• List of Articles sand filter

      • Open Access Article

        1 - Investigating the effects of height, effective size and uniformity coefficient of rapid sand filters on removal of turbidity and coliform bacteria in water treatment plants of Tehran
        Mohammad Bozorgmehr Ali Torabian Amir Hesam Hasani Malihe Alinagi Noushin Osouleddini Mohammad Abdollahzadeh
        Background and objective: Drinking water supply with proper quality is one of the main goals of water treatment plants. Filtration is a process which has the largest share of quality making in water treatment plants and about 20% of the cost is allocated to this process More
        Background and objective: Drinking water supply with proper quality is one of the main goals of water treatment plants. Filtration is a process which has the largest share of quality making in water treatment plants and about 20% of the cost is allocated to this process. The main indicator used for filters efficiency is water turbidity at outlet. Methods: In this research, the effect of various heights (20-50-70-90 cm), effective sizes (0.75-1) and uniform coefficients (1-1.5) sand filter’s packing on turbidity removal and coliforms has been studied for four months from May 2010. Sampling was performed according to standard procedures and the samples were analyzed immediately in Tehran Islamic Azad University of Science Research laboratories and water treatment plant laboratory. Finding: Results of coarse packing filter show the maximum efficiency of turbidity reduction was 83.58% for turbidity of 5 NTU and packing height of 90cm. The minimum turbidity reduction was 29.25% for turbidity of 10 NTU and packing height of 20cm. The maximum coliform reduction was about 87.92% for turbidity of 2 NTU and packing height of 90cm and the minimum coliform reduction was about 38% for turbidity of 10 NTU and packing height of 20cm. The effective height which causes maximum turbidity and coliform reduction is 90cm. The longest operation time in the context of a coarse bed was 35 hours in turbidity of 2 NTU and the shortest operation time in the context of a coarse strainer was 23 hours in turbidity of 10 NTU. Conclusion: Results of fine packing filter show the maximumefficiency of turbidity reduction which was 93% for turbidity of 2 NTU and packing height of 90cm. The minimum turbidity reduction was 54.9% for turbidity of 7 NTU and packing height of 50cm. The maximum coliform reduction was about 91.92% for turbidity of 2 NTU and packing height of 90cm and the minimum coliform reduction was about 45% for turbidity of 10 NTU and packing height of 20cm. The effective height which causes maximum turbidity and coliform reduction is 90cm. According to the results, efficiency of the fine bed and coarse bed filter directly depends on outlet turbidity and operation of previous unit (sedimentation). The maximum and minimum operation times in fine bed were about 28 hours (NTU=2) and 14 hours (NTU=10) respectively. Manuscript profile
      • Open Access Article

        2 - Investigation of Functional Units and Method of Construction of Water Treatment Plants
        Fariborz Yousefvand Ramin Bayat
        Background and purpose: Purified water is one of the most important elements in the health of human societies, so trying to purify water through water treatment plants is justifiable even with high costs. Surface waters often have a greater variety of pollutants than un More
        Background and purpose: Purified water is one of the most important elements in the health of human societies, so trying to purify water through water treatment plants is justifiable even with high costs. Surface waters often have a greater variety of pollutants than underground waters, and for this reason, treatment processes may be more complicated for such waters. In water treatment plants, the purification process starts through the inlet pipe to the treatment plant and enters the urban water stream by passing through garbage collection structures, aeration, microstrainer, rapid mixing, superpulsator, sand filter and tank. Like the concentrator, the recycling tank and the contaminated mechanical dewatering are divided into two parts that can be treated and cannot be treated, and the non-degradable solids are directed out of the tank.  Research method: This article has investigated the construction method and performance of different parts of water treatment plants in an executive and scientific way by reviewing reliable scientific databases and the experiences of the authors. Findings: The performance of different parts of the treatment plant and their construction methods have been analyzed and the importance and position of each part has been discussed. Discussion and conclusion: The process of water purification from the time of entering the water treatment plant to the time of its exit was investigated in detail, including the construction method, which provides useful information for planners, designers and activists in this field Manuscript profile