Aerobic Granular Sludge for Dye Biodegradation in a Sequencing Batch Reactor With Anaerobic/Aerobic Cycles

Abstract

This study investigated the formation of aerobic granular sludge with the main objective of Acid Red 18 (AR18) biodegradation in an altering anaerobic–aerobic sequencing batch reactor. According to the obtained results, the cultivated granules showed a stable structure in the treatment of synthetic wastewater containing 50 mg/L AR18, while no considerable variety in their characteristics and no granule break up were observed. As reported by many researchers, decolourization of AR18 is due to the anaerobic biodegradation of the azo bond; however, monitoring of the dye biodegradation through UV‐Vis spectroscopy showed that the contribution of the aerobic phase in dye removal was significant. This indicates the penetration of AR18 into the inner layers of granules and the ability of anaerobic microorganisms within the granules to degrade the dye through the consumption of tightly bound extracellular polymeric substances (EPS) as a carbon and energy source. The aerobic granules were not able to decompose anaerobically formed AR18 intermediates under aerobic conditions. The increase of the initial dye concentration from 50 to 100 mg/L caused the production of excess loosely bound EPS, which led to instability of the granules and hampered the dye removal efficiency.

Performance of Aerobic Microbial Granules in Organic Carbon Removal as a Method in the Treatment of Biodegradable Wastewater

“…This indicates that on day 14 the extent of thickening in the process of granules sedimentation is limited, this is also in line by visual observation where granules begin to be formed on day 14. The initial value of ratio SVI30 to SVI5 is 0.64 then increases and tends to be stable until day 32 with value of ratio SVI30 to SVI5 is 0.97 and this result is higher compared to the SVI30 ratio of SVI5 conducted by Moghaddam, S.S. & Moghaddam, M.R.A [17], where the highest value of ratio SVI30 to SVI5 at the granule formation stage with acetate feed is 0.81.…”

“…5. [17] that removal efficiency of COD in granulation period with acetate as a source of carbon was 90-97% and Garucci et al [1] mentioned higher result with acetate removal efficiency reached on 99%. Those results prove that organic carbon could be completely degraded by aerobic granules.…”

La‐modified vermiculites for efficient adsorption of Congo red

“…Considerable efforts have been made to treat dye‐containing effluents, including membrane separation, flocculation/coagulation, ion exchange, biological treatment and photocatalytic degradation . Adsorption has been considered as an effective technique of choice, which is superior to others in terms of several advantages, such as low cost, easy operation, suitability in removing different colouring materials, insensitivity to other toxic pollutants and formation of non‐harmful by‐products .…”

“…Considerable efforts have been made to treat dyecontaining effluents, including membrane separation, flocculation/coagulation, ion exchange, biological treatment and photocatalytic degradation. [6][7][8][9][10][11] Adsorption has been considered as an effective technique of choice, which is superior to others in terms of several advantages, such as low cost, easy operation, suitability in removing different colouring materials, insensitivity to other toxic pollutants and formation of non-harmful by-products. [12] So far, various materials, including natural and modified clays, [13,14] metal oxides, [15] calcined and uncalcined layered double hydroxides [16] and biomaterials [17,18] have been developed in order to achieve high-performance removal of dyes from water.…”

Role of Layered Double Hydroxide in Improving the Stability of Aerobic Granular Sludge

“…Aerobic granular sludge (AGS) has been studied by many researchers in recent years . Compared with flocculent activated sludge, AGS has been demonstrated to have distinct advantages, such as good settling performance, residual sludge minimization, and simultaneous high biological nitrogen and phosphorus removal efficiencies .…”