Treatment of Textile Wastewater by Coagulation–Flocculation Process Using Gossypium herbaceum and Polyaniline Coagulants

The present study is carried out to evaluate the performance efficiency of biopolymeric and synthetic polymeric coagulants for the removal of color, chemical oxygen demand (COD), and turbidity from textile industrial wastewater. Shells of Gossypium herbaceum (GHC), a bio‐polymeric coagulant from bio‐waste, and polyaniline coagulants (PAC) (a synthetic polymeric) are chosen for the present study. A Box‐Behnken design (BBD) is employed for the optimization of the effects of the four process variables, such as pH, coagulation dose, contact time, and agitation speed, on the removal of color, COD, and turbidity of the wastewater. Fourier‐transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) are carried out to understand the functional characteristics and surface morphology of the coagulants. The maximum removal of color, COD, and turbidity with GHC is found to be 90.13, 72.96, and 85.48%, respectively, at pH 5.5, coagulant dose 2.2 g L −1 , and contact time 35 min, while the maximum removal of color, COD, and turbidity with PAC is found to be 94.38, 91.45, and 89.36%, respectively, at pH 8.0, coagulant dose 1.6 g L −1 , and contact time 35 min. The experimental results show that pH and coagulant dose influence the treatment efficiency of GHC and PAC. From the experimental observations, it is concluded that the performance of the biopolymeric coagulant is highly compatible in the treatment of textile industrial wastewater.