Sembiring, H. ., and M. . Br Karo. “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, vol. 10, no. 3, Sept. 2023, pp. 2348-54, doi:10.15379/ijmst.v10i3.1962.