Coagulation/flocculation of textile effluent using a natural coagulant extracted from Dillenia indica

Abstract

The aim of this study was to assess the efficiency of mucilage extracted from the fruit of Dillenia indica for enhancing coagulation in the treatment of textile effluent. The mucilage extraction was carried out in water at room temperature. The pH, concentration of coagulant FeCl3.6H2O, and concentration of mucilage solution were optimized with star-type central composite design (CCD). We were able to analyze the synergistic effects between the FeCl3.6H2O and mucilage concentrations: the process of coagulation/flocculation (CF) for chemical oxygen demand (COD) removal was more efficient at a low chemical coagulant concentration (8.00 mg L-1) and a higher natural coagulant (NC) concentration (15.00 mgL-1). This demonstrated the potential of this mucilage to treat textile effluents, with 67.66%% COD removal, 96.86% turbidity removal and 91.12% apparent color reduction. The characterization of the mucilage of Dillenia indica was done using Fourier transform infrared spectroscopy (FTIR) and solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13C NMR), and the signals obtained indicated the presence of polysaccharides, which are responsible for enhancing the CF process.