You need a very dilute ...
Published by LOKESH PUNJ, A B.TECH. Agr Engg, PGDM-SPA IIMA (1977-9) 25 yrs in Water Piping / Irrigation/Infra Projects
You need a very dilute Sulphuric acid , and sodium/ calcium sulphate...Once metal sulphates get formed then, add Lime to do flocculation and filter out precipitated sulphate salts..