Application of a fluidized bed bioreactor for cod reduction in textile industry effluents

The biodegradation of textile industry effluents, in an aerobic fluidized bed reactor with a working volume of 3.6 L, was investigated in this work. The system was batch fed and the biomass was adhered to small PVC cylinders acting as a support. The activation of the support was carried out with 95% concentrated nitric acid, under magnetic stirring, for 20 min at ambient temperature. Seven different effluents were tested with the aim of determining the degradability of different textile industry effluent streams using an aerobic process in a fluidized reactor with adhered biomass. The results demonstrated that the adhered biomass resists well the variation in the influent composition, since there was no sudden variation in the COD of the reactor outlet on starting feeding with a new effluent. The variation in pH at the reactor outlet remained at around 8.5, regardless of the pH of the input material, demonstrating a closed-lid system. The results show that regardless of the stream fed to the system, the final COD was around 200 mg/L; the filtered COD reduction efficiency for the different effluent inputs were: 80 and 72% for the effluents of the stabilization tank; 60 and 28% for the holding tank streams and 74% for the neutralization tank stream. This study reveals that the application of aerobic processes with biofilms is an excellent alternative for reducing COD in industrial textile effluents, without the use of chemicals compounds, which are utilized in the traditional effluent treatment processes, making this biofilm technology “environmentally friendly”.