Recycling of Liquid waste for effective and satisfactory Pretreatment in Cotton wet Processing

Textile industries are focusing on minimizing their production costs by using sustainable technologies and by inventing new methods. Pretreatment is the heart of textile wet processing. Most of the Textile Companies are using combined pretreatment process with exhaust and semi-continuous method. After the treatment is over, the bath with residual chemicals are drained out into effluent treatment plant. In this study, an attempt has been made to reuse the residual chemicals by replenishing the measured amounts of chemicals again for combined pretreatment process. The concentration of the main chemicals, after pretreatment, before draining was analyzed and quantified. In case of pretreatment process in a Jigger machine, the liquor is drained out after three turns (6 ends) with residual chemicals, then the concentrations of H2O2 and NaOH was assessed in that. In case of pad-roll bleaching, the fabric roll is rotated in the steaming chamber for twelve hours and washed in a counter current washing machine, then the concentration of chemicals was analyzed after washing is over. Based on the chemical analysis results, by replenishing with measured amounts of chemicals, pretreatment is done in both laboratory scales repeatedly up to four times without changing water and on the bulk production; it has been done by mixing used water and fresh water. The effectiveness of pretreatment was evaluated in terms of absorbency, whiteness, yellowness and the effect in subsequent reactive dyeing and pigment printing in terms of colour strength, colour difference and fastness properties after each pretreatment. It was observed that acceptable results which can fulfill the requirements of the products can be obtained by reusing the pretreatment bath.