city of Assiut, Egypt. To achieve that, many ores and natural materials which aid in the removing of the algal blooms from surface water during the purification processes were tested. The examined materials should be technically and economically proper for improving the removal of algae from treated surface water for drinking purposes. The results showed that the kaolinite and bentonite (K and B) when coupled separately with aluminum sulfate (alum.) (the main coagulant agent) associated with the raw surface water in the flocculation basin were more efficient in the algae removal from treated surface water before reaching the sand filters by ratio up to 90%. [ABSTRACT FROM AUTHOR]

In an attempt to improve the quality of the agricultural drain in Egypt for its reuse again in the irrigation, low-cost solution such as sand filter along with/without other filtration media has been used in this research. As a result of that, pilot plant of sand filter mixed with other filtration media was tested for its ability to improve the sand performance in removing the suspended solids and organic matters from agricultural drain water of the Belbeis drain (in Sharkia governorate in Egypt). Sand only, sand mixed with sponge, sand mixed with activated carbon and sand mixed with ceramic cylinders have been tested to find the best media combination and optimum mixing sand/ medium ratio and optimum infiltration rate. The work has been done on four runs. It was found that sand mixed with ceramic cylinders gave the best removal efficiency with respect to total chemical oxygen demand and chemical oxygen demand for solution which were 77, 74%, respectively, whereas sand mixed with sponge had the best removal efficiency with respect to total suspended solids which was 89%. Also, all tested media combination had effluent quality that complied with Egyptian law 48 for the year 1982 regarding the disposal of wastewater into agricultural drains (chemical oxygen demand ≤ 80 mg/l, total suspended solids ≤ 50 mg/l). [ABSTRACT FROM AUTHOR]

The Kafr El-Sheikh Water Plants in Egypt, which are treating River Nile water, are confronted with high consumption of water for backwashing the rapid sand filters and elevated levels of turbidity in the effluent of the clarifiers and sand filters. It turned out that these problems are connected with the formation of foam layers in the clarifiers. The appearance of foam layers is attributed to the formation of tiny “air bubbles” in the water entering the clarifiers, resulting in the flotation of the sludge particles. Tiny “air bubbles’’ are most likely formed due to supersaturation with air and/or oxygen of the raw water. Supersaturation might occur in the open channels through which the raw water travels over the long distances from the Nile to the plants. Such a supersaturation with air might be caused by increasing the temperature during the journey of the raw water and/or the growth of algae, which use to produce oxygen during day time. To mitigate the problems due to the formed sludge layers, low-cost gutters, and sprinkler devices are installed. These measures resulted in a substantial reduction of the consumption of water for backwashing the rapid sand filters and improved turbidity of the effluent of the clarifiers and filters. [ABSTRACT FROM AUTHOR]