Textile effluent treatment in a pilot-scale UASB bioreactor followed by biofilter and aerobic processes

Abstract

This paper presents an overview of an industrial textile effluent treatment for 12 years of 24-h operating conditions in the UASB (up-flow anaerobic sludge blanket) bioreactor, followed by a biofilter and aerobic processes. The textile effluent pollution parameters, such as pH, temperature, dissolved oxygen (DO), chemical oxygen demand (COD), total suspended solids (TSS), color, and total dissolved solids (TDS), were tested at 3-month intervals. The raw textile wastewater consisted of dark in color (405 ± 15 Pt–Co scale), high pH (12 ± 2.0), COD (2016 ± 1125 mg L⁻¹), temperature (65 ± 5 °C), TSS (250 ± 125 mg L⁻¹) and TDS (9000 ± 1200 mg L⁻¹). The UASB bioreactor was more effective for removing 55.0% of COD, 84.0% of TSS, and 80.7% of color. The biofilter removed TDS (39.0%) and increased the DO level effectively, while the aerobic process was found less effective in removing color from the textile effluent. The combination of the UASB, biofilter, and aerobic processes effectively removed 93.05% of COD and 86.41% of color at the maximum organic loading rate (OLR) with 52.64 hrs of hydraulic retention time (HRT). Among the other pollution parameters, the combined system had an overall removal efficiency of 96.0% of TSS and 77.8% of TDS. This system also raised the DO level from 0.0 to 6.04 ± 1.02 mg L⁻¹, and the pH of the final treated effluent was neutral. This study concludes that the combined process is a workable option for treating textile effluent, which fulfills the national standard of effluent quality for discharging to the environment.