This study examined the combined use of chitosan and sodium alginate in the treatment of wastewater containing heavy-metal ions and dye. Wastewater samples were divided into two equal parts before chitosan and sodium alginate solutions were added to each part. When these two solutions were mixed together, the heavy-metal ions and dye molecules were separated from the water as the positively charged chitosan and the negatively charged sodium alginate precipitated each other. The effects of the concentration and ratio of chitosan and sodium alginate, the treatment temperature, and the time on the efficiency of metal-ion and dye removal were investigated. The results showed that when used in combination, sodium alginate and chitosan were effective in removing copper, cadmium, lead, and silver ions as well as acid dye molecules (c) 2007 Wiley Periodicals, Inc.