OPTIMIZED PERFORMANCE EVALUATION OF SLOW SAND FILTER FOR SURFACE WATER: A CASE STUDY IN ENARJ ENAWUGA WATER TREATMENT PLANT

Abstract

A straightforward method for purifying water is slow sand filtration. The fundamental design characteristics of the slow sand filter and its possible uses in water treatment have not been thoroughly examined in Ethiopia, despite the fact that it is a widely recognized technique. Clogging is a slow sand filter design and operating issue that arises on this treatment plant as a result. In order to address some of the issues raised by the failure of a full-scale slow sand filter installed in Enarj Enawuga Woreda for the water treatment project, this study used design of a small-scale/model of Prototype slow sand filter treatment plant made from fiber glass material. To identify which arrangement or parameter is increase effectiveness of the system, optimization work was conducted using three containers with variations in supernatant water, free board depth and sand existing on above the supporting gravel. All optimized containers and Prototype model fulfill the WHO standards for drinking water at the end of filtration period except the parameter of TSS. Container B has a high removal efficiency within a short period. According to the filtration rate of Containers with in depth arrangement of supporting gravel with drain, filter sand, supernatant Water and freeboard respectively A(9,15,23,3), B(9,20,18,3), C(9,15,20,6), and Prototype model (9,20,18,3) of clogging time of the system 32, 27, 29 and 26 days respectively. However, to facilitate removal efficiency the Schemuzedke, which is positioned above the most effective and efficient sand, corresponding to parameters of Turbidity, Total suspended solids, and Total dissolved solids, EC and pH are lower in Container A as compared with Container B and C. High removal efficiency is typically observed in designed containers with a low supernatant water level and a high infiltration depth of effective sand due to pressure head of water above the sand. Therefore, container B was selected and applying on real prototype of Enarje Enawuga slow sand filter water treatment plant. The main reason for the clogging of the system was not the effective sand size (0.3 mm) and its uniformity coefficient (1.6). removal efficiency of prototype model orderly Turbidity, TSS, TDS, EC, and pH within the value of 92.12%, 84.82%, 62.78%, 54.55%, and 19.39%, respectively, conclude that silt accumulation occur at the outlet of the reservoir to ensure that take a water sample at the top part of raw water Storage reservoir approved that lack of preliminary treatment or intake before slow sand filter.