Current　work　is　exploring　the　feasibility　of　using　potassium　manganate　(K2MnO4)　in　drinking　water　treatment.　The　manganate　species　(MnO42-)　can　act　as　both　an　oxidant　and　a　coagulant/adsorbent　arising　from　the　formation　of　insoluble　manganese　dioxide　from　the　chemical　reduction　of　Mn(VI)　to　Mn(IV).　Extensive　tests　have　been　undertaken　to　investigate　the　treatability　of　humic　acids　by　manganate,　with　and　without　the　co-addition　of　ferrous　sulphate.　In　these　tests　solutions　of　commercial　humic　acid　(HA)　have　been　reacted　at　varying　concentrations　of　K2MnO4　and　FeSO4　and　pH.　A　high　degree　of　HA　removal　has　been　demonstrated,　particularly　at　low　pH　(pH　5),　as　expected　from　conventional　theories　of　charge　interaction　and　solid　phase　adsorption.　In　attempting　to　understand　the　mechanisms　of　HA　reaction　and　separation　by　manganate,　given　the　heterogeneous　nature　of　HA,　laboratory　tests　have　been　undertaken　also　with　resorcinol　as　a　model　compound　of　HA.　Since　manganate　disproportionates　during　its　aqueous　reaction　to　permanganate　and　MnO2,　the　comparative　reactivity　and　separation　of　resorcinol　by　manganate　(Mn(VI))　and　permanganate　(Mn(VII))　have　been　considered.　During　the　chemical　reduction　of　potassium　manganate　and　potassium　permanganate　insoluble　manganese　dioxide　(Mn(IV))　is　produced　which　can　adsorb　un-reacted　resorcinol　and　reaction　products.　The　adsorption　of　resorcinol　by　MnO2　was　studied　by　pre-forming　MnO2　by　the　reaction　of　the　Mn(VI)　and　Mn(VII)　with　sodium　thiosulphate,　prior　to　the　addition　of　the　resorcinol.　The　results　at　pH　5　have　shown　that　resorcinol　can　be　removed　to　a　moderate　degree　by　MnO2　adsorption.　In　reaction　with　both　Mn　oxidants,　the　ratio　of　oxidant　to　resorcinol　had　a　significant　effect　on　compound　removal,　with　the　removal　increasing　substantially　at　higher　ratios　of　oxidant　to　resorcinol.　During　the　chemical　oxidation　and　MnO2　adsorption　experiments　with　the　two　Mn　oxidants,　varying　the　respective　periods　of　oxidation　and　adsorption　had　only　a　moderate　effect　on　the　compound　removal　efficiency.　Comparatively,　the　treatment　performance　of　potassium　manganate　was　superior　to　that　of　potassium　permanganate.　(C)　2011　Elsevier　B.V.　All　rights　reserved.