Title: Combination of adsorption and biological treatment in a SBR for colour elimination in municipal wastewater with discharges of textile effluents
Abstract: In most cases, conventional activated sludge processes do not eliminate wastewater color.This is due to the fact that aerobic bacteria do not degrade azo-dyes, which are the most used dyes in textile mills.In this way, discharges of textile wastewaters to municipal wastewater treatment plants (MWWTPs) entail presence of color in the final effluent what causes a negative impact on the environment and, additionally, hinders an efficient disinfection by UV lamps.In this work, a combined process consisting in the addition of powdered activated carbon (PAC) to a sequencing batch reactor (SBR) was studied.The main objective was to reduce the wastewater color in order to obtain transmittance values in the final effluent above 60%, measured at a wavelength of 254 nm, with the aim of ensuring the disinfection with UV-lamps.Experiments were performed both with simulated wastewater including the azodye Reactive Black 5 and with wastewater from a MWWTP receiving discharges from a textile mills area located in Valencian Region (Spain).The concentration of PAC needed to have a final effluent with a transmittance value above 60% was 250 and 400 mg/L for the simulated effluent and for the wastewater, respectively.PAC had to be periodically added to cover its loss in the waste sludge and in the treated wastewater stream.