ABSTRACT
One of the industries studied dyed spools of yarn by introducing the dye in a solution under pressure and high temperature. After equilibrium was reached, the spools were removed and the solution was discharged to the municipal wastewater plant. Since this created problems for the municipality, they required pretreatment for color removal. Each coagulant has an optimum isoelectric point for a given dye which must be determined experimentally. Treatability studies were conducted to determine if the colors of two textile wastes could be destroyed by oxidation or removed by coagulation since the literature indicated that either might be effective. The dyes from each of the manufacturers reacted quite similarly to the addition of ferric chloride, and the dye remained in a precipitated form that would settle out at the wastewater treatment plant. The industry's wastewater required the addition of alkalinity after the ferric chloride was added to achieve a good flocculation of the color.
