1) Ion exchange removes negative ions or arsenate (H3AsO4- or HAsO42- or AsO43-). This is similar to conventional water softening except for the charge on the ions.
2) Microfiltration removes arsenic by a membrane with micron-sized holes using embedded ferrous hydroxide.
3) A third method uses activated alumina to attract arsenic.
4) Nano-sized beads remove arsenic. (bottom picture) The beads are iron-infused because arsenic is attracted to iron.
5) A small packet of chemicals can purify 10 liters of water. (right picture)