The effectiveness of local sands of Indonesian South Sulawesi as filtration material in water treatment plant

The regional water company in Sulawesi Island of Indonesia uses sand from Sumatra and Java islands to perform water filtration. However, this is time consuming and expensive. In fact, South Sulawesi Province has abundant local sand that may be used as filtration material. Therefore, the aim of this study is to determine novel alternatives for filtration materials in water treatment plants using local sand available in South Sulawesi. The proposed alternatives are implemented using four local sand sources, namely Malimpung, Bira, Jeneberang, and Tanralili in Pinrang, Bulukumba, Gowa, and Maros Regencies, respectively. The effectiveness of each sand source is analyzed by modeling a filter in the laboratory with a rapid sand filter system. The experimental work is conducted under unsaturated conditions for sand. We have considered three variations of initial raw water turbidity, namely 25, 50, and 109 NTU representing low, medium, and high turbidity levels, respectively. The initial total suspended solids (TSS) for each variation of initial turbidity is calculated as 19, 51, and 99 mg/l, respectively. In addition, we have applied three variations of filter thickness, namely 10, 20, and 30 cm. The results indicated that only Malimpung sand meets the physical requirements, namely effective size of 0.23, uniformity coefficient of 2.19, specific gravity of 2.69 g/cm(3), and percentage of SiO2 as 97.07%. It was also clarified that Malimpung sand is the most effective in removing physical pollutants based on turbidity and TSS with an efficiency of 72% and 84%, respectively, during the observation time of 600 s.