In　this　paper　the　Mannich　reaction　product　of　dimethylamine,　acetone　and　formaldehyde　was　grafted　onto　hydroxymethylated　lignin　to　form　a　lignin-base　cationic　polyelectrolyte　(L-DAF).　L-DAF　samples　with　different　cationic　strengths　and　molecular　weights　were　synthesized　and　characterized.　Their　performance　as　a　cationic　flocculant　in　removing　three　anionic　azo-dyes　(Acid　Black,　Reactive　Red　and　Direct　Red)　from　simulated　dye　wastewater　was　evaluated.　The　removal　of　anionic　dyes　by　L-DAF　was　ascribed　to　two　simultaneous　mechanisms,　which　included　coagulation　by　charge　neutralization　and　flocculation　by　bridging.　There　was　a　different　optimum　dose　of　flocculant　for　each　dye　wastewater,　at　which　dye　removal　can　reach　above　95%.　Furthermore,　a　longer　settling　time　and　a　lower　solution　pH　increased　the　efficiency　of　the　decolorization　process.　During　the　treatment,　more　than　89%　of　chemical　oxygen　demand　(COD)　reduction　was　achieved　with　sludge　production　being　less　than　5.4%.　©　2010　Elsevier　Ltd.　All　rights　reserved.