Magnetite/activated sludge hybrid process for the treatment of dye containing simulated textile wastewater

Addition of a magnetically separable magnetite as an adsorbent to the activated sludge (AS) process can provide significant advantages in the treatment of dye-containing textile wastewater. This study investigated the potential of magnetite/activated sludge (M/AS) as an adsorption/biodegradation hybrid process to treat Reactive Red 195 (RR195) containing simulated textile wastewater. RR195 and chemical oxygen demand (COD) removal studies were performed separately with magnetite, activated sludge, and M/AS hybrid processes. The Freundlich isotherm was determined to be the best model with (R2 = 0.999) to describe the adsorption of the RR195 onto magnetite. Different concentrations of mixed liquor suspended solids (MLSS) of the activated sludge process and the magnetite were used simultaneously in the M/AS hybrid process. The M/AS hybrid process experiments showed that the RR195 removal efficiency increased with increasing MLSS and the magnetite concentrations. 4,000 mg/L was determined as the optimum MLSS concentration to remove the RR195 from simulated textile wastewater by the M/AS hybrid process. While the RR195 removal efficiency was 76.10% by activated sludge containing 4,000 mg/L MLSS in 90 min, the RR195 removal efficiency increased to 99.5% with the simultaneous use of 2.5 g/L magnetite and activated sludge containing 4,000 mg/L MLSS. The COD removal efficiency was determined as 94.32% by simultaneous using activated sludge containing 4,000 mg/L MLSS and 5 g/L magnetite. The magnetite particles can be separated from simulated textile wastewater and activated sludge biomass after M/AS hybrid process treatment by applying a magnetic field. The results of the study have shown that the M/AS hybrid system is an effective process for the treatment of dye-containing textile wastewater.