Removal of Mg2+, K+, SO4-2 Ions from Seawater by Precipitation Method Caecilia Pujiastuti, Ketut Sumada, Yustina Ngatilah and Prasetyo Hadi MATEC Web of Conferences, 58 (2016) 01022 Published online: 23 May 2016 DOI: 10.1051/matecconf/20165801022