SEMBIRING, H. .; BR KARO, M. . Test the Capability of the Down Flow-Up Flow Combination Filter Rate Lead (PB), Iron (FE) and Manganese (MN) which are Contained on Water Well Drill Public Residential Still Village Ndokum Siroga I Subdistrict Intersection Four Regency Karo . International Journal of Membrane Science and Technology, v. 10, n. 3, p. 2348-2354, 15 Sep. 2023.