Textile Wastewater Treatment Using a Modified Coal Fly Ash as a Low-Cost Adsorbent

Direct, reactive and acid dyes are the carcinogenic dyes since they have a complex structure and difficult to extract from industrial wastewater using conventional approaches. In this study, the fly ash obtained from a coal combustion was activated by a thermo-chemical method using microwave radiation and hydrochloric acid in order to improve its adsorption characteristics. A lab scaled pilot plant consists of three stages mixing, sedimentation and filtration was designed and implemented to investigate the ability of activated fly ash (AFA) to remove chemical oxygen demand (COD), biological oxygen demand (BOD5), total dissolved solids (TDS) and dyes from textile wastewater. A series of fly ash physico-chemical analysis namely, particles size analysis, scanning electron microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray fluorescence (XRF) were presented. The study found that the average size of particles for raw fly ash (RFA) was 1.25 µm. After using hydrochloric acid and microwave radiation in a thermo-chemical modification process, the average particle size decreased to 0.65 µm. The model also showed that the COD, TDS and dye concentration values decreased significantly from 2226, 3045 and 19 mg/L in the influent to 442, 523 and 2.5 mg/L in the effluent, respectively, with removal efficiency of 80%, 82.8% and 88%.