The　backwashing　residuals　from　iron　and　manganese　removal　biological　filter　of　underground　waters　was　made　into　granular　adsorbent　(GA)　and　magnetic　powder　adsorbent　(MPA)　to　solve　the　problem　that　it　is　difficult　to　separate　the　exhausted　backwashing　sludge　powder　adsorbent　(BSPA)　and　treated　water.　The　arsenic　removal　capability　of　BSPA,　GA　and　MPA　were　compared.　And　their　structure　and　surface　feature　were　compared　by　SEM,　TED,　XRD,　BET　and　FTIR　to　find　the　cause　of　difference　in　arsenic　removal　capability　among　these　three　adsorbents.　Results　showed　that　the　maximum　As　(V)　adsorption　capacity　of　BSPA,　GA　and　MPA　were　40.980,　5.048　and　8.694mg/g　respectively.　As　it　suggested,　the　As　(V)　adsorption　capacity　of　GA　and　MPA　decreased　compared　to　BSPA.　BSPA　was　a　mixture　with　amorphous　structure,　lepidocrocite　was　the　main　ingredient,　goethite　and　poor　crystallized　ferrihydrite　also　mixed　in　it.　The　XRD　spectrum　of　GA　appeared　crystal　diffraction　peaks　of　quartz　crystal　and　a　small　amount　of　hematite,　while　the　main　component　of　MPA　was　maghemite　with　high　crystallinity.　There　are　hydroxyl　functional　groups　that　are　conducive　to　adsorption　in　all　three　materials.　The　specific　surface　areas　of　BSPA,　MPA　and　GA　were　253.150,　238.660　and　43.803m2/g　respectively.　Phase　changes　and　increase　of　crystallinity,　reduction　of　surface　hydroxyl　group　and　decrease　of　specific　surface　area　may　be　the　main　factors　lower　the　adsorption　capacity　of　GA　and　MPA　compared　with　BSPA.　©　2018,　Editorial　Board　of　China　Environmental　Science.　All　right　reserved.