Dyeing and printing wastewater treatment using fly-ash coated with chitosan

Printing and dyeing industry is a considerable source of environmental contamination. In this study treatment of printing and dyeing wastewater with a new type of sewage treatment agent, fly-ash coated with chitosan particles (FCCP), was examined. The effects of pH, stirring time, sedimentation time and temperature on color, COD, turbidity and NH₃-N removal were determined. The optimum dosage of FCCP and the influence of individual factors on removal efficiency were tested. The optimum parameters determined using the L₁₆(4⁵) orthogonal experiment were as follows: FCCP (weight ratio of chitosan to fly-ash 1:6) dosage, 4 g·L^?1; temperature, 35°C; pH, 4. The stirring time and sedimentation time were 20 min and 5 h, respectively. Under these optimum conditions, the color, COD and NH₃-N removal ratios were 97%, 80% and 75%, respectively.