Use of submerged anaerobic membrane bioreactor (SAMBR) containing powdered activated carbon (PAC) for the treatment of textile effluents

Abstract

This work investigated the use of submerged anaerobic membrane bioreactors (SAMBRs) in the presence and absence of powdered activated carbon (PAC) for the treatment of genuine textile wastewater. The reactors were operated at 35 °C with an HRT of 24 h and the textile effluent was diluted (1:10) with nutrient solution containing yeast extract as the source of the redox mediation riboflavin. The results showed that although both SAMBRs exhibited an excellent performance, the presence of PAC inside SAMBR-1 enhanced reactor stability and removal efficiency of chemical oxygen demand (COD), volatile fatty acids (VFA), turbidity and color. The median removal efficiencies of COD and color in SAMBR-1 were, 90 and 94% respectively; whereas for SAMBR-2 (without PAC) these values were 79 and 86%, In addition, the median values of turbidity and VFA were 8 NTU and 8 mg/L for SAMBR-1 and 14 NTU and 26 mg/L for SAMBR-2, indicating that the presence of PAC inside SAMBR-1 led to the production of an anaerobic effluent of high quality regarding such parameters.

Influence of the Applied Organic Load (Olr) on Textile Wastewater Treatment Using Submerged Anaerobic Membrane Bioreactors (Sambr) in the Presence of Redox Mediator and Powdered Activated Carbon (Pac)

“…During phases 4 (with yeast extract) and 5 (without yeast extract) the reactors were fed raw textile wastewater (without dilution) and the presence of yeast extract led to color removal efficiencies 3 times higher in SAMBR-1 and 2.7 higher in SAMBR-2. These results are in accordance with the literature (Baêta et al, 2012;Baêta et al, 2013), confirming that the kinetics of azo dye (one on the many dye classes found in textile wastewater) degradation is accelerated in the presence of redox mediators such as riboflavin, which have intermediate reduction potential values. It is important to highlight that there is only a handful of studies evaluating the effect of redox mediators on color removal of real textile wastewater.…”

Evaluation of soluble microbial products and aromatic amines accumulation during a combined anaerobic/aerobic treatment of a model azo dye

“…Such results evidence the contribution of PAC in the removal of organic matter in anaerobic systems, as previously demonstrated[12].…”

“…It can be seen that throughout operational phases 2 and 3 the efficiency of RGYRNL removal was significantly higher (p-value < 0.05) in the reactor An2 (80.6% phase 2 and 90.4% phase 3) when compared to reactor An1 (78.2% phase 2 and 86.1% phase 3). Such outcome was expected, since other studies performed by our research group also showed higher color removal in anaerobic reactors operated with PAC (4 g/L) when they were fed with synthetic and industrial effluents [12,24]. …”

“…Data of COD removal from the combined systems An1/Ar1 and An2/Ar2 are shown in Baêta et al [12] employed membrane bioreactors to treat textile effluents and observed that the presence of PAC inside the anaerobic reactor favored the adaptation of anaerobic microorganisms, minimized stress factors and led to higher removal efficiencies. This is due to PAC's capacity of adsorbing toxic components, such as aromatic amines or VFA, which thermodynamically limits the bacterial conversion of propionate, (iso)butyrate and (iso)valerate into acetate.…”

“…Due to such reasons, some authors state that biological processes are the most economically feasible technology to efficiently degrade industrial organic compounds such as the azo dyes and their byproducts [9,10,11,12].…”